(see also :

• Plantae chemicals in General biochemistry and plant immunology
• concerns for loss of biodiversity
• human diseases caused by plantae)

• Plant phylogeny

The earliest land plants, similar to present-day liverworts, arose at least 475 million years ago, suggest tiny fossilized fragments from Oman. Up to 420,000 different plant species may be growing on Earth, of which perhaps 80% have been found and named. The Index Kewensis, a species record held at Britain's Royal Botanic Gardens in Kew, near London, lists more than a million Linnaean titles : plants are going extinct before botanists can record their existence
Web resources :
• dmoz Open Directory Project (ODP) : Botany
• The Virtual Library - Botany
• Forestry
• Forest Genetics and Tree Breeding
• International Plant Names Index (IPNI)
• Dendrome : forest trees
• Deep Green Project : phylogeny of green plants
• U.S. Plants National Database
• Carnivorous Plants Database
• Until now, researchers believed that pitcher plants—studied since the 17th century, Federle said—captured most insects using waxy crystals making slippery inner walls. However, when Federle's team studied Nepenthes bicalcarata—one of the few species of pitcher plants that have no slippery waxy inner walls but are nevertheless able to capture insects—after a rainfall
• Gardener Encyclopedia
• Plant Fossil Record
• Plant TrackerVascular Plant Image Gallery
• W3TROPICOS - The Missouri Botanical Garden vascular plant database
• IOPI Global Plant Checklist Prototype
• Index Nominum Genericorum
• USDA/Agricultural Research Service taxonomy
• Internet Directory for Botany (IDB)
• CalFlora (California flora on-line
• TROPICOS Missouri Botanical Garden bryophyte database
• New York Botanical Garden bryophyte catalog
• The Angiosperm Phylogeny Group
• The Families of Flowering Plants (Watson and Dallwitz)
• Usenet bionet.maize
• Plant biology
• botany : the science of plants or of the vegetable kingdom.
• medical botany : the botany of plants used in medicine.
• plant cell biology : some definitions (in addition to those valid for all multicellular Eukarya)
• cell wall = it is made up of
• cellulose : a b(1-4) D-glucose homopolysaccharide, is the most abundant carbohydrate polymer in nature. Although abundant, it is extremely difficult to degrade, as it is insoluble and is present as hydrogen-bonded crystalline fibres. Anaerobic microorganisms (symbiont in ruminant guts) have evolved a system to break down plant cell walls that involves the formation of a large extracellular enzyme complex called the cellulosome (also in some Protozoa (symbiont in termite gut) and some Fungi ?)
• hemicellulose
• xilans : b(1->4) heteropolysaccharides of D-Xil
• glucomannans : b(1->4) Glc- and Man- containing heteropolysaccharides)
It arises from a cellular plate during mitosis.
• phragmoplast = the developing cell wall between the nuclei of a vegetal cell in telophase
• protoplast = a vegetal cell deprived (by lisozime) of its cell wall in an isotonic environment
• median lamella = a pectin structure between adjacent cell walls
• plasmodesm = cytoplasmic channel between cells (20-30 nm diameter) whose lumen is occupied by a central desmotubule arose from smooth endoplasmic reticulum
• glyoxisome = the vegetal equivalent of animal peroxisome
• tonoplast = the membrane of the vacuole
• plastids = vegetal organelles
• chloroplasts
• leukoplasts
• modification : a mantainance methylase creates N⁵-methylC in CpNpGp box in both strands during chromosome replication using SAM as donor
• photosynthesis
• plant cuticular lipid export : up until now, we knew that plants produce this waxy coating on their cuticle, which is essential for water conservation, and for their ecology in general, but no one knew how these highly hydrophobic molecules that are made in the cells get out of the cells. Plants export wax from epidermal cells to the surface of their aerial parts through CER5, a lipid transporter similar to ABC transporters present in mammalian cells. This is the first component of the plant lipid export system to be characterized functionally. Traditionally, wax precursors were thought to be exported by a vesicular pathway from their site of synthesis to their destination at the plant surface. The identification of the CER5 transporter does not absolutely rule out the vesicular hypothesis. Because of the limited resolution of fluorescence imaging, it remains possible that CER5 is localized in a compartment involved in secretion. The simplest hypothesis, advanced by the authors, is that the transporter located in the plasma membrane has a pore that goes from the inside to the outside through which lipids go out. It could also have a side pore, similar to the bacterial MsbA ABC transporter, through which the lipids enter or exit the transporter. A third possibility is that the transporter is not a pore but a flippase that flip-flops fatty acids from the inner to the outer leaflet of the plant cell plasma membrane
• a cellular-automaton model (simple, discrete 'particles' programmed to switch between different states depending on the states of their neighbours) can explain the way that plants regulate their uptake of CO₂, which they use for photosynthesis, and their loss of water vapour. Leaves have openings called stomata that open wide to let CO₂ in, but close up to prevent precious water vapour from escaping. Plants attempt to regulate their stomata to take in as much CO₂ as possible while losing the least amount of water. But they are limited in how well they can do this: leaves are often divided into patches where the stomata are either open or closed, which reduces the efficiency of CO₂ uptake. Patches of open or closed stomata in leaves of the cocklebur plan sometimes move around a leaf at constant speed, for example
• stoma : any minute pore, orifice, or opening on a free surface
• pistil / gynecium : the female part of a flower
• stigma : the uppermost part of a pistil, which secretes a moist, sticky substance to trap and hold the pollen that reaches it
• leaf : a flattened structure of vascular plants, attached to the plant by a stem and usually green in color, that is the primary site of photosynthesis and transpiration
• root : the lowermost part of a plant or other structure
• invading plant species, such as the Centaurea, establish monocultures in novel habitats by displacing the indigenous plant communities. It is thought that the absence of "natural enemies" and/or the release of phytotoxins from the invading plants by allelopathy promote this process. The European spotted knapweed (Centaurea maculosa) releases racemic catechin; the antimicrobial (+)-catechin and the phytotoxin (-)-catechin that inhibits germination and growth of a number of nature plants (including Arabidopsis thaliana and Centaurea diffusa) by altering gene expression, resulting in rapid reactive oxygen species wave, similar to that observed for root cell death, but proceeding cell death by 5-10'. This increase in ROSs induced Ca²⁺-dependent triggering of cell death. Gene expression analysis of A. thaliana showed that 10 genes were upregulated 10' after treatment, with 956 genes being upregulated 50' later. Many of the 956 gene products are linked to oxidative stress and the phenylpropanoid and terpenoid pathways. At 12 hours, many of these genes were repressed, possibly as a result of the onset of cell death. Allelopathy challenges the conventional ecological perspective that a species' invasiveness is mainly due to enhanced resource competition after escape from natural enemies and highlights the role for the biochemical potential of the plant as an important determinant of invasive success
• the world's biggest-ever bloom, at more than 2.7 metres tall, the Titan Arum flowered in the University of Bonn Botanical Garden on May 23, 2003. It beats the previous record - set 70 years ago - by 7 centimetres. More than 2,000 people have so far rushed to witness the event, as the spadix, the blossom's fleshy central column, is expected to collapse on Saturday afternoon. The growth, smell and warm temperature of the spadix were closely studied in 4 flowers between 1987 and 1989. Amorphophallus titanum, the blue whale of botany comes from the rainforests of western Sumatra, Indonesia. It was discovered in 1878 by the Florentine botanist Odoardo Beccari. He sent the seeds to Kew Royal Botanical Gardens in London, where the first cultivated specimen flowered in 1889. Famously, 3 blooms appeared at Kew last year. Hothouse Titan Arums rarely flower, but when they do, they are hard to ignore. The colossal lily-shaped blooms smell of rotting flesh - hence the plant's nickname 'the corpse flower'. By mimicking a carcass in decay, the brownish flowers attract insects that deposit their eggs inside the plant, spreading its pollen in the process.
• 
• most flowering plants arrange their leaves and petals in spirals around their stems. And in most species, the angle between successive elements is close to the so-called golden angle, 137.5°, a number derived from mathematic theory that correlates to artistic aesthetics and biological patterning. This convergence has puzzled researchers for 250 years : the arrangement minimizes the shadow each leaf casts on those below it, maximizing the plant's light-gathering ability. Once built an optimality model of light capture, the angle between leaves tends towards 137.5° as leaves became thinner. The model's predictions matched results from an earlier study on geometry and light-capture efficiency of the forest-dwelling daisy Adenocaulon bicolor. But there are many examples where the leaf spiral doesn't match the golden angle, and some cases where it does but the plant is not oriented to gather maximum light
• trees grow tall where resources are abundant, stresses are minor, and competition for light places a premium on height growth. The height to which trees can grow and the biophysical determinants of maximum height are poorly understood. Some models predict heights of up to 120 m in the absence of mechanical damage, but there are historical accounts of taller trees. Current hypotheses of height limitation focus on increasing water transport constraints in taller trees and the resulting reductions in leaf photosynthesis. The tallest known tree on Earth (112.7 m) is a redwood (Sequoia sempervirens) in wet temperate forests of northern California. Regression analyses of height gradients in leaf functional characteristics estimate a maximum tree height of 122–130 m barring mechanical damage, similar to the tallest recorded trees of the past. As trees grow taller, increasing leaf water stress due to gravity and path length resistance may ultimately limit leaf expansion and photosynthesis for further height growth, even with ample soil moisture^ref.
• plant mitochondrial genes are transmitted horizontally across mating barriers with surprising frequency, but the mechanism of transfer is unclear. Horizontal gene transfer from parasitic flowering plants to their host flowering plants occurs as a result of direct physical contact between the 2. Genes can also be transferred in the opposite direction, from host to parasite plant^ref.
• The unicellular conifer tracheid should have greater flow resistance per length (resistivity) than the multicellular angiosperm vessel, because its high-resistance end-walls are closer together. However, tracheids and vessels had comparable resistivities for the same diameter, despite tracheids being over 10 times shorter. End-wall pits of tracheids averaged 59 times lower flow resistance on an area basis than vessel pits, owing to the unique torus-margo structure of the conifer pit membrane. The evolution of this membrane was as hydraulically important as that of vessels. Without their specialized pits, conifers would have 38 times the flow resistance, making conifer-dominated ecosystems improbable in an angiosperm world^ref
• When plants experience drought or cold, they cannot get themselves a glass of water or move to a warmer place. Instead, their ability to survive lack of water, extreme temperatures and such stresses as high salt levels relies heavily on a plant hormone called abscisic acid (ABA). Binding of 2 proteins, FCA and FY, to one another results in a decrease in expression levels of Flowering Locus C (FLC), causing a transition from vegetative growth to flowering. The FCA–FY complex also causes synthesis of a truncated, non-functional FCA messenger RNA in a negative feedback loop that results in fewer full-length FCA mRNA transcripts and less FCA protein. Binding of abscisic acid (ABA) to FCA abolishes the interaction of FCA with FY, leading to an increase in full-length FCA transcripts and — through increased FLC activity — a delay in flowering. Red lines depict negative regulation^ref


Web resources :
• Raven : Biology of Plants
• World Botanical Associates
• Phytochemical World : secondary metabolism of plants (alkaloids, terpenoids)
• Plant Hormones
• Cytokinin signaling pathway by Jen Sheen at STKE
• Arabidopsis cytokinin signaling pathway
• Jasmonate biochemical pathway at STKE
• schematic of the structures of jasmonate and its precursors
• The Arabidopsis Information Resource (TAIR) by the Carnegie Institution of Washington Department of Plant Biology and the National Center for Genome Resources (NCGR)
• (see also Arabidopsis thaliana resources in Multicellular eukarya sequencing projects section)
• Plant Microarrays
• Bioimages collection by Steve Baskauf
• The plant endomembrane research group
• Phyllotaxis : plant spirals exhibit
• Autumn Foliage Changes at Harvard University
• Usenet
• bionet.plants
• bionet.photosynthesis
• sci.bio.botany
• Major food crops
• brassicas
• cabbage - Brassica oleracea (68 169 651 metric tonnes, 2004)
• canola (oil) - there are 2 types of canola, the short-growing season Polish type (Brassica rapa and Brassica campestris) and the longer-season Argentine type (Brassica napus). Canola is produced extensively in Europe, Canada, Asia, Australia, and to a limited extent in the United States.
• cauliflower - Brassica oleracea (16 404 125 metric tonnes, 2004)
• cereals/grains : grass that produces an edible grain (2 264 030 480 metric tonnes, 2004)
• barley - Hordeum vulgare (153 624 393 metric tonnes, 2004)
• maize - Zea mays (721 379 361 metric tonnes, 2004). The people of Mesoamerica are largely responsible for the golden corn we grow today, having domesticated tough teosinte grass thousands of years ago and bred it into modern maize. A mutant maize that was found in South America in the 1920s is unable to grow branches or flowers, and happens to resemble a particular rice mutant in this respect. Because the sequence of the gene that causes the effect is known for rice, the sequence in maize was pinned down and called barren stalk1 : the normal version of barren stalk1 regulates how the maize plants branch and is also located within one of five regions that maize researchers have identified as targets of domestication. So, was it one of the genes that the Mesoamericans unknowingly selected for as they tamed teosinte (Zea mexicana)? To investigate further, the researchers compared the number of variants of the barren stalk1 gene in teosinte, which still grows wild in Mexico's Sierra Madre, with the number in modern maize. In teosinte, there are about 12 common variants of the gene, all of which probably produced subtly different branching patterns in the plants. It is common for this number of variants to be present in a particular species of plant. But in modern maize, only one variant exists, suggesting that the others must have been eliminated by rigorous selective breeding. Why did the Mesoamericans plump so strongly for one branching pattern rather than another? Presumably there was something about the branching of maize with that particular variant that was useful. In combination with other genes it probably had some impact on the architecture that was important to the Mesoamericans, perhaps bigger seeds. The next step will be to paste all the variants of the barren stalk that exist in teosinte into modern maize : once you see what the differences are in maize, it will be easier to guess why a particular variant was chosen. Teosinte grass (left) compared to "reconstructed" primitive maize, created by crossing teosinte with Argentine pop corn :


The most critical step in maize (Zea mays ssp. mays) domestication was the liberation of the kernel from the hardened, protective casing that envelops the kernel in the maize progenitor, teosinte. This evolutionary step exposed the kernel on the surface of the ear, such that it could readily be used by humans as a food source. This key event in maize domestication is controlled by a single gene (teosinte glume architecture or tga1), belonging to the SBP-domain family of transcriptional regulators. The factor controlling the phenotypic difference between maize and teosinte maps to a 1-kilobase region, within which maize and teosinte show only seven fixed differences in their DNA sequences. One of these differences encodes a non-conservative amino acid substitution and may affect protein function, and the other 6 differences potentially affect gene regulation. Molecular evolution analyses show that this region was the target of selection during maize domestication. Modest genetic changes in single genes can induce dramatic changes in phenotype during domestication and evolution^ref.
• millet (28 765 100 metric tonnes, 2004) :
• millet (pearl) - Pennisetum glaucum
• millet (proso) - Panicum miliaceum
• oats - Avena sativa (25 899 616 metric tonnes, 2004)
• rice - Oryza sativa (605 758 530 metric tonnes, 2004)

Web resources : International Rice Research Consortium (IRRI)
• rye - Secale cereale (17 820 475 metric tonnes, 2004)
• sorghum - Sorghum bicolor (58 884 435 metric tonnes, 2004)
• wheat (627 130 584 metric tonnes, 2004) :
• common wheat, Triticum aestivum L. subsp. aestivum
• durum wheat, Triticum durum
Common bread wheat/spring wheat is typically planted in Florida in late November to early December and harvested in late April to May, predominantly in the panhandle counties. Wheat occupied ca. 10 000 acres in the 2003 growing season. The annual growth rate in wheat production in India dropped from a healthy 3.57% in the 1980s to 2.11% in the 1990s and below 1% in the current decade. After hitting a peak of 76 million tons in 2000, wheat harvest has been hovering around 72 to 74 million tons, according to the Food Corporation of India (FCI). In fact, the erosion of FCI's stock need not be viewed with concern, as it has been the result of a deliberate move to shed burdensome inventories through subsidized exports and liberal use of grains in welfare and food-for-work programs. The relatively lower wheat procurement also should not be a cause for much concern. It only reflects higher purchases by private trade and withholding of some stocks by big farmers in anticipation of better prices in lean seasons. These stocks have to, sooner or later, come out in the market. However, the below-anticipation wheat harvest for the 5th successive year should be a matter of real discomfiture and should make wheat scientists and policy makers sit up. The agriculture ministry, which had earlier reckoned the wheat harvest to be around 74.05 million tons, has scaled it down to 73.5 million tons. Wheat experts, who were hoping to bag a harvest of around 75 million tons, now feel that the production would be just around 73 million tons. The wheat trade, on the other hand, is projecting a still lower output of around 71 to 72 million tons. Some causes for a low wheat yield have, of course, been identified. Noted wheat expert and Indian Agriculture Research Institute (IARI) director S. Nagarajan believes that the unexpected emergence of 2 diseases so close to ripening of the crop is responsible for yield drop. Black rust, a dreaded plant disease, resurfaced after over 10 years, affecting the predominant cultivar PBW-343 in Punjab and adjoining areas when the crop was heading towards maturity. Another relatively lesser-known disease, called head scab, struck the durum wheat (hard wheat used for making noodles and pasta products) around the same time to cause yield loss. This disease is endemic to North America and has not been reported in India in the recent past. Poor wheat yields in earlier years of this decade had been caused largely by unfavorable climatic factors, such as untimely rains or temperature rise. Moreover, 2 dreaded weeds, Phalaris minor and wild oats, had posed a formidable danger to wheat cultivation. But fortunately, their control was discovered through pesticides and agronomic management. More recently, rust diseases -- yellow, brown and black rusts -- spread like an epidemic throughout the northwestern wheat belt. Fortunately, they were tamed by breeding rust-resistant varieties and breaking the disease cycle by saturating the wheat-growing southern hilly region with rust-immune varieties. That was the region where the rust pathogen used to survive in summer when the crop was not being grown in the plains. Wheat, being a non-monsoon-dependent winter season cereal, is critical for the country's food security, and any deceleration in its production growth is unwarranted. Wheat output needs to grow annually by at least 2.5% to keep pace with the rise in demand. The major wheat-producing countries of northern Asia are India, Pakistan, Nepal, Bangladesh and Myanmar in order of importance. Most of the wheat is produced in the Ganges and Nurmada basins of India and the Indus River Valley of Pakistan. Much of the wheat in India and Pakistan is irrigated, while in Nepal and Bangladesh it is mostly rain fed. White grain cultivars are preferred and are primarily of spring habit, but are usually sown in November and December and harvested in April and May. Consumption is highest in Pakistan at 141 kg/caput and lowest in Myanmar at 3 kg/caput. World production as of 2004 is 624 093 306 metric tons. India is one of the largest wheat producers in the world, with about 25 million a [1 hectare= 10,000 square meters] under production and averaging almost 60 million tons in recent years. > 90% of the area is sown to bread wheat, which is grown throughout the country. Durum or macaroni wheat accounts for around 8% of the area. The crop is grown in most parts of the country, but nearly 70% lies in the northern plains and 20% in central India. A rice-wheat rotation is the dominant cropping sequence. Crops other than rice that precede wheat are also used, particularly in the central and southern regions. In the large wheat research and development program in India, much germplasm is screened for important biotic and abiotic stresses. Important biotic pests include the rusts, Karnal bunt, foliar blight, powdery mildew, common bunt, flag smut and nematode and insect pests. Salt, heat and drought are the major abiotic stresses. Large amounts of NPK fertilizers are used to produce the wheat crop in India. Over the past 3 decades, increased agricultural productivity in Pakistan occurred largely due to the deployment of high-yielding cultivars, increased fertilizer use and greater availability of irrigation water. By the mid-1980s, semidwarf wheat cultivars had been adopted on almost all irrigated land, and over 100 kg/ha on average of fertilizer was being applied to wheat. Pakistan production averaged 16.1 million tons on 8.2 million ha each year during the period 1993-1995. Rice-wheat, berseem-wheat and cotton-wheat are major systems of intense cropping in Pakistan. Wheat scab (also known as Fusarium head blight) is caused by the fungus Fusarium graminearum. It is a common problem in Europe, Asia, South Africa, and the Midwestern and Eastern U.S.A. Scab severity is very erratic and depends heavily on wet weather conditions. Scab often causes reduction in test weight, sometimes down to near 50 lb/bu. In addition, scabby kernels count as "damaged" in the grading process. Although scabby wheat is often very good, it may contain the mycotoxins DON (vomitoxin) and zearalenone (an estrogen analog). Swine are most sensitive to scabby wheat mycotoxins, and as little as one ppm of DON can significantly reduce daily weight gains in pigs. Higher concentrations result in feed refusal and vomiting. Swine reproduction is also sensitive to disruption by the zearalenone mycotoxin. Non-breeding cattle and poultry seem to tolerate both toxins better than swine^{ref1, ref2, ref3, ref4}
There are 3 main rust diseases of the cereal crop plant wheat. These are wheat stem rust (Puccinia graminis f.sp. tritici), wheat leaf rust (P. triticina aka P. recondita f. sp. tritici) and wheat stripe rust (P. striiformis f. sp. tritici), all caused by species of the fungus Puccinia. Severe losses that can occur due to wheat stem rust have been abated in the USA since the 1960's by effective resistance breeding, though the knowledge of resistance breaking strains of the pathogen, such as Ug99 in Uganda, is a concern [note "see also"]. Severe losses are still a possibility with leaf rust. As recently as 1993, leaf rust destroyed over 40 million bushels of wheat in Kansas and Nebraska. In 1985, Texas and Oklahoma lost 95 million bushels of wheat to leaf rust. The USDA Cereal Disease Laboratory St. Paul, MN publishes regular reports on cereal rusts in the USA during the crop season. 10 were published between March and September 2005.  Each report gives detailed state-by-state information, including a summary map, all in pdf file format. Wheat is not doing well in early 2006 in southern states because of drought, e.g. in Texas and Oklahoma.  This condition is also not conducive for leaf rust, which partly explains the low levels of incidence reported so far March in 2006.
In Central Asia, yellow rust (Puccinia triticina)^ref, tan spot (Pyrenophora triticirepentis), common bunt (Tilletia caries), and Tilletia laevis are major foliar diseases of spring wheat, although Septoria leaf blotch (Mycosphaerella graminicola and Phaeosphaeria nodorum), leaf rust (Puccinia recondita f. sp. tritici), and cereal cyst nematode (Heterodera latipons) also occur in some areas. Yellow rust and leaf rust are also very important in the Caucasian countries. As researchers develop new varieties resistant to these diseases, progress is tested through a step-by-step evaluation at different locations in the region. In the first step, resistance to yellow rust, leaf rust, stem rust, Septoria leaf blotch, cereal cyst nematode, and common bunt is evaluated at Tel Hadya, ICARDA's headquarters, where wheat nurseries are artificially inoculated with these diseases. In the 2nd phase, varieties identified as resistant are further screened for resistance to different diseases in heavily infected areas in different countries in Central and West Asia and North Africa (CWANA) in collaboration with local scientists at 3 to 5 sites per country. It is difficult to assess disease loss given the information available. The fact that about 350 000 ha. were treated with fungicides indicates that farmers needed to try to control the diseases affecting their crops^ref.
Web resources : Wheat Food Council
• citrus (108 535 488 metric tonnes, 2004) : on a worldwide basis, there are at least 6 citrus viroids: Citrus exocortis viroid (CEVd), Citrus bent leaf viroid (CBLVd), Hop stunt viroid (HSVd), Citrus viroid III (CVd-III), Citrus viroid IV and Citrus viroid OS (CVd-OS). CEVd causes the bark-scaling citrus exocortis disease on trifoliate orange (Poncirus trifoliata) [Pt] root stocks, and some HSVd variants cause citrus cachexia disease in sensitive hosts such as mandarins (Citrus reticulata). CEVd,  HSVd, and CVd -III are predominately found in introduced cultivars such as lemons and oranges, while CVd-OS, HSVd, and CVd-III are frequently found in the domestic cultivar 'Shiranui'. Other viroids induce different degrees of stunting. Since commercial citrus trees are commonly infected with viroid mixtures, only limited information is available on their effects in species other than Etrog citron. In general, yield reduction was associated mainly with loss of production of large fruits. Bark-cracking of Pt may be caused by CEVd, CVd-IV, and HSVd, but not by CBLV d or CVd-III. The International Committee on Taxonomy of Viruses (ICTV) has proposed the name Citrus dwarfing viroid (CDVd) as a replacement for CVd-III.  Disease management depends upon sterilizing pruning shears with bleach before moving to the next tree. Modern techniques for detection of viroids in citrus are required as well, because viroid-infected plants are often symptomless^{ref1, ref2}. A multiplex RT-PCR has been developed to detect 6 citrus viroids (Citrus exocortis viroid (CEVd), Citrus bent leaf viroid (CBLVd), Hop stunt viroid (HSVd), Citrus viroid III (CVd-III), Citrus viroid IV and Citrus viroid OS (CVd-OS)) and Apple stem grooving virus (ASGV, synonym: Citrus tatter leaf virus (CTLV)) from citrus plants. The multiplex RT-PCR was also designed to distinguish CVd-I-LSS (a distinct variant of CBLVd) from CBLVd. By the multiplex RT-PCR, 1-8 fragments specific to the pathogens were simultaneously amplified from 1 sample and identified by their specific molecular sizes in 6% PAGE. The results of the multiplex RT-PCR were consistent with those of other diagnoses, such as uniplex RT-PCR, to detect each of the pathogens. The multiplex RT-PCR provides a simple and rapid method for detecting various viroids and ASGV in citrus plants, which will help diagnose many citrus plants at a time^{ref1, ref2}
• grapefruit - Citrus reticulata
• orange - Citrus sinensis
• tangerine - Citrus paradisi × Citrus reticulata
• cucurbits
• cucumber - Cucumis sativus (40 860 985 metric tonnes, 2004)
• gourds - Luffa acutangula, Luffa cylindrica, Lagenaria siceraria
• pumpkin/squash - Cucurbita maxima, Cucurbitamixta, Cucurbita moschata, Cucurbita pepo
• watermelon - Citrullus lanatus
• oil crops (132 726 738 metric tonnes, 2004)
• canola - Brassica rapa, Brassica campestris, Brassica napus
• cottonseed - Gossypium sp.
• pome fruits
apple - Malus domestica (61 919 066 metric tonnes, 2004)
• pear - Pyrus communis (18 097 558 metric tonnes, 2004)
• pulses
• bean - Phaseolus vulgaris
• pea - Pisum sativum
• chickpea - Cicer arietinum
• cowpea - Vigna unguiculata ssp. unguiculata
• lentil - Lens culinaris
• peanut (groundnut) - Arachis hypogaea (35 723 285 metric tonnes, 2004)
• soybean - Glycine max (204 266 176 metric tonnes, 2004). There are 8 growth stages for soybean :
• R1(1 flower at any node)
• R2 (flower at node immediately below the node with a completely unrolled leaf)
• R3 (pod is 1/2 cm long at 1 of the 4 uppermost nodes with a completely unrolled leaf)
• R4 (pod is 2 cm  long at 1 of the 4 uppermost nodes with a completely unrolled leaf)
• R5 (seeds beginning to develop [can be felt by squeezing or at least 1/8 inch long]) at 1 of the 4 uppermost nodes with a completely unrolled leaf)
• R6 (pod containing a green seed that fills the pod cavity at 1 of the 4 uppermost nodes with a completely unrolled leaf)
• R7 (Pods yellowing [1 normal pod on the main stem that has reached its mature pod color - brown or tan])
• R8 (95% of the pods have reached their mature pod color, approximately 5 to 10 days prior to harvest).
• solanaceous crops
• eggplant - Solanum melongena
• peppers - Capsicum annuum
• potato - Solanum tuberosum (327 624 417 metric tonnes, 2004). Sprouting is one of the biggest problems when storing potatoes. Untreated potatoes start to sprout after 60 days. Lower temperatures reduce sprouting, but they also increase the sugar content of the potato. When deep-fried, this sugar caramelizes, giving fries a nasty brown colour that turns consumers off. A quick dose of low-energy electrons stops potatoes sprouting for up to four months, even if they are stored at room temperature. The researchers used a Van der Graaf generator to deliver a beam of electrons to potatoes moving along a conveyor belt. The electron beam works by preventing cell division within the sprout bud tissue, similar to the way that radiotherapy stops cancer cells multiplying. The method could replace the potentially harmful chemical sprays such as chloropropham (also known as CIPC, whose residues can linger on a potato's skin, worrying consumers and regulatory bodies alike) and expensive g-radiation treatments that are currently used to stem the surging sprouts (a special facility in Hikkedo, Japan, treats > 100,000 tons of potatoes annually. But the process is expensive and requires hefty shielding to protect workers). Camote is a type of sweet potato having somewhat dry, bland, yellowish to white flesh, used as a staple food in many tropical countries, and is also called boniato or batata

Web resources :
• National Potato Council
• Idaho Centre for Potato Research and Education
• tomato - Lycopersicon esculentum originated in South America, were introduced into Europe in the 16th century, and are now a popular food worldwide. The Roma tomato was developed in the mid-1950s as a firmer and more disease-resistant variety^ref. Uncooked tomatoes have become an integral and nutritious component of the daily diet. Approximately 5 billion pounds of fresh market tomatoes are eaten annually in the USA (120 384 017 metric tonnes, 2004)
• stone fruits
• apricots - Prunus armeniaca (2 642 222 metric tonnes, 2004)
• cherry - Prunus avium, Prunuscerasus (1 875 504 metric tonnes, 2004)
• plum - Prunus domestica, Prunusinsititia
• peach/nectarine - Prunus persica (15 408 553 metric tonnes, 2004)
• others
• banana - Musa x paridasiaca L., Musa acuminata is the 4th most important global food crop after rice, wheat and maize in terms of gross value of production. Total world Musa production is currently about 97 million tones annually (FAOSTAT, 2003), of which bananas cultivated for export account for only 10%. Hence, they are important for food security in the humid tropics and provide income to farmers. It is a major staple food, supplying up to 25% of the carbohydrates for approximately 70 million people in Africa's humid forest and mid-altitude regions. The East and Central Africa sub-region alone produces nearly 20 million tons of bananas annually (71 343 413 metric tonnes, 2004)
• cacao / cocoa - Theobroma cacao (3 607 052 metric tonnes, 2004)
• cassava - Manihot esculenta - is a hardy, drought-resistant tuber with an edible root that grows in tropical and sub-tropical areas of the world. It provides an important source of energy for millions of people in Africa. (202 648 218 metric tonnes, 2004). Cassava is among the most common crops in sub-Saharan Africa, accounting for > 50% of world production with over 90 million tons of fresh product, more than any other crop in Africa. Cassava is vital to the livelihood of over 200 million people and plays a key food security role for rapidly expanding rural and urban populations and has huge potential for commercialization, income generation, and poverty reduction
• East African cassava mosaic virus (EACMV)
• South African cassava mosaic virus (SACMV)
• cassava brown streak disease virus (CBSDV)
• date palm - Phoenix dactylifera (6 832 602 metric tonnes, 2004)
• coconut - Cocos nucifera (54 736 517 metric tonnes, 2004)
• coffee, green - Coffea arabica (7 761 397 metric tonnes, 2004)
• grapevine - Vitis labrusca, Vitis vinifera (66 569 761 metric tonnes, 2004). Wine enchants because of its complexity, but that very trait makes it difficult to regulate. That bottle full of aromatic red liquid with hints of cherry may be genuine Pinot Noir from the California coast, or it may be a New Jersey Merlot, diluted with water and tarted up with sugar or sophisticated synthetic flavourings. In the arms race between the adulterators and the regulators, detection systems have become ever more sophisticated, as have the cheaters. But at least one common ruse - claiming that the wine is one variety, when it is actually entirely or partly another - may come to a sudden stop if DNA can be successfully extracted from wine on the shelf.
• stable isotope analysis. Carbon, hydrogen and oxygen atoms all occasionally show up in versions with slightly different mass. The amounts of such isotopes vary from region to region, so when they are incorporated into grapes, they tell a tale about where the wine was made. The snag is that they also vary with local weather conditions, so samples of wine from each region have to be taken each year for comparison and entered in the European Wine Data Bank. For example, 2003 wines were collected before the late rains, so there were values for oxygen that were more like Southern Italy.
• chromatography creates a graph showing which wavelengths of light are absorbed, and software types wines according to absorption pattern with decent accuracy. Things fall apart a bit, however, with blends. In Germany, the world's largest wine importer, regulators often compare the ratios of two forms of anthocyanin, the molecules that make wine red. This ratio is determined by the genes of the vine, and was thought to be an unalterable marker that could tell you what variety of wine you were drinking. But some processing techniques can change this ratio quite significantly. Techniques can involve long fermentation, high temperatures and adding enzymes. Many producers of Cabernet Sauvignon have had their wine unfairly rejected by the German government and been forced to sell it at half price. More kinds of anthocyanins should be used to type wine.
• extraction and purification of grape-skin DNA from bottles of wine, confident that if forensic scientists can get DNA from ancient skeletons, he can do the same for a bottle of Pinot Gris. Researchers are also working to identify a set of genetic markers to differentiate the 2,500 or so varieties of grape in existence. Short sections that repeat a different numbers of times in different varieties seem like a good bet.
All this fuss stems not just from a passion for authentic tastes, but from economic motives. What other food has such a big price range? It goes from $2 to $200 for the same size bottle. > 50 different viruses and viroids are known to infect grapevines worldwide, and undoubtedly many unknown ones that have yet to be detected. Evolution of new viruses is a constant threat to grapevine producers and their spread by man^{ref1, ref2, ref3, ref4, ref5}.
• lettuce - Lactuca spp.. Ruccola is the Italian word for arugula, a popular leafy lettuce in the USA. In other parts of the world, it is referred to as raketsla, roquette, notensla, or zwaardherik.

mango - Mangifera indica (26 573 579 metric tonnes, 2004)
• okra - Abelmoschus esculentus
• onion - Allium cepa
• sugar beet - Beta vulgaris (249 208 061 metric tonnes, 2004) is a globally important crop producing 27% of world sucrose supplies. It is grown in Europe, North America, Chile, Uruguay, China, the Middle East, North Africa, and countries of the former Soviet Union.
• sugarcane - Saccharum officinarum (1 323 951 980 metric tonnes, 2004)
• sunflower seed/oil - Helianthus annuus (26 108 358 metric tonnes, 2004)
• sweet potato - Ipomoea batatas (127 139 553 metric tonnes, 2004), ranked 7th in worldwide food production (5th in developing countries). China is the biggest producer in the world. The most harmful diseases in sweet potatoes are caused by a complex of viruses of which the most common is the aphid-transmitted potyvirus sweet potato feathery mottle virus (SPFMV). When the whitefly-transmitted sweet potato chlorotic stunt virus (SPCSV) is also present, it breaks down resistance to other viruses in sweet potato cultivars, which results in the severe sweet potato virus disease (SPVD) and high or complete yield loss. SPCSV was tested for but not found in this Italian study, but it is known in Spain. SPFMV alone can cause severe cracking and corking of sweet potatoes before and after harvest. When infected roots are used to produce slips for new plantings, then plants derived from the infected root will also be diseased. Therefore, it is extremely important to use virus-free seed piece stock^{ref1, ref2, ref3, ref4, ref5}.
• taro - Colocasia esculenta (10 642 322 metric tonnes, 2004)
• tea - Camellia sinensis (3 295 287 metric tonnes, 2004)
• yam - Dioscorea batatas, Dioscorea alata, Dioscorea rotundata (40 048 149 metric tonnes, 2004)
• pulses (60 452 593 metric tonnes, 2004)
• Phytopathology
• Viroids
• Avsunviroidae
• Avsunviroid
• Avocado sunblotch viroid
• Eggplant latent viroid
• Pelamoviroid
• Chrysanthemum chlorotic mottle viroid
• peach latent mosaic viroid (PLMVd) on peach is transmitted by grafting and by aphids (Myzus persicae) but not by mites or pollen^ref.
• Pospiviroidae
• Apscaviroid
• apple dimple fruit viroid
• apple scar skin viroid
• Australian grapevine viroid (AGVd)
• citrus bent leaf viroid
• citrus viroid III
• grapevine yellow speckle viroid (GYSVd) is an elusive disease whose outward expression is conditioned by climatic and possibly varietal factors. Symptoms, when shown, consist of a few to many minute chrome yellow spots or flecks scattered over part or all of the leaf surface or gathering along the main veins to give a vein banding pattern. GYSVd-induced vein banding is very similar, if not identical, to the symptoms of a disease also known by the name of vein banding, which has long been regarded as part of the fanleaf degeneration complex. Although vein banding may show in GFLV-free vines, it is more often associated with GFLV infections. In fact, it has been suggested that the presence of GFLV enhances the expression of GYSVd in the form of vein banding patterns. Similar enhancement may occur in vines concurrently infected by grapevine chrome mosaic virus. Unlike GFLV-induced yellow discolorations, the symptoms of yellow fleck appear in the height of summer on a limited number of mature leaves, and they persist for the rest of the vegetating season. Yellow speckle symptoms may also show concurrently with symptoms of other diseases such as, for instance, leafroll. No vector for GYSVd is known. Natural dissemination occurs by mechanical inoculation through surface-contaminated cutting tools during management operations (pruning and propagation); by graft transmission: and by distribution of infected propagating material. The absence of symptoms in most European scion varieties and all American rootstocks greatly facilitates inadvertent viroid dissemination, making viroid dispersal virtually impossible to prevent. None of the grapevine viroids is known to be seed-transmitted
• grapevine yellow speckle viroid 1
• grapevine yellow speckle viroid 2
• pear blister canker viroid (PBCVd) : pear (Pyrus communis) and quince (Cydonia oblonga) are the only known natural hosts^ref
• Cocadviroid
• citrus viroid IV
• coconut cadang-cadang viroid (CCCVd) => cadang-cadang, which comes from a Bicol term "gadan-gadan" meaning dead or dying, is a premature decline and death of coconut and palm trees restricted to the Philippines, first reported in 1937. CCCVd is the most serious of all known viroids because of its lethality. It has killed over 40 million coconut palms and still kills between 200 000 - 400 000 palms annually. It is spread by unknown means, is seed-transmitted (1/320 seedlings), and also transmitted by pollen. CCCVd contains 246 or 247 nucleotides and is the smallest known nucleic acid-containing pathogen. Coconut palms less than 10 years old are rarely affected, but disease incidence increases rapidly to about 40 years, remaining constant thereafter. Disease management basically involves eradication of infected palms when they become symptomatic. No resistance to CCCVd has been identified. In the Philippines, the disease occurs in the central region (southern Luzon, Samar, Masbate, and smaller islands within a zone about 600 km x 300 km). Disease management requires use of sterilized pruning tools to avoid spread of the viroid
• coconut tinangaja viroid (CTiVd) => Tinangaja, first reported in 1917, shares about 65% overall sequence with CCCVd and is confined to Guam, where it affected 30% of coconut plants and led to the end of commercial production on the island following the death of 30 million trees in the period from 1950 to 1980. Incidence of the disease is about 30%. There is some evidence that CTiVd is seed-transmitted at very low levels.
• hop latent viroid
CTiVd and CCCVd are the only viroids that infect monocotyledons. Both cause lethal infections in coconut, causing death within 10 years of diagnosis. Inasmuch as CCCVd and CTiVd occur separately in the Philippines and Guam, respectively, it would be interesting to monitor differences in genomic sequences between the 2 viroids over time.
• Coleviroid
• Coleus blumei viroid
• Coleus blumei viroid 1
• Coleus blumei viroid 2
• Coleus blumei viroid 3
• Hostuviroid
• hop stunt viroid (HSVd) causes a severe disease in hop (Humulus lupulus). The fruit crop plant plum, Prunus domestica, develops dapple or no symptoms when infected by HSVd. HSVd consists of a 295-303 nucleotide circular single-stranded RNA. It has been found in a wide range of herbaceous and woody hosts, where the infection seems to be latent (such as grapevine, apricot, pear) or may induce specific disease symptoms such as hop stunt, citrus cachexia, and dapple fruit of plum and peach. It has also been reported in cucumber. HSVd is not difficult to find in plum in China, despite this being the 1st report in that host. No symptoms have been associated with these findings. The detection of HSVd in plum in China is significant in part because this is the geographical origin of the species and because of the threat this pathogen could have to the other crops it infects. Like other viroids, HSVd is transmitted mechanically, by budding and grafting, and by vegetative propagation. Note that HSVd has been reported in grape and apricot in China^{ref1, ref2}. Isolates of HSVd have been classified into 5 groups; 3 major types (plum, hop and citrus) each containing isolates from only a limited number of isolation hosts, and 2 minor ones (plum-citrus and plum-hop-citrus) presumably derived from recombination between members of the main groups. HSVd apparently has a wide host range, infecting hop, cucumber, grapevine, citrus, plum, peach, pear, apricot, pomegranate and almond. It has been found latent in a wide range of herbaceous and woody hosts (grapevine, apricot, pear) and may induce peculiar symptoms such as hop stunt, dapple fruit of plum and peach, and citrus cachexia. HSVd is very contagious and is found worldwide. In the Czech Republic, HSVd incidence in grapevine planted in the vicinity of hop gardens was found to be about 70%. Previous work has characterized HSVd isolates from France, Italy, Japan, Spain and USA. Current studies have revealed 16 new sequence variants from Cyprus, Greece, Morocco, and Turkey, where HSVd had not been described previously. The origin and route of the intrusion of HSVd into Canada remain unknown. Both PLMVd and HSVd are also easily transmitted by grafting or by use of contaminated pruning tools, but evidence of their transmission by vectors is apparently lacking for HSVd. Viroid disease management depends upon sanitation; plant viroid-free trees, sterilize shears after pruning each tree, and eradicate infected trees^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8}. Transmission of grapevine yellow speckle viroid 1 and hop stunt viroid via seeds has been confirmed in 11 seedlings of 8 grapevine Vitis vinifera varieties using a combination of RT-PCR, dot-blot hybridization and northern hybridization assays. This indicates that budwood stocks must be checked for the presence of HSVd. At least 16 new sequence variants of HSVd have been obtained from 4 Mediterranean countries (Cyprus, Greece, Morocco and Turkey) where this viroid had not previously been described. At present it appears that HSVd is limited to Japan. In some hosts, such as grapevine and apricot, the infection appears to be latent but in other cases, specific disorders such as hop stunt, dapple fruit of plum and peach and citrus cachexia have been associated with HSVd infection. Phylogenetic analyses revealed that sequence variants belonging to the 2 minor recombinant subgroups are more frequent than previously though
• citrus cachexia viroid is a graft-transmissible viroid that causes phloem deterioration and blockage in many mandarin, mandarin hybrids, Citrus macrophylla Wester, Rangpur lime, and sweet lime. This disease causes decline, stunting, and crop reduction. Sour orange is tolerant to the viroid. There appears to be consensus among viroid specialists, based on molecular genetic studies, that the viroid moved from grapevine to hop.
• on Nagpur mandarin (Citrus reticulata) and mosambi (Citrus sinensis)^{ref1, ref2, ref3}.
• Pospiviroid
• chrysanthemum stunt viroid
• citrus exocortis viroid (CEVd) : etrog citron (Citrus medica) is an indicator host onto which scions are grafted
• columnea latent viroid
• iresine viroid 1
• Mexican papita viroid (MPVd), found in 1982 in symptomlessly infected Solanum cardiophyllum in Aguascalientes state, suggest that MPVd may be the putative ancestor of crop viroids. MPVd, present in symptomlessly infected solanaceous plants, may have been transferred by chewing insects (aphids, grasshoppers, flea beetles, tarnished plant bug, leaf beetle, and Colorado potato beetle) to breeding plots and commercial potato crops.
• potato spindle tuber viroid (PSTVd) has been reported from Solanum tuberosum (France) and tomato (Lycopersicon esculentum) (Netherlands and UK). In tomatoes, PSTVd symptoms develop slowly, often not becoming apparent until 4 or 5 weeks after infection. Infected plants become stunted and show "bunchy top" symptoms (crowded foliage, due to shortening of internodes, and occasional formation of spindly shoots). Leaf symptoms include yellowing and purpling as well as considerable leaf distortion including downward curling of the leaflets (epinasty), curling, and twisting (rugosity). Severe necrosis along the veins develops later in the lower and middle leaves, which eventually die. Younger leaves at the top of the plant remain but are reduced in size. Flowers are often aborted, and fruit ripening is erratic. Fruits becomes small and hard and can turn dark green. Overall yields can be significantly reduced. Disease management basically depends on planting viroid-free transplants, adherence to a strict phytosanitary regimen to prevent contamination and subsequent spread of the viroid. Benches, tools, storage bins, and sacks can be disinfected with 3% hypochlorite^ref. Once PSTVd has been introduced onto a farm or nursery, it can be rapidly spread from plant to plant through the use of contaminated cutting tools and/or machinery, by handling, or simply by direct plant to plant contact. PSTVd can also be transmitted via infected pollen. To prevent the spread within growers' fields, good hygienic practices are necessary to prevent contact with potentially infected plants, and, to avoid subsequent spread of the viroid. Contaminated benches, tools, etc. should be disinfected. 2-3% hypochlorite has been shown to be effective. PSTVd can reduce yields by as much as 65 and 50% in potato and tomato, respectively. Other natural hosts include pepino (Solanum muricatum), avocado (Persea americana), and a range of solanaceous crops. PSTVd was reported in the 1930's to be transmitted by chewing insects (aphids, grasshoppers, flea beetles, tarnished plant bug, leaf beetle, and Colorado potato beetle) and is a nasty pathogen
• tomato apical stunt viroid (TASVd)^{ref1, ref2} was first found and characterized in Ivory Coast in 1980's, but no data was given on its epidemiology or economic impact. Another strain was found in Indonesia in 1980's, but again without data on potential economic impact. Both cause significant crop loss. The genomes of the 2 viroids are very similar (99.7% identity) despite their distant geographic origins. A third strain, isolated from Solanum pseudocapsicum [Jerusalem cherry], does not occur naturally in tomato but can infect tomato by mechanical inoculation. First found in Israel (on tomato (Lycopersicon esculentum) grown under plastic houses in the coastal region) in 2003 for samples collected in 1999/2000; first found in Tunisia in 2006^ref. The RNA sequence of the Tunisian, Israeli and Indonesian strains are very similar. Affected tomato plants in Israel showed shortened internodes (bushy appearance), leaf deformation and yellowing, reduced fruit size, and pale red discoloration of fruit. Up to 100% disease incidence could be observed at single sites with heavy yield losses. The present article also noted 100% disease incidence once temperatures were high, which is a characteristic of several diseases caused by viroids. TASVd can be transmitted from infected to healthy tomato plants by grafting or mechanical inoculation (in experimental conditions). No data is available on pollen or seed transmission, though some viroids are known to be transmitted by these means. Introduction on transplants is a strong possibility. Control of viroids is difficult in practice, so it would be desirable to avoid any further spread of a potentially serious disease of tomatoes. This new report from Tunisia acts as a warning to other countries. Other viroids that have been detected in Tunisia are noted in the archive below^ref
• tomato planta macho viroid
These pathogens are ubiquitous, and unfortunately some induce ephemeral symptoms that complicate their detection. PCR-based diagnostic detection systems are now available for some of them. AGVd appears to be the result of recombination between nucleotide sequences in PSTVd, CEVd, Apple scar skin viroid (ASSVd), and GYySVD-1. Interestingly, Vein banding disease in grapevine results from the synergistic interaction between grapevine viroids and Grapevine fanleaf nepovirus (GFLV). There is evidence that some viroids are seed-and pollen-transmitted in grapevine. Disease management requires the planting of viroid-free planting stock, sterilization of pruning tools, and eradication of infected vines.
• unclassified viroids
• apple fruit crinkle viroid (AFCVd), a graft-transmissible fruit and/or bark disorder of apple, was first reported in Japan. I was unable to obtain information about the viroid outside of Japan. Apple scar skin viroid (ASSVd) has 37% sequence homology with GYYSVd.  Both viroids share a common sequence in the central region of the molecule, but lack the central conserved sequence of viroids in the potato spindle tuber viroid group. Other homologous residues also occur as blocks of base-paired residues in the secondary structures of ASSVd and GYSVd. ASSVd viroid also has some homology with members of the Potato spindle tuber viroid group but not with Avocado sunblotch viroid^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8}
• cherry small circular viroid-like RNA
• citrus dwarf viroid
• citrus viroid Ia (CVd-Ia)
• citrus viroid II
• citrus viroid OS
• citrus viroid-I-LSS
• tomato chlorotic dwarf viroid
Disease management is based on prevention of viroid transmission, especially in nursery production of viroid-free planting material. Strict measures must be in place to reduce infestation of cutting tools and implements by using chemical compounds to inactivate viroids. Only viroid-free stock should be planted. However, cold treatment can be effective, e.g. storage at 4°C for > 6 months, followed by apical shoot-tip-culture grafting, can be used to eliminate HLVd. Pre-inoculation with protective mild strains of viroids has proved effective to control PSTVd^{ref1, ref2}.
• Viruses
• ssDNA viruses
• Geminiviridae

=> geminivirus-like symptoms (stunting, reduced leaf size, and leaf curling "chino")
Web resources : Gemini Detective : Geminiviridae:Begomoviruses whitefly-transmitted geminiviruses
• Begomovirus : plant virologists continue to report new begomoviruses, and new ones will undoubtedly emerge. The combination of high temperatures, presence of high populations of whiteflies, and suitable natural host plants apparently results in a mix that is conducive to generating new begomovirus strains in the region. The begomovirus-satellite disease complexes are associated with economically important diseases and have been isolated from vegetable and fiber crops, ornamental plants, and weeds throughout Africa and Asia. Their widespread distribution and diversity, coupled to the global movement of plant material and the dissemination of the whitefly vector, suggests that these disease complexes pose a serious threat to tropical and sub-tropical agro-ecosystems worldwide.
• Ageratum yellow vein virus

=> Ageratum yellow vein disease is caused by the whitefly-transmitted monopartite begomovirus Ageratum yellow vein virus (AYVV) and a DNA beta satellite component. Naturally occurring symptomatic plants also contain an autonomously replicating nanovirus-like DNA 1 component that relies on the begomovirus and DNA beta for systemic spread and whitefly transmission but is not required for maintenance of the disease. Systemic movement of DNA 1 occurs in Nicotiana benthamiana when co-inoculated with the bipartite begomovirus Tomato golden mosaic virus and the curtovirus Beet curly top virus (BCTV), but not with the mastrevirus Bean yellow dwarf virus. BCTV also mediates systemic movement of DNA 1 in sugar beet, and the nanovirus-like component is transmitted between plants by the BCTV leafhopper vector Circulifer tenellus. A 2nd nanovirus-like component, referred to as DNA 2, has only 47% nucleotide sequence identity with DNA 1. AYVV disease occurs throughout the Indian subcontinent (Nepal, India, Pakistan), China and parts of Africa. The disease may be associated with distinct virus species at these locations. Ageratum conyzoides, a weed species widely distributed throughout southeast Asia, frequently exhibits striking yellow vein symptoms associated with infection by AYVV Geminiviridae (genus Begomovirus). The widespread presence of AYVV-infected Ageratum conyzoides constitutes a major inoculum source. Ageratum ranges from Southeastern North America to Central America, but the center of origin is in Central America and the Caribbean. Most taxa are found in Mexico, Central America, the Caribbean, and Florida. Ageratum conyzoides now is found in several countries in tropical and sub-tropical regions, including Brazil. It is widely utilized in traditional medicine by various cultures worldwide^{ref1, ref2, ref3}
• cabbage leaf curl virus^ref
• cotton leaf curl virus (CLCuV)

There are at least 5 strains/isolates of CLCuV known, most of which are reported from Pakistan and western India. Cotton leaf curl Gezira virus is the more cosmopolitan strain, occurring in Egypt and Sudan, and is known to be present in Central Africa, Chad, Nigeria, Togo and West Africa. Cotton leaf curl disease (CLuCD) is a serious disease of cotton and several other malvaceous plant species that is transmitted by the whitefly Bemisia tabaci. Control of CLCuD is mainly based on insecticide treatments against Bemisia tabaci. Roguing, particularly of ratoon cotton from the previous seasons crop, is recommended but appears to have little affect in reducing disease incidence. Resistant cotton cultivars have been introduced that were developed by conventional breeding and selection. However, recent reports have suggested that the virus complex has overcome the resistance^{ref1, ref2, ref3, ref4,ref5, ref6, ref7, ref8, ref9, ref10, ref11}
• cotton leaf curl Multan virus (CLCuMV) causes cotton leaf curl disease (CLCuD), a major constraint to cotton production on the Indian subcontinent. It has been shown to be caused by a monopartite begomovirus and a novel ssDNA satellite molecule termed CLCuD DNA-beta. The satellite molecule is trans-replicated by CLCuMV but does not possess the iteron sequences of this virus. Field surveys across all the cotton-growing regions of Pakistan indicate that dual and multiple infections are the norm for CLCuD with no evidence of synergism. Despite the diversity of begomoviruses associated with CLCuD, only a single class of DNA-beta has been detected, suggesting that this satellite has the capacity to be recruited by unrelated begomoviruses. As of 2003, an 26 additional DNA beta molecules, associated with diverse plant species obtained from different geographical locations, have been cloned and sequenced. They were shown to be widespread in the Old World, where monopartite begomoviruses are known to occur. Analysis of the sequences revealed a highly conserved organization for DNA-beta molecules consisting of a single conserved open reading frame, an adenine-rich region, and the satellite conserved region (SCR). The SCR contains a potential hairpin structure with the loop sequence TAA/GTATTAC, similar to the origins of replication of geminiviruses and nanoviruses. 2 major groups of DNA-beta satellites were resolved by phylogenetic analyses. One group originated from hosts within the Malvaceae and the 2nd from a more diverse group of plants within the Solanaceae and Compositae. Within the 2 clusters, DNA-beta molecules showed relatedness based both on host and geographic origin. These findings strongly support coadaptation of DNA-beta molecules with their respective helper begomoviruses. The begomovirus-satellite disease complexes are associated with economically important diseases and have been isolated from vegetable and fiber crops, ornamental plants, and weeds throughout Africa and Asia. Their widespread distribution and diversity, coupled to the global movement of plant material and the dissemination of the whitefly vector, suggests that these disease complexes pose a serious threat to tropical and sub-tropical agro-ecosystems worldwide.
• East African cassava mosaic virus (EACMV) : cassava mosaic disease (CMD) is the most important constraint to cassava (Manihot esculenta) production in Africa. Since the 1990s, the importance of the disease has been greatly increased by the spread through East and Central Africa. The most likely means of spread of EACMV-UG into Burundi would be via viruliferous whiteflies (Bemisia tabaci) and movement of infected cassava cuttings. The fact that EACMCV has reached epidemic status in Nigeria threatens the food security of that country and is a setback to plant pathologists who have been contending with control of CMD. The virus is present in many parts of Africa (Congo Republic, Democratic Republic of Congo, Kenya, Malawi, Rwanda, Tanzania, Uganda and possibly in Madagascar, Zimbabwe, Zambia and Mozambique). Disease management strategies include cultural control (planting of virus-free stocks and use of stem branches of moderately resistant and resistant genotypes as sources of cuttings), development of resistant lines through crosses between cassava and wild species (Manihot glaziovii) to restore root quality and resistance to CMD, as well as lines derived from Nigeria and local Nigerian genotypes. Moreover, breeding for the specific needs of farmers in different regions of Nigeria should be considered^{ref1, ref2, ref3}. Cassava production in Africa faces new challenges from CMD. Disease has spread in recent years, bringing increased risk of food insecurity to millions of rural and urban households, particularly in eastern Africa. Research and extension programs have helped limit the geographic spread of CMD, but the potential magnitude of the problem threatens to overwhelm these efforts. CMD continues to be prevalent in all the main cassava-growing areas in the ECA (Economic Commission for Africa) sub-region and is regarded as the most important disease, causing 20-90% crop losses based on the cultivar, viral strain and environmental factors. Deterioration in the status of CMD is a fact in East Africa, Uganda, DR Congo, and Kenya. Plants infected via white fly-transmission dominate affected areas. Lower leaves of infected plants look apparently healthy, while leaves above the point of 1st infection show severe symptom expression, drastic reduction in leaf size with marked distortion. Plants harbor numerous adult white fly (Bemisia tabaci (Bt)) populations on young shoots and large nymph populations on the lower surface of the apparently healthy lower leaves. Lack of alternative propagation stock in disease-infected areas leaves farmers no choice but to use material from the previous harvest of infected plants as planting stock for the next generation. Environmental factors favoring the development and fecundity of Bt enhance disease spread, and spread of CMD is therefore highly linked to the vector. To alleviate the situation, a number of African countries (Kenya, Burundi, and Madagascar) have made significant progress in selecting resistant/tolerant clones, which are being evaluated within their different ecological zones. The research discussed in this piece was completed in 2002, and normally I would not post a piece that took almost 3 years to be published in "New Disease Reports, but I believe that it is important to recognize new virus threats to the food security of Sudan and other African countries^{ref1, ref2, ref3}
• mungbean yellow mosaic India virus (MYIMV) : the interaction between MYIMV and satellite DNA-beta results in more severe symptoms compared to plants inoculated with MYINV alone. Similar results have been reported for other DNA-beta molecules and viruses. DNA-beta molecules are symptom-modulating, ss-DNA satellites associated with monopartite begomoviruses belonging to the Geminiviridae^{ref1, ref2, ref3, ref4}
• pepper golden mosaic virus (PepGMV), formerly designated as Serrano golden mosaic virus (SGMV) and Texas pepper virus (TPV), is present in Costa Rica, Guatemala, Honduras, Mexico (7 states), and USA (Texas), and causes significant crop losses. Scientists in Mexico are attempting to select tomato plants that appear to be asymptomatic following inoculation with PepGMV, suggesting that they may be useful in developing resistant cultivars. Part of the resistance mechanism appears to be the lack of virus movement in infected plants. At least 2 closely related strains of PepGMV (Tamaulipas and La Paz) are present in Mexico.

Web resources : PepGMV at Gemini Detective
• sida golden yellow vein virus (SiGYVV) has not been previously reported to infect bean. Weeds such as Sida rhombifolia have been suggested as natural reservoirs from which the whitefly, Bemisia argentifolii, spreads SiGYVV to tomato (Lycopersicon esculentum), a preferred host. In addition to SiGYVV, there are at least 4 other geminiviruses that infect Sida spp. (golden mosaic, mottle, yellow vein, and yellow mosaic)
• South African cassava mosaic virus (SACMV) in cassava (Manihot esculenta)
• squash leaf curl virus (SLCV)
• SLCV (type strain)
• squash leaf curl China virus (SLCV)
• squash leaf curl Philippines virus (Yunnan)
It is transmitted by 2 whitefly species -- the sweet potato whitefly Bemisia tabaci and the silverleaf whitefly, Bemisia argentifolii -- although some taxonomists suggest that these species are really biotypes. Squash and watermelon (Citrullus lanatus) are preferred hosts. Disease management utilizes cultural control (eradication of infected plants, use of UV-absorbing greenhouse plastic films, and aluminum plastic mulches) and biological control (use of parasitoids such as Encarsia spp. and Eretmocerus spp.). Use of insecticides is not very efficacious because whiteflies tend to congregate on the undersides of leaves. In most instances, the incidence of SLCV-affected plants in Israel was close to 100% and was always associated with high populations of the whitefly, Bemisia tabaci. SCLV has been reported from USA (Arizona, Texas, and California) as well as from Guatemala, Honduras, Sinaloa and Sonora states in Mexico, Nicaragua, and Panama. Epidemic caused by a 'New World' geminivirus in the Eastern Hemisphere has also been reported.
• sweet potato leaf curl virus (SPLCV)

=> leaf curl in the crop plant sweet potato, Ipomoea batatas. SLCV or sweet potato with leaf curl symptoms has been detected or reported in Taiwan, Japan, Brazil, China, Mexico, Puerto Rico, and the USA, and Kenya (2005). The causal agent is the whitefly-transmitted SPLCV. Viral genomic ssDNA can be detected in plant samples using PCR with SPLCV-specific primers. SPLCV-like isolates cluster into 3 groups, and all of them might have evolved from the same common ancestor possibly from the Old World^{ref1, ref2}
• tomato leaf curl Karnataka virus (ToLCKV)

=> leaf crumple disease in soybean (Glycine max) in India. An incidence of > 80% was observed in Lucknow. Diseased plants exhibited severe yellowing, crumpling and distortion of leaves. Infected plants were stunted, and had a very low yield.  The virus is not uncommon in solanaceous crops like tomato in India, but detection in soybean is a 1st report.  The complexity of different begomoviruses in India and neighboring countries that cause similar diseases can be followed in the posts listed below. Diversity is driven by an abundant active vector, the whitefly Bemisia tabaci, many weed and crop reservoirs, and the capacity for this group of ssDNA viruses to share/swap genetic information thereby creating new viruses and strains. Their ability to cause severe disease is demonstrated in this report^{ref1, ref2, ref3}.
• tomato leaf curl Mayotte virus. The agricultural sector on Mayotte is divided into subsistence farming and farming for export. Subsistence farming, which provides the staples making up 75% of the islanders' diet, consists of coconuts, cassava, bananas and rice. Small quantities of fish and meat are also consumed. Mayotte is not self-sufficient and must import a large portion of its food requirements, mainly from France. Exports are mainly ylang-ylang (perfume essence), vanilla, copra, coconuts, coffee, and cinnamon
• tomato leaf curl New Delhi virus (ToLCV-NDe / ToLCNDV) a bipartite begomovirus

=> leaf curl disease in potato (Solanum tuberosum), Nicotiana benthamiana, tomato (Lycopersicon esculentum), and watermelon (Citrullus lanatus) crops in the Indian subcontinent^ref. Chilli pepper (Capsicum annuum), an important crop on the Indian subcontinent, often shows symptoms similar to tomato leaf curl, such as yellowing, leaf curling, reduction in leaf size and stunting. Since chilli and tomato crops overlap in the field, chilli peppers may become infected with tomato begomoviruses. Tomato-infecting begomoviruses are particularly damaging to solanaceous crops. In the 1970's there were only 3 tomato-infecting begomoviruses in the Americas, but at present there are at least 14 new ones, of which 7 are distinct ToLCNDV species. Recombination or pseudorecombination are driving forces in the evolution of new viruses, especially in tropical regions. Disease management of ToLCV depends in part on preventing movement of Bt-infested plants (e.g.. tomato transplants) to virus-free areas, where the virus can become established and implementation of phytosanitary procedures. Various control options include removal of infected plants (roguing) and removal or burial of infected crop residues and intercropping in combination with chemical insecticides and use of available resistant cultivars. Use of plastic UV-absorbing screening material to exclude Bt is another method. Genetic resistance to begomoviruses has been reported in some wild Lycopersicon species such as L. hirsutum and L. peruvianum which might be transferred to tomato. In Pakistan, resistance to leaf curl virus has been incorporated into tomato and chili cultivars^{ref1, ref2, ref3, ref4}. A whitefly-transmitted begomovirus originating in sponge gourd (Luffa cylindrica) in Northern India has been shown to be closely related to ToLCV-NDe. What is interesting is that the new virus is a relatively rare example of a sap-transmissible begomovirus. Based on genome sequence analysis, it is closely related to ToLCV-NDe but less closely related to other ToLCV isolates/strains. At least 3 other begomovirus strains/isolates have been reported from Asia. The one associated with cucumber yellow leaf curl disease in Thailand shares 95% nucleotide sequence similarity with the DNA-A of ToLCV-NDe, and pumpkin yellow vein mosaic virus is most closely related to the same virus.
• In June 2003, symptoms of stunting and leaf curling resembling symptoms of tomato leaf curl disease, as well as reductions in yields, were observed on tomato plants in the western (Combani and Kahani) and eastern (Dembeni, Kaoueni, and Tsararano) regions of Mayotte, a French island in the Comoros Archipelago located in the northern part of the Mozambique Channel. The whitefly, Bemisia tabaci, was observed colonizing tomato plants and other vegetable crops at low levels
• there are 7 ToLCNDV isolates that have been reported from India and 2 from Thailand. Recombination or pseudo-recombination are driving forces in the evolution of new begomoviruses, especially in tropical regions. Disease management of ToLCNDV depends in part on preventing movement of Bt-infested plants (e.g.. tomato transplants) to virus-free areas. Various control options include removal of infected plants (roguing), removal or burial of infected crop residues and intercropping in combination with chemical insecticides and the use of available resistant cultivars. Use of plastic UV-absorbing screening material to exclude Bt is another method. Genetic resistance to begomoviruses has been reported in some wild Lycopersicon species such as L. hirsutum and L. peruvianum, which might be

transferred to tomato. In Pakistan, resistance to leaf curl virus has been incorporated into tomato and chili cultivars^{ref1, ref2, ref3, ref4, ref5, ref6}
• tomato severe leaf curl virus (ToSLCV) : strains have been reported from Mexico, Guatemala, Honduras, Nicaragua, and Cuba. Cucumber (Cucumis sativus) and tomato (Lycopersicon esculentum) are natural hosts. These strains likely originated in Central America and the Caribbean region. The genomes of these viruses are either monopartite or bipartite, the viruses are transmitted by whiteflies (Bemisia tabaci), and they infect a range of dicotyledonous plants. Disease management involves procedures to delay infection, regulated applications of insecticides, use of biopesticides (parasitoids and predators), and planting resistant cultivars if they are available.
• tomato yellow leaf curl virus (TYLCV)^{ref1, ref2}, an Old World virus first described in Israel in 1964, was apparently unwittingly introduced into the Caribbean region in the early 1990s and continues to cause severe damage to tomato (Lycopersicon esculentum) crops in the New World^ref.

=> tomato yellow leaf curl (TYLC)^{ref1, ref2} is one of the most devastating viral diseases of cultivated tomato in tropical and subtropical regions. It is spread efficiently by an insect vector (Bemisia tabaci [Bt]), and the difficulty of its management is compounded by the existence of distinct biotypes, of which the 'B' and 'Q' biotypes are of key interest in southern Europe. The disease is difficult to identify because of great variation in symptom expression. Infected seedling transplants may serve as the route for long-distance spread of the virus and, when introduced into areas of high Bt populations, results in extensive and rapid spread of the virus. High levels of resistance to TYLCV were detected in 7 of 9 accessions of Lycopersicon peruvianum and in all 5 accessions of Lycopersicon chilense tested. In contrast, plants of 7 accessions of Lycoperison hirsutum and 3 of 4 accessions of Lycopersicon pimpinellifolium were highly susceptible. Plants of accession CIAS 27 (L. pimpinellifolium) showed moderate resistance to TYLCV^{ref1, ref2, ref3, ref4, ref5, ref6, ref7}. Its introduction into the region is an excellent example of the interaction between the whitefly vectors (Bemisia tabaci [Bt] and Bemisia argentifolii) and tomato that results in rapid spread of a geminivirus. Bt is an efficient vector of TYLCV; susceptible host plants, such as squash, can serve as virus reservoirs. TYLCV acquired during a short period of time by 1-2 day-old Bt adults remain associated with the insect for several weeks and were detectable for the life of the insect. Although infectivity decreased with age, Bt was able to infect test plants for > 4 weeks. It is present in most Mediterranean countries and parts of sub-Saharan Africa, Middle East, South East Asia, Japan, Australia, Central America, Mexico, the Caribbean Islands (including Guadeloupe), and locally in the U.S. states of Florida, Georgia, and Louisiana. Tomato yellow leaf curl disease is well-established in Reunion Island after 7 years of cropping : Bt predominates on the island, but some specimens belonged to another biotype (also present in Madagascar, Mauritius, Seychelles and designated biotype Mascareignes). Genetic resistance to TYLCV in tomato cultivars appears to controlled by at least 5 genes, and crossing experiments yielded only tolerant hybrids. Disease losses can be catastrophic, leading to complete loss. Disease management includes the use of available resistant cultivars, use of virus-free transplants, control of the whitefly vector with chemical insecticides, application of strict phytosanitary measures, avoidance of peak times of vector activity, changes in cultural practices such as the control of between-season, alternate hosts, as well as the identification of resistance sources and the production of transgenic plants containing resistant genes from wild species^{ref1, ref2, ref3, ref4, ref5, ref6}.
• tomato yellow leaf curl Morondava virus (TYLCMV) isolates from Madagascar
• tomato leaf curl virus (TLCV-Aus) is a begomovirus that has caused disease in tomato in Australia since 1971 and is described and mapped in the A2 list of EPPO for TYLCV and similar viruses. TLCV-Aus is known to be very similar to a strain of TYLCV from Thailand (TYLCV-Thai). It remains to be seen which of the multiple strains of TYLCV this new Australian isolate resembles. A summary of the Australia begomoviruses and a set of diseased tomato photographs^ref. Recent outbreaks of begomoviruses causing severe disease in tomato in Indonesia, Uganda and South Carolina USA
Tomato plants are severely stunted with shoots becoming erect. Leaflets become reduced in size and pucker. Leaves curl upwards, become distorted, and have prominent yellow margins. Flowers wither or appear normal, and the fruits that set either show no symptoms from the viral infection or they may be small, dry and unsaleable when infections come early in the season. While it is impractical to completely eradicate a vector-borne viral disease, a combination of production practices may minimize the impact of the disease.  These include using disease-free transplants, roguing the infected plants (early in the season), and managing whitefly populations using various insecticides or reflective mulches. The Ugandan virus is similar to TYLCV from Dembeni, Mayotte, Comoros Islands but differs from other African strains. The Indonesian virus is similar to pepper yellow leaf curl Indonesia virus and an eggplant isolate of TYLCV from Thailand. The USA - South Carolina virus is similar to TYLCV isolates from Florida, the Dominican Republic, Cuba, Guadeloupe, and Puerto Rico. The combination of reports points out the genetic diversity of this virus family. The USA find in South Carolina seems to be an example of the introduction of a virus from another state on transplanted seedlings, in this case tomato and pepper^{ref1, ref2, ref3, ref4}
• watermelon chlorotic stunt virus (WmCSV / WCSV), vectored by Bemisia tabaci, is likely established in the affected areas of Israel. Its natural host range includes several other species, including Citrullus lanatus var. citrioides [citron], Citrullus echirrhosus, and Citrullus colocynthis [bitter apple], which may function as alternate hosts as sources of inoculum
• unclassified Begomovirus
• bell pepper leaf curl virus : begomoviruses are continually evolving in Asia, especially in India and Pakistan. The combination of high temperatures, presence of high populations of whiteflies, and suitable natural host plants apparently results in a mix that is conducive to generating new begomovirus strains in the region. The begomovirus-beta satellite complexes referred to above are associated with economically important diseases and have been isolated from vegetable and fiber crops, ornamental plants, and weeds throughout Africa and Asia. Their widespread distribution and diversity, coupled to the global movement of plant material and the dissemination of the whitefly vector, suggests that these disease complexes pose a serious threat to tropical and sub-tropical agro-ecosystems worldwide. Collaborative work, involving research scientists at the Plant Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), PO Box 577, Jhang Road, Faisalabad, Pakistan and the Department of Disease and Stress Biology, John Innes Centre, Colney, Norwich, UK NR4 7UH, contains information suggesting that these disease complexes are rapidly expanding in geographical distribution and host range. As an example, cotton leaf curl disease, originally a major problem in central Pakistan, is now causing extensive damage in India. In the same region, new diseases are emerging in crops such as tomato, tobacco, chillies and papaya. The presence of such a diverse population of begomoviruses in a single region, coupled with the propensity of these viruses to exchange genetic material by recombination, increases the probability of new virus diseases emerging in the region. These viruses will likely cause epidemics in previously unaffected crops, a problem that will be exacerbated by the selective use of elite cultivars, movement of infected plant material and widespread

introduction of the whitefly vector (Bemisia tabaci). Continued growth in international trade and travel could result in these whitefly-transmissible disease complexes reaching the New World, as was demonstrated when Tomato yellow leaf curl virus (TYLCV-Is) appeared in the eastern Caribbean in Cuba, the Dominican Republic, and Jamaica. In the case of the Dominican Republic, it was believed to have been introduced on infected but asymptomatic tomato transplants from the eastern Mediterranean region. An isolate of TYLCV-Is from the Dominican Republic and 98% identical to an isolate from Israel appeared to have entered the United States in Dade County, Florida, in late 1996 or early 1997. Subsequently, infected tomato transplants produced for retail sale at 2 Dade County facilities were rapidly distributed via retail garden centers throughout the state^{ref1, ref2, ref3}
• tomato mosaic Havana virus (ToMHV)^ref
• tomato yellow vein streak virus (ToYVSV) : it is interesting that it took over 20 years to recognize that ToYVSV and Potato yellow deforming virus were one and the same virus. In potato, the apical leaves showed yellow or green mottle which developed into leaf distortion with yellow blotches (apparently no natural infection have been found on potato). About 20% of young tomato plants showed virus symptoms. Tomato is an important crop in the EPPO region, and both indoor and outdoor and the virus vector is present in many parts of the EPPO region. The disease appears so far, limited in Brazil but data is lacking about its extent and severity. The original isolate of PYDV was recorded in the 1980s in southern Brazil^{ref1, ref2}. About 20% of young tomato plants showed virus symptoms. Tomato is an important crop in Europe, where production systems are extremely intensive, and yields can be very high (up to 700 tons/ha). The virus vector [whitefly] (Bemisa tabaci) is present in the region of the European & Mediterranean Plant Protection Organization (EPPO). The disease appears, so far, to be limited in Brazil, but data is lacking about its extent and severity. ToYVSV infects both tomato and potato crops in Brazil.
• Mastrevirus
• chickpea chlorotic dwarf virus (CpCDV) is transmitted only by specific insect vectors (Orosius spp., family Cicadellidae). In addition to India and Iran, the virus has been reported on chickpea in Egypt and Iraq. Disease management depends upon an integrated pest management program (IPM). Management options include use of resistant host plants, biological control, suitable agronomic practices, and habitat management.
• wheat dwarf virus (WDV) : in Sweden, it is periodically an important pest on wheat. It is transmitted by the insect Psammotettix alienus, family Cicadellidae. The genetic diversity among wheat-infecting isolates of WDV was found to be low throughout Sweden and Europe, while WDV isolates infecting barley were distinctly different. WDV was also identified in samples of wild grasses and the insect vector. WDV spreads in Bulgaria, the former Czechoslovakia, France, Hungary, and the former USSR; found, but with no evidence of spread, in Sweden^ref.
• Nanoviridae
• Bubuvirus
• banana bunchy top virus (BBTV) is transmitted by the banana aphid (Pentalonia nigronervosa). It causes banana bunchy top disease (BBTD), the most destructive viral disease of banana [Musa x paridasiaca, M. acuminata and M. textilis, a Philippine plant known as abaca (Manila hemp)]. It was 1st reported in Fiji in 1879. Countries in which banana bunchy top disease has been recorded^ref : Region or Country / Initial report / BBTV detected
• South Pacific
• north-eastern Australia  / 1927  / +
• Fiji  / 1927 /  +
• Guam / 1982 /
• Hawaii (USA)  / 1991  / +
• Kiribati (formerly Gilbert Islands) / 1980 /
• New Caledonia  / 2001  / +
• Samoa (American) / 1967 /
• Samoa (Western)  / 1967  / +
• Tonga  / 1967  / +
• Tuvalu (formerly Ellice Islands) / 1926 /
• Wallis Island  / 1933 /
• Asia
• China  / 1996  / +
• India  / 1953  / +
• Indonesia  / 1978  / +
• Japan (Bonin Islands)  / 1926 /
• Japan (Okinawa)  / 1993  / +
• Malaysia (Sarawak)   / ? /  +
• Pakistan  / 1993  / +
• Philippines  / 1961  / + (devastated many plantations in the Bicol Region of the Philippines for > 50 years)
• Sri Lanka  / 1921  / +
• Taiwan  / 1961  / +
• Vietnam  / 1969  / +
• Africa
• Burundi  / 1988  / +
• Central African Republic  / 1996 /
• Congo   / 1961  / +
• Democratic Republic of Congo (formerly Zaire)  / 1982 /
• Egypt  / 1927  / +
• Gabon  / 1982  / +
• Malawi  / 1997  / +
• Rwanda  / 1988 /
It has not appeared in Central or South America or in Western Australia. BBTV is vectored by the banana aphid (Pentalonia nigronervosa). Disease management is predicated on integrated pest management (IPM). Strategies include long-term aphid control (killing of weed hosts for aphid control, use of predators and parasites, control of aphids on alternate hosts), frequent scouting for diseased plants, destruction of diseased trees, planting of virus-free material, and heat treatment of infected tissue cultures to provide virus-free plantlets^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9}.
• Nanovirus
• faba bean necrotic yellows virus
• milk vetch dwarf virus
• Subterranean clover stunt virus (type species)
Their genomes consist of multiple circular ssDNAs of about 1 kb
• dsRNA viruses
• Reoviridae
• Fijivirus
• Fijivirus group 2
• maize rough dwarf virus (MRDV) was first reported in Zea mays from Israel in 1959. It is spreading in Argentina, the former Czechoslovakia, France, Israel, Italy, Norway, Spain, Sweden, and the former Yugoslavia. Susceptible hosts include oat (Avena sativa), barley (Hordeum vulgare) and several grasses. The virus is transmitted by several leafhoppers including Delphacodes propinqua, Dicranotropis hamata, Laodelphax triatellus and others in the family Delphacidae. Maize seedlings infected at early stages produce almost no seeds. MRDV is related to several other fijiviruses (rice black-streaked dwarf (RBSDV), Pangola stunt (PaSV), Mal de Rio Cuarto (MRCV)), although MRCV has been suggested as a distinct virus species. RBSDV commonly infects maize in China. A virus considered to similar to MCRV was reported from maize in India in 2001
• Varicosavirus
• lettuce big-vein virus (LBVV)

=> it plays no etiological role in lettuce big-vein disease (BVD) expression in lettuce (Lactuca sativa) and does not affect the outcome of MiLV infection. Both LBVV and MiLV are vectored by the soil-inhabiting fungus Olpidium brassicae. LBVV virions are fragile, somewhat rigid rods (320-360 nm long).
• unclassified dsRNA viruses
• High Plains virus (HPV) - A newly discovered virus that infects corn and wheat. It originally was discovered in the High Plains region but since has been found in Israel, Chile, Florida and many places besides the High Plains. The fact that HPV has been detected in Australian wheat is not surprising. It has been recorded in the Americas, and there are unconfirmed reports of its presence in Russia. HPV can cause severe disease in barley, maize, oats, rye, and some grasses. Disease management depends upon interrupting the life cycle of the mite vector (Aceria tosichella) by plowing down volunteer wheat seedlings at least 2 weeks before seeding the next crop. The mite cannot survive in the absence of susceptible hosts for more than 24 hours. At present there is no information on how HPV presence will affect wheat production in Australia. Time will tell. An intriguing aspect of this report is that HPV appears to share some properties of a group of filamentous, eryiophyid mite-transmitted viruses (fig mosaic, thistle mosaic, rose rosette, redbud yellow ringspot, and wheat spot mosaic, all transmitted by A. tosichella) and possibly pigeonpea sterility mosaic, transmitted by Aceria cajani, and known to infect pigeonpea crops in India. There is little information about the structural properties of HPV and others in the group^{ref1, ref2}.
• ssRNA negative-strand viruses
• Bunyaviridae
• Tospovirus : There are at least 15 recognized tospoviruses. The type member, Tomato spotted wilt virus (TSWV), has one of the broadest host ranges among plant viruses. It is well established in many parts of the world and affects crops such as potato, lettuce, tomato, pepper, groundnut, mungbean, and tobacco : it constitutes a severe threat to Capsicum cultivation worldwide. Rough estimates calculate the worldwide loss due to tospoviruses at USD 1 billion. Lettuce crops in Hawaii have suffered serious damage due to TSWV for several successive years, forcing growers to switch to other crops. Annual losses due to peanut bud necrosis virus (PBNV) in Asia are estimated at more than US$ 89 million. A new approach to disease management of TSWV is peptide-mediated, broad spectrum plant resistance, as described by Rudolf, Schreir, and Uhrig at the Max Planck Institute for Plant Breeding Research, Cologne and Bayer Crop Science in Mohnheim, Germany^ref, to which the numbered references in this comment refer, and which includes a comprehensive review). An example is the development of broad spectrum resistance which is expressed by specific viral proteins. There are unambiguous examples of protein-mediated virus resistance -- mainly expression of viral coat proteins (3,4,10) -- but cases of protein-dependent pathogen-derived resistance due to expression of viral movement proteins or replicases are also known (9,11,12). In some instances, resistance is based on the expression of intact, functional proteins; in others the expression of the intact protein leads only to weak resistance or even to enhanced susceptibility. In contrast, expression of a dysfunctional protein may lead to strong resistance (12,13). Presence of the viral gene product in inappropriate amounts, form or time, is thought to interfere with viral infection. However, in some cases it is difficult to distinguish between an RNA- and protein-mediated resistance (8,9). Despite the number of successful examples, the molecular basis of protein-mediated virus resistance is, in most cases, not understood. Further research and development are required^{ref1, ref2}
• impatiens necrotic spot virus (INSV)

=> impatiens necrotic spot in potato is a conundrum, of sorts because it involves production of potato in an experimental glasshouse rather than a production field. Under the growing conditions prevailing in the glasshouse, the virus failed to replicate sufficiently to maintain the virus in infected potato. The interesting aspect of this disease is that INSV-infected N. benthiamiana is an effective indicator of the disease. Disease management would require applications of insecticides to reduce populations of the insect (Frankliniella occidentalis). Other thrips have not been identified as vectors, but that may have changed. The biology of INSV is similar to that of TWSV, such that the 2 viruses are often recorded together^{ref1, ref2, ref3, ref4}
• iris yellow spot virus (IYSV) has been reported from over 50 countries worldwide : in addition to infected onion crops in Washington and Colorado, IYSV is present in Brazil, Iran, Israel, the Netherlands, and Slovenia. IYSV has been endemic in south western Idaho and eastern Oregon onion, leek, and chive seed production fields for over 10 years. IYIS is a major constraint to onion production in parts of the USA, and new outbreaks continue to be reported. The economic impact of IYSV varies from low in IYSV-infected leek in the Netherlands but, in Brazil, IYSV-infected onion crops can range up to total loss. It has also been detected in onion seed plants from California and Arizona. The virus is vectored by onion thrips (Thrips tabaci) but not by western flower thrips (Frankliniella occidentalis), which are an efficient vector of the virus. Although there is no cure, diseased plants can still produce reasonable yields through irrigation and good soil fertility. Not much is known about resistance to IYSV in onion. Recommended disease management options include removal of culled onions so as to reduce sources of infection, reduction of plant stressors so that the crop has sufficient soil and fertility, reduction of soil compaction and irrigation stresses, and management of thrips populations by appropriate chemical insecticides. Natural enemies, including predaceous mites, minute pirate bugs, and lacewings, are often found feeding on thrips. These beneficial insects are very susceptible to insecticidal sprays, however, and are thus unlikely to be effective in biological control of insects in fields treated with insecticides^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8}. IYSV attacks a number of vegetable, fruit, and flower crops causing considerable economic damage. Disease management employs several cultural control options, including avoiding planting thrips-susceptible crops following small grains, managing vegetation in fields and field edges, using colored mulches, and avoiding high nitrogen levels. Some cabbage and onion varieties are somewhat resistant to thrips attack. Several beneficial insects suppress thrips levels. Organically-acceptable pesticides are available for thrips control^ref. IYSV is difficult to readily identify. Research results to date have shown: i) disease incidence varies among varieties; ii) IYSV may be associated with plant stress (i.e. moisture, temperature extremes, salinity, soil compaction, pink root, etc. ); iii) in more susceptible varieties, IYSV incidence is initially higher along field edges and lower in the center of the field (similar to the pattern of onion thrips). This pattern of thrips distribution occurs when they immigrate from surrounding vegetation, but their distribution may become more uniform in the field as the season progresses. Entomologists at Cornell University are studying the ecology of onion thrips and their movement patterns within and between fields; and iv) IYSV incidence decreases as plant population increases, possibly because onion thrips are challenged to locate a single plant when plant populations are high. In a IYSV pesticide trial, it was found that Actigard + imidacloprid resulted in a 34-38% yield increase of the jumbo class. A complete integrated approach will be necessary for successful IYSV and thrips management^{ref1, ref2}. IYSV has been reported from North America for several years and recently in Australia. The virus is mainly transmitted by onion thrips (Thrips tabaci) and to some extent by the western flower thrips (Frankliniella occidentalis), which causes considerably more damage to the crop. Onion seed, bulbs, and roots are not known to carry the virus, but volunteer onions are often symptomatic in early spring in Colorado. The virus likely over-winters in perennial and winter annual weeds, over-wintering onion, and adult thrips. To my knowledge, there is no biological control for IYSV. Disease management depends upon use of thrips-free transplants, utilization of crop rotation (at least 3 years between crops), elimination of culls and weed hosts of the vector, and avoidance of plant stress by providing appropriate irrigation, and avoidance of soil compaction and saline soils. There are no completely IYSV-resistant onion cultivars available, but there are some less resistant ones that can be used. Thrips control may provide some reduction in Iris yellow spot, but thrips control alone is not sufficient to economically control the disease. Thrips resistance to commonly applied insecticides is widespread in Colorado and other onion production regions of the High Plains in the USA^{ref1, ref2, ref3}. It mainly infects onion, garlic, leek, lisianthus and iris (it was 1st isolated from iris, hence the name Iris yellow spot virus). There is no evidence of it being seedborne. The industry is concerned about the potential impact of IYSV in Washington state, particularly because it has been recorded as present in Colorado, Arizona, Utah and California. IYSV-infected onions cannot be cured. Infected plants should be removed and destroyed, along with cull piles and volunteers. Maintaining good cultural management practices will help to reduce stress on the plants, thus lessening the disease's effect. Other management practices include maintaining good soil fertility and adequate irrigation supplemented with good management of thrips and weeds. Onion thrips are best managed with chemical insecticides. Although no cultivars are known to be resistant to IYSV, research has shown that cultivars vary in their susceptibility to both the virus and the thrips vector^{ref1, ref2, ref3, ref4, ref5}. In 2006 it was 1st reported in onions (Allium cepa) in Peru. The samples tested were collected in 2003 and 2005 near the owns of Supe^ref and Ica^ref in Peru, extending the range of the virus in South America from previous reports in Brazil (1999) and Chile (2005). The disease distribution map for other countries, including USA, Spain, and Australia^ref. It causes disease in the crop plants onion and leek and in the ornamental plant iris (where it was first detected). Affected onion plants show numerous eyelike spots on the leaves and flower stalks resulting in flower abortion^{ref1, ref2}. The economic impact of iris yellow spot virus can be severe in Brazil, where up to 100% loss has been observed in onion fields. Thrips tabaci can transmit the virus, but Frankliniella schultzei and F. occidentalis are not thrip vectors. Recent studies showed that onion bulbs and seeds did not transmit the virus to progeny. Further studies are needed to better understand the epidemiology of the disease in the field. In order to manage the disease, infected plants should be removed and destroyed, along with cull piles and volunteers. Other management practices include maintaining good soil fertility and adequate irrigation supplemented with good management of thrips and weeds. Onion thrips are best managed with chemical insecticides. Although no onion cultivars are known to be resistant to IYSV, research has shown that cultivars vary in their susceptibility to both the virus and the thrips vector^{ref1, ref2}
• tomato fruit yellow ring virus (TFYRV) has an extensive host range (Ghotbi, et al. 2005) but it is found most often in tomato and in mixed virus infections with TSWV. It was found infecting tomato in Iran : the virus originated from the Varamin area where > 30% of the tomato crop was infected with TSWV
• tomato spotted wilt virus (TSWV) is regarded as one of the 10 most economically destructive plant pathogens. During the past 2 decades, it has spread around the world by thrips (small insects that feed on plants), causing very high losses to a variety of vegetable (e.g. tomatillo (Physalis ixocarpa)), ornamental, and agronomic crops. TSWV is now common in temperate, subtropical, and tropical regions around the world and is a major constraint to onion production. 4 thrips species are the major vectors of TSWV: Frankliniella occidentalis (western flower thrips); F. schultzei, Frankliniella fusca (tobacco thrips); and Thrips tabaci (onion thrips). The western flower thrips (Frankliniella occidentalis) and the tobacco thrips (Frankliniella fusca) are major species in Florida. Until recently, growers sprayed toxic, broad-spectrum insecticides in an attempt to control thrips, but the chemicals do not prevent virus transmission. The solution is to use a variety of new, environmentally friendly strategies known as integrated pest management (IPM). IPM includes new cultural practices (a new plastic bed cover that reflects UV light and repels thrips : anyway UV-reflective mulches also repel aphids, drastically reducing both feeding and probing by them in sweet pepper and baby marrow (zucchini)), natural insecticides (spinosad is a mixture of 2 of the most active, naturally occurring metabolites (spinosyns A and D) produced by the soil-inhabiting actinomycete Saccharopolyspora spinosa : upon ingestion of the spinosyns, death follows due to extremely rapid excitation of the insect nervous system), bio-control agents or natural predators, and a new treatment that boosts the plant's resistance system against viral and bacterial pathogens (Actigard^®). Resistance to TSWV but not to other tospoviruses, based on a hypersensitive reaction, has been found only in accessions of Cc 'PI152225' and 'PI159236'. The resistance, carried by the dominant gene Tsw, is broken at high temperatures and depends on plant age, with young plants being more susceptible. The Tsw gene has been introduced into several commercial sweet and hot pepper cultivars with good agronomic performance. Resistance-breaking strains of TSWV systemically infecting resistant plants have been found under experimental conditions and in the field^{ref1, ref2, ref3, ref4}. In 2004, leaf samples of a processing tomato variety carrying the Sw5 resistance gene to Tomato spotted wilt virus (TSWV) were collected from field grown plants in Mesagne (BR), Apulia (Southern Italy). Leaf extracts were tested by lateral flow and/or ELISA (Roggero et al. 2002) for TSWV, Impatiens necrotic spot virus (INSV), Cucumber mosaic virus (CMV), Tobacco mosaic virus (TMV) and Potato virus Y (PVY). Leaf dips were also observed with a transmission electron microscope and 2 of these samples were inoculated mechanically on to a set of test plants. Only TSWV was detected in all the field samples tested. One of the TSWV field isolates, T992, was investigated for the ability to overcome the resistance gene Sw5. T992 was mechanically inoculated onto 20 plants of each F1 hybrid tomato cultivar carrying the Sw5 gene (Cvs Donald, York, Rovente, Valiente, Hermes, UGX 9233, Diaz, ISI 19343, Es 5302, Scipio and Herdon); cv Marmande was used as a susceptible control. Another set ofF1 hybrids was mechanically inoculated with strain p105; a wild-type strain of TSWV (Roggero et al., 2002). Tomato plantlets were inoculated at the 4-5 true leaf stage and systemic infection was tested 20 days post-inoculation using ELISA. All hybrids carrying the Sw5 gene were uninfected systemically by strain p105, with the exception of 4 plants of F1 UGX 9233. In contrast, T992 systemically infected all F1 hybrids tested. Marmande was infected systemically by both p105 and T992. These results showed that strain T992 can overcome Sw5 gene resistance. Portions of the S and M genome of T992 were cloned and sequenced, and the data deposited in GenBank (accession numbers AY848922 and AY848921, respectively). Using a 560-bp fragment corresponding to part of the non-structural protein of the middle segment (NSm), the closest identity was to the SAN-1 isolate (AY124966), previously described from Apulia (Finetti-Sialer et al., 2002). Using a 780 bp N fragment the closest identity was to the LE98-527 strain from Bulgaria (99.6% identity at the nucleotide level) (Heinze et al., 2001). T992 was classified as an A-type isolate according to the MaeI restriction pattern used previously

(Finetti-Sialer et al., 2002). This was the 1st confirmed report of resistance-breaking (RB) strains of TSWV in tomato in Italy. Previously, RB strains of TSWV on tomato in Europe were identified only in Spain (Aramburu & Marti, 2003)^ref. This is the 2nd instance of a resistance-breaking strain of TSWV reported in Europe in the past 3 years. TSWV resistance-breaking strains have previously been reported from Italy in Capsicum spp. carrying the Tsw gene (Roggero et al., 2002) and from Spain in tomato species carrying the Sw5 gene (Aramburu & Marti, 2003). Resistance-breaking strains can spread, resulting in increased losses in fruit production and quality.  Similarly, in Australia, 3 of 1386 TSWV-infected Capsicum chinense accessions also expressed systemic symptoms when manually inoculated with specific TSWV strains. Resistance-breaking strains are a dangerous factor in crop production systems^{ref1, ref2, ref3}.
• Ophiovirus
• Mirafiori lettuce virus (MiLV)

=> lettuce big-vein disease (BVD) in lettuce (Lactuca sativa) ? : chlorotic vein banding that become ruffled and distorted. Symptoms are usually accompanied by reduced plant size and absence of head formation. Both LBVV and MiLV are vectored by the soil-inhabiting fungus Olpidium brassicae. Virions of MiLV are highly kinked filaments, about 3 nm in diameter, that form masses of 2 classes of particles differing in length that appear to be closed circles, suggestive of tenuiviruses. Disease management basically requires strict measures to kill the vector in the plastic growing trays. Other strategies include developing resistant
cultivars using a wild lettuce (Lactuca virosa) in crosses with cultivated lettuce and a range of biological control agents^{ref1, ref2}.
• ranunculus white mottle virus (RWMV) is similar to known tenuiviruses such as citrus psorosis-ringspot virus (CPsV) and tulip mild mottle mosaic virus (TMMMV), members of the genus Ophiovirus, family Bunyaviridae. Comparison of the core RNA-dependent RNA-polymerase (RdRp) motifs of negative-stranded RNA viruses supports grouping CPsV, RWMV, and MiLV in the Ophiovirus, creating a monophyletic group separated from all other negative-stranded RNA viruses
• Rhabdovirus
• citrus leprosis virus (CiLV)

=> citrus leprosis (EPPO A1 list) is a devastating viral disease of citrus. It has persisted in Brazil and Argentina since the early 1930s and as the previous postings referenced below and the disease distribution map indicate, it seems to be spreading in South and Central America.  It causes significant mortality of new wood growth, reduction in tree canopy development, premature leaf and fruit drop, and significant yield reduction. Citrus leprosis occurred in Florida citrus between the mid-1800s and 1962, with severe outbreaks between 1907 and 1925. No occurrence of the disease has been reported over the past 40 years in Florida and recent surveys in 2001-2002 did not detect the disease. Citrus leprosis differs from many other plant viruses, which are usually systemic in plant tissues. Sweet orange varieties are susceptible. Planting resistant citrus cultivars, pruning to reduce disease inoculum and seasonal acaricide sprays to control the mite vectors are the only existing means of minimizing the current impact of this disease.  Continued expansion of this viral pathogen in South and Central America can be seen as a warning that spread could occur to other citrus-producing areas. Because the disease is strongly symptomatic on leaves and twigs, this would probably require the introduction of viruliferous mites, probably on rooted plant materials, into areas that may already have the mite vector but not the virus. Citrus leprosis is non-systemic and so far, 3 mite species have been demonstrated to transmit the disease within and between citrus trees in the orchard, Brevipalpus phoenicis, B. californicus, and B. obovatus (Acari: Tenuipalpidae). In addition to Brazil, the disease occurs in other South American countries and it was recently identified in Central America in Panama, Costa Rica and Guatemala^ref. CiLV-infected plants show localized chlorotic lesions with necrotic rings in leaves, depressed chlorotic or brownish fruits and lesions in the bark and stems. Fruit drop often occurs and heavy infection can lead to death of trees. The disease is considered as one of the most important citrus diseases in Brazil, causing millions of dollar in damage annually to the citrus industries of Argentina, Brazil, Panama, Paraguay, and Venezuela. CiLV has been moving northward since 1941 and poses a serious threat to the billion-dollar U.S. citrus industry. The newly developed PCR procedure will certainly facilitate rapid detection of CiLV. The major production cost with citrus in Brazil is miticide applications. Current research in Venezuela suggests that CiLV may be pass through nurseries, with leaf lesions developing after the budlings have been planted into the field^{ref1, ref2, ref3}. Citrus leprosis has cost millions of dollars in damage to crops in South America, where it is well established. Symptoms include small, chestnut-brown spots -- commonly referred to as nailhead rust -- that appear on fruit, leaves, and green twigs of afflicted trees. The resulting loss of tree canopy growth combined with premature fruit and leaf drop reduce plant productivity. Sweet orange and some mandarin varieties are most susceptible. Citrus leprosis virus, which substantially damaged Florida's orange crop in the early 20th century, is slowly progressing northward from its outbreak epicenter in South America. The disease's presence in Central America has raised warning flags among U.S. Department of Agriculture (USDA) scientists at ARS and at the Animal and Plant Health Inspection Service (APHIS). The northbound spread of CiLV is considered a serious threat to the citrus industry of the USA. Brazilian scientists depended upon analyses of symptoms and transmission electron microscopy (TEM). However, accurate assessment of symptoms require field experience and can be confused with those caused by other plant pathogens. A region of the CiLV genome was sequenced and used to design specific primers that recognize only CiLV. These primers were used in RT-PCR to test more than 70 citrus plants from different species and varieties, originating from various geographic locations, and were shown to recognize only CiLV-infected plants. This is the 1st report on the development of a molecular-based method for the diagnosis of citrus leprosis. Disease management depends upon application of miticides and pruning infected branches from trees. Disease management of citrus leprosis is by control of the mite vector. Most of the currently available chemicals used to control mites are effective. Some of the products presently recommended in Brazil are azocyclotin, cyhexatin, hexythiazox, fenbutatin oxide, propargite and quinomethionate^{ref1, ref2, ref3, ref4, ref5, ref6, ref7}.
• ssRNA positive-strand viruses, no DNA stage
• Benyvirus
• beet necrotic yellow vein virus (BNYVV) (EPPO A2 list) occurs in Ukraine and Lithuania

=> rhizomania is a disease of beet (Beta vulgaris subsp. vulgaris). The disease is most serious on sugar beet, although it is also known to infest fodder beet, red beet, spinach beet, seakale beet, swiss chard and spinach (Spinacea oleracea). If left unchecked, there are significant reductions in sugar beet yields through reductions in root weight and accompanying reduction in sugar content. 3 different pathotypes (strains) of the virus have been identified, the 'A', 'B' and 'P' pathotypes. Sugar beet cultivars have been developed that are both tolerant and show some resistance to infection. It can greatly reduce sugar yield and tonnage. Further losses to producers in infested areas can result when movement of agricultural products is restricted by quarantine laws. The soilborne fungus, Polymyxa betae (Pb), serves as a vector of BNYVV by carrying the virus to healthy roots. The association of BNYVV with Pb is an unusual biological relationship that results in rhizomania development when a susceptible host is present and conditions are favorable for infection. Sugar beet serves as a host for both Pb and the virus. Although some weeds, primarily in the goosefoot family, also serve as hosts, their role in rhizomania development is not clear. Data from field surveys in Wyoming and Nebraska showed that Pb is relatively common and, when not carrying BNYVV, usually causes little damage to the sugar beet. Because BNYVV is spread is favored by conditions that favor both infection of sugar beet and rhizomania development. Pb forms 2 types of spores during its life cycle, resting spores and motile zoospores. Clusters of tiny, thick-walled resting spores, also called cystosori, enable Pb to survive in soil or in resting spores for 15 years or longer in the absence of a suitable host. When soil conditions become favorable for infection, germination of the resting spore is triggered by the presence of a host-plant root. As resting spores germinate, motile zoospores are released that actively swim to the root surface where new infections occur. Once a field becomes Pb-infested, crop rotation will not appreciably reduce disease risk because of the long-term survival of viruliferous cystosori. However, some soil fumigants such as those containing 1,3-dichloropropene may kill enough cystosori to reduce disease development to acceptable levels. Fumigation treatments are very expensive, and research is being done to determine their efficacy and conditions under which they should be used. Expenses associated with fumigant application may be justified, because significant sugar beet acreage is routinely treated with 1,3-dichloropropene for nematode control. The use of soil-applied fungicides has not been effective for rhizomania control in infested fields. Currently available tolerant or resistant varieties perform satisfactorily in the presence of rhizomania in some production areas, especially when used in combination with soil fumigation. However, these varieties must be tested in each production area to evaluate their performance under local environmental conditions and production practices. They also must be evaluated for performance after exposure to local diseases, insects, and weed pests. Research on the development of resistant varieties is progressing rapidly, with some having dual resistance to both rhizomania and Beet curly top virus. Management of rhizomania involves application of phytosanitary measures such as containment of spread in the affected area, avoiding movement  of soil from infested areas, use of rubber boots or disposable footwear, and cleaning and removal of adhering soil at the field site. Moreover, soil contractors, machinery, and highway vehicles should be removed. Removal of soil at the field site is necessary because resting spores are extremely difficult to kill with chemical disinfectants, especially when associated with soil. Therefore, infested soil removed from footwear and equipment is likely to remain infested and will serve as a potential source of contamination^{ref1, ref2, ref3}
• Bromoviridae
• Cucumovirus
• cucumber mosaic cucumovirus (CMV), the type member of the genus, is worldwide in its distribution, has the largest host range of any plant virus, infecting more than 800 species, and is transmitted by > 60 aphid species in a nonpersistent manner. Virus strains can be subdivided into 2 major subgroups, I and II (by serological and molecular methods), but all yield essentially the same subdivisions of isolates. Subgroup I, typified by isolate DTL, occurs predominantly in the tropics and subtropics, while subgroup II, typified by ToRS, is prevalent in temperate regions. Both subgroups, however, occur on bananas. Strains on banana vary from those that are symptomless to those inducing mild to severe symptoms. The heart-rot strain found in Morocco is particularly severe. The virus may cause chlorosis, mosaic, and heart rot, and is the etiological agent of infectious chlorosis disease in banana. In general, CMV does not have a major impact on banana production, but serious outbreaks have occurred. Bunch weight reductions of 45-62% have been reported. CMV has been reported as an emerging threat to the cultivation of banana in Kerala, India, especially where cucurbitaceous vegetables are cultivated as intercrops in banana. It is especially important to control CMV where mass propagation of in vitro banana material is employed, as levels of CMV in these plantings can be high. While considered worldwide in its distribution, CMV and CMV strains have been reported for the 1st time on bananas in a number of developing countries recently, probably due to the availability of efficient detection and identification methods. Disease management include planting CMV-free source plants, ensuring plants for propagation are free of virus, deployment of sensitive diagnostic procedures, and elimination of weed hosts from plantations and surrounding areas to control the virus and banana plantations should not be  close to crop hosts of CMV (e.g., cucurbits, tomatoes, and tobacco). Research has been directed to a program of virus elimination in the Plant Pathology Unit (FUSAGx, Belgium) in collaboration with the Laboratory of Tropical Crop Improvement (K.U.Leuven, Belgium). Different in vitro techniques, including thermotherapy, chemotherapy, electrotherapy or meristem culture, and cryotherapy were tested for their virus elimination capacity^{ref1, ref2, ref3}
• Ilarvirus
• Ilarvirus subgroup 1
• tobacco streak virus (TSV)  is transmitted by several species of thrips (genera Frankliniella occidentalis and Thrips tabaci; Thysanoptera) (possibly by allowing virus from the surface of infected pollen to enter through feeding wounds; Sdoodee and Teakle, 1987). The virus is transmitted by mechanical inoculation and grafting. TSV is readily transmitted via seed to high levels in Phaseolus vulgaris^{ref1, ref2, ref3}. It is also transmitted by pollen to pollinated plants. Disease management depends mainly on planting virus-free seed. Dahlia spp., Gossypium herbaceum [levant cotton], Melilotus alba [white sweet clover], Trifolium pratense [white clover], Phaseolus vulgaris [common bean], Cucumis sativus [cucumber], gherkin (Cucumis anguria), and Glycine max [soybean] are natural hosts. Capsicum frutescens [chili pepper] is susceptible to experimental transmission.
• Ilarvirus subgroup 3
• apple mosaic virus (ApMV), one of the oldest known and most widespread apple viruses, is probably distributed worldwide. It used to be rare in European apple trees but was disseminated by widespread distribution of the 1st infected Granny Smith clones, where it is latent and produces no symptoms. It can also cause line pattern symptoms in plum. ApMV is related to Prunus necrotic ringspot virus. ApMV-infected apple trees develop pale to bright cream spots on spring leaves as they expand. These spots may become necrotic after exposure to summer sun and heat. Most commercial cultivars are affected, but vary in severity of symptoms. Golden Delicious and Jonathan are severely affected, whereas Winesap and Mclntosh are only mildly affected. Except in severe cases, a crop can still be produced by infected trees; yield reductions vary from 0 to 50%. In some cultivars, bud set is severely affected. ApMV is transmitted by mechanical inoculation and root grafting, possibly not transmitted by pollen to the pollinated plant. Disease management basically consists of digging up infected trees and destroying them^{ref1, ref2, ref3}
• prunus necrotic ringspot virus
• Ilarvirus subgroup 4
• prune dwarf virus
• Closteroviridae
• Closteroviruses are transmitted by aphids, whiteflies or mealybugs, depending upon the virus. The outbreak of BnYDV in early 2004 occurred in approximately 20% of all bean-producing glasshouses in 3 Spanish provinces (Almeira, Granada and Malaga) destined for the fresh market. Yield losses have been reported from 25-100%, depending on local conditions. Disease management will depend upon reducing populations of Bt as well has clearing away vegetation that might support the vector^ref
• bean yellow disorder virus (BnYDV)
• Grapevine leafroll-associated virus 1 (GLRaV1)
• Grapevine leafroll-associated virus 2
• Grapevine leafroll-associated virus 3
=> leafroll in Vitis vinifera. It is transmitted by the insect vector mealybug (Planococcus spp.). GLRaV is probably the most wide-spread virus disease of grapevines world-wide. There are currently 9 different viruses associated with leafroll, but GLRaV 1 and 3 are most commonly found. In the U.S. national grapevine survey conducted in 1994-1995, GLRaV-1 was present in 1.0% of samples tested, whereas GLRaV-3 was present in 10.5% of samples tested. Since then Grapevine leafroll-associated viruses 2, 4 and 5 have been detected in imported grapevines. Yields of GLRaV-infected vines have reduced yields, and are increasingly sensitivity to environmental stress. Delayed maturity of grapes may result in a reduction of 10-70 percent in growth and yield, a 25-50 percent reduction in sugar content, and poorly coloured fruit. Long distance spread of GLRaV depends upon movement of infected planting material. Several mealybug and soft scale insect species have been shown to transmit leafroll-associated viruses under experimental conditions. Rapid leafroll spread has been reported in European vineyards having significant insect vector populations. In California, a very low rate of natural spread within vineyards has been observed. The common grape mealybug (Pseudococcus maritimus), which occurs in the Okanagan valley of British Columbia, is a vector of GLRaV-3. The etiology of GLRaV disease is not well established, but several filamentous viral particles have been associated with it, including 7 serologically unrelated closterovirus-like particles referred to as grapevine leafroll associated viruses 1 to 7 (GLRaV 1 to 7). Grapevine leafroll has also been associated with grapevine virus A (GVA), a trichovirus included in the rugose wood complex. 4 mealybug species (Pseudococcus longispinus, Planococcus ficus, Planococcus citri, and Pseudococcus affinis are known). The only Pseudococcidae reported to transmit GLRaV-3 are Planococcus ficus and Pseudococcus longispinus, but the scale insect Pulvinaria vitis may also be a vector. Several reports on field transmission of grapevine leafroll disease have confirmed the role of mealybugs as vectors of GVA and GLRaV- 3; although, in other studies, no vectors were identified. Leafroll of grapevines occurs worldwide in all grape-growing areas. Germany suffered an 80% leafroll infection in 1936. In Nuriootpa, Southern Australia, natural spreading of leafroll symptoms in Pinot noir clone material was observed. In 1993, 6% of vines displayed leafroll symptoms, which escalated to 21 and 36% in 1994 and 1995, respectively. In France some vineyards are reported to be 80% infected with leafroll. The incidence of leafroll infection over recent years in New Zealand has increased rapidly. The virus is now causing concern in New Zealand with possible rapid spread on the North Island.  The article chosen from several in early June 2006 points out that the virus is not new and may simply be catching the attention of some growers for the 1st time.  Management is by testing of existing groves for the virus, the use of clean (virus-tested) planting stock when replanting or establishing new vineyards, and by vector control. Despite the attempt to minimize alarm, it is clear from the article that the presence and spread of the virus is leading to systematic and accelerated replanting of some vineyards in New Zealand^{ref1, ref2, ref3, ref4, ref5}
• Crinivirus are filamentous viruses containing 2 separate genomic segments (650-850 and 700-900 nm), both of which are required for infectivity. Tomato (Lycopersicon esculentum) (field and glasshouse) is the main host, but other crops such as potato (Solanum tuberosum) and lettuce (Lactuca sativa are susceptible. 2 weed species (Jimson weed, Datura stramonium and Black nightshade, Solanum nigrum) are also hosts that may contribute to maintaining these viruses in the wild. Once either virus is established in an agricultural environment containing susceptible hosts, it is very difficult to prevent infection. Disease management requires use of virus-free transplants, avoidance of susceptible hosts (especially weeds), roguing (physical removal) of infected plants, and control of insect vectors by insecticides. Criniviruses are an emerging genus worldwide, containing new species that have evolved over time and are now evident as causal agents of new plant diseases. Their symptoms are easily mistaken for those of physiological or nutritional disorders or pesticide phytotoxicity, thus confounding their identification. Symptoms can vary, depending upon the host species, to include interveinal leaf yellowing, loss of photosynthetic capability, leaf brittleness, reduced plant vigor, yield reductions and early senescence. Criniviruses remain confined to cells associated with the plant phloem and symptoms are considered to result from plugging of the phloem with large viral inclusion bodies, thus likely interfering with normal vascular transport in infected plants. Both TICV and ToCV were first reported during the 1990s in the United States, and ToCV has been reported to occur in the Mediterranean countries, Portugal, Spain, and Italy. 4 crinivirus species transmitted by greenhouse white fly (GHWF) have been identified to date, including Beet pseudo yellows virus (BPYV), Strawberry pallidosis-associated virus (SPaV), ToCV and TICV. The latter viruses have exerted significant pressure on vegetable and fruit production in North America, Europe, and other parts of the world, affecting both greenhouse-grown crops as well as field crops. 3 viruses, primarily BPYV, SPaV, and TICV, are transmitted exclusively by GHWF, and are currently responsible for economic damage to vegetable and fruit production. Although ToCV is transmitted by the GHWF and impacts tomato production, it is much more efficiently transmitted by B. tabaci [Bt] biotype B than by GHWF, and its incidence is associated more closely with the presence of Bt in fields and greenhouses than with GHWF. These criniviruses have host ranges of varying size, ranging from quite narrow in the case of SPaV, to extremely broad in the case of BPYV. Although all GHWF-transmitted criniviruses infect weed species and wild relatives of cultivated crops, their primary agricultural impact occurs on 3 major groups of crops. Thus TICV and ToCV exert their main economic impact on tomato production in both greenhouse and field settings. SPaV is a problem in strawberry; BPYV, with its extensive host range, infects numerous cucurbit species, as well as strawberry and blackberry. Disease management is straightforward; use of virus-free transplants, avoidance of susceptible hosts, especially weeds, roguing of infected plants, and control of insects by chemical insecticides^{ref1, ref2, ref3, ref4}.
• beet pseudoyellows virus (BPYV) is transmitted in the semi-persistent manner by the greenhouse whitefly (Trialeurodes vaporariorum) and infects melon crops in glasshouses (Cucumis melo var. reticulatus) and in open fields for the cultivation of winter melon (Cucumismelo var. inodorus). The host range of BPYV includes several crop species such as beet (Beta vulgaris), lettuce (Lactuca sativa), endive (Cichorium endiva), shepherd's purse (Capsella bursa-pastoris), cucumber (Cucumis sativus), dandelion (Taraxacum officinale), and poison hemlock (Conium maculatum). 1st reported in beet  from Salinas, CA, in 1965, BPYV is spreading in Australia (Tasmania), France, Japan, the Netherlands, USA (California), and more recently reported from Italy, Crete, and possibly Spain. BPYV was discovered in 1965 in California and was the 1st crinivirus reported in the literature. It is transmitted by the greenhouse whitefly (GHWF) (taxonomically, Trialeurodes vaporariorum [Tv]), which has since been identified in production greenhouses throughout the world. The only known vector is the GHWF, which is often a chronic problem. BPYV has an exceptionally large natural host range among crop and weed species, infecting plants in at least 12 different taxonomic families, particularly for BPYV and to a lesser degree, for Tomato infectious chlorosis virus (TICV) and Tomato chlorosis virus (ToCV). Typical BPYV symptoms vary among hosts, expressing severe yellowing, reduced fruit size and possibly early senescence in cucumber and pumpkin. Greenhouse-grown cucumbers and melons are often infected with BPYV, which is facilitated by the accumulation of GHWF in closed environments. Some nurseries employ virus indexing programs and methods for eradicating viruses through tissue culture techniques. Application of these methods to GHWF-transmitted criniviruses, coupled with effective vector control, will reduce spread of these viruses as well as limit damage to susceptible crops both in greenhouse and field environments. There is little information on the availability of resistance to GHWF-transmitted criniviruses in any of the predominantly affected crops. Although a source of BPYV resistance has been identified in melon, this source has not been advanced into commercial cultivars. Ongoing research is examining wild tomato germplasm for sources of resistance to TICV, but no sources of resistance have been identified to date. Currently, the most effective method for control of criniviruses is an effective insecticide-based control program. Imidocloprid-based products are most frequently used for whitefly control, and can be applied as a foliar spray, a seed treatment or through drip application. While insecticides effectively reduce whitefly populations, they are inefficient for control of viruses, since whiteflies can transmit a virus before being killed by an insecticide. Most GHWF-transmitted criniviruses do not produce symptoms until 3 to 4 weeks after infection occurs, by which time it may be too late for implementation of control measures^{ref1, ref2, ref3}.
• citrus tristeza virus (CTV) in citrus plants for planting in Belize, Italy and Malta

=> tristeza, known as "quick decline" in the USA, is the most destructive disease of citrus in the western hemisphere and is worldwide in distribution, causing death and decline of trees on sour orange rootstocks and a debilitating stem-pitting disease in limes, grapefruit, and sweet oranges. It affects trees on all rootstocks and reduces yield. About 25 million trees on sour orange are at risk from CTV decline. Affected trees may suffer from quick decline, which leads to wilting and death in a few weeks. Other syndromes are seedling yellows and stem pitting disease. Only trees on sour orange rootstock are affected by tristeza decline. CTV causes an incompatibility at the bud union, resulting in girdling of affected trees. The virus is spread in a persistent manner by Toxoptera citricida (brown citrus aphid (BrCA)) and Aphis gossypii (cotton or melon aphid), and Aphis spiraecola (=citricola, green cotton aphid). Species composition and seasonal occurrence vary in different countries and regions. T. citricidus is not found in the Mediterranean area or North America, while A. spiraecola invaded the Mediterranean region in the 1960s and has become a serious citrus pest there. T. aurantii is not a major species, although it is abundant on tea in Japan (Komazaki et al. 1985). The most efficient vector is Toxoptera citricidus. This Old World species has been in South America for some years and reached Central America in 1989 and has been spreading through Central America and the Caribbean since then. Most CTV isolates can be detected by grafting to plants of Mexican lime (Citrus aurantifolia), or by ELISA. The monoclonal antibody MCA-13 detects most CTV strains that affect tops on sour orange rootstocks. Disease management utilizes certified bud-stock and resistant rootstocks, production of virus-free trees by shoot-tip grafting or heat treatment, production of trees in areas known to be free of CTV, inoculation of bud-stock trees with mild CTV strains, and occasional applications of chemical insecticides to reduce aphid populations^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9}. Disease management involves removal of declining trees on sour orange and replacement with trees budded on a tolerant rootstock is recommended when a tree is no longer economically viable; suppression and eradication of severe, stem-pitting CTV strains. Other measures include implementation of mild strain cross-protection; and introduction of virus resistance into desirable citrus varieties. Immunity to CTV present in Poncirus trifoliata has been transferred into sweet orange type plants suitable for use as breeding parents by conventional plant breeding techniques.  Symptom expression in citrus hosts is extremely variable and depends on the environment, the host and the virus isolate. Mandarins in general are tolerant to CTV and rarely show any symptoms. Sweet orange, sour orange, rough lemon and Rangpur lime are normally symptomless but will react to some severe CTV isolates. Limes, grapefruit, some pummelos, Citrus macrophylla, and some citrus hybrids will react to CTV infection. Symptoms of CTV infection can include total tree collapse, stunting, stem pitting, leaf cupping, vein clearing, chlorosis and reduced fruit size. Budwood testing negative for CTV is important in preventing primary infections of tristeza in CTV-free areas as well as the introduction of new perhaps more severe isolates in areas where the disease is already present. Detection and disease eradication or suppression has been effective in areas where low levels of infection prevail. Where orchards planted with sweet orange on sour orange rootstocks are declining, they should be replanted using CTV-tolerant rootstocks such as rough lemon, Rangpur lime, trifoliate orange, trifoliate orange hybrids of mandarins. Use of mild strain cross-protection may be a viable option for control.
CTV infects almost all citrus species, hybrids, and relatives. Consequently there are many strains of the virus that contribute to the diversity of symptoms associated with CTV infection. Mild CTV strains are basically asymptomatic in their hosts. Severe CTV strains express a range of symptoms including one or more of the following: seedling yellows; root stock decline on sour orange; grapefruit stem-pitting; and sweet orange stem-pitting. CTV-D strains cause death of the phloem at the bud union, which produces a girdling effect that can result in overgrowth of the scion at the bud union, paucity of feeder roots, stunting, leaf yellowing, reduced fruit size, poor growth, die-back, wilting, and death. Trees affected by decline on sour orange rootstock may also exhibit pinholing or honeycombing on the inner face of the bark, or brown discoloration at the bud union. Trees on sour orange exhibiting decline are routinely removed and replaced. Tolerant rootstocks include Carrizo citrange, Cleopatra mandarin, and Swingle citrumelo. Other virulent and damaging CTV strains cause stem-pitting (deep pits in the wood under depressed areas of bark) in scion cultivars and induce stunting and reduced production. Twigs on infected trees are brittle and break easily when intentionally bent or blown off by wind under fruit load. Stem-pitting may not be apparent until the bark is peeled from twigs. Rope-like external symptoms can also be caused by stem-pitting strains in grapefruit tree trunks and/or sweet orange scions. Stem-pitting of scions caused by CTV results in decline but does not usually cause tree death. The economic impact of these strains results from reductions in tree size and vigor, and reduction in fruit set, size, and quality. Stem-pitting is especially severe in limes and grapefruit, but can affect some sweet oranges. Mandarins are commonly tolerant, but some hybrids are affected. These CTV strains commonly occur in Asia, Australia, Southern Africa, Brazil, Columbia, Venezuela, and other areas. Host resistance is probably the single most attractive approach to control of virus diseases in long-lived horticultural crops such as citrus, where short-term measures do not give any benefit. However, development of new citrus cultivars is difficult because the citrus breeding cycle is usually 8-10 years. Moreover, most citrus cultivars are highly heterozygous, and the chances of combining virus resistance with all other essential horticultural features are low. Genetic engineering offers a means of incorporating virus resistance into existing desirable cultivars. Introduction of viral genes into plant genomes to confer resistance is well established in some systems, e.g. use of CTV coat protein to mediate cross-protection. Transformation and resistance can be demonstrated in a relatively short period, but the evaluation of transformed plants for fruit production is a long-term process. Mild strain cross-protection has been used successfully in several locations to reduce losses from CTV stem pitting, but has failed in others. It is difficult to find isolates that are both mild and protective and then show that these are not harmful to other cultivars or crops. This has limited the wider application of mild strain cross-protection. Our inability to predict or control all potential hazards has also precluded the preventative use of cross-protection. Shoot-tip grafting, a technique based on the fact that apical meristems contains little or no virus, has been used successfully to produce virus-free citrus plants.  It is a powerful tool to free existing cultivars of virus infection. Continued improvement in indexing procedures also makes verification of virus freedom much easier, and augments other regulatory approaches to control. Even once a virus is well established, selective certification or
regulation to curtail movement of the more severe isolates can be an effective component of management. Suppression of inoculum sources is also useful in some situations^{ref1, ref2, ref3}
• cucurbit yellow stunting disorder virus (CYSDV) is a virus endemic in Portugal and transmitted by the whitefly Bemisia tabaci and will spread internally in any area where the virus is introduced on vegetatively-propagated plants. It is on the EPPO A2 action list. At present, CYSDV has been detected and causes problems in France, Spain, Portugal, Morocco, Cyprus, the Arab Emirates and North America. In Spain, the yellowing symptoms caused by CYSDV are frequently observed in 100% of the plants when they are found in an affected greenhouse or screenhouse^{ref1, ref2}
• sweet potato chlorotic stunt virus (SPCSV) is whitefly-transmitted and in double infections with SPFMV cause sweet potato virus disease (SPVD), a serious sweet potato (Ipomoea batatas) disease in Africa. During the past decade, sweet potato plants showing symptoms similar to SPVD have been observed in most areas of Spain. SPVD is considered the most damaging virus disease of sweet potato in Africa and may be the most serious disease in the crop worldwide. SPCSV has been reported only from Africa (Nigeria, Uganda, Kenya, Zaire), Asia (Taiwan, China, Indonesia, Philippines), America (USA, Brazil, Argentina, Peru) and Israel. The fact that both viruses are present in Spain indicates that SPVD can be expected to spread in the country. Virus research at the International Potato Center in Peru is focused on SPVD because of its debilitating effect on resource-poor farms, especially in sub-Saharan Africa. Unfortunately, SPFMV-resistant cultivars originating from CIP were found to be susceptible to SPVD. Identification of genes for resistance to both SPCSV and SPFMV is a high priority. In China, using healthy planting materials resulted in yields that were 2-3 times greater than SPVD-infected plants. Similar results were obtained in African trials^{ref1, ref2, ref3}
• sweet potato sunken vein virus
• tomato infectious chlorosis virus (TICV) is transmitted only by Trialeurodes vaporariorum. 1st reported during the 1990s in the United States
• tomato chlorosis virus (ToCV) is transmitted by several insect vectors, including the greenhouse whitefly Trialeurodes vaporariorum, the banded-wing whitefly (Trialeurodes abutilonea), and by Bemisia tabaci (biotype A) and Bemisia argentifolii (biotype B). The virus is a nasty pest, especially in glasshouse operations. Although it can cause severe crop losses in fresh market and glasshouse-produced tomatoes, damage is generally minor. It also infects several other food crops such as lettuce (Lactuca sativa and potato (Solanum tuberosum). The fact that ToCV and TICV induce identical symptoms in tomato requires careful diagnosis to distinguish between the 2 viruses. Disease management depends upon use of virus-free transplants, control of susceptible weed species, roguing of infected plants, and control of insects by chemical insecticides^{ref1, ref2}. 1st reported during the 1990s in the United States, ToCV has been reported to occur in the Mediterranean countries, Portugal, Spain, and Italy. Fruit size and number appear reduced by ToCV infection. Disease management involves raising and maintaining Bt-free tomato transplants. To prevent entry of the various vectors into production sites, greenhouses and screenhouses have to be constantly monitored for the presence of vectors. Use of approved chemical insecticides can reduce disease incidence. Florida producers can obtain recommended information from the latest Insect Management Guide^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8}.
• bean yellow disorder virus (BnYDV) was first reported in the autumn of 2003 in French bean (Phaseolus vulgaris) grown commercially in Spain. Symptoms resembling nutritional disorders consisted of interveinal mottling and yellowing in leaves, combined with stiffness or brittleness, were produced on the middle to lower parts of affected plants. Similar plants infested with whiteflies (Bemisia tabaci) were observed in greenhouses. Reproducible symptoms were observed when the virus was transmitted from bean to bean by Bt (9/10) but not by mechanical inoculation (0/30)
• unassigned species in the family Closteroviridae
• little cherry virus-1
• little cherry virus-2
• little cherry virus-3

=> little cherry disease (LChD) occurs in Canada, Germany, Belgium, UK, the Netherlands and Switzerland, but their relation to the disease in USA is not known. It has not been reported from Spain, Italy or France, suggesting a tendency to be confined to northern regions. In USA LChV-1 occurs in both eastern and western cherry-producing areas. Of particular interest is that ornamental flowering cherries are symptomless carriers of LChV-1. Symptoms on sensitive cultivars include discolored fruit that remain small, pointed in shape, and tasteless^{ref1, ref2}.
• Comoviridae
• Comovirus
• bean pod mottle virus (BPMV) causes significant crop losses in soybean. It is spread primarily by the bean leaf beetle Cerotoma trifurcata (bean leaf beetle), Colaspis brunnea (grape colaspis), Diabrotica balteata, and southern corn root worm (D. undecimpunctata). BPMV is stable, easily transmitted mechanically and occurs at relatively high levels in seed coats from seeds of infected soybean. Yields from infected plants are lowered by 10-40%, grain quality is reduced both in oil and protein, seed germination is lower and delayed maturation results in a condition known as 'green stem.' The fact that BPMV has been reported in Iran is interesting, suggesting that infected seed may have been used for planting. This report may be the 1st finding of BPMV outside of North America^{ref1, ref2, ref3, ref4}. BPMV was 1st reported in Phaseolus vulgaris cv. Tendergreen; from Charleston, USA; by Zaumeyer and Thomas in 1948. It causes significant crop losses in soybean. It is spread primarily by the bean leaf beetle Cerotoma trifurcata (bean leaf beetle), Colaspis brunnea (grape colaspis), Diabrotica balteata, and southern corn root worm (D. undecimpunctata). BPMV is stable, easily transmitted mechanically and occurs at relatively high levels in seed coats from seeds of infected soybean. Yields from infected plants are lowered by 10-40%, grain quality is reduced both in oil and protein, seed germination is lower, and delayed maturation results in a condition known as "green stem." It can also be transmitted by mechanical inoculation, by grafting, but is not transmitted by seed or by pollen. BPMV spreads in the North American region. The fact that BPMV has been reported in Iran is interesting, suggesting that infected seed may have been used for planting. BPMV undoubtedly entered Iran in virus-infected seed. Growers should consider a later planting of soybean, especially if BPMV was a yield limiting factor in 2004. Late planting can result in an increased risk of soybean aphid activity at a sensitive growth stage. Plant soybean varieties with the ability to yield in the presence of BPMV. Use good quality seed that is not mottled, and consider the field history of this problem before making decisions as to whether to spray for the bean leaf beetle. Sprays must be carefully timed to be effective. Partial resistance to BPMV exists in soybean varieties. Partial resistance is expressed as acceptable yield, low seed mottling and a low incidence of green stem in the presence of BPMV. Soybean varieties differ in yield and incidence of mottled soybean seed in the presence of BPMV. Early soybean planting can coincide with high populations of over-wintered bean leaf beetle adults moving into soybeans to feed and lay eggs. This timing increases the chance of BPMV transmission to soybeans^{ref1, ref2, ref3, ref4, ref5}.
• radish mosaic virus (RaMV) occurs naturally only in cruciferous plants (e.g. cauliflower (Brassica oleracea) and turnip (Brassica rapa)) but can be detected following inoculation in some non-cruciferous species (necrotic local lesions on Chenopodium amaranticolor, chlorotic ring spot on Nicotiana tabacum cv. Samsun, and chlorotic local lesions followed by systemic mosaic on Brassica rapa). It is transmitted by several beetle species (Phyllotreta, Epitrix hirtipennis, and Diabrotica undecimpunctata; Coleoptera). It is also transmitted by mechanical inoculation and by grafting, but, it is not transmitted by seed. RaMV occurs in Austria, Germany, Hungary, Italy, Iran, Japan, Morocco, the USA, the former USSR, and the former Yugoslavia. RaMV is common in turnip crops in Yugoslavia. Disease management is mainly by application of chemical insecticides^ref
• squash mosaic virus (SqMV)
• Nepovirus
• grapevine fanleaf virus (GFLV)

=> mild systemic mottling and leaf malformation in Cucumis quinoa and Nicotiana tabacum and systemic chlorosis in Cucumis sativus, and Vitis vinifera. GFLV causes a degenerative disease that is considered to be the most serious grapevine virus disease. Affected vines are smaller than healthy vines, and they show progressive decline. Fruit quality is poor and yield losses range up to 80%. Moreover, the productive life of vineyards are shortened and winter hardiness is decreased. GVLF is transmitted by the nematodes Xiphinema index and X. italiae.  Natural hosts are Vitis vinifera, V. rupestris and many other Vitis spp. and  interspecific hybrids. Symptom expression includes systemic green or yellow  mosaic, ring and line patterns and flecks, leaf and nodal malformation. GFLV is probably distributed worldwide (in all areas where Vitis vinifera and American hybrid rootstocks are grown)
• subgroup A
• Arabis mosaic virus (ArMV)

=> leaf mottling and flecking, stunting and leaf deformation including enations. Many infections are latent and plants are symptomless. Symptoms vary greatly by variety, rootstock and environment conditions. Yield losses of up to 50% may occur through reduced growth, dieback and severe fruit drop. Long-distance spread occurs primarily by movement of infected propagative material. ArMV virus is transmitted by the nematode Xiphinema diversicaudatum, which is present in permanent pasture and woodland sites in Europe and parts of the U.S., in scattered locations in Canada, and in Australia. It also infects many other herbaceous and woody hosts such as raspberry, strawberry, rhubarb, cherry, peach, and plums.
• raspberry ringspot virus (RpRSV) is transmitted by the nematodes Longidorus elongatus and L.macrosoma. The virus is transmitted by mechanical inoculation, by infected seed and by pollen to the seed. RpRSV spreads in the Eurasian region and the Mediterranean region; Austria, Belgium, Bulgaria, the former Czechoslovakia, Finland, France, Germany, Greece, Hungary, Ireland, Luxembourg, the Netherlands, Norway, Poland, Spain, Switzerland, Turkey, the UK, the USA, the former USSR, the former Yugoslavia. Found, but with no evidence of spread, in Denmark. Control of this disease includes pre-plant soil fumigation of vineyard sites to kill the dagger nematode vector. If diseased vines are present in an established vineyard, all infected vines will need to be identified and removed. The soil should then be tilled for one growing season. Fumigate late-summer or autumn soil prior to replanting with certified virus-tested clean stock. See MSU Extension Bulletin E-806 "Vineyard Preparation for Nematode and Virus Disease Control" and the Michigan Fruit Management Guide, (Extension Bulletin E-154) for further recommendations concerning control by soil fumigation
• tobacco ringspot virus (TRSV)

Of the many diseases caused by TRSV, bud blight of soybean is the most severe and causes the greatest losses. Yields may be reduced by 25 to 100%. TRSV is the type member of the nepovirus group of plant viruses and is related to arabis mosaic virus, grapevine fanleaf virus, tomato black ring virus, and tomato ringspot virus. Several strains of TRSV naturally infect soybean. TRSV is easily sap-transmissible. Nymphs of Thrips tabaci transmit it to soybean at a low level of efficiency. The dagger nematode Xiphinema americanum also is a vector, but its efficiency in transmitting the virus to soybean is low. Nematode transmission of TRSV to plant roots may be of no  significance, because the infection generally remains confined to the roots. Seed transmission is the most important mode of long-range dissemination and carry-over from season to season. Disease management involves planting a few soybean cultivars with resistance to a some TRSV strains. One genotype (PI 407287) of the annual ancestor of soybean (Glycine soja) is resistant to the virus. Other resistant USDA plant introductions are  92713 and 154194. Virus-free soybean seeds should be used in commercial fields, and it may be desirable to avoid fields infested with dagger nematodes or treat them with an appropriate nematicide, if feasible^ref.
• subgroup C
• cherry leaf roll virus (CLRV)

=> grapevine
• tomato ringspot virus (ToRSV)

=> chlorotic local lesions with systemic top necrosis in Chenopodium amaranticolor, necrotic local lesions followed by systemic ring pattern in Nicotiana tabacum, and chlorotic lesions followed by chlorosis in Cucumis sativus, and Vitis vinifera. Soil-inhabiting nematodes (Xiphinema spp.) acquire the virus during feeding on infected plants and transmit it to roots of neighboring plants. Long-distance spread is by movement of virus-infected seed
• Flexiviridae
• Capillovirus
• apple stem grooving virus
• citrus tatter leaf virus (CTLV)
• cherry virus A (CVA) has been reported in sweet cherry in Germany, Poland, Canada, and Great Britain. CVA has been detected in leaf and bark material taken from 15 of 16 sweet cherry trees as well as from apricot and peach. No data are available on the impact of CVA on fruit yield from sweet cherry orchards, but it appears to be ubiquitous in the UK. CVA is graft-transmissible, may also be seed-transmitted, and is widely distributed in sweet cherry trees in Germany and Canada. CVA may not cause disease in cherry trees, but it may be a synergist necessary for disease development.
• Carlavirus
• cowpea mild mottle virus (CPMMV)

Vector transmission of CPMMV by Bemisia tabaci appears to be due to virus contamination of the stylet and/or the foregut following feeding on infected plants. High densities of Bt would likely increase the rate of transmission. CPMMV is also transmitted mechanically, and some isolates are transmitted by seed. The virus has been reported from Asia, Africa, Brazil, and Oceania but is not reported from EU countries to date. It appears to be unrelated to known members of the Carlavirus genus. It primarily infects tropical field crops. Its quarantine pest status in EU countries is very minor, if not doubtful^ref.
• garlic common latent virus is of minor significance, but combined with other viruses can cause severe disease in Europe, South and Central America, India and China
• Foveavirus
• cherry green ring mottle virus (CGRMV) (a.k.a. sour cherry green ring mottle virus and cherry green ring mottle foveavirus). Usually CGRMV disease remains latent on sweet cherry and peach, sour cherry and ornamental _Prunus_ species. It develops leaf yellowing and dark mottles around secondary veins in early June in the United States. Fruits are often necrotized. On P. serrulata (Japanese cherry) the disease is very severe with twisting and atrophy of the youngest leaves. In early summer the bark cracks and the young tips die. About 5% of cherry and peach cultivars are contaminated with latent CGRMV. It seems to be evenly distributed in the plant and not epidemic. Indexing on P. serrulata and recently developed PCR tests are used for detection of the virus. In Europe, research has established that CGRMV-infected trees in the Campania region of Italy can also be infected with Apple chlorotic leaf spot leaf spot virus (ACLSV). At times indicator trees showed irregular ringspots and a marked clearing of the principal veins. To evaluate the possible presence of other viral agents, DsRNAs purified from the infected GF305 indicator  trees were used as templates in a polyvalent PCR detection assay. Besides ACLSV, PCR products corresponding to 2 additional viral agents could be amplified and sequenced. One of the agents appeared to be a new Trichovirus, while the other appears to be a Foveavirus closely related to Cherry green ring mottle virus (CGRMV). A new molecular technique to detect these 2 cherry flexiviruses in _Prunus_ spp has been developed. It is sensitive and reliable, and can detect both viruses simultaneously. The method is more cost-efficient, takes up less space, and is completed in 2 days instead of 4 months^{ref1, ref2, ref3, ref4}
• cherry necrotic rusty mottle virus (CNRMV)
• Trichovirus
• apple chlorotic leaf spot virus
• cherry mottle leaf virus (CMLV)
• Vitivirus are a genus of viruses associated with the rugose wood disease complex. All are transmitted by mechanical inoculation, those infecting grapevine with greater difficulty. Transmission is by grafting, and dispersal through propagating material is common with grapevine-infecting species. Detection technologies include grafting to indicator hosts, serology (primarily ELISA) and PCR. Disease management depends upon use of certified healthy stock or known to be virus-free. Trees should not be planted in soils where viruses have been found previously. Trees exhibiting suspicious symptoms should be removed^{ref1, ref2, ref3, ref4, ref5}.
• grapevine virus A (GVA) is associated with Kober Stem Grooving and affected vines may show swelling at the graft union and fail to thrive. Ungrafted vines may be infected, but usually do not show symptoms. GVA has also been associated with grapevine leafroll-associated virus
• grapevine virus B (GVB) is transmitted in a semi-persistent manner by different species of pseudococcid mealybugs in the genera Pseudococcus and Planococcus. GVB is widely distributed. Vitviruses are presently linked with rugose wood disorders, and some progress has been made in the understanding of their basic genome structure. Full-length infectious molecular clones of GVA and GVB from Italy have been used to inoculate grapevines in an attempt to provide essential pathology

=> corky bark in grapevine. The disease affects only grafted vines. The severity of corky bark is more pronounced in vines infected with other rugose wood complex viruses. Corky bark causes an incompatibility to develop at the graft union. Leaf symptoms resemble those of Leafroll but are more severe. Leaves on cultivars such as "Pinot Noir" may develop a yellow chlorosis before they turn red. The wood at the base of canes may swell slightly, causing the bark to split. Depending on the cultivar, various wood groovings also may occur.
• grapevine virus C (GVC)
• grapevine virus D (GVD)

Neither GVC nor GVD have been proven to cause disease in grapevine, but their structure and genetic profiles have shown that they belong to the Vitivirus genus.
=> rugose wood disease complex
• Idaeovirus
• raspberry bushy dwarf virus (RBDV)
• Luteoviridae
• Luteovirus
• soybean dwarf virus (SbDV) causes widespread economic losses on soybean (Glycine max (L.) Merr.) in Japan, and has been reported on soybean in Virginia, in various legumes in the southeastern United States, and in peas in California. SbDV is transmitted by an aphid (Acyrthosiphon (Aulacorthum) solani

(some isolates also by Acyrthosiphon pisum) in a persistent manner. Both
aphid species are present throughout the USA and also worldwide. Common
names of Acyrthosiphon (Aulacorthum) solani are pea aphid and green pea
louse. For Aulacorthum solani, the common name is the foxglove aphid. SbDV has been reported from Australia, Japan, New Zealand, and the USA (California). The 1st natural appearance of SbDV was in Blacksburg, Virginia in 1999. SbDV is serologically related to beet western yellows, barley yellow dwarf (strains RPV and MAV), bean leaf roll, potato leaf roll, and tobacco necrotic dwarf viruses. A 50% incidence of field infection may result in as much as 40% reduction in crop yield. Subterranean clover red leaf virus is so closely related that it is often
considered to be the same species. Regarding the reproductive (R) stages of soybean, there are 6 stages: R1, beginning bloom; R2, full bloom; R3, beginning pod; R4, full pod; R5, beginning seed; and R6, full seed^ref.
• Polerovirus
• cucurbit aphid-borne yellows virus (CABYV) has isometric particles of 25 nm in diameter. The genome of CABYV consists of a single molecule of positive sense ssRNA. CABYV was widely distributed with high frequency (nearly 50% of samples tested) in these 4 cucurbit species in the major growing areas of Iran.  This conclusion is based on an extensive survey by ELISA throughout Iran conducted during 2001 to 2004. CABYV was first reported in France in 1992 (Lecoq et al. 1992). So far, it has been recorded in other European countries (including Greece, Spain and Cyprus) and African countries (including Tunisia, Morocco, Sudan, and Zambia) and in the USA (California). Typical symptoms of CABYV on cucurbits include yellowing and thickening of old leaves. The major veins of these leaves remain green. These symptoms can be masked by mixed infection with other cucurbit viruses, and this was noted in the current study. Yield reduction in infected cucumber crops can reach about 50%. Major vegetable species susceptible to CABYV  include watermelon, muskmelon, cucumber, zucchini squash and lettuce (Lactuca sativa). CABYV can be transmitted persistently by the aphid Aphis gossypii with great efficiency and also by the aphid Myzus persicae. CABYV is not transmitted mechanically. The source of the virus is unknown, possibly wild cucurbits. Resistant curcubit cultivars are not available, but sources of resistance to CABYV have been identified in melon accessions^{ref1, ref2, ref3, ref4, ref5}. So far, it has been recorded in a few African countries that include Morocco, Sudan, and Zambia (Lecoq, personal communication). Typical symptoms of CABYV on cucurbits include yellowing and thickening of old leaves. Yield reduction in infected cucumber crops can reach about 50% (Lecoq et al. 1992). It has a narrow host range. Major vegetable species susceptible to CABYV include watermelon (Citrullus lanatus), muskmelon (Cucumis melo), cucumber (C. sativus), zucchini squash (Cucurbita pepo), and lettuce (Lactuca sativa). CABYV is not transmitted mechanically. According to Abou-Jawdah and colleagues at American University, Beirut and INRA, France, viral diseases are the major cause of economic losses in commercial cucurbit production in Lebanon. A survey revealed that Zucchini yellow mosaic potyvirus (ZYMV) and CABYV are the most common viruses of field-grown cucurbits in Lebanon. Other viruses involved were watermelon mosaic virus (WMV), papaya ringspot virus-watermelon strain (PRSV-W) and cucumber mosaic cucumovirus (CMV). Inoculation of squash with a mild strain of ZYMV (strain WK) gave significant protection against severe virus symptoms and resulted in significant yield increase as compared to the control, as did silver plastic mulch. The best protection and highest total yield were obtained with floating row covers (flexible nets or other types of screens). Integration of cross-protection with silver mulch or floating row covers improved the protection obtained with either approach. Cross-protection is still a useful disease management option for reducing yield loss and maintaining reasonable quality of product. Resistant curcubit cultivars are not available, but sources of resistance to CABYV have been identified in melon accessions^{ref1, ref2, ref3}. Resistance towards CABYV in Sudanese melons was only detected in the wild agrestis melons. Among different melon genetic resources collected from different parts of the world and evaluated for resistance against CABYV, the Sudanese Humaid accession T-EK 92-2 was found segregating for resistance (Dogimont et al. 1996). Further, the wild melon (Humaid) line HSD 2445-005 was found to be homogenously resistant, while the Humaid accession HSD 2441 was also found segregating for CABYV resistance. Yield reduction in infected cucumber crops can reach 50%. According to Abou-Jawdah and colleagues at American University, Beirut and INRA, France, viral diseases are the major cause of economic losses in commercial cucurbit production in Lebanon.
• potato leafroll virus
• Potexvirus
• pepino mosaic virus (PepMV) was originally described from pepino (Solanum muricatum) in Peru (found in 2 tomato (Lycopersicon esculentum) crops in 1974 and then no longer observed) it was identified in 1999 as the causal agent of a severe tomato disease in commercial greenhouses in the Netherlands and has been reported as a serious problem in greenhouse tomatoes throughout Europe (Bulgaria, Hungary, Germany, UK, Belgium, France, and Spain), Canada, and the USA . The prevailing assumption is that PepMV was brought to Europe from South America by unknown means. In most of these countries it is under control or has been eradicated. Unfortunately, pepino mosaic is present in outdoor tomato production areas in Spain, where it causes serious crop loss in localized areas. Results of studies (symptoms on plant indicator hosts and % homology in a 547-bp PCR fragment derived from the RNA-dependent RNA polymerase gene) all of 15 PepMV isolates from countries within Europe and elsewhere are considered members of the same strain, designated as the tomato strain of PepMV. Moreover, the high similarity between the various isolates suggests that the outbreaks in Europe likely originated from a common locus. Pepino mosaic is difficult to manage as it is a very contagious disease that spreads easily by use of contaminated tools, shoes, clothing, hands, and plant-to-plant contact. Moreover, movement of workers can spread the virus by brushing against infected plants. While a high density of bumblebees has been associated with PepMV spread in a crop, the risk of spreading the virus via hand pollination may be greater. PepMV can be transmitted by grafting or pinching suckers from mother plants. Virus can be spread over long distances by transportation of infected tomato fruits or contaminated seeds. Very strict phytosanitary procedures (use of virus-free seed and transplants, sterilization of equipment and facilities, and disinfection of circulated irrigation water) are required to maintain healthy plants, especially in glasshouse operations. Also infects tomato seeds, vegetables in Chile, Sweden, UK, Netherlands, France, and Spain (detected in a shipment of tomato seeds originating from China). PepMV is extremely contagious, and infectious virus is present on seed surfaces, in seed pulp, and in wash water from infected seeds. Transmission through seed is considered unlikely. As a precaution, tomato seed in commercial production is treated with acid under controlled conditions to eradicate any virions on the seed surface. According to the International Seed Health Initiative for Vegetable Crop's Manual of Seed Health Testing Methods Detection, testing for PepMV on seeds is a 2-stage process: an ELISA, and, a bioassay, in that order. During drying, storage, and, with disinfection treatments, the majority of seed-borne PepMV virions degrade and lose infectivity. Both infectious and non-infectious virus particles are detected in ELISA. Hence, a negative (but not a positive) ELISA result is conclusive on the seed health status of the seed lot. In the bioassay, only infectious PepMV is detected. Hence, both a negative and a positive bioassay result are conclusive on the seed health status of the lot^{ref1, ref2, ref3, ref4}. PepMV has been detected for the 1st time in Ecuador in wild populations of Lycopersicon pimpinellifolium along the Pacific coast of the South American continent in 2005. Potexviruses are extremely infectious but they are not known to be naturally spread by vectors. PepMV is easily spread via contact with infected plants. PepMV has been detected in the potato cultivar 'Yungay' growing in the Andes in Peru. Moreover, 14% of tested accessions in the potato germplasm at the International Potato Center in Peru are infected with PepMV. More research is required to determine the risks of PepMV infection in potato. Spread from tomato to potato may be possible under field conditions in southern Europe. PepMV induced serious losses in tomato fruit quality in trials at Efford in the UK in 2003. In the 'worst case' scenario, these losses could be in the order of GBP 37.5 million [USD 64.4 million] in the GBP 79 million [USD 135 million] UK industry, assuming that the disease becomes endemic in all tomato fruit production areas. In practice, losses may not be as great. Because the UK industry is based almost exclusively on production of high-quality fruit, with virtually no tomato processing industry, any losses of quality would be significant. Any drop in quality could be catastrophic for producers. Contrary to experimental results in the UK, numerous field and several experimental observations in the Netherlands and a few other EU countries indicate that PepMV has only a very minor or a non-significant economic impact on tomato production on average. More damage might be expected if PepMV-affected plants are also attacked by Verticillium sp. The economic impact due to PepMV is also influenced by the marketing system in a country. In the UK, only Class 1 fruit is profitable. This is not the case in several other EU Member States where, as a consequence, the grower can still profitably sell fruit of less than top quality.
• potato virus X
• Potyviridae
• Bymovirus
• barley yellow mosaic virus (BaYMV)
• barley mild mosaic virus (BaMMV) are transmitted by the soil-inhabiting and spore-forming bacillus Polymyxa graminis. Both viruses occur on barley in Europe and Asia and are economically important, soilborne pathogens of winter barley. Until recently, laboratory diagnosis of these pathogens has relied upon ELISA using polyclonal antiserum. Because of inherent virus particle instability, combined with the inability to sap-transmit BaYMV, high quality antiserum has been difficult to obtain and ELISA is often unsatisfactory. As an alternative approach, 2 TaqMan assays (1 BaYMV-specific and the other BaMMV-specific) have been developed. These assays have been validated for 3 seasons, by testing samples in parallel with ELISA. TaqMan assays are a more reliable detection method than ELISA, especially with late-season and mixed infection samples. Both fungi acquire the viruses following encystment on host roots, which then germinate to form a pre-penetration swelling termed an adhesorium. The protoplast is "injected" into the plant host cell by a bullet-like mechanism, causing infection in the root. The protoplast then grows into a multinucleate plasmodium which eventually converts into a sporangium to release further zoospores. As an alternative, the multinucleate plasmodium can convert into numerous thick-walled resting spores which are released when the host cells decay and can survive as an inoculum pool for many years in soil^{ref1, ref2, ref3, ref4, ref5, ref6}
• Ipomovirus
• beet virus Q : Polymyxa betae (Pb) is thoroughly established in Iranian soils. During a survey on soilborne viruses in sugarbeet, 2 viruses with rod-shaped particles were isolated, in addition to beet necrotic yellow vein furovirus (BNYVV). The Ahlum isolate proved to be serologically closely related to beet soilborne virus (BSBV), which was 1st described in England and has since been found in all sugarbeet growing areas worldwide. Recent data revealed that the 2nd serotype (Wierthe) should be considered a distinct virus species named Beet virus Q (BVQ). These 2 pomoviruses are also transmitted by Pb. Although their contribution to rhizomania remains a matter of debate, it is not uncommon to find them associated with rhizomania-infested fields. Moreover, occurrence of 3 different viruses, transmitted by a similar vector, within a single sugar beet raises questions regarding the epidemiology of rhizomania syndrome. Virus particle of the Genus Pomovirus are morphologically similar to other rod-shaped viruses, i.e. in the genera Furovirus, Pecluvirus, Hordeivirus, Tobravirus, Tobamovirus and Benyvirus. The derived amino acid sequences for the putative RNA 1-encoded proteins also suggest relatively close relationships to the genera Furovirus, Pecluvirus, Hordeivirus and somewhat more distant ones to the genus Tobamovirus. Affinities not only to genera Pecluvirus, Hordeivirus and Benyvirus, but also to genera Potexvirus and Carlavirus, are suggested by the derived amino acid sequences of their triple gene block-encoded proteins. The folding properties of the 5-UTRs of their genomic RNAs suggest affinities to the genus Tymovirus, those of the 3'-UTRs to genera Tymovirus, Tobamovirus and Hordeivirus. BVQ was isolated together with BNYVV from a sugarbeet tap root obtained from a rhizomania field near Braunschweig, Germany. Like BNYVV, it causes local lesions on C. quinoa, but those of BVQ appear about 5 days earlier after mechanical inoculation. They both have a more irregular shape with a tendency to spread along the veins. Systemic infections of C. quinoa were not observed. BVQ and BNYVV were separated from originally mixed infections by single lesion transfers. BVQ could not be transmitted to Nicotiana benthamiana or Nicotiana clevelandii, nor could it be re-transmitted by mechanical means to sugarbeet leaves or roots. It is possible that this isolate can be transmitted only by a soilborne vector, or it may have lost its infectivity for beets after several years of cultivation on C. quinoa. BVQ proved to be extremely difficult to purify; nevertheless, an antiserum was obtained with a partially purified virus preparation which, despite some additional reactivity with constituents of healthy C. quinoa, could be used in immunocapture RT-PCR, immunosorbent electron microscopy (IEM) and the immunoelectron microscopical decoration test. BVQ has been repeatedly observed by IEM repeatedly during the past decade in sugarbeet samples from various areas in Germany and abroad, indicating that it is widely spread. The most frequently detected virus was BSBV, followed by BVQ and then BNYVV. In no case was BVQ found alone. BVQ has been found in Bulgaria, Belgium, France, Germany, Hungary, Italy, and the Netherlands, but not from Turkey. From an epidemiological point of view, although the role of BNYVV in rhizomania syndrome is well established, there is controversy regarding the role of Pb in seedling growth and in severe stunting of sugar beet, and still others reject the notion that Pb has any effect on sugar beet growth. The controversy is emphasized by the study of 2 other viruses, which were possibly undetected in the Pb used in previous studies. Our study confirms the ubiquitous presence of BSBV in sugar beet fields. It was present in > 80% of the analyzed samples, with a frequency much higher than that observed for BNYVV. The limited number of samples tested does not preclude further detection possibilities on different sugar beet cultivars or on different species. In all cases, BNYVV occurred with BSBV and often with BVQ as well. It would be very interesting to check a possible interaction of pomoviruses with BNYVV^{ref1, ref2, ref3}
• cassava brown streak virus (CBSV) : 1st reported in cassava (Manihot esculenta), by Storey from East Africa in 1936. A devastating virus that causes cassava brown streak disease (CBSD), it is gaining in severity, threatening food and livelihood securities for millions of farmers and cassava consumers in Sub-Saharan Africa. CBSD is considered the most important disease of cassava disease in coastal lowlands of Eastern and Southern Africa, and, is also found along the shores of Lake Malawi in Malawi and Tanzania^{ref1, ref2, ref3}. In Tanzania, the rate of infection of CBSD ranges up from 2 - 83%, depending on cultivar and location. The peak period of disease spread occurs in cassava planted in April and May, and this correlates very well with peak populations of whiteflies (primarily Bemisia tabaci), confirming that it is indeed the vector. A recently developed RT-PCR assay can detect CBSV in symptomless germplasm and planting material with good success. Research efforts are being directed to increase the availability and utilization of improved cassava varieties, and to strengthen the national germplasm generation and deployment capacities in Kenya, Tanzania, and Mozambique. Interspecific crosses between domesticated cassava and the wild Manihot melanobasis at the Amani research station in Tanzania have resulted in good levels of resistance to CBSV. Local tolerant cultivars in southern Tanzania and Mozambique are also of use in disease management^{ref1, ref2, ref3}.
• sweet potato mild mottle virus
• Potyvirus
• bean common mosaic virus (BCMV) infects Phaseolus vulgaris crops in many regions of the world. It is transmitted in a non-persistent manner by aphids and is also readily seed-transmitted. The disease it causes decreases crop production. In Australia, BCMV has been reported in New South Wales, Queensland, Tasmania and Victoria, based on serology and amino acid composition. BCMV almost certainly entered Western Australia via infected seed. Its seedborne nature guarantees its spread, and infected seedlings are sources of virus inoculum. Many BCMV strains have been distinguished (Drijfhout et al., 1978). Those once grouped as serotype A are now considered isolates of a separate potyvirus species -- Bean common necrosis virus -- and several viruses, once considered to be distinct, have now been shown to be strains of this virus (McKern et al., 1992). The latter include: azuki bean mosaic virus, blackeye cowpea mosaic virus, cowpea (aphid-borne) mosaic virus, cowpea (blackeye) mosaic virus, cowpea vein-banding mosaic virus, peanut blotch virus, peanut stripe virus and some isolates from soybean. Genetic studies using F2 populations of P. vulgaris from crosses between differential cultivars of P. vulgaris and novel isolates of BCMV and Bean common mosaic necrosis virus (BCMNV) from Africa have revealed that there are previously undescribed resistance genes in P. vulgaris. These genes are currently under investigation using other novel isolates of BCMV and BCMNV. The primary aim of research on the molecular genetics of legume viruses is for the genetic improvement of Phaseolus vulgaris in Africa for resistance to viruses. Disease management is basically planting of virus-free seed^{ref1, ref2, ref3}
• cassava brown streak disease virus (CBSDV)

=> cassava brown streak disease (CBSD) in cassava (Manihot esculenta) no insect vector has been identified. As is the case with cassava mosaic disease, the CBSD virus may be transmitted by whiteflies -- a  group at the University of Bristol (U.K.) has reported transmission of the virus by whiteflies. CBSD infection causes a dry necrotic rot in the storage roots, decimating yields, often leading to complete spoilage or significant reductions in quality. Disease management involves planting of stem cuttings from healthy plants without leaf chlorosis, shoot tip die-back, cankers, fungus patches, or streaks on the stems. The International Institute of Tropical Agriculture (IITA) has begun a major, proactive emergency program to combat the disease and stabilize production of this important food crop. Locally grown cassava cultivars with apparent resistance -- or tolerance -- to CBSD have been identified in Tanzania and Mozambique and are being evaluated. These less susceptible cultivars have been made available to selected farmers in villages in Tanzania, and in Mozambique for evaluation by National Agricultural Research Services and the International Institute for Tropical Agriculture (IITA) programmes to screen a wide range of cassava material for resistance to CBSD^{ref1, ref2, ref3, ref4, ref5, ref6}.
• chilli veinal mottle virus (ChiVMV) : a aphid-transmitted potyvirus reported in chili pepper (Capsicum chinense)^ref in Hainan Province^ref, China from samples collected in 2003 and 2004^ref. ChiVMV is one of the most predominant viruses of peppers in Asia. Surveys in 16 Asian countries have shown that 30% of pepper crops are affected by this disease. Flower drop is normally severe following infection with this virus and therefore crop loss can be heavy. Growing transplants in insect-proof facilities, avoiding weeds and other solanaceous crops (e.g. tomato), planting early to avoid aphid flights, and using mineral oil sprays are methods used in attempts to manage the disease. Capsicum chinense, the crop plant infected, remains the least understood of the domesticated pepper taxa with respect to center of origin and its probable progenitor. Fruit shape can vary from long and slender to short and obtuse. Fruit can be extremely pungent and aromatic, with persistent pungency when eaten. The best-known cultivars are the very hot Habanero peppers, such as Scotch Bonnet^{ref1, ref2, ref3, ref4, ref5}
• leek yellow stripe virus causes severe disease in autumn and winter leek crops in western Europe and is probably present in leek production areas worldwide.
• garlic mosaic virus
• garlic virus 2
• onion yellow dwarf virus (OYDV) is transmitted by Myzus persicae and other aphid species, or mechanically to onions and other crops such as garlic, leek and some narcissus species. It is not spread by seed, but infected bulbs (transplants and volunteers) always produce diseased plants and serve as a source of contamination for following seasons, especially when aphid populations are high. Disease management relies on use of disease-free transplants and crop rotation out of onion production for at least 3 years. Other disease management recommendations include isolation from other susceptible crops or volunteer self-sown onions. Insecticides may suppress vector populations but generally are not necessary or effective^ref
• papaya ringspot virus (PRSV) cucurbit isolate (W) and papaya isolate (P) infects only hosts in the Cucurbitaceae (e.g. watermelon (Citrullus lanatus) and bottlegourd (Lagenaria siceraria)). PRSV-W is transmitted by aphids in a non-persistent manner, following acquisition of virus particles from a host reservoir, and are capable of transmitting it for 10-15 minutes in most cases. PRSV-W has been reported from Hawaii, Taiwan, Brazil, Thailand, the Caribbean islands and the Philippines. It is the major limiting factor in production of the crop. Disease management includes (1) the application of quarantine measures (prevention of the introduction of infected plants into a clean area; (2) preventing movement of papaya plants from areas known to be infected with the virus; (3) roguing of infected plants; and (4) use of tolerant and resistant cultivars which do not produce severe symptoms^{ref1, ref2, ref3, ref4}
• Pennisetum mosaic virus (PenMV) isolated from a perennial grass (Pennisetum centrasiaticum) : maize from only 1 region (Shanxi Province in northern China) has been found to be infected and the symptoms it caused, especially on sorghum, were significantly milder when compared to those of SCMV. Because it is a potyvirus, PenMV can be expected to spread via several aphid species, and seed transmission should be examined in maize and perhaps other species such as Panicum, Eleusine, and Setaria. Sequence comparisons and phylogenetic analysis showed 3 distinct groups of Chinese SCMV sequences (sugarcane isolates from Zhejiang province, a maize isolate from Guangdong and maize isolates from other provinces). It will be interesting to know more about the genomic relationships between PenMV and other maize-infecting potyviruses such as Maize dwarf mosaic, Johnsongrass mosaic, Sugarcane mosaic, and Sorghum mosaic.
• plum pox virus (PPV) infects apricot, plum and peach trees. Plum pox is the most devastating viral disease worldwide of stone fruit including peaches, apricots, plums, nectarines, almonds, and sweet and tart cherries^{ref1, ref2}. The disease significantly limits stone fruit production in areas where it is established. > 100 million stone fruit trees in Europe are infected. The virus can infect many wild species. It is transmitted by aphids and therefore extremely difficult to control. The Slavic name for plum pox, Sharka, is the most commonly used name for the disease around the world. PPV has been known in Europe since the beginning of the 20th century. First described on plums in Bulgaria in 1915, plum pox has spread to a large part of Europe, the Mediterranean, the Middle East (Egypt and Syria), India, and Chile. Since 1950, spread became more rapid, and in 1999 it reached Canada and the USA. An estimated 100 million trees are infected in Europe. Symptoms depend on the cultivar, the age of the plant and the nutrient status. On leaves, light green discolorations and yellow or light green rings may appear. Fruits develop pigmented rings or line patterns and are often deformed. For plums, premature fruit fall is abundant. Trees can remain without symptoms for up to 3 years after infection. At least 4 major strains of the virus are known, named PPV-D, PPV-M, PPV-C and PPV-EA, differing in symptom severity and patterns of spread. All strains are considered to be worldwide quarantine organisms, and fast eradication of infected trees is the most important instrument to manage the disease. In this report, PPV-D is the strain detected from samples collected from a single grove in November 2004 in Argentina. PPV was found in 1992 in neighboring Chile but is now eradicated^ref. In the fall of 1999, plum pox was detected for the 1st time in North America in a Pennsylvania orchard, and has subsequently spread to several provinces in Canada (Ontario in June 2000). 4 PPV groups have been described to date:  PPV-D in apricot trees from southeastern France, PPV-M in peach trees from Greece, PPV-EA in apricot trees from El Amar, Egypt, and PPV-C in sour cherry trees from Moldova. PPV-M isolates are more aggressive in peach, are aphid-vectored more efficiently, and spread more rapidly in an orchard.  PPV-M has been reported to be seed-transmitted, while other PPV strains are known not to be transmitted through seeds.  Both PPV strains M and D infest peach, plum, and apricot. The strain present in Pennsylvania has been determined to be PPV-D. PPV-C infects sweet and tart cherry naturally and has infected other Prunus hosts experimentally.  To date, no other PPV strains have been reported to infect cherry naturally.  Scientists use several techniques to distinguish PPV strains, monitoring the behavior of host trees, ELISA and molecular tests such as PCR, and sequencing of PCR products or cutting PCR products with enzymes at locations in the DNA sequence that are unique to each strain. Control and prevention measures for PPV include field surveys, use of certified nursery materials, use of resistant plants (when available), aphid control, and elimination of infected trees in nurseries and orchards. Sources of resistance exist in Prunus but are not abundant.  A team of scientists from the USA and France has genetically engineered a PPV-resistant plum (otherwise known as C5), and the resistance can be transferred through hybridization to other plum trees. This provides a unique source of germplasm for future breeding programs worldwide. There has been no similar success in attempts to genetically modify other Prunus species. The disease is very difficult to manage. Management strategies include prevention of spread to virus-free areas, eradication of infected trees, decreasing spread by aphids, and breeding for virus resistance. There is no cure or treatment for the disease once a tree becomes infected; infected trees must be destroyed. Several aphid species can transmit plum pox within an orchard and over short distances (about 1000 feet [300 m]) to trees in nearby orchards. Long-distance spread usually occurs as a result of the movement of infected nursery stock or propagative materials. Strain typing of detected isolates was especially important, because an unusual and potential new strain of PPV was detected recently in plum that originated from Eastern Europe. It is interesting that, in spite of identification as D strain based on RFLP analyses, the Kazakhstan plum and apricot isolates displayed atypical electrophoretic mobility of the CP subunits, migrating similar to that of the M isolate. The DAG motif was detected in both the plum and apricot isolates of PPV from Kazakhstan, indicating that they have the potential for aphid transmission. The 6-nt (2 amino acid residues) deletion observed in the plum isolate of PPV described in this study is the 1st deletion of this nature observed among isolates of PPV, but its biological significance is not known at present. The plum and apricot isolates appear to be closely related, sharing a number of nucleotides that appear to be unique to the Kazakhstan isolates. Based on these results, it is possible that the plum isolate was derived from the apricot isolate, because the latter appears to be more typical in terms of the number of nucleotides in the CP coding region of the genome^{ref1, ref2, ref3, ref4, ref5, ref6, ref7}
• potato virus A
• potato virus Y
• soybean mosaic virus (SMV) : resistance-breaking strains of SMV is a blow to plant breeders and pathologists. SMV is one of the most widespread viruses in soybean, and new resistance-breaking strains continue to emerge. An example is the cultivar Hutcheson, developed in Virginia, that is resistant to the common strains of SMV, but new resistance-breaking (RB) isolates of SMV have emerged in natural infections to break the resistance of Hutcheson containing the Rsv1 allele. Resistance to SMV is controlled by single dominant genes at 3 distinct loci, Rsv1, Rsv3, and Rsv4. The Rsv3 gene induces extreme resistance, hypersensitive response, or restriction to virus replication and movement, which are strain-specific. The Rsv4 gene functions in a non-strain specific and non-necrotic manner, restricting both cell-to-cell and long-distance movement of SMV. The Rsv1, Rsv3, and Rsv4 resistance genes exhibit a continuum of SMV-soybean interactions that include complete susceptibility, local and systemic necrosis, restriction of virus movement (both cell-to-cell and long distance), reduction in virus accumulation, and extreme resistance with no detectable virus. Cultivars containing 2 genes for resistance (Rsv1 and Rsv3 or Rsv1 and Rsv4) were resistant to multiple strains of SMV tested and show great potential for gene pyramiding efforts to ensure a wider and more durable resistance to SMV in soybeans^{ref1, ref2}.
• sugarcane mosaic virus (SCMV), the prevalent potyvirus infecting maize across China : mosaic followed by reddening and necrosis of the lamina
• sweet potato feathery mottle virus (SPFMV) is ubiquitous and aphid-transmitted :  in double infections with sweet potato chlorotic stunt virus (SPCSV) it causes sweet potato virus disease (SPVD)
• turnip mosaic virus (TuMV)
• zucchini yellow mosaic virus (ZYMV) (originally named muskmelon yellow stunt virus), first observed in 1981 in France and Italy, has since been reported from most southern and southwestern states in the US as well as and has been found in at least 22 countries on 5 continents, especially in Mediterranean countries, Central Europe and USA : France, the USA, Lebanon, Japan, Taiwan, Jordan, Singapore, Greece, Nepal and likely in other counties. It is one of the major members in the Potyvirus genus infecting cucurbits. It induces extreme symptoms on all melon types, including severe yellow mosaic on leaves, which is usually associated with distortion, deformation and fruit blistering. Plants are often stunted and fruit set is poor. The first few leaves affected on rockmelons may progress from chlorosis to full necrosis.  A number of ZYMV variants have been described, some strains of which may induce lethal wilting, others can cause cracks on fruits or mosaic and hardening of the fruit flesh. The virus has characteristics very similar to watermelon mosaic virus (WMV)-1 and Watermelon virus 2 (nonpersistent aphid transmission, etc.), and like WMV-2, its host range is not limited to cucurbits. Currently, none of the genetic factors that confer resistance to WMV-1 or WMV-2 are able to control ZYMV, but other resistance sources have been identified^{ref1, ref2, ref3}. It affects crops in. Cucurbita pepo (pumpkin), Cucumis melo (melon) and watermelon (Citrullus lanatus) are the predominant susceptible hosts. ZYMV is often associated with papaya ringspot virus (PRSV) or with watermelon mosaic virus (WMV) in tropical countries. The virus is transmitted by several aphids including (Aphis citricola, Aphis gossypii, and Myzus persicae). Evidence of seed transmission is equivocal. Symptoms include mosaic, yellowing, shoestringing, stunting, and fruit and seed deformations. Typical of aphid-transmitted viruses, it is extremely difficult to control with insecticides, reflective mulches, or mineral oils. Disease management involves use of resistant cultivars and control of infected weeds from which aphids can acquire the virus. Application of chemical insecticides is usually not economical. Disease management utilizes reflective mulches, judicious application of insecticides, and resistant cultivars. Some wild cucurbits are sources of ZYMV resistance genes, which may have application for developing resistant cultivars^{ref1, ref2, ref3}. Resistance is present in some lines of Cucumis sativus from China and in an accession of C. melo from India. Unfortunately, this resistance is strain-specific and thus not effective against a 2nd pathotype. Resistance is available in a wild squash (Cucurbita ecuadorensis) and in a C. moschata line from Nigeria. All tested commercial cultivars of Citrullus lanatus (watermelon) are susceptible, but resistance is available in some accessions of C. colocynthis from Nigeria. A very high level of resistance was found in some races of C. lanatus from Zimbabwe, but it confers resistance to the Florida strain only. In recent years, new squash lines possessing the coat protein gene of this virus have been developed and proved to be resistant under field conditions. The ZYMV coat protein gene has also been incorporated into melon and cucumber^ref.
• watermelon mosaic virus (WMV)
• Tritimovirus
• wheat streak mosaic virus (WSMV) infects wheat, barley, maize, oats and rye and some pasture and weed grasses. WSMV causes severe disease in some winter wheat crops in the Great Plains of North America, with average losses of 3%. There is one report from South America. It occurs throughout the Mediterranean Basin at low incidence and is reported from Eastern Europe and Australia. The virus is transmitted by the eriophyid mite Aceria tosichella^ref. Characteristic WSMV particles (700 x 15 nm) were observed in electron micrographs from infected wheat and confirmed by serological tests. Damage to wheat crops can range from complete crop failure to severe reduction in yield. The outbreak in Argentina was observed in cvs. ACA 223, Baguette and Buck Guapo in wheat fields in Cordoba province. WSMV has been reported from Canada, China, Czech Republic, Hungary, Iran, Jordan, Mexico, Poland, Rumania, Russia, Turkey, Ukraine, USA, the former Yugoslavia and Syria. In South America the first report occurred in 2004 in Argentina. In North America, conditions favoring spread of the disease are the presence of a source of infection coupled with early planting of winter wheat. Severe losses can occur in early planted fields of winter wheat and spring wheat. A. tosichella needs living plants to survive year-round. Nymphal mites can acquire the virus after feeding for 15 minutes or more on infected plants, and they remain viruliferous for several days in the absence of infected plants. High sequence identity of US and Turkish WSMV genotypes suggests that humans assisted the movement of WSMV across the Atlantic. Immigrants from the Crimea initiated the hard red winter culture in South Dakota, Nebraska, and Kansas in the 1880s, and germplasm exchange was frequent between the Great Plains of North America and the Black Sea. WSMV is reportedly seedborne at low rates (0.1-0.2%) in maize and wheat, and both the virus and its vector could have been transported across the Atlantic in grain shipments. Disease management depends upon eliminating or destroying volunteer wheat and susceptible weeds before the new crop is sown^{ref1, ref2, ref3, ref4, ref5, ref6}
• unclassified Potyviridae
• cucumber vein yellowing virus (CVYV)^{ref1, ref2}, first reported from Israel in 1960, has subsequently spread within the EPPO region (Israel, Jordan, Portugal, Spain, Turkey) and Sudan. The disease affects cucumber, pumpkin, squash, and watermelon (Citrullus lanatus). CVYV wreaks havoc on cucurbit hosts in the eastern Mediterranean region, causing considerable crop loss. Information on disease management is meager. Attempts to reduce losses center on use of virus-free seedlings, provision of screens in glasshouse production systems to prevent viruliferous whiteflies (Bemisia tabaci) from feeding on plants, use of chemical insecticides, implementing a period of at least a month between seeding new crops, and biological control using predacious insects (Encarsia formosa), a parasitic wasp, and the beetle Delphasutus pusillus. The fact that cucumber vein yellowing disease is present across the southern flank of Europe is of concern to plant pathologists and entomologists. CVYV is well established in Israel, Jordan, Turkey, Spain and Portugal. Symptoms in both cucumber and melon have been described as vein yellowing, vein clearing and stunting, with a corresponding yield reduction. Sudden death, an uncommon outcome for plant virus disease, was observed on melon in Spain. Avoiding infected propagation plants, management of whiteflies and weed reservoirs are the main ways to manage disease problems. Attempts to select or engineer useful tolerant or resistant varieties are being made^{ref1, ref2, ref3}
• Sequivirus
• Dandelion yellow mosaic virus (DaYMV) was isolated from dandelion and lettuce in Europe. Lettuce mottle virus (LeMoV), a putative sequivirus, is often found in mixed infections with Lettuce mosaic virus (LMV) in Brazil. DaYMV, LeMoV and LMV cause similar mosaics in field-grown lettuce. Differences in biology and sequence suggest that DaYMV and LeMoV are distinct species. Plants of lettuce (Lactuca sativa) cv 'Veronica' showing mottle symptoms were submitted to biological, serological and physicochemical tests as well as electron microscopy to determine a possible association of a virus matching the expressed symptomatology. Mechanical inoculation of sap extracts resulted in local lesions on Chenopodium quinoa and isometric virus particles were observed. The host range was restricted to a few species of Asteraceae, Chenopodiaceae and Solanaceae, and most commercial lettuce cultivars developed mottle symptoms when mechanically inoculated with the virus. Helichrysum bracteatum (strawflower), a spontaneous Asteraceae, was found to be a potential differential host since it is susceptible to the virus and not to Lettuce mosaic virus (genus Potyvirus). A serological relationship with Dandelion yellow mosaic virus was demonstrated by plate-trapped antigen-enzyme linked immunosorbent assays (PTA-ELISA). The fact that LeMoV has spread to the western side of the Cordillera de Los Andes is of significance to growers in that region, as is the finding that this is the 1st report of a sequivirus infecting field lettuce in Chile^ref.
• Sobemovirus
• rice yellow mottle virus (RYMV) causes symptoms of the disease yellow mottle in the crop plant rice, Oryza sativa. Symptoms include stunting, reduced tillering, mottling and yellowish streaking of the leaves, delayed flowering or incomplete emergence of the panicles and, in extreme cases, death of plants. The disease is a major constraint to rice production in Africa. RYMV was 1st reported in Kenya in 1966 and later found in most countries in Africa where rice is grown. RYMV is transmitted mechanically and by chrysomelid beetles but not by seed (a property of some Sobemoviruses). Chaetocnema pulla Chapuis is thought to be an important vector of the disease in Tanzania. Much of the spread may not be due to transmission by beetles but rather by mechanical inoculation. Very few rice varieties are resistant to RYMV. The highest level of resistance was provided by a cultivar of Oryza sativa indica, "Gigante," and a few cultivars of Oryza glaberrima series Tog. These varieties showed a natural high resistance characterized by a low virus titre and the absence of symptoms. In this 1st report of RYMV in Uganda, 4 samples were collected from symptomatic plants growing in a subsistence rice field north east of Lake Victoria, close to the Nile River, in 2000. The samples contained RYMV serotype 4, a serotype found in eastern Africa (Madagascar, Kenya, and Tanzania). It differs from (88% identity) the basal strains from eastern Tanzania. Rice is a relatively new crop in Uganda. It was introduced on a large scale in the 1960s and is now widely grown in many parts of the country, especially in the eastern and northern regions. To meet the increasing demand for rice, Uganda imports about USD 100 million worth of rice every year. The presence of RYMV will not be good news for those making efforts to increase rice production in Uganda, including expansions into the upland areas^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9}
• Southern bean mosaic virus (SBMV), 1st reported in common bean in samples from USA (Louisiana and California) in 1943, also infects Vigna unguiculata, [Vu] V. mungo and Glycine max, causing mosaic and/or mottle, and stunting (especially in Vu). It is transmitted in a semi-persistent manner by bean leaf beetles (Ceratoma trifurcata and Epilachna varieties), mechanical inoculation, grafting, by seed (3-44%) and by pollen. SBMV has been reported from Africa (Morocco) and from regions in the Americas (North, South and Central), and France. SBMV is transmitted to bean seedlings if germinating seeds are in contact with infective extracts or are planted in soil near roots of infected plants. Disease management essentially involves use of virus-free seed^ref. SBMV was 1st reported in Phaseolus vulgaris from samples collected in Louisiana and California, USA by Zaumeyer and Harter in 1943. There are several strains (cowpea strain (strain C), Ghana strain (strain G), severe bean mosaic strain or Mexican strain (strain M) and the type strain (strain B). Symptoms persist in P. vulgaris, Vigna unguiculata, V. mungo and Glycine max. Symptoms include mosaic and/or mottle, and stunting (especially in Vigna unguiculata). SBMV is transmitted by beetles (Ceratoma trifurcata and Epilachna variestis). It can also be transmitted by mechanical inoculation, by grafting, seed (3-7% in V. unguiculata cv. Early Wilt Resistant Ramshorn), by pollen to the seed and transmitted by pollen to the pollinated plant. It has been reported from the African region, the North American region, the South and Central American region and France. SBMV probably entered Iran via infected seed. The strategy for disease management involves managing the bean leaf beetle. Resistance to SBMV is not yet available
• Tobamovirus
• cucumber green mottle mosaic virus
• odontoglossum ringspot virus
• sunn-hemp mosaic virus
• tobacco mild green mosaic virus (TMGMV) probably occurs in all tropical and subtropical regions where Nicotiana glauca is distributed (North America, Australia and many European and African countries, including Madeira, the Mediterranean and Canary Islands; also in peppers (Capsicum annuum) in Taiwan).
• tobacco mosaic virus (TMV)
• tomato mosaic virus (ToMV), usually expresses characteristic mosaic symptoms, leading to considerable plant damage and yield losses. 3 resistance genes, Tm-1, Tm-2 and Tm-2(2) have been identified in crosses between wild and cultivated tomato species in efforts to prevent systemic infection and losses in fruit yield and quality caused by Tobacco mosaic virus (TMV) and ToMV. The Tm-2(2) resistance gene is used in most commercial tomato cultivars for protection against infection with tobacco mosaic virus (TMV) and its close relative tomato mosaic virus (ToMV). Observations suggest that the resistance conferred by the Tm-2(2) gene against ToMV depends on specific recognition events in this host-pathogen interaction rather than interfering with fundamental functions of the 30-kDa MP^{ref1, ref2, ref3}.
Tobacco mosaic and odontoglossum ringspot viruses are closely related, and cucumber green mottle mosaic and sunn-hemp mosaic tobamoviruses are distantly related. Disease management involves application of phytosanitary measures, especially avoiding contact between infected and virus-free plants. Production benches and equipment used in glasshouse production systems must be sterilized^{ref1, ref2, ref3}
• Tombusviridae
• Aureusvirus
• Pothos latent virus (PoLV). The scientific name for pothos is Epipremnum aureum; its common name is devil's ivy
• Necrovirus
• beet black scorch virus (BBSV)

=> black scorch in sugarbeet (Beta vulgaris). BBSV was first reported in the late 1980s in China. The virus is responsible for serious damage to the sugar beet crop in the Xinjiang, Ningxia, Inner Mongolia, Gansu, and Heilongjiang provinces of China. BBSV infects sugar beet plants systemically through the roots after transmission with Olpidium brassicae zoospores and causes black scorch symptoms on the leaves.  Sugar beets are grown as a commercial source of sucrose (sugar).  BBSV can result in significant loss of root yield and sugar recovery. BBSV has been reported in China and in 2006 in the USA and possibly elsewhere. It remains to be seen if this becomes a major disease problem.  The USDA is seeking the development of a suitable test for BBSV^ref, which is an indication that there are concerns^ref
• unclassified Tombusviridae
• cucumber leaf spot virus (CLSV), previously classified as definitive species in the genus Carmovirus. Aureusviruses are soil-borne viruses readily transmitted by sap inoculation to a moderate range of hosts. Natural transmission of CLSV is by the chytrid fungus Olpidium bornovanus [Ob], (previously O. radicale), whereas PoLV infects the host without the apparent intervention of a vector. A bulk culture of Olpidium radicale (now classified as Ob) from melon roots collected at Montfavet, France did not transmit CLSV or the cucumber fruit streak strain of CLSV (CLSV-FS). CLSV is sap-transmitted, and is seed-borne (c.1%) and soil-borne. Found naturally only in cucumber. Reported from Germany, Greece, Great Britain and Jordan (Weber et al., 1982, 1986; Gallitelli et al., 1983) and Spain. CLSV is most likely related to Melon necrotic spot carmovirus (MNSV), red clover necrotic mosaic dianthovirus (RSNMV) and cucumber necrosis tombusvirus (CNV). CLSV is an Aureusvirus in the family Tombusviridae and is most closely related to Pothos latent virus^{ref1, ref2, ref3, ref4, ref5, ref6}
• Tymoviridae
• Tymovirus
• melon rugose mosaic virus (MRMV)
•  Retro-transcribing viruses (a.k.a. Retroid viruses)
• Caulimoviridae
• Badnavirus
• banana streak virus (BSV)

=> banana streak disease was first described in Morocco and the causal virus, Banana streak badnavirus, was described in 1986. BSV has subsequently been recorded in Africa, Europe (Canary Islands and Madeira), Asia, North America (Florida), Central and South America, and the Pacific Islands. Infection of Musa by BSV limits development of new Musa hybrids in breeding programs worldwide. BSV has been transmitted experimentally by mealybugs (Planococcus citri and Saccharicoccus sacchari) [Ss] both of which colonize banana. Results of surveys in Uganda show that Dysmicoccus
brevipes [Db] and Ss were the most prevalent mealybugs, and the incidence of banana streak was correlated with the presence of Db. Disease managementis complicated because infected plants may be symptomless; but use of PCR and ISEM has facilitated rapid detection of BSV. 400 million people in developing countries depend on bananas and plantains as a staple food. Plant breeders need access to as much diversity as possible in order to develop higher-yielding varieties with resistance to pests and diseases. For bananas, the world's biggest collection is maintained in trust for humanity at the Katholieke Universiteit in Leuven, Belgium.KUL sends plants to researchers worldwide through IPGRI's International Network for the Improvement of Banana and Plantain (INIBAP). International guidelines, however, allow only movement of disease-free plants, but a  substantial part of the collection has been blocked because it is infected with BSV. Researchers from KUL and the Gembloux Faculty of Agriculture have already developed several techniques for eliminating viruses from sterile cultures in the banana collection. These techniques are effective against other diseases, but BSV remained a problem. Knowing that BSV is quite closely related to HBV, and uses some of the same chemical processes,  the banana scientists got together with the Rega Institute for Medical Research at KUL. This institute was responsible for developing adefovir and tenofovir, antiviral compounds tested and approved for the treatment of hepatatis B and AIDS. The researchers grew infected banana cells in the presence of small doses of the drugs for 6 months. Testing of whole plantlets produced from those cells demonstrated that up to 90% of the plantlets showed no sign of BSV.
• Caulimovirus
• cauliflower mosaic virus (CaMV) is found worldwide, especially in temperate areas of the USA and Europe. Its natural host range is limited to the Cruciferae (cabbage, cauliflower, Brussels sprouts, and others). The main sources of CaMV are infected brassica crops or cruciferous weeds on which any of several aphid species have overwintered. It is often found as a mixed infection with turnip mosaic virus (TuMV), resulting in more severe synergistic symptoms than when either virus is present alone. Disease management requires adequate weed control and sanitation, especially the rapid plowdown of previous crops. Transplant beds should be isolated from commercial crop fields and overwintering cruciferous weed hosts. Symptoms of CaMV are often confused with those of TuMV. Resistance to CaMV is found in most cabbage cultivars^{ref1, ref2, ref3, ref4}.
• unclassified viruses
• pigeon pea sterility mosaic virus (PPSMV) (a.k.a. pigeonpea sterility mosaic virus)

=> sterility mosaic disease (SMD) is the most damaging disease of pigeonpea endemic in the Indian subcontinent. It causes yield losses exceeding USD 300 million per annum in India and Nepal alone. SMD-affected plants show severe stunting and mosaic symptoms on leaves, with complete or partial cessation of flowering. The SMD causal agent is spread by the arthropod mite vector Aceria cajani. Cultivating SMD-resistant genotypes is the most viable way to manage this serious disease of pigeonpea. Pigeonpea (Cajanus cajan), is a grain legume that is a very important subsistence crop in marginal farming systems adopted by millions of smallholder farmers in the Indian subcontinent. It is grown for its seed for human consumption and for income generation by trading surpluses in local and commercial markets, but is widely used for diverse purposes, including as animal fodder and for soil conservation. It is grown on about 5.25 million ha, yielding 3 million tonnes, and contributes to about 5% of total world production of pulses. About 90% of global pigeonpea is grown in India and Nepal, and the remainder is cultivated in Africa, the Caribbean and Southeast Asia. There are no reports of SMD from Africa or the Americas. Infection by SMD in plants < 45 days old results in 95-100% loss, while older plants suffer losses of 26-97%. SMD is the most significant disease of pigeonpea in India, causing losses over of USD 280 million in 1993. A previously undescribed virus, Pigeonpea sterility mosaic (PPSMV), shows properties similar to viruses in the genus Tenuivirus. However, all tenuiviruses are phloem-limited, are transmitted by Delphacid planthoppers and only infect species in the Poaceae, thus ruling out PPSMV as a tenuivirus. Ultrastructural studies of PPSMV-infected pigeonpea showed 100-150 nm quasi-spherical-membrane-bound bodies (MBBs) and fibrous inclusions (FIs). The filamentous VLPs of PPSMV resemble the nucleoprotein particles of Tomato spotted wilt virus (TSWV), and PPSV VLPs are slightly larger than those of TSWV. PPSMV shows no serological relationship to Maize stripe virus tenuivirus or Peanut bud necrosis tospovirus. PPSMV and High plains virus share some common properties: transmission by the eriophyid mite A. cajani, 4-7 similar-sized MBBs and similar morphology. Similar MBBs have been detected in plants infected with fig mosaic, wheat spot mosaic, thistle mosaic and rose rosette, suggesting that these viruses may constitute a new virus genus. Disease management of SMD will depend upon identification of broad-based resistant genotypes. These are relatively rare in the pigeonpea gene pool, but a related wild species, Cajanus scarabaeoides (a.k.a. C. indicus) has high levels of resistance to several pigeonpea biotic constraints. SMD thrives readily in crops under irrigation or near irrigated fields, and such crops are at risk of early infection^ref
• unclassified :
• mature vine decline and fruit rind necrosis in cucurbits in Florida (the second largest producer of watermelon (Citrullus lanatus) in the United States)^{ref1, ref2}
• eggplant mottled dwarf virus

=> a virus that is widespread in the Middle East has now been detected in tomato and potato in Slovenia. It has previously been reported in Bulgaria and Italy in pepper and cucumber and is known to infect tobacco and cucumber in Greece and eggplant in Turkey. EMDV was first reported in eggplant (Solanum melongena) in southern Italy in 1969. In addition to cucumber and pepper, the natural host range of the virus includes black nightshade (Solanum nigrum), and S. sodomaeum that, in Morocco, may be a perennial source of infection. The virus is transmitted by contact inoculation and grafting but not by seed. It spreads in Algeria, Italy, Morocco, Tunisia, Turkey, and the Canary Islands.  The vector of ECMV is unknown, but because percentage of infection is generally low, a polyphagous insect with low vector specificity may be involved in transmission. Transmission was achieved by the agallian leafhopper (Agallia vorobjevi) in a study in Iran^{ref1, ref2, ref3}.
• cellular organisms
• Bacteria
• Actinobacteria
• Actinobacteria (class)
• Actinobacteridae
• Actinomycetales
• Micrococcineae
• Microbacteriaceae
• Clavibacter
• Clavibacter michiganensis (Cm)
• Clavibacter michiganensis subsp. michiganensis [Cmm]

=> bacterial canker in Lycopersicon esculentum and pepper affects field and greenhouse production systems, often inducing severe, in some cases total, crop loss, in Thailand, France, Turkey. The primary source of the pathogen is contaminated seeds
and transplants. The pathogen can survive in non-decomposed tomato crop residues and on seed for up to 5 years. Infested seed is the principal means of long-distance spread. Solanaceous weeds can be alternate hosts of the pathogen. Strategies for avoiding the disease include pre-season sanitation of all equipment, pipes, containers etc., use of certified seed and transplants, use of available tolerant cultivars, use of seed that has been treated to inactivate the pathogen, rogue out volunteer plants and solanaceous weeds near production glasshouses, and crop rotation in tomato fields (3 years of planting non-host crops). If disease occurs in glasshouses, eradicate entire production. If disease is present in fields, use appropriate bactericides, plow down the crop and incorporate into soil for active decomposition. Some degree of control can be obtained by applying chemical and antibiotic treatments, but they should be used sparingly so as to prevent development of resistant strains of the pathogen. According to the manufacturer, Virkon S (source : Antec International) is effective in disinfecting tomato seeds from canker infection without any adverse effects on seed germination or seedling stand.
• Clavibacter michiganensis subsp. sepedonicus (Cms) (EPPO A2 list)

=> bacterial ring rot (BRR) : Cms occurs throughout Europe, after being identified in recent years in France, the Netherlands, Slovakia and Denmark. 3 outbreaks have occurred in the UK since November 2003. Defra officials consider it one of the most serious diseases of potato^{ref1, ref2, ref3}. Cms is spread by infected tubers, and a major concern for plant pathologists in Wales and other parts of the UK is the possibility that seed potato stocks could be infected. Sanitation is the key to disease management. Only classified seed should be used for planting; all machinery, equipment, vehicles, containers such as potato sacks, storage facilities such as bins, and any other possible source of the pathogen must be identified and rigorously cleaned and thoroughly disinfected. Finally, if possible, dispose of all potato waste at an approved tip (dump) or by incineration. The disease is especially damaging to seed producers since disease-free seed is the foundation of any seed potato production program. Disease management depends upon zero tolerance of the pathogen and application of very strict phytosanitary measures to maintain freedom from contamination. Quaternary ammonia, bleach, chlorine dioxide, iodine, and phenol groups are useful disinfectants. Cms can remain latent in tubers, so adequate laboratory testing of seed lots is required. Damage is caused by destruction of vascular tissues and subsequent wilting and dying of plants and secondary rotting of tubers. Crop losses have been mainly reported from North America (up to 50%) and from Russia (15-30% of plants infected, up to 47% crop loss). Where ring rot occurs in the EPPO region, the disease appears more sporadically and at low levels of infection. The low disease occurrence in this area is due to the fact that cutting of potato seed, and use of pricker-type planters, is uncommon in Europe. When tubers are cut, however, higher levels may also occur (up to 30% crop loss in France). Economic losses are due to wilt and tuber rotting in the field and in storage. Indirectly, expenses related to the disinfection of sacks, machinery, stores etc., prohibition of potato cultivation, and restriction, or prohibition, of export trade may increase economic loss^{ref1,ref2, ref3, ref4}.
According to Antec International, a balanced, stabilised blend of peroxygen compounds, surfactant, organic acids, and an inorganic buffer system [Virkon-S  (source : Antec International)] is recommended as a means of controlling Cms. Sanitation, cleanliness, and disinfection are the keys to eradication of bacterial ring rot. If either pathogen is confirmed on a commercial farm, a thorough clean-up of storage and equipment must be carried out to reduce the chance of any bacteria remaining and causing contamination of incoming certified seed lots destined for the following year's potato crop. Access to seed storages and equipment by commercial growers and their trucks should be limited and controlled. Equipment should not be shared between commercial and seed farms, and all trucks from commercial potato farms should be cleaned and disinfected before they enter seed storages or seed handling areas
• Curtobacterium
• Curtobacterium flaccumfaciens
• Curtobacterium flaccumfaciens pv. flaccumfaciens [Cff] causes bacterial tan spot in bean (Phaseolus vulgaris) and soybean (Glycine max). It is internally seedborne in legumes. Pathogenesis is facilitated by higher temperatures (25-30°C). Disease incidence can be reduced by planting pathogen-free seed or by using seed of less susceptible cultivars. Cff grows throughout the water-conducting tissues of the plant and impedes water movement, resulting in a wilt. Symptom development is favored by temperatures > 32°C. Infection is often caused by the planting of infected seed, but Cff may also survive in infested crop debris.  Cff bacteria are more confined to internal infection of plant vascular tissue, and apparently are not spread as readily by rain or movement of machinery among wet plants as compared to the halo blight pathogen (Pseudomonas syringae pv. phaseolica) or the common bacterial blight pathogen (Xanthomonas campestris pv. phaseoli). Infection through natural openings on the plant are rare, but hailstorms and wounding favor infection. Cff is disseminated among fields by irrigation water and movement of infested crop debris or contaminated seed. Disease management strategies include planting high-quality certified seed free from the bacterial wilt pathogen.  There are varietal differences in their susceptibility to bacterial wilt, and resistant or tolerant varieties should be planted if available.  A 2-year crop rotation to non-hosts such as small grains is recommended. Avoid reuse of irrigation water if possible and practice strict sanitation of crop debris and volunteer beans to reduce pathogen survival between bean crops. Antibiotic seed treatment can reduce surface contamination of seed, but chemical controls are most effective when integrated with sound cultural practices^{ref1, ref2, ref3, ref4, ref5}
• Leifsonia
• Leifsonia xyli
• Leifsonia xyli subsp. xyli (previously named Clavibacter xyli subsp. xyli )

=> ratoon stunting disease (RSD), a difficult pathogen to detect, and tissue blot immunoassay are required. RSDis considered by many to be the most important disease affecting sugarcane production worldwide. It can cause a 5-15% loss in crop yield without the grower even knowing his fields have been infected. The disease is caused by a bacterium. RSD has no easily recognized external symptoms, only stunting of growth, which may not always be apparent in the field. Although RSD has been reported in Jamaica since 1961, presence of the pathogen had never been confirmed in symptomatic tissues before 2005^{ref1, ref2}.
• Bacillus / Clostridium group (low G+C Gram-positive Bacteria)
• Bacilli (facultative anaerobes or strictly aerobes spore-forming Bacteria)
• Bacillales
• Bacillaceae
• Bacillus
• Bacillus subtilis [Bs]

=> melting decay in grapes. Initial symptoms are usually observed after 2 weeks of cold storage (-0.5 to 0°C and 90-95% relative humidity). The fact that the incidence in cold storage has increased dramatically from the 1990s to 2003, suggests that perhaps a new strain of Bs has evolved under those conditions. There is a report in 1992 of Bs being associated with soybean seed, but that requires confirmation. Infection of grapes by the 2 yeast species is of interest and may be related to environmental conditions in the field as well as in cold storage. Bs is widely used as a fungicide on flowers and vegetables, including crop plants.
• Firmicutes
• Mollicutes
• Acholeplasmatales
• Acholeplasmataceae
• Candidatus Phytoplasma (plant yellows agents) : phytoplasma-induced diseases are being recognized as significant pathogens of food crops. Phytoplasmas are a group of prokaryotic, microscopic plant pathogens that cause over 700 diseases of food, fiber and ornamental plants. They are found mainly in the phloem sieve tubes of their plant hosts and in certain sucking insects, which can act as vectors. They can also be spread by grafting, by parasitic plants or by seed transmission. Detection of phytoplasmas is by grafting to susceptible host plants, microscopy, serology (ELISA), nucleic acid hybridization or DNA amplification using the polymerase chain reaction (PCR). Symptoms displayed by plants infected with phytoplasmas include foliage yellowing, petal greening, shoot proliferation, stunting, little leaf formation, necrosis and a decline of vigor leading to death^{ref1, ref2, ref3}
• 16SrI (aster yellows (AY) group) aster yellows group (16SrI) phytoplasmas are associated worldwide with > 100 diseases, several of which are quarantine-regulated and economically important. Scientists from the Molecular Plant Pathology Laboratory at Beltsville, MD, USA found that combined use of 16S rRNA and ribosomal protein gene sequences enabled differentiation of 18 distinct subgroups in the AY group. A new species, 'Candidatus Phytoplasma asteri', was proposed to represent the AY phytoplasma group. This accomplishment will aid plant quarantine agencies in implementing new regulations to prevent these pathogens from being introduced into new regions. Ing-Ming Lee, a USDA scientist specializing in mycoplasmas, and his colleagues constructed the first comprehensive phytoplasma classification system in 1993, based on RFLP analysis of 16S rDNA. Further work led to an expanded system by 2000 that included 15 major phytoplasma groups and over 40 subgroups, providing the most comprehensive phytoplasma classification system available. In northern Tunisia, grapevines (Vitis vinifera) were found exhibiting symptoms of grapevine yellows that included plant weakness, incomplete lignification, flexible shoots and drooping. Affected leaves were thicker than normal, brittle, rolled downward and showed veinal yellowing and necrosis. In addition, grape bunches became dry and shrivelled before fruit could fully develop and ripen^ref
• a new phytoplasma causes hoja de perejil (parsley leaf disease) of tomato (Lycopersicon esculentum) cv 'Rio Grande' and Calotropis little leaf (Morrenia variegata (Mv)) in the Bolivian provinces of Santa Cruz and Sucre. An infection rate of 60% suggests that the disease may be widespread in some areas, but there are no data on crop loss in tomato. Obviously the phytoplasma is well-established in Mv in affected areas of Bolivia and constitutes a source of inoculum.
• 16SrIII (X-disease group)
• peach yellow leafroll phytoplasma

=> peach yellow leafroll (PYLR) was 1st described in 1948, occurring primarily in Butte, Placer, Sutter, Yuba and San Juaquin and Stanislaus counties of Bolivia. It caused moderate losses in the 1950s and 1960s, killing approximately 4800 trees, but the incidence of PYLR increased dramatically in the late 1970s when a major epidemic killed over 35 000 trees in 1979. The incidence of PYLR has declined but continues to be a chronic problem in the northern California counties of Yuba, Sutter, El Dorado and Placer
• 16SrIV (Coconut lethal yellows group)
• Coconut lethal yellowing phytoplasma

=> coconut lethal yellowing (LY) disease : symptoms include premature nutfall, necrosis of immature inflorescences, progressive frond yellowing, and eventual palm death. It spreads rapidly, destroying coconut and other palms. Millions of coconut palms (Cocos nucifera, Atlantic tall ecotype) have been killed in the Caribbean region over the past 40 years. LY disease has swept through the coconut-growing regions of Jamaica, Cuba, the Cayman Islands, and Florida and is presently destroying palms in the Yucatan Peninsula, Honduras, Guatemala (however, the syndrome differed from that reported for LY, as inflorescence necrosis was evident after, rather than before, frond yellowing), as well as mainland Belize. Similar diseases have been identified in Africa (Kenya, Mozambique, Tanzania, Nigeria, Ghana, and Cameroon). If unchecked, LY disease may spread to South America. Millions of coconut palms on the Caribbean and Atlantic coasts are endangered, because the common cultivar is highly susceptible to the phytoplasma. LY, described by some as the "dengue of palm trees," is spread by the planthopper Myndus crudus, but other planthopper species are being assessed for their role as vectors. Infected palms die within 6-9 months after symptoms are 1st expressed. The vascular systems of infected palms are plugged with the phytoplasma thus stressing the palms and accelerating the onset of death. Research scientists at Ft. Lauderdale, FL, and Meridia, in Yucatan, have identified other phytoplasma strains associated with coconut palm that express leaf-yellowing syndromes in southern Mexico that are distinct from LY phytoplasmas. There is no effective cure for LY-infected palms. Previously ravaged areas have been replanted with resistant cultivars and hybrids such as 'Maypan'. There is some work being done on genetic modification of palms, but transformation of palms with genes of interest including LY resistance, and other traits, is still in the offing^{ref1, ref2, ref3}
• 16SrV (Elm yellows group)
• flavescence doree (PD) phytoplasma

=> grapevine yellows (GY)
FD and boid noir phytoplasma (BN) are common in European vineyards, FD being more important. The principal host of FD is grape (Vitis vinifera). Of considerable significance is that Convovulus arvensis (field bindweed) and Solanum nigrum (black nightshade) are common in German vineyards, thus providing an inoculum source. The principal vector for the FD phytoplasma is Scaphoideus titanus (vine leafhopper), but the vector for BN is Hyalesthes obsoletus, also known as the vector for potato stolbur. Local spread of FD is about 5-10 km per year, while that of BN is much slower. Uncontrolled spread of FD is usually catastrophic, particularly in the cultivars Chardonnay and Pinot Blanc. BN spreads much more slowly, and its economic impact is much less. Management of the disease is based on use of suitable planting material and control of vectors by chemical insecticides^{ref1, ref2}
• 16SrVI (Clover proliferation group) Subgroup A (16SrVI-A)

=> dry bean phyllody (DBPh) disease in dry bean (Phaseolus vulgaris L.) cultivars of Andean origin grown in Mattawa and Paterson, WA. Symptoms of DBPh became apparent during mid-to-late pod development and were characterized by leafy petals (phyllody) and aborted seed pods resembling thin, twisted, and corrugated leaf-like structures. Deformed sterile pods that were small, sickle-shaped, upright, and leathery were also observed. The infected plants generally exhibited chlorosis, stunting, or bud proliferation from leaf axils. Phyllody describes a retrograde metamorphosis of the floral organs to the condition of leaves. Because floral tissues in phytoplasma-infected plants revert to vegetative tissues, no seeds are produced, and crop losses due to phyllody can be very high. Phyllody-affected crop plants can be cured of phytoplasmas by heat treatment or by subjecting cuttings to tissue culture. The beet leafhopper, Circulifer tenellus (Ct), is the only known vector of Vinca virescence phytoplasma / beet leafhopper-transmitted virescence agent (BLTVA), although not much is known about other vectors. Phytoplasmas infect and multiply in their leafhopper vectors. The BLTVA is vectored in the same manner as other phytoplasmas are by other  leafhoppers. Ct acquires BLTVA only by feeding on infected plants. Prophylactic use of insecticides is the only known means to prevent transmission of BLTVA. The Washington vegetable seed industry has been plagued with BLTVA for years, and even the prophylactic use of insecticides has not always successfully managed it. Some vegetable seed crops are no longer grown in the Columbia basin due to inadequate control of BLTVA.
=> potato purple top (PPT) / aster yellows / haywire / purple dwarf and Purple-top wilt : upright terminal shoots, upward leaf rolling, chlorosis, red or purplish discoloration of new leaves, proliferation of axillary shoots with basal swelling, and the formation of aerial tubers. It has been a factor in disease losses for many years in Washington state but is seldom a major factor affecting potato crops in the Columbia Basin. However, PPT is endemic in potato crops in Mexico, where it ranks 2nd to late blight caused by Phytophthora infestans.
=> potato hair sprouts (PHS) is found in Mexico. PHS has the greater impact, since infected, but symptomless, tubers generally fail to sprout or may sprout poorly. Moreover, PHS-infected stems are weakened because they are deficient in chlorophyll (etiolated). Moreover, psyllid nymphs inject a toxin into potato tissue, causing PPT-like symptoms, which confounds diagnosis. Disease management basically depends upon planting certified seed in areas free of phytoplasmas or, in the case of areas infested with infected weeds and leafhoppers, use of insecticides to reduce vector numbers. Development of resistance to phytoplasmas may offer a measure of control^{ref1, ref2, ref3}.
• 16SrX (Apple proliferation group)
• Candidatus Phytoplasma mali / apple mosaic ilarvirus / apple proliferation (AP) phytoplasma

=> apple proliferation (AP) is one of the most important phytoplasma diseases of apple (Malus) in Germany and France, affecting almost all cultivars, reducing size (by about 50%), weight (by 63-74%) and quality of fruit, as well as reducing tree vigour and increasing susceptibility to powdery mildew (Podosphaera leucotricha). It is transmitted by grafting and is disseminated in budwood (both scion and rootstock). The plant louse Psyllid Cacopsylla melanoneura (Homoptera: Psyllidae) has been implicated as a vector, and the overwintered adults are probably important in the spread of AP in apple orchards^{ref1, ref2}. In Europe apple proliferation phytoplasma is an EPPO A2 quarantine organism and is known in Austria, Bulgaria, Czech Republic, France, Germany, Greece, Hungary, Italy, Moldova, Poland, Romania, Slovakia, Slovenia, Spain, Switzerland, UK (eradicated), Ukraine, Yugoslavia. Further spread or propagation of the disease in infected budwood or plant material could lead to considerable yield losses throughout the European and Mediterranean apple cultivation areas. It has not been detected in the USA^{ref1, ref2, ref3, ref4, ref5, ref6}
• Candidatus Phytoplasma prunorum / European stone fruit yellows phytoplasma (ESFY)
• Candidatus Phytoplasma pyri / pear decline (PD) phytoplasma : is vectored by the pear psylla (Cacopsylla pyricola). Expression of the disease depends on rootstock susceptibility, tree vigor, and psylla numbers. Poor shoot and spur growth, shoot dieback, upper rolling of leaves, reduced leaf and fruit size, and premature leaf drop characterize pear decline. Sudden tree collapse can result from tissue damage at the graft union on highly susceptible rootstocks such as Pyrus serotina or Pyrus ussuriensis, but slow decline of trees is more common. Management of the disease is based on use of tolerant pear root stocks and Pyrus betulaefolia. Pyrus betulaefolia is a rootstock that is tolerant of infection by pear decline (PD). Consequently it is used in orchards as the rootstock underlying the tree. In addition to P. betulaefolia seedling Bartlett and Winter Nelis are also used as rootstocks. Apparently there is no known biological control for pear decline phytoplasma. The phytoplasma apparently does not multiply in pear trees as well as it does in pear psylla. Control of pear psylla usually results in disease remission even when rootstocks are highly susceptible. Poor shoot and spur growth, shoot dieback, upper rolling of leaves, reduced leaf and fruit size, and premature leaf drop characterize PD. Trees on tolerant rootstocks may show mild to moderate symptoms that occasionally become severe if very high psylla populations occur in conjunction with other tree stresses. Commercial pear rootstocks, with the exception of Pyrus calleryana, are available which are essentially tolerant to PD and produce excellent crops in spite of recurring pear psylla populations and exposure to PD. To keep PD in remission on susceptible rootstocks, control pear psylla and maintain trees in good vigor, and reduce stress caused by inadequate irrigation, nutrient deficiency, weed competition, lack of pruning, and pest damage. There is no known biological control of the PD phytoplasma. Indirectly, biological control of pear psylla can reduce disease expression. Based on dissimilarities of restriction sites detected by rDNA RFLPs, 9 primary 16S rDNA groups (termed 16Sr groups) and 14 subgroups were recognized in a classification scheme proposed by Lee, Hammond, Davis, and Gundersen. At least 14 primary 16Sr groups consisting of 16SrI, aster yellows; 16SrII, peanut witches'-broom; 16SrIII, X-disease; 16SrIV, coconut lethal yellows; 16SrV, elm yellows; 16SrVI, clover proliferation; 16SrVII, ash yellows; 16SrVIII, loofah witches'-broom; 16SrIX, pigeonpea witches'-broom; 16SrX, apple proliferation; 16SrXI, rice yellow dwarf; 16SrXII, stolbur; 16SrXIII, Mexican periwinkle virescence; 16SrIV, Bermuda grass white leaf, and at least 32 strain subgroups have been recognized. 45 subgroups were identified when ribosomal protein gene RFLP data were also considered in the analyses^{ref1, ref2, ref3}
• 16SrXII (Stolbur group)
• stolbur phytoplasma

=> potato stolbur (PS ; a.k.a. tomato stolbur) disease incidence in potato (Solanum tuberosum) can be high, leading to significant crop loss, but the disease tends not to persist in stocks. PS is one of a group of phytoplasmas causing yellows-type diseases in Europe within the broad concept of European aster yellows. Parastolbur and metastolbur are strains of stolbur; northern stolbur is probably caused by potato witches' broom phytoplasma, pseudoclassic stolbur is poorly defined, and pseudostolbur is a physiological disorder. A little leaf disease of tomatoes, Capsicum, and eggplants in southeastern France has been attributed to a phytoplasma distinct from stolbur. PS infects 45 species in the Solanaceae; principal hosts are potato (Solanum tuberosum), tomato, peppers and eggplant. Of concern to plant pathologists are infected plants species in the Asteraceae, Convolvulus arevensis and Fabaceae (Trifolium spp.) that are sources of inoculum. PS occurs in 15 countries of the EPPO region, Asia (8 countries) and the EU. The most important vector in eastern Europe is Hyalesthes obsoletus, but there are several others that are of concern. Local spread in a field appears to originate from infected weed species rather than from crops. PS can be detected using specific stains in infected tissues, by indirect immunofluorescence, and by a tissue blot technique^{ref1, ref2}
• Candidatus Phytoplasma asteris
• apple sessile leaf phytoplasma (AsPL). Considering the fact that apple is a very popular fruit cultivated in many countries worldwide, the most significant aspect of this report is that ApSL may become a threat to apple production in states of the European Union. ApSL obviously occurs in Lithuania, and I would suspect that it occurs in other areas in Europe, but there are no other reports of its occurrence to my knowledge. Phytoplasmas are transmitted by leafhoppers, planthoppers and psyllids. Development of PCR for detection of ApSL is a major step forward in detecting the phytoplasma in the food crops featured in this piece and will certainly facilitate its detection in budwood and propagation nurseries^{ref1, ref2}
• aster yellows phytoplasma

=> aster yellows (AY) is the most widespread plant disease among those known to be caused by phytoplasmas. AY phytoplasmas are associated with diseases in more than 100 plant species worldwide, predominantly in herbaceous dicotyledonous plants. In North America, AY diseases are attributed primarily to phytoplasma strains belonging to subgroups 16SrI-A (termed Eastern AY phytoplasma) and 16SrI-B (termed California AY or Western AY phytoplasma) in the AY group (16SrI). Both 16SrI-A and 16SrI-B phytoplasmas are transmitted by a variety of polyphagous leafhopper species and have a wide range of plant hosts. On the basis of RFLP patterns of the 16S rDNA, the OatP phytoplasma was classified as a member of group 16SrI (group I, aster yellows phytoplasma group). The RFLP patterns of the 16S rDNA were indistinguishable from those of 16S rDNA from tomato big bud (BB) phytoplasma and other phytoplasmas classified in group I, subgroup A (subgroup I-A, tomato big bud phytoplasma subgroup). Disease management depends upon the crop involved. Monitoring of leafhoppers and early detection of AY yellows symptoms are important for those crops in which hand-removal of diseased plants is feasible. For field crops, there are very few management options available. Crop rotation will not reduce aster yellows, because it is not a soil-borne disease, and most crops are susceptible to the phytoplasma. There are no fungicides available to control aster yellows. I rather doubt that there are varieties that possess resistance to the AY phytoplasma^{ref1, ref2}.
• tomato big bud phytoplasma (a.k.a. tomato big bud mycoplasma-like organism), reported mainly from regions outside the EPPO region, causes a disease similar to potato stolbur and some taxonomists regard them as synonymous.
• a new phytoplasma related to potato stolbur phytoplasma was detected in potato (Solanum tuberosum) using PCR samples collected in Texas and Nebraska in 2005. The report is noteworthy because the pathogen causes discoloration of potato tubers that may result in rejection of a shipment for the chipping industry. The main vectors are insects of the leafhopper family (Macrosteles sp., Hyalestes sp.). The disease is found in Central and in southern Europe, as well as the Middle East, the USA, Australia, and Asia. Stolbur is classified as a quarantine parasite in the European Union. Destruction of alternative hosts and the use of certified seed pieces are the main tools to manage these kinds of diseases^{ref1, ref2, ref3}
• Entomoplasmatales
• Spiroplasmataceae
• Spiroplasma
• Spiroplasma kunkelii

=> corn stunt disease (CSD) : beyond stunting of plants, it causes production of multiple ears that fail to fill. In the fall, leaves in the upper portion of infected plants take on a reddish color. It is of significant economic importance in a number of Latin American countries. It occurs from the southern U.S. states to Brazil and Peru. Sk and the maize bushy stunt phytoplasma (MBSP) together with maize rayado fino virus constitute the CSD complex. Using a  PCR assay for Sk, the pathogen was found in El Salvador, Guatemala and Panama. Significant yield reductions can follow from dual infections of Sk and MBSP. Disease management depends heavily on cultural practices (disking fields containing volunteer corn, herbicide applications to eradicate alfalfa). In California, all current commercial cultivars of field and sweet corn are susceptible. Generally, insecticides are ineffective in controlling the corn leafhopper (Dalbulus maidis), which is common throughout the southeastern and southwestern U.S. : brownish or tan in color and less than one-eighth of an inch long, it is the only vector of corn stunt disease in California.
• Proteobacteria
• Alphaproteobacteria
• Rhizobiales
• Rhizobiaceae
• Candidatus Liberibacter is a fastidious prokaryote that remains refractory to culture on artificial media
• Candidatus Liberibacter africanus (South African form/strain, which induces severe disease symptoms on citrus between 22-24°C), vectored mainly by Trioza erytreae
• Candidatus Liberibacter asiaticus (heat-tolerable Asian form, which induces symptoms in warm climates (27-32°C)), vectored mainly by Diaphorina citri (Dc). Dc has been recorded in South, Central, and North America (Florida and Texas), West Timor, in several districts of Timor-Leste and in the north of the Indonesian province of Papua (formerly Irian Jaya) on the island of New Guinea. HLB was recently found at Sorong and Jayapura in northern Papua.
=> citrus huanglongbing (HLB) / citrus greening disease. The HLB agent is spread by propagation, and, by 2 citrus psyllids which can vector either pathogen. Most citrus cultivars, except pumello, are susceptible to the Asian form. There is no cure for the disease at present. Trees gradually decline in vigor and yield, and eventually die. The best control for HLB is exclusion. In areas where HLB has been established, management to reduce losses include propagation of HLB-free trees for planting, reduction of the psyllids populations by removing species which continually flush, application of insecticides when threshold population levels are attained, and by pruning symptomatic sectors from the trees. Use of parasites to control psyllid populations has been successful in Reunion and some other areas. Before the development of shoot tip-grafting methods to eliminate graft-transmissible pathogens, budwood was therapeutically treated at an elevated temperature, up to 60 deg C, for a few minutes before propagating. > 20 plant diseases are associated with, or known to be caused by, these bacteria-like organisms, which range in size from 0.25 to 0.5 by 0.8 to 4.0 mm. HLB has been reported in India, Asia (Papua New Guinea, East Timor, but not Australia), Southeast Asia (including Indonesia and The Philippines), the Arabian Peninsula, in South Africa, in south Miami-Dade County (Florida, USA) and in in Sao Paulo's orchards, Brazil (the state produces about 90% of Brazil's frozen concentrated orange juice (FCOJ) exports, and, around half of the world FCOJ market). A similar disease (cucurbit yellow vine disease) has been reported to infect cantaloupe, pumpkin, squash and watermelon in the USA (Oklahoma, Texas, Tennessee, Massachusetts). HLB is the major constraint to citrus production, affecting 29 countries in Asia and Africa. Infected citrus trees in Brazil have been by officials to be infected with the most dangerous strain of HLB (Candidatus Liberibacter asiaticus). Its arrival in Brazil signals probable spread to citrus groves in Brazil and possibly to other citrus-growing areas in South America, thus possibly exposing citrus groves in Central and North America to infection. The HLB bacterium infects nearly all citrus species, cultivars, and hybrids and some citrus relatives. Prevention of spread is the best control for HLB. HLB symptoms are similar to other decline diseases such as citrus blight and citrus tristeza and develop slowly, and infected trees may not be recognized as those of a new disease. In areas where HLB has been established, management to reduce losses include propagation of HLB-free trees for planting, reduction of psyllid populations by removing species which continually flush, application of insecticides when threshold population levels are attained, and by pruning symptomatic sectors from infected trees. Disease management includes heat treatment to eradicate the pathogen in budwood. The most effective method of preventing the disease is to control the insect vectors. Agricultural practices, including the careful selection of vector-free production areas, good crop husbandry, and careful selection of trees, are key to successful management. The HLB bacterium can cause catastrophic losses of an important crop. Infection rates of up to 95% have been seen in Thailand, and crop losses of 100% have been reported in some areas of South Africa, resulting in destruction of entire crops. It invades conducting tissues, causing a decline of citrus trees and rendering them unproductive. Affected trees citrus trees may live for 5-8 years and never produce usable fruit. HLB probably originated in China. Once a tree has been infected, it cannot be 'cured' of HLB. Where the disease exists, management strategies rely on preventing its spread into uninfected areas. A variety of measures are employed, including regulation of the movement of propagating material, destruction of infected trees, and control of insect vectors^{ref1, ref2, ref3, ref4, ref5,ref6, ref7, ref8, ref9, ref10, ref11, ref12, ref13, ref14, ref15, ref16, ref17, ref18}. The Asiatic or oriental citrus psyllid, Diaphorina citri [Dc], is widely distributed in southern Asia where it has been a major pest of citrus in several countries, particularly India, where there has been a serious decline of citrus in recent years. Dc had not been recorded to occur in North America or Hawaii but was reported in Brazil, by Costa Lima (1942; Rio de Janeiro) and Catling (1970). However, in June 1998, Dc was detected in Florida, distributed along Highway 1 on the east coast of Florida, from Broward to St. Lucie counties, but was apparently limited to dooryard host plantings at the time of its discovery. By September 2000, Dc had spread to 31 counties in Florida (Halbert 2001). Dc and one of its parasites are also present in the Rio Grande Valley of Texas. Both species appear to have been accidentally introduced in the spring of 2001 on potted Murraya originating in Florida. The fastidious bacterial pathogen Serratia marcescens [Sm], which causes HLB, exists in sieve tubes. Electron microscopy, using serial sections and a 3-dimensional configuration confirms the presence of mature forms of the pathogen, generally rigid rods with dimensions ranging from 0.25 to 0.5 by 0.8 to 4.0 mm. The cells are pleomorphic, and produce flexible elongated rods which grow into new organisms. Multiplication is generally accomplished by budding, less frequently by binary fission or beading. Since 1988, cucurbit crops, particularly watermelon, cantaloupe, and squash grown in Oklahoma and Texas have experienced devastating losses from cucurbit yellow vine disease (CYVD), caused by Sm. Squash bug [Anasa tristis] is a putative vector of the pathogen. In 2000-01, overwintering populations of the squash bug collected from DeLeon, TX were tested for their ability to harbor and transmit Sm. Individual squash bugs (n = 76) were caged for a 7-day period on a series of at least 4 squash seedlings. 3 studies were conducted, one with insects collected in November placed on 1st leaf-stage seedlings and the 2nd and 3rd with insects from an April 2001 collection placed on 3-5 leaf-stage squash. Controls consisted of squash seedlings caged without insects. Squash bug transmission rates of the pathogen in Studies I-III were, respectively 20, 9.1, and 3.6%. Overall, 10.5% of the squash bugs harbored and successfully transmitted the bacterium to squash seedlings. All control plants were negative for CYVD symptoms or presence of Sm. Female squash bugs killed a significantly greater proportion of young 1st leaf-stage seedlings than males. Feeding on 3-5 leaf stage squash resulted in no plant mortality regardless of squash bug gender. This study demonstrated that the squash bug harbors Sm in its overwintering state. The squash bug/Sm overwintering relationship greatly elevates the pest status of squash bug and places more importance on development of integrated strategies for reducing potential overwintering and emergent squash bug populations. Dc is often referred to as "citrus psylla", but this is the same common name often applied to Trioza erytreae, the psyllid pest of citrus in Africa. To avoid confusion, T. erytreae should be referred to as the African citrus psyllid or the 2-spotted citrus psyllid (the latter name in reference to a pair of spots on the base of the abdomen in late stage nymphs). These 2 psyllids are the only known vectors of the etiologic agent of citrus greening disease and are the only economic species on citrus in the world. 3 other species of Diaphorina have been reported on citrus (2 in Swaziland, one in India), but these are non-vector species of relatively little importance. Dc ranges primarily in tropical and subtropical Asia and has been reported from the following geographical areas: China, India, Myanmar, Taiwan, Philippine Islands, Malaysia, Indonesia, Sri Lanka, Pakistan, Thailand, Nepal, Cecum, Hong Kong, Ryukyu Islands, Afghanistan, Saudi Arabia, Reunion, Mauritius, and Brazil. The discovery of Dc in Saudi Arabia (Wooler et al., 1974) is the 1st record from the Near East. T. erytreae also occurs in Saudi Arabia, preferring the eastern and highland areas where the extremes of climate are present, whereas Dc is widespread in the western, more equitable coastal areas^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9}
• Betaproteobacteria
• Burkholderiales
• Burkholderiaceae
• Ralstonia
• Ralstonia solanacearum [Rs]

Epidemiology : Rs is thought to have originated in the temperate highland regions of Peru but has subsequently spread to Europe, Asia, South and Central America, and Australia, as 25-30°C is the optimum temperature for the strains. In February 2003, Rs race 3, biovar 2, not known to occur in the USA, was detected and confirmed in geraniums imported from Kenya and eradicated. Subsequently it occurred again in late December 2003 in geranium imported from Guatemala. Some control actions have already taken place, and importations into the United States have ceased. Most races of the bacterium, and their associated diseases, appear to be limited to tropical, sub-tropical and warm temperate climates, and thus pose no long-term threat to agriculture in cool temperate climates. However, Rs race 3, biovar 2A, which has a very wide host range, is now considered to be a quarantine pest in the more temperate regions of Europe, Canada, and the United States, primarily on potato and tomato as well as on some weed species which would serve as inoculum sources. Bacterial wilt of potato has been estimated to affect about 3.75 million acres in around 80 countries, with global damage estimates currently exceeding $950 million per annum. Consequently, race 3 (biovar 2A) is listed as a quarantine pest in Canada, Europe and the USA. Of major significance is that race 3 infects also geranium (Pelargonium spp.), and infected plants have entered the flower trade. Disease management requires regular disinfection of all hand implements, use of disinfectant foot baths at entry points to each production glasshouse, washing of hands, wear newly laundered clothing daily, destroy weeds that are potential hosts of Rs in and around glasshouses, and use effective disinfectants such as quaternary ammonia, peroxygen compounds and bleach^{ref1, ref2, ref3, ref4, ref5}.
=> wilt disease in several important agricultural crops such as potato (potato brown rot (PBR)), tomato, pepper, and eggplant.
Rs can survive for several years in the soil and also remain alive on host plants belonging to the Nightshade family (tomato, nightshade, capsicum, aubergine, tobacco, etc.) as well as other plants. It is spread by irrigation water or by infected seed potatoes. There are 3 races of Rs on the basis of pathogenicity. Within the species 38 RFLP groups have been distinguished, and they form 2 genetically
distinct major divisions with origins in Australasia and the Americas. The host range, which includes over 200 plant species, is one of the widest of all the phytopathogenic bacteria. Species infected by Rs include the Solanaceae, but > 50 other plant families also contain susceptible species. Worldwide, the most important are: tomatoes, Musa spp., tobacco, and potatoes. Many weeds are also hosts of the pathogen and therefore increase the potential of Rs to build up inoculum. Different pathogenic races within the species may show very limited host ranges.
• race 1 affects tobacco, tomatoes, potatoes, aubergines, diploid bananas, and many other (Solanaceous) crops and weeds, and has a high growth temperature optimum (35-37°C)
• race 2 affects triploid bananas and Heliconia spp., and has a high temperature optimum (35-37°C)
• race 3 biovar 2 has a lower temperature optimum (27°C) and affects mainly potatoes and tomatoes.
A considerable number of additional symptomless weed hosts have been reported, which may enable race 3 biovar 2 to survive in latent form, or in their rhizosphere. Several weed species commonly inhabit edges of waterways, thus providing an inoculum source. There are also reports of natural occurrence of race 3 biovar 2 in Pelargonium hortorum. Within the EPPO-region, race 3 biovar 2 (equivalent to biovar 2), is present and has potential for spread. Rs is a contentious topic in agricultural trade negotiations in the EU and is subject to strict quarantine and eradication regulations in the USA. No economically feasible controls exist. Avoid planting on land with a previous history of BW. Instead, grasses, legumes, and cucurbits should be planted to reduce inoculum of Rs^{ref1, ref2, ref3}.
Transmission : through soil, contaminated irrigation water, equipment, or personnel. Rs does not readily spread from plant to plant via splashing water, casual contact, or aerially.
Signs : in geranium are wilting of leaves and/or abnormal yellowing of lower leaves
• Moko disease of banana is caused by Rs, race 2 (biovar 1). The disease occurs in Trinidad, Amazonian Brazil, Peru, Guatemala, southern Mexico, Grenada, Philippines, and Central and South America. Moko disease is considered a greater threat to both commercial and subsistence farmers than Fusarium spp. and Sigatoka leaf spot of bananas. > 85 000 farmers grow bananas on about 10 000 hectares of land in several parishes. The industry earned > USD 27 million in 2003 and is a constant cash flow for thousands in barely marginal existence. Rs also infects tomato, taro, and coconut. Unfortunately there is no known resistance to Rs. The pathogen is spread rapidly by insects contaminated with bacteria following foraging on infected floral tissues. Disease management is difficult and expensive, and can only be effectively implemented on large commercial plantations due to cost. Recommendations to restrict the spread of the disease include weekly inspection of crops for symptoms and strict implementation of standard phytosanitary measures. Replanting of any field with banana, plantain or other host crops should be prohibited for > 1 year after infected plants have been killed. Movement of vehicles from an infected farm to other banana or plantain fields should be prohibited^ref
Prevention : spread can be controlled in greenhouses by application of sound sanitation practices. Key management strategies include use of strict phytosanitary regimens to eliminate the pathogen and the use of certified disease-free seed. According to Antec International, a balanced, stabilised blend of peroxygen compounds, surfactant, organic acids, and an inorganic buffer system [Virkon-S  (source : Antec International)] is recommended as a means of controlling Rs. A continuing problem in some circumstances is infection of solanaceous plants near potato washing and waste operations. Runoff of contaminated water leads to infection of reservoir hosts such as Solanum dulcamara (climbing nightshade) along waterways, thus perpetuating these 2 pathogens.
• Comamonadaceae
• Acidovorax
• Acidovorax avenae
• Acidovorax avenae subsp. citrulli

=> a quarantine pest for Israel, has been found infecting watermelon (Citrullus lanatus) and melon (Cucumis melo) at a limited number of production sites. Bacterial fruit blotch has great potential to cause significant economic losses to cucurbit production and has been responsible for up to 90% losses of marketable yield in some watermelon fields.  Although all cucurbits are susceptible, bacterial fruit blotch is only a problem on watermelon. The fruit symptoms (irregularly shaped water-soaked lesions with cracks) that are most obvious and distinctive. Fruit blotch can be introduced in infected seeds as part of the international seed trade. PCR-based detection methods in seed are being developed.  Use of clean seed and disease-free transplants is necessary in order to manage the disease. Because the pathogen is seedborne, and a significant portion of commercial watermelon fields are planted with seedlings raised in greenhouses or other transplant production facilities, recognition of symptoms on seedlings is important. Control in the field involves rotation out of cucurbits and control of volunteer watermelon plants. Sprinkler irrigation can lead to spread through the field^{ref1, ref2, ref3, ref4}.
• Gammaproteobacteria
• Enterobacteriales
• Enterobacteriaceae
• Erwinia
• Erwinia amylovora [Ea]

=> fire blight in apple and pear. Management of Ea is a major problem for tree fruit growers and an irritating nuisance for growers of ornamental fruit trees. Removal and burning of all blighted tree limbs and cankers is essential. There is no effective chemical control of the disease, but elemental sulphur or copper may be of some use. Streptomycin has been used for controlling Ea on apple and pear trees. Prevention strategies include removal of suckers and water sprouts, avoidance of excessive water or high-nitrogen fertilizers, and clean cultivation below trees. Resistant cultivars, if available, should be planted^{ref1, ref2}.
• Erwinia persicina [Ep] (previously known as Erwinia persicinus^ref) was first described in 1990 after being isolated from a variety of fruits and vegetables, including bananas, cucumbers, and tomatoes. In 1994, Ep was shown to be the causative agent of necrosis of bean pods and was also reported to be the 1st human isolate of Ep. The strain was isolated from the urine of an 88 year old woman who presented with a urinary tract infection. By the hydroxyapatite method, DNA from this strain was shown to be 94.5% related at 60°C and 86% related at 75°C to the type strain of Ep. The biochemical profile of Ep is most similar to those of 2 plant pathogens, Erwinia rhapontici and Pantoea agglomerans, and species of Enterobacter. It is negative in tests for lysine, arginine, ornithine, dulcitol, and urea and is motile and positive in tests for D-sorbitol and sucrose. It is susceptible to the expanded-spectrum cephalosporins, aminoglycosides, and fluoroquinolones, but it is resistant to ampicillin, ticarcillin, and cefazolin. There have been several other bacterial plant pathogens reported to be involved in human infections^{ref1, ref2, ref3}
• Erwinia rhapontici

=> infection of pulse crop seeds such as lentil and chickpea is reported to cause reduced germination and stunting of seedlings. Concern has been expressed by plant pathologists regarding spread of Er to pulse crops in western Canada. Plants are most susceptible to Er infection at the young pod stage. Er overwintered well in experiments conducted in western Canada. Viable Er cells were found in 47% of seeds and in 59% of stems left on the soil surface during the winter of 2000-2001, and survival percentage increased markedly in seed buried at a depth of 6 cm. The fungus is an opportunistic pathogen, reported also on bread wheat, durum wheat, and onion. Use of disease-free seed is the best method of disease management
• Pantoea
• Pantoea stewartii
• Pantoea stewartii subsp. stewartii
=> Stewart's wilt (a.k.a. bacterial leaf blight of maize) is transmitted primarily by corn flea beetles (Chaetocnema pulicaria) and by seed. Disease management includes using resistant cultivars and insecticides to reduce flea beetle populations
• Pectobacterium
• brittle leaf is a new lethal disease of date palm (Phoenix dactylifera). The fact that no pathogen has been identified is not too surprising, given that other priorities may be more urgent. Efforts will have to be directed at finding the causal agent(s). Reference to a low molecular weight dsRNA in affected date palm is of interest but there are dsRNAs in apparently healthy crops (for example, black-seeded common bean) which seem to have no apparent relation to disease expression. Presumably Fusarium oxysporum f. sp. albedinis, the causal agent of Bayoud disease, Fusarium proliferatum and Erwinia chrysanthemi have been considered as possible pathogens. The date palm is often the only available staple food for the inhabitants of desert and arid lands, and thus it is vital to millions throughout North Africa and the Middle East. According to FAO, there are 90 million date palms in the world, each of which can grow for more than 100 years. 64 million of these trees are grown in Arab countries, which produce 2 million tons of dates between them each year. Trees start producing after 4-5 years and reach full production after 10-12 years. Major Arabian date palm producers include the Maghreb countries (Morocco, Algeria and Tunisia), Egypt, Libya and Saudi Arabia.
• Pectobacterium carotovorum subsp. carotovorum (Pcc; a.k.a. Erwinia carotovora subsp. carotovora)

=> bacterial stem rot. Ecc is ubiquitous, causing disease in glasshouse crops and appears to be present at low frequency in various regions of Italy. 2 greenhouse pepper (Capsicum annuum L.) isolates of Ecc characterized in this report were pathogenic in tomato, thus possibly putting that crop at risk. Diagnosis of the disease requires careful analysis, because the tomato pith pathogen,Pseudomonas corrugata can be confused with Ecc. Ecc survives readily in field residues. Disease management depends upon use of hypochlorite-treatment of seeds, avoidance of wounding, and early detection of the pathogen. Should an outbreak occur in glasshouse production units, all plants should be destroyed, and the crop should be treated with fixed copper sprays. At the close of production, all plant residues should be removed and subjected to solarization for at least 45 days during summer.
• Pseudomonadales
• Pseudomonadaceae
• Pseudomonas
• Pseudomonas corrugata
• Pseudomonas fluorescens : strains of Pf suppress plant diseases by protecting seeds and roots from fungal infection This occurs as a result of the production of several secondary metabolites including antibiotics, siderophores and hydrogen cyanide. Competitive exclusion of pathogens as the result of rapid colonization of the rhizosphere by Pf may also be an important factor in disease control^{ref1, ref2, ref3, ref4}. Pseudomonas fluorescens (Pf-5) naturally safeguards roots and seeds from infection by harmful microbes that cause plant diseases : the genome of this microbe is composed of 7.1 million base pairs^ref
• Pseudomonas mediterranea
• Pseudomonas viridiflava [Pv] causes bacterial leaf blight of melon, tomato and eggplant and other food crops. It is rarely found in the region of Asturias in northern Spain and has been traditionally considered an epiphyte or opportunistic pathogen. Pseudomonas strains with an atypical LOPAT profile (where LOPAT is a series of determinative tests: L, levan production; O, oxidase production; P, pectinolitic activity; A, arginine dihydrolase production; and T, tobacco hypersensibility) have been differentiated.  Since 1999, a new Pseudomonas type with an atypical LOPAT profile (convex colonies with uncharacteristic yellowish mucoid material in hypersucrose medium [L test]; O negative; P variable; A negative; and T positive) was frequently isolated from and associated with disease in plants in common bean (Phaseolus vulgaris). It has also appeared in material from other plants with disease symptoms, including kiwifruits (from spring of 2000) and lettuce (from 2001). A novel family of peptide antimycotics, termed ecomycins, is described from Pv. Ecomycins B and C have molecular masses of 1153 and 1181, and they contain equimolar amounts of hydroxyaspartic acid, homoserine, threonine, serine, alanine, glycine and an unknown amino acid. Fatty acids were detectable after hydrolysis, methylation and gas chromatography and mass spectroscopy. The ecomycins have significant bioactivities against a wide range of human and plant pathogenic fungi, including Cryptococcus neoformans and Candida albicans. Pv also produces what appears to be syringotoxin, an antifungal lipopeptide previously described from Pseudomonas syringae^{ref1, ref2, ref3, ref4, ref5}.
=> tomato pith necrosis, is one of the most destructive diseases of tomato in Europe. Symptoms are yellowing and wilting of lower leaves which progressed upwards, brown areas on stems and yellow-brown discoloration of the pith
• Pseudomonas syringae group
• Pseudomonas syringae group genomosp. 1
• Pseudomonas syringae pv. pisi

=> Pisum sativum seeds, New Zealand, Israel
• Pseudomonas syringae group genomosp. 3
• Pseudomonas syringae pv. syringae (Pss) is a pathogen on mango and causes citrus blast disease on trees of orange (Citrus cinensis cv. Washington) and mandarin (Citrus reticulata cv. Marisol). Pss is an epiphytic bacterium and usually causes damage following an injury, such as wind damage, frost, hail, etc. Frost causes the removal of the epidermis thus allowing the bacterium to invade floral tissues. Low temperature and wet conditions favor disease development. Boron deficient trees are more susceptible to disease. Disease management involves protection from frost, removal of contaminated shoots, and use of copper sprays (Bordeaux mixture) at bud-swelling stage. In years of heavy rainfall, a 2nd application of Bordeaux mixture may be necessary. The 2nd link shows good pictures of diseased tissues on pear; I could not find good photographs for citrus, but the photographs of pear are useful and should give you a good idea of disease symptoms^{ref1, ref2, ref3}.
• Pseudomonas syringae pv. tomato (Pst)

=> bacterial speck disease in tomato. Small (1 to 2 mm), water-soaked, dark brown-to-black spots similar to those observed in the greenhouses of commercial seedling companies and commercial greenhouses that produce tomato develop on the young expanding leaves of inoculated plants within 7 to 10 days. There are 2 possible routes for infection. The 1st is that tomato seed contaminated with Pst was used to establish seedling transplants. The 2nd is that the seedling production facilities were contaminated by the Pst. In either case, the bacterium can be efficiently spread. Disease management includes use of seed produced on disease-free plants, disease-free transplants, crop rotation with non-solanaceous crops for at least 2-3 years between tomato crops, and resistant cultivars. Proper sanitation such as disinfecting interior glasshouse surfaces is strongly recommended before seeding or transplanting^ref.
• Xanthomonadales
• Xanthomonadaceae
• Xylella
• Xylella fastidiosa [Xf] (EPPO A1 list)

PCR methods were developed in USA for the detection, differentiation and quantification of Xf strains. 5 PCR systems were developed based on the currently available genomic sequences of 4 strains: Pierce's disease of grapevine, almond leaf scorch, oleander leaf scorch and citrus variegated chlorosis. These PCR systems were able to differentiate each strain specifically in suspensions containing a mixture of strains (whole bacteria or DNA) and in DNA extractions from field-collected samples. Brazil currently produces > 1/3rd of the world's oranges. Citrus production in several states in Brazil is threatened by Citrus variegated chlorosis (CVC), a bacterial disease that affects primarily sweet orange (Citrus sinensis) cultivars. A xylem-limited gram-negative bacterium, Xf is the confirmed pathogen of CVC. CVC symptoms include foliar necrotic spots, leaf scorch, tree-stunting, and reduction of fruit size and yield. Xf is spread from plant to plant by grafting with infected bud material and by sharpshooter leafhoppers (Hemiptera: Cicadellidae). Xf causes citrus variegated chlorosis disease in Brazil and Pierce's disease of grapevines in the USA. Both of these diseases cause significant production problems in their respective industries. The recent establishment of the glassy-winged sharpshooter in California has radically increased the threat posed by Pierce's disease to California viticulture. Control of CVC by pruning of symptomatic branches is effective under certain circumstances^{ref1, ref2, ref3}.
• Xanthomonas
• Xanthomonas campestris
• Xanthomonas campestris pv. armoraciae [Xpa] is present in the USA, Ukraine, Australia, Japan, Brazil, China, Turkey, and India and causes cabbage leaf spot. The disease is favored by cool temperatures in fall and winter, although it infects susceptible hosts over a wide temperature range. Infected plant debris is a source of inoculum and Xpa is known to be soil- and seed-borne. Disease management involves use of bacteria-free seed, planting in well-drained soils, and rotation of non-cruciferous crops on a 3-year cycle. Apparently there are no tolerant or resistant cultivars.
• Xanthomonas citri
• Xanthomonas axonopodis
• Xanthomonas axonopodis pv citri [Xac]

Epidemiology :
• Australia : 4 outbreaks in 2004, 1993, 1991, and 1924^{ref1, ref2, ref3}. Because symptoms are generally similar, separation of these types from each other is based on host range, cultural and physiological characteristics, bacteriophage sensitivity, serology, plasmid fingerprints, DNA-DNA homology, and, by various RFLP and PCR analyses. The latter DNA-based assays demonstrate that these strain types are genetically, as well as pathologically, unique. The decision to destroy non-commercial citrus trees is a major departure and it will profoundly affect residential homeowners. There is no option but to destroy citrus trees in private backyards in order to reduce or eliminate CC. The outbreak began almost 12 months ago; the cost so far to growers is about $100 million; and the cost to government is another $13 million^ref
• USA : Xac continues to spread in southern Florida. Eradication of infected citrus trees is the primary means of disease management. Local spread of Xac is primarily by wind-driven rain, overhead irrigation and contaminated equipment and long-distant movement is by infected plant material. Much success was achieved by implementing a policy of destroying infected trees and pruning all green wood on trees within 50 feet of the infected trees, but in the latest eradication program with citrus leafminer involvement, the general policy of removing infected trees plus exposed trees within a 1900 ft radius is now in place. This epidemic of citrus canker (1995 - present) has impacted many areas of Florida including 15 counties. Citrus canker has erupted again in Martin County. The disease was reported on 7 Dec 2004 in 1 tree in a grove near the Indian River/St. Lucie county line. On 25 Jan 2005 a routine Sentinel Tree Survey conducted by USDA found 3 suspected citrus trees on 2 adjacent properties in Sebastian. Officials of the State Citrus Canker Eradication Program immediately launched a comprehensive survey of these areas to identify the extent of the infection and to prevent further spread. Commercial control actions (quarantine removal) were implemented to remove 16 878 trees including 226 trees confirmed to be infected by the citrus canker bacterium. In Florida, the predicted negative economic impact of allowing citrus canker (CC) to become endemic clearly favors eradication. The Florida approach to CC eradication has evolved over time. In the first program from 1915 to 1933, infected trees were usually doused with an incendiary fuel and burned in place. In later programs, infected trees have been burned in place or removed mechanically. The necessity of removing exposed -- in addition to obviously infected -- trees was recognized in the 1986 program, and a guideline calling for removal of all citrus within 125 ft of infected citrus was adopted based on studies of inoculum dispersal in Argentina. In the latest eradication program with citrus leafminer involvement), even the 125-ft radius was deemed inadequate for eradication in most situations. The "1900-foot rule" was established in January 2000 and put in practice in March 2000, requiring the removal and destruction of diseased citrus trees and of all citrus trees within a 1900-ft radius of a diseased tree). The 1900-ft rule presently serves as the operational basis of the CC eradication program. Each circle of 1900 ft radius represents 0.41 square miles (1.06 square km). The implementation of the 1900-ft rule results in removal of the majority of dooryard citrus within infected areas. Through risk assessment, exposure zones are determined commensurate with the amount of disease, age of infection, inoculum dispersal opportunities, environment, susceptibility of hosts, physical access to potential hosts for regular inspection, plus other factors. In these exposure zones, all citrus is removed. Guidelines call for quarantine areas to extend one to 2 miles in all directions from infected citrus. No citrus material is allowed to move into or out of the quarantine zone unless risk-assessed. Survey and inspection crews should practice rigorous sanitation of hands, shoes, clothing, or any equipment that comes in contact with citrus before moving from property to property. Quaternary ammonium disinfectants are available for use on both inanimate surfaces and for application to bare skin and clothing. In areas of the world where CC is endemic, disease management involves use of resistant varieties, windbreaks to hinder inoculum dispersal and timely applications of copper-containing bactericides. Selective pruning of infected tissues is also utilized in citrus growing areas where labor-intensive practices prevail. CC has been present in Florida for over 100 years : CC may be spreading throughout the state because humans are the main mode of its spread. Other modes of spread include overhead irrigation, flooding, insects, and birds. Long-distance spread of CC has to be managed by preventing the transportation of infected plant material and by using decontamination procedures. There is no cure for CC. In areas of the world where CC is endemic, disease management involves use of resistant varieties, windbreaks to hinder inoculum dispersal, and the timely application of copper-containing bactericides. These strategies are costly and not completely reliable. Currently, the only management option for CC in Florida is to eradicate the disease. CC has caused exceptionally high crop losses in the Florida citrus industry. The hurricane seasons in 2004 and 2005 have taken a heavy toll on growers. Eradication is the only option for managing the disease for citrus growers. John-Thor Dahlburg, a Los Angeles Times staff writer, likened 2004's hurricanes to dropping a bacteriological bomb on Florida's already sorely challenged citrus industry, widely dispersing a virulently contagious germ that causes CC. Florida officials say the possibility that hurricanes could further scatter the bacteria has created the most serious threat in decades to the state's signature crops. State agriculture officials say they have no yardstick to determine when -- and if -- they should abandon the attempt to wipe out citrus canker despite spending 10 years and about $650 million in what has, so far, been a losing battle. Florida has not decided the conditions under which it would drop its controversial eradication policy in favor of other approaches. The ultimate cost of the eradication program could top $1 billion^{ref1,ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9, ref10, ref11}
=> citrus canker (CC)^ref is one of the most destructive bacterial diseases affecting citrus fruits in Florida and other citrus-producing areas of the world. CC affects all types of citrus, including oranges, sour oranges, grapefruit, tangerines, lemons (Citrus limon) and limes. Infected citrus trees undergo progressive decline in health and fruit production and, ultimately, cease to produce fruit.
Transmission : spread locally primarily by wind-driven rain, overhead irrigation, and contaminated equipment. Long distance spread is by movement of infected planting material. Citrus leaf miner (Phyllocnistis citrella) may help spread Xac because of leaf damage due to mining activity^{ref1, ref2, ref3, ref4, ref5}.
• strain "A" affects members of the plant family Rutaceae, including most citrus species and hybrids, especially, grapefruit, lime, sweet lime, and trifoliate orange. All known U.S. infestations have been associated with the "A"
• strain "B" infects lemons in Argentina, Uruguay, and Paraguay
• strain "C" (more cosmopolitan) infects a wider range (Mexican or key lime, sour orange, Rangpur lime, sweet lime, citron, and occasionally, sweet orange, and mandarin orange) and infects only Mexican lime in Brazil strain
Disease management relies on the use of more resistant types of citrus, such as Valencia oranges and mandarins, use of cultural practices that reduce disease severity (allowing vegetation to reduce wind-blown sand, planting of windbreaks, and, avoidance of working in infected areas when trees are wet from dew or rain, because bacteria ooze from lesions onto moist surfaces). Frequent applications of copper-containing bactericide sprays have been shown to be somewhat effective in suppression of the disease but are not cost effective. There is no known chemical compound that will destroy the bacteria within the plant tissue. In order to eradicate the disease, infected and exposed trees must be cut down and disposed of.
• Xanthomonas axonopodis pv. phaseoli [Xap] : comparative tests (1995-1998) have evaluated several semi-selective media for use in the detection in bean seed. 2 media XCP1 and MT have been chosen for their ease of use and selectivity for Xap. Both media rely on the ability of Xap to hydrolyze starch. The fact that a PCR-based system for detection of Cff was recently developed in Italy suggests that development of a similar system for Xap might be worth investigating
• Xanthomonas axonopodis pv. vesicatoria [Xav] has been in Turkey for some time. Long-distance spread of the pathogen in the country is likely, mainly by movement of infected or infested tomato seed. The fact that Xav has infected tomato may be the consequence of environmental conditions. Xav is comprised of strains (races) that infect only sweet pepper or tomato (Lycopersicon esculentum), or both crops
• Xanthomonas campestris pv. musacearum (Xcm)

=> banana bacterial wilt (BBW), 1st reported in Ethiopia, caused only minor damage, because banana production was practiced on a small-scale basis. It is also known to cause wilt of ensete, a variety of banana found in Ethiopia. Its spread to Uganda^ref and other areas of eastern Africa is a direct threat to banana, which is a staple food crop, and over 90% of production is from smallholders for home consumption or local trade. BBW erupted in Bulyanti village, Kyabaala parish, in Mukono district in September 2001 and has spread to 21 of the 56 districts by August 2004 and 33 in August 2005. In the 1970s, Uganda produced between 15 to 20 tonnes of bananas per acre but yields are currently about 6 tonnes per acre. High-density production of banana in Uganda is intensive and thus disease spread is rapid and difficult to control. The mode of transmission suggests that Xcm may spread by aerosol or by insects. Although the only eradicative procedure is burning of affected plants, disease management in the long term must depend upon selection or development of resistant cultivars. It would be interesting to know whether there are differences in the genotypes of Xcm collected from different areas in Africa^{ref1, ref2, ref3, ref4}. . Major banana-producing countries such as Uganda, with 10 million tons annually, Rwanda, with 1.5 million and the Democratic Republic of the Congo (DRC), with 1 million, are experiencing sharp losses due to attacks by Xcm. At Goma, in the DRC's eastern province of Nord-Kivu, the price of wine bananas and cooking bananas has doubled, resulting from losses of 60%. Production in Kichanga and Rutshuru has fallen by around 60%, and they have been forced to turn to producers in the area of Bweremana, 50 km from Goma. Even with that, they are not managing to satisfy the increasingly important Rwandan and Ugandan demands. According to initial estimates, only 8 of 2500 hectares of the region's plantations already infected have had their plants uprooted. It is difficult to eradicate BBW once it has become established in smallholder production systems, and outbreaks must be managed effectively and quickly to prevent the spread of the disease. Disease management strategies used include disposal and destruction of infected plants, disinfection of tools in managing the plantation, avoidance of planting materials from infected fields, removal of male buds (to reduce insect transmission of the disease), keeping browsing animals out of infected fields, replacing bananas with another crop for at least 2 years, and use of quarantine measures to prevent introduction of BBW into new areas. Strict discipline by farmers to avoid transmission on contaminated tools and crop residues can help halt the advance of BBW. Infected trees have to be burned. For him and his neighbors, it is a matter of preventing the disease spreading from plant-to-plant. Farmers are not always prepared to make such a sacrifice. Reluctance to uproot their banana plants makes the battle against this scourge difficult. There are no known resistant cultivars. Strict application of phytosanitary practices are required^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9, ref10}
• Xanthomonas oryzae
• Xanthomonas oryzae pv. oryzae [Xoo]

=> bacterial leaf blight [BLB] of rice. They have reduced Asia's annual rice production by as much as 60%. In Japan, about 300 000 to 400 000 hectares of rice were affected by BLB in recent years. 20-50% yield losses have been reported in severely infected fields. In Indonesia, losses were higher than those reported in Japan and in India, millions of hectares were severely infected, causing yield losses = 6-60%. Removal of weed hosts, rice straws, ratoons (sprouts from the root or crown), and volunteer seedlings is important to reduce infection. Maintaining shallow water in nursery beds, providing good drainage during severe flooding, and plowing under rice stubble and straw following harvest are also useful management strategies. Proper application of fertilizer, especially nitrogen, and proper plant spacing are recommended for management of BLB. Planting resistant varieties is the most common and effective approach to management by farmers in Asia. When different strains of bacteria are present, it is recommended to grow resistant varieties possessing field resistance genes. Let the paddy go to fallow and allow it to dry thoroughly. Seed treatment with bleaching powder (100 mg/ml) and zinc sulfate (2%) reduce bacterial blight. Control of the disease with copper compounds, antibiotics, and other chemicals has not proven highly effective.
• Xanthomonas vesicatoria in India and Mexico
=> Brassica oleracea convar. botrytis, seeds, Japan, Israel
• Eukaryota
• Plasmodiophorida
• Plasmodiophoridae
• Plasmodiophora
• Plasmodiophora brassicae

=> clubroot (CR) remains one of the important diseases affecting members of the mustard family (Cruciferae). It is a soilborne disease of field crops such as canola, mustard, cabbage, broccoli, cauliflower, radish, and turnip. Clubroot is not a new disease and is common in British Columbia and eastern Canada. Given the previous reports of clubroot in home and market gardens, it is possible that vegetable gardens may be acting as initial foci of infection, particularly if growers are unknowingly importing contaminated transplants^{ref1, ref2, ref3}. CR is a soil-borne disease that affects crucifer crops, including cabbage, broccoli, cauliflower, canola and mustard. The disease is found in many parts of the world. In Canada, it has been a problem for commercial vegetable producers in British Columbia, Quebec and Ontario. According to Kent MacDonald, P.Ag., CCA, crop specialist with Agriculture Alberta, there were no reported disease problems with canola during 2004. In 2005, however, there were reports of CR in several new fields in the Edmonton area. CR is especially problematic because the fungus persists in soil for many years, and there are no crop protection products currently registered for its use in Canada. Plasmodiophora brassicae Woronin causes CR. It infects the roots and causes formation of irregular club-like galls. These galls restrict the flow of water and nutrients to leaves, stems and pods. Plant symptoms include wilting, stunted growth, yellowing, premature ripening and shriveled seed. Plants infected early in the growing season may resemble those suffering from heat or drought stress. Crops that have finished flowering may express symptoms resembling sclerotinia stem rot or possibly fusarium wilt. In most cases, CR can be diagnosed by a close examination of the root system. Based on using CLIMEX, a computer software program designed to predict potential distribution and relative abundance of species (insect, disease, etc), the Edmonton region was likely regarded as one of the few areas of western Canada where CR would induce significant economic crop loss. Other Alberta areas with similar climatic conditions still have the potential for CR development and need to be aware of the potential significance of the disease. Although CR problems are not widespread, the economic impact of the disease can be significant for individual producers. MacDonald says that canola yield losses from research data indicate that CR infestations are approaching 100 per cent, leading to yield losses of 50%. The percentage of yield loss from CR is generally half of the percentage of infected plants. There is no real cure for CR. The best management strategy is prevention, and that includes: long rotations (4 years) between canola crops as the single most important preventative strategy. Fields that have CR problems have a history of short (often 1-in-2 years) canola rotations. Lengthening the canola rotation may reduce profitability in the short term, but the long-term gains will be substantial if the longer rotation prevents CR. Field equipment requires application of phytosanitary measures such as cleaning soil from equipment, including tires; and avoiding hay and straw purchases from regions known to be infested or suspected to be infested with CR because straw and hay could be carrying soil and the CR pathogen. Once land is infected with CR, management strategies are more difficult and/or expensive. Canola should not be seeded on infected land for 5-7 years. The CR pathogen can survive in soil for up to 17 years, so a 5-7 year break from canola may not eliminate the problem. The extended rotation away from canola must also include diligent control of species susceptible to CR. Volunteer canola, weeds in the mustard family, dock, hoary cress, orchardgrass, red clover, red-top, and perennial ryegrass will minimize soil erosion with zero or minimal tillage. Since CR is a soil-borne disease, the fungus will move with wind or water-eroded soil. There is evidence that liming
soils to pH 7 or higher will reduce the viability and longevity of spores in the soil. CR is a very difficult disease to manage, and heavily infested areas may have to be abandoned for crucifer production. Some control may be achieved with the following measures: use a good crop rotation program, growing crucifers on the same soil no more than every 3rd or 4th year, is essential to retard development of a large population of spores on land not already heavily infested; liming (calcite) soil to pH 7.2 or above may be helpful but avoid raising the soil pH too high so as to interfere with growth of succeeding crops other than crucifers; planting with pathogen-free plants in pathogen-free seedbeds and uninfected plants is essential to prevent introduction of the disease; application of a fungicide in transplant water or rototilled in a band prior to planting may help to reduce disease development; clean and disinfect all machinery before moving it from infested to non-infested land and use resistant cultivars if available, although plant resistance has not been very useful in CR control because of rapid development of new races of the fungus^{ref1, ref2, ref3, ref4, ref5}
• Spongospora
• Spongospora subterranea

=> potato (Solanum tuberosum)
• Fungi/Metazoa group
• Fungi
• Ascomycota
• Macrophomina phaseolina (Mp) is a highly variable fungus, with isolates differing in microsclerotial size and the ability to produce pycnidia. The pathogen infects and causes diseases of canola, corn/maize, soybeans, and sunflower. It is a weak pathogen killing plants that are stressed, especially by high temperatures. It is an important pathogen in southern USA, Mexico, and Africa. Sclerotia survive in soil, thus providing inoculum for future infections of the crop. Crop rotation, use of early maturing varieties to avoid late season heat/drought stress, and water management are methods used to manage the disease^{ref1, ref2}
• Pezizomycotina
• Dothideomycetes
• Myriangiales
• Elsinoaceae
• Elsinoe
• The fungus associated with mango scab in Queensland has been compared with the type collection of Sphaceloma mangiferae, and found to be conspecific with that taxon. Morphological characteristics indicate that it is placed incorrectly in Sphaceloma, and the new combination Denticularia mangiferae is proposed. Pathogenicity to mango leaves has been demonstrated with a culture isolated from mango in Queensland, and with inoculum taken directly from sporulating leaf lesions. Elsinoe mangiferae has also been reported to cause a similar disease in Australia in January 1997 as a result of intense investigation into severe scarring and distortion of mangoes in the Darwin rural area of the Northern Territory. Both pathogens can cause severe infections, resulting in development of scar tissue and fruit drop. Mango scab is usually not important in commercial groves, because fungicides containing copper also control scab. Infection in nurseries can be prevented by frequent sprays of neutral copper on young leaves^{ref1, ref2, ref3}
• Elsinoe ampelina

=> grape anthracnose. The fungus overwinters in infected plant material. In the spring when the temperature is > 2.2°C, spores are spread by wind and splashing rain and can infect all aboveground parts of the plant. However, warmer conditions (up to 32.2°C) promote more severe infections. The primary winter survival mode for the fungus is in mummified berries and in other infected plant material. Management of grape anthracnose disease consists of the following procedures: 1) pruning and destroying diseased plant material while they are dormant to reduce the potential for disease in the following year; 2) removing wild grapes in the vicinity because they can harbor pathogens; 3) avoiding planting anthracnose-susceptible grape cultivars; 4) and promoting drying of the canopy by pruning, training, row orientation, and proper spacing. Grapes in New Zealand are treated with regular dormant and regular fungicide sprays during the season^{ref1, ref2, ref3, ref4}
• Elsinoe australis on citrus; South America
• mitosporic Elsinoaceae
• Sphaceloma
• Sphaceloma mangiferae
• Pleosporales
• Leptosphaeriaceae
• Leptosphaeria
• Leptosphaeria maculans complex
• Leptosphaeria maculans (a.k.a. blackleg of rapeseed fungus) (anamorph = Phoma lingam) causes the most important disease of canola (Brassica napus) worldwide, especially prevalent in Australia, Canada, France, Germany, and the United Kingdom). Isolates can be categorized into 4 pathogenicity groups (PGs) on the basis of the interaction phenotypes (IP) on the differential canola cvs. Westar, Glacier, and Quinta by using a standard screening protocol in the greenhouse. Isolates in PG1 are weakly virulent as they generally cause superficial lesions on the leaves. However, isolates in PG2, PG3, and PG4 are highly virulent because they can produce stem canker at the base of the canola plant, causing significant yield loss.

=> black leg / Phoma stem canker. Disease management includes cultural control, fungicides, and genetic resistance. Weeds and volunteer canola must be controlled. Pathogen-free seed should be used. Lm survives on stubble, so fields affected by the pathogen should undergo crop rotation for at least 3 to 4 years, and new plantings should be at least 500 metres from such fields. Seed treatment with fungicides (benzimidazole, dicarboximide, and morpholine) results in almost complete elimination of seed transmission of the pathogen. Resistant cultivars are the most important and sustainable means of blackleg control, but the choice of cultivars depends upon availability and the strain of Lm in the production area. Blackleg in western Canada will continue to change, and new strains will continue to appear in canola fields. Farmers will have to be prepared to adapt to new varieties and means of identifying new strains of the pathogen. The industry's action plan for coping with new disease strains includes ongoing evaluation of varietal resistance over time, developing a system to identify new strains, and developing polygenic resistance to the blackleg pathogen. New strains (PG3 and PGT) were identified in 2003. Most current commercial varieties appear to have resistance to the new PG strains, but pathologists agreed they can't yet advise growers which ones may be resistant. Disease management depends upon planting canola no more than once in 3 years and choosing varieties rated as resistant or moderately resistant to blackleg^{ref1, ref2}. Most isolates of L. maculans in western Canada belong to PG2, but PG3 and PG4 isolates were recently found in Manitoba. PG3 isolates are aggressive to Q2 and Defender, and additional susceptible cultivars will undoubtedly be identified in future. This does not mean that all varieties will be attacked by PG3, because genes conferring resistance to PG3 have been probably incorporated into many current canola varieties. Varieties originating from areas where PG3 is endemic have long been used to breed Canadian canola, so resistance genes have almost certainly been introduced. PG3 distribution in western Canada is currently unknown, but the strain may already be present in Canadian blackleg nurseries, so many varieties may have already been "pre-screened" for resistance. The appearance of PG4 may be evidence of pathogen population changes occurring under high-selection-pressure exerted by resistance genes in commercial cultivars, or through importation of PG4 isolates with canola seed. Australian plant breeders identified a new source of blackleg resistance Brassica sylvestris [Bs], a wild relative of canola. The
resistance was successfully incorporated into canola, resulting in an almost immune response to blackleg. After further breeding, Pacific Seeds released varieties for the Australian market in 2000, and their adoption by growers has led to substantially reduced yield losses associated with blackleg. However, in early 2003, Pacific Seeds issued a press release stating that blackleg stem cankers had been observed on these varieties which had previously been immune to blackleg. In addition to the 2 sites identified by Pacific Seeds (Port Lincoln, SA and Cudal, NSW), Agriculture WA also reported the breakdown of Bs resistance at Mt. Barker in Western Australia. During
2003, the strain of blackleg able to attack the Bs resistance spread across Eyre Peninsula, causing an estimated cost of 20 million dollars to local farmers. At some locations, varieties based on this type of resistance are now very susceptible to blackleg and may experience almost complete yield loss. Blackleg strains able to attack plants containing the Bs resistance appear to be unable to infect varieties containing polygenic resistance. This development is of considerable concern to farmers and pathologists to the say the
least^{ref1, ref2}. Canola is the major oilseed crop grown in the Prairie Provinces in Canada and its coverage area is expanding. It is also an economically important and serious disease of canola (Brassica napus) in Australia, France, Germany, USA and the United Kingdom. It is the most serious disease of anola/rapeseed in the prairies, and may cause major crop losses in some years. The infections of blackleg may occur on cotyledons, leaves, stems and pods. Stem canker is the most serious symptom, as it can girdle the stem, causing plant lodging leading to yield loss. 3 disease prevention methods -- crop rotation, genetic resistance and seed treatment with fungicide have proven to be effective. In Manitoba, L. maculans population consists mainly of PG2 (virulent on cv. Westar; avirulent on cvs. Glacier and Quinta) and a few PG1 isolates (avirulent on all 3 differential hosts). PG3 isolates (virulent on cv. Westar and Glacier; avirulent on Quinta) are found in Europe, Australia, USA and eastern Canada. The existence of PG3 in western Canada had not been established until its isolation in 2002)^{ref1, ref2}.
• Phaeosphaeriaceae
• Phaeosphaeria
• Phaeosphaeria nodorum (a.k.a. Septoria nodorum) : an investigation spanning some 160 years of data has shown how air pollution is linked to plant diseases. The study reveals that industrial emissions directly affect which microbes attack wheat. Each year, US wheat farmers lose some US$250 million as a result of damage caused by the fungus Mycosphaerella graminicola. And European farmers spend about US$400 million annually on fungicides to control the spread of this pathogen and Phaeosphaeria nodorum, which similarly hits crop yield. Over the course of the past century, European farmers have seen P. nodorum become more prevalent, and the once dominant M. graminicola fall into the background. The prevalence of P. nodorum DNA in an archive of British wheat samples that was started in the autumn of 1843 doesn't correlate with rising temperatures due to global warming, but rather with changes in air pollution,  specifically with levels of sulphur dioxide, an air pollutant spewed out by industrial installations such as coal-fired power stations. In 1844, for example, sulphur dioxide emissions in Britain were about 1 million tonnes a year, and M. graminicola was 3 times as common as P. nodorum. But as this figure climbed to 6 million tonnes in 1970, the M. graminicola virtually disappeared, and P. nodorum exploded to 100 times its 1844 amount. With reduced coal burning over the past 2 decades (and a subsequent drop in sulphur dioxide emissions), the ratio of these wheat pathogens in Europe has returned to more or less the same as it was in pre-industrial times. How exactly might pollution exert this influence on plant disease? The fungi may react differently to increases in rain acidity caused by sulphur dioxide, particularly when it comes to forming reproductive spores. But he adds that the mechanism is likely to be very intricate, involving ozone as well as sulphur dioxide.

=> Septoria leaf blotch of wheat
• Pleosporaceae
• Alternaria
• Alternaria alternata group
• Alternaria alternata (Aa) is the most frequently reported Alternaria species causing plant disease. It is primarily a weak pathogen, attacking already stressed plants, but may also be pathogenic on healthy plants. It is interesting to note that all of the previous posts related to Aa concern citrus. Wounding is required, especially during harvest, leading to post-harvest and storage infections of tubers and fruits, or by insects and nematodes. Insects facilitate infection and act to stress the entire host-plant system, thereby reducing overall plant resistance. Furthermore, insects may act as vectors by dispersing inoculum throughout the crop. Infection pathways include nutrient, water, or microclimate-originated stresses. Recommendations for disease management include a 3-year crop rotation for tomato or potato, planting of crops that are not hosts of Aa, removal and burning of infected debris and eradication of weed hosts to further reduce inoculum. Combining resistant cultivars and other control measures greatly decreases disease progress^{ref1, ref2}. In India, the present approach has been to find bio-pesticides that are free of hazardous residues and environmental pollution. In the light of increasing awareness about adverse effects of pesticide residues in food on human health, which is often reflected in adoption of more and more stringent regulations by many countries, a well equipped pesticide residue laboratory was establish at Tocklai which will direct research towards integrated approach to pest and disease management through uses of, biocides, parasites, predators, cultural methods and safer chemicals. For biological control of pests, survey for natural enemy complex of pests is in progress. Experiments on mass breeding of promising species of parasitoids and predators of the major tea pests are also in progress under controlled laboratory conditions. Fungal pathogens such as Trichoderma spp. are being effectively used for the control of Poria hypobrunnea, which causes stem canker in North-East India. Application of bioformulations of T. harzianum

and Gliocladium virens to the soil and for wound dressing at the time of pruning suppresses the development of canker. The bacterium Bacillus subtilis is effective in the control of black rot disease caused by Corticium invisum and C. theae. Blister blight disease caused by Exobasidium vexans is an important leaf disease leading to heavy crop loss in South India and Darjeeling. Manipulation of the micro climate by shade regulation contributes greatly reduces disease incidence. However, it will be necessary to spray copper oxychloride to control this disease under the agroclimatic conditions of South India. In the new planting areas, it is necessary to avoid the planting of cultivars which are highly prone to the incidence of major pests and disease^{ref1, ref2, ref3}
• Alternaria brown spot (ABS) of tangerine hybrids is known to occur in South Africa, Turkey, Israel, Spain, and Colombia as well as Florida and possibly in other citrus-growing regions. The disease first appeared in Florida citrus groves about 30 years ago and has become a serious problem on some varieties in recent years. It was first reported in Australia in 1962, but it is not known when the fungus arrived in Florida. It is assumed that the conditions in Iranian citrus groves are similar to those in Florida. Fungicides are the primary means of controlling ABS. However, there are many management practices which are helpful in reducing disease severity. New groves should be established with disease-free nursery stock. If Alternaria is present from the outset, it increases to high populations during the period of vegetative growth on young trees and is difficult to control on fruit. For new groves, it is best to locate susceptible varieties in high areas where air drainage and ventilation are good and leaves can dry more rapidly. Less vigorous rootstocks such as Cleopatra mandarin should be selected rather than vigorous ones like Carrizo citrange. Groves of

Minneola tangelos in low, wet areas have conditions so favorable for
disease that ABS may be virtually uncontrollable. Trees of susceptible
varieties should be spaced more widely than oranges to promote rapid drying of the canopy. In existing plantings, it is important not to promote excessive vegetative growth. Overwatering and excessive nitrogen fertilization should be avoided. Light hedging should be done frequently rather than hedging severely but less often. For products registered for control of Alternaria brown spot, see the Florida Citrus Pest Management Guide. The number of fungicide applications needed for control varies greatly with the susceptibility of the variety and the severity of the infestation. In the worst cases, the 1st spray should be applied when the new shoots are about 4-6 inches long to prevent buildup of Alternaria on the spring flush. The 2nd application should be made at petal fall. Thereafter, applications may need to be made as often as every 10 days to achieve good control on fruit and foliage. When frequent applications of copper fungicides are being used, rates can be reduced to as little as one pound of metallic copper per acre. During dry periods which often occur in April and early May, pray intervals can be increased. Likewise, less susceptible varieties or less severely affected groves do not need such intense spray programs. Groves of susceptible varieties should be monitored frequently to determine the disease status. Spraying can be discontinued in late June, since fruit usually become resistant to Alternaria in July as fruit growth slows. It is probably not economical to try to control the disease on late summer flushes of growth^{ref1, ref2, ref3, ref4}
• Alternaria brassicae
• Alternaria raphani

=> gray leaf spot / black spot is present in all canola and rapeseed production areas. The disease overwinters on plant debris and seed. All above-ground plant parts are susceptible to infection from the spores produced on plant debris or infected seed. Polish-type canola cultivars are more susceptible than Argentine-type cultivars. Argentine varieties have a higher yield potential and are also taller and have a higher oil content than Polish varieties. Argentine varieties require about 95 days to reach maturity, while Polish varieties need approximately 80 days to reach maturity. Disease management depends upon planting certified, disease-free seed, a rotation of 1-4 years, and control of weedy mustards and volunteer self-sown canola. It is most likely that the introduction of grey leaf spot was the result of planting infested seed. Fungicides containing iprodione and azoxystrobin are registered for control of gray leaf spot on canola, but I do not know if they are recommended for use in Argentina. Using fungicide-treated seed may help to increase stand establishment when infected seed is planted^{ref1, ref2}.
• Alternaria mali (Am) is a common saprophyte (an organism capable of growth and survival without the aid of another living organism) which can become somewhat infectious to apple fruit that has been predisposed to infection because of injury to the host. Common injuries that can lead to Am rot include mechanical or chemical injury, sunscald, or chilling. Infection can occur before or after harvest, although it is more commonly a post-harvest problem. Am leaf spot is aggravated by European red mites. Disease management consists of mite control, application of fungicides, and adequate tree spacing and other cultural practices that enhance drying conditions. The disease is managed by avoiding injury during harvest and packing. Additionally, post-harvest fruit dips in chlorine solutions can help to prevent post-harvest disease problems. Controlled cold storage is another good practice that will reduce disease problems^{ref1, ref2, ref3}
• Alternaria tenuissima complex
• Alternaria tenuissima

=> leaf spot disease of eggplant (Solanum melongena) was observed during 1997-2000 in Guntur district Andhra Pradesh, India
• Alternaria triticina (At)

=> Alternaria leaf blight (ALB) of wheat (Triticum aestivum) is generally regarded as a weak, minor pathogen that mainly affects old local cultivars, particularly of durum wheat. The disease is common in the eastern and central areas of the Asian Subcontinent. ALB can be very severe if environmental conditions are favorable for disease development; major losses can result when susceptible cultivars are grown^ref
• Cochliobolus
• Cochliobolus carbonum

=> Zea mays seeds, Italy, Israel
• mitosporic Cochliobolus
• Bipolaris
• Bipolaris incurvata (syn. Helminthosporium incurvatum or Drechslera incurvata causes coconut leaf blight (CLB). It is a minor pathogen of coconut (Cocos nucifera) but it can be severe in nurseries. There are no alternate hosts of CLB. CLB is present in Australasia, Central and South America, Pacific and Seychelles. It is an invasive pathogen and is listed as a new emerging and re-emerging plant disease in the United States. Researchers realized that NaCl applications could help restore infertile soils in the Philippines back to productive plantings. In the mid-1970's, researchers found applications of NaCl would suppress leaf spot disease caused by CLB on coconut seedlings and that this treatment worked as well as fungicides. The relative cost of NaCl versus chemical fungicides resulted in significant savings to farmers. Because of lethal yellowing disease, growers are advised to plant resistant Malayan strains, often called dwarf or pygmy coconuts, and labelled yellow, golden, red, and green, according to the color of their fruits, such as 'Golden Malayan Dwarf'. The Malayan palms are very similar to the Jamaican Tall except for having straight trunks. The red strain is the most rugged of the 3 but has the least attractive foliage. The variety `Maypan', a hybrid of Malayan x Panama Tall, has the most robust and rapid growth yet retains its resistance to lethal yellowing disease. All Coconut Palms are highly salt-tolerant and make nice street trees if planted when they are tall enough. Be aware that falling fruit can damage vehicles or hit pedestrians and the flower stalks (in spring) or developing fruit (summer) may need to be removed. Lethal yellowing disease, virus diseases, and fungi all affect coconut palms.  Ganoderma butt rot can infect the lower trunk and roots, and can kill the palm. Avoid injury to the palm in this area. There is no control for butt rot, only prevention^{ref1, ref2, ref3, ref4}
• Bipolaris sacchari (Bs) (Sivanesan, 1987) causes eye spot disease in sugarcane, and wheat stem-base disease
• Bipolaris sorokiniana (teleomorph Cochliobolus sativus) is the causal agent of common root rot, leaf spot disease, seedling blight, head blight, and black point of wheat and barley. That fungus is one of the most serious foliar disease constraints for both crops in warmer growing areas and causes significant yield losses. High temperature and high relative humidity favour the outbreak of the disease, in particular in South Asia's intensive irrigated wheat-rice production systems. In general, disease management would involve use of approved seed treatment, plowing down of crop residues, and several years of rotation to non-cereal crops.
• Pyrenophora
• Pyrenophora teres (barley net-spot blotch disease agent)
• Pyrenophora teres f. maculata

=> spot form of the disease
• Pyrenophora teres f. teres

=> net blotch
.. are important foliar pathogens of barley. Estimated losses worldwide are up to 20%. Isolates derived from single conidia were evaluated for their virulence phenotypes on 25 differential barley genotypes. In general, the Ptft isolates exhibited a broader spectrum and a higher level of virulence on the host differentials than the Ptfm isolates. 8 barley genotypes were resistant to all 19 pathotypes identified and should be useful in breeding barley for resistance to both forms of P. teres. Genetic variation was also examined by restriction fragment length polymorphism (RFLP) analysis. A 0.46-kb DNA fragment (ND218) generated by PCR from genomic DNA of a California isolate of Ptft was used as a probe. Every P. teres isolate tested with ND218 exhibited a unique RFLP pattern. Cluster analysis, based on both the virulence phenotypes and RFLP patterns, indicates that P. teres possesses a high degree of diversity at the species and subspecies levels. The high degree of polymorphism revealed by ND218 will make this probe a useful tool for the DNA fingerprinting of P. teres isolates. Sequence analysis of the 18s rDNA revealed 100% homology between the 2 forms. This intron distinguishes P. teres from the barley leaf spot pathogen Cochliobolus sativus, the symptoms of which are often confused with those of Ptfm. The closely related P. tritici-repentis, which causes similar spot lesions, also lacked this intron. DNA sequence analysis of the ITS1 and ITS2 spacer regions revealed only 1.6% divergence between the 2 forms. Disease management involves the use of seed treated with fungicide, avoidance of direct sowing on stubble without ploughing, and starting fungicidal treatment according to local advice when symptoms occur on one of the last 3 barley leaves. When plants are severely attacked, applications of fungicide should commence at the one node stage to delay possible disease outbreak^{ref1, ref2, ref3, ref4}
• Pyrenophora tritici-repentis (anamorph Drechslera tritici-repentis)

=> tan spot of wheat commonly infects wheat in the Canadian prairies. Resistance to tan spot is not widely dispersed in the International Maize and Wheat Improvement Center (CIMMYT) germplasm, but moderate resistance is known to occur (Rees and Platz, 1992). Some newer CIMMYT lines, such as Milan, Attila, Corydon and Tinamou, and some Chinese wheats and their derivatives, such as Luan, are also reported to carry high to moderate resistance (Diaz de Ackermann and Kohli, 1998). Tan spot is increasing in areas where reduced tillage practices are being combined with stubble retention. CIMMYT has an ongoing project to search for new and better sources of resistance to tan spot for these areas. The fungus over-winters on infected wheat straw or stubble. Spores are dispersed primarily by wind. Wheat is the primary host, but forage grasses and rye are alternate hosts. Barley and oats are highly resistant to tan spot. Ways to reduce tan spot include rotating between cereal and broadleaf crops, such as oilseeds and pulses, planting disease-free seed or seed that has been treated with a recommended fungicide, planting cultivars with known resistance to one or more leaf spot diseases, and, if leaf spots are present and rain is forecast, applying a registered foliar fungicide might be advisable^{ref1, ref2, ref3, ref4}
• Venturiaceae
• Venturia
• Venturia inaequalis (a.k.a. Fusicladium pomi)

=> apple scab is a serious disease causing maximum economic loss. A sound forecasting and early warning system has been developed for prediction of AS. Also, a judicious fungicide spray schedule has been devised. Under high disease pressure, systemic fungicides performed better, while under low disease pressure, ergosterol biosynthesis inhibiting (EBI) fungicides were as good as protectants. Ascosporic inoculum produced by over-wintered apple leaves could be substantially reduced by giving post-harvest applications of Bavistin (0.1%) and EBI chemicals Penconazole (0.5%) and Flusilazole (0.01%), as pre-harvest fungicidal sprays control scab during storage. AS survives on infected plant parts, including fruits. Disease management depends upon spraying with proper fungicides, at the proper time of application, at the optimum dose^{ref1, ref2}. India produces all deciduous fruits, including pome fruits (apple and pear) and stone fruits (peach, plum, apricot and cherry), in considerable quantity. These are mainly grown in the northwestern Indian States of Jammu and Kashmir, Himachal Pradesh and in the Uttar Pradesh hills. The North-Eastern Hills region, comprising the States of Arunachal Pradesh, Nagaland, Meghalaya, Manipur and Sikkim, also grows some of the deciduous fruits on a limited scale. Due to introduction and adaptation of low-chilling cultivars of crops like peach, plum and pear, they are also now being grown commercially in certain areas of the north Indian plains. Out of all the deciduous fruits, apple is the most important in terms of production and extent. Based on previous evaluation of local cultivars, a program for breeding cider apple (Malus domestica) cultivars was initiated in the SERIDA of Asturias (NW Spain) in 1989 with 3 major aims: to improve the durable resistance to diseases and pests of local cultivars, to obtain cultivars with no biennial bearing and to improve fruit quality. To achieve the 1st objective, Asturian cultivars with low susceptibility to scab were crossed with "Florina", which carries the Vf gene for resistance to apple scab caused by Venturia inaequalis and shows very low susceptibility to fire blight caused by Erwinia amylovora and resistance to the rosy apple aphid (Dysaphis plantaginea). The 1st cross, performed in 1989, was "Raxao" x "Florina." After greenhouse and nursery evaluation, 34 hybrids resistant to scab (the presence of the Vf gene has been confirmed with molecular markers) and low susceptibility to powdery mildew (Podosphaera leucotricha) were pre-selected. After evaluation of these hybrids against the rosy apple aphid, fire blight, apple scab and powdery mildew, as well as characterization of their productivity and quality, 4 hybrids were selected and are in registry at the present time. Numerous other crossings have been performed since then and are in different phases of evaluation and selection^ref.
• Dothideomycetes et Chaetothyriomycetes incertae sedis
• Botryosphaeriaceae
• Botryosphaeria
• Botryosphaeria rhodina (a.k.a. Lasiodiplodia theobromae, Botryodiplodia theobromae) is a pathogen that causes fruit spot on eggplant (Solanum melongena). Other fungal pathogens infecting eggplant are a leaf  and fruit spot caused by Phoma sp., leaf spot caused by Cercospora melongenae and fruit rot caused by Rhizopus stolonifer
• Guignardia
• Guignardia citricarpa

=> citrus black spot disease, one of the most serious citrus diseases affecting citrus production in South America, South Africa, Netherlands, and Australia. Black spot affects all commercial citrus cultivars and is particularly severe in Citrus limon. The disease is particularly virulent late in the season, and postharvest losses can also occur
• mitosporic Botryosphaeriaceae
• Sphaeropsis
• Sphaeropsis pyriputrescens^ref

=> sphaeropsis rot [SR] is a newly reported postharvest fruit rot disease of d'Anjou pears and apple. First found on d'Anjou pear, it was shown to be much more severe on apples. In one instance, 2% of the apple fruit in storage bins was rotted by SR after several months of storage. SR has been recorded on d'Anjou pear and on several apple varieties (Red Delicious, Golden Delicious, Fuji, and Granny Smith). Surveys for diseases of stored pears in Washington State in the late 1930s and in the past 60 years did not yield detailed data. 75 distinct fungal species belonging to 22 genera are associated with fruit rots in stored pears but no Sphaeropsis spp. were reported in the latter study. The SR fungus grows at -3-25°C, does not grow at 30°C but survives at this temperature. Optimum temperaturefor mycelial growth is between 15 and 20 deg C. Conidia germinate at 0 to 30 deg C, and a minimum wetness duration of 5-6 h is required for germination at optimum temperature. Conidia can germinate at relative humidity as low as 92%. SR causes twig dieback and cankers on apple and crabapple trees. 'Manchurian' crabapple trees are very susceptible to twig dieback and cankers caused by this fungus. It also appears to be associated with dead bark or twigs on trees. Fruiting bodies (pycnidia) of the fungus are often present in diseased tissues on infected trees. The fungus primarily infects the stem and calyx of fruit and causes stem-end rot and calyx-end rot, respectively. SR inoculum is apparently present in the orchard. Disease management is relatively simple. Cankers and diseased twigs with dieback symptoms should be removed from orchards to reduce inoculum. For orchards with a high percentage of crabapple trees as pollinizers, pruning diseased twigs is particularly important to disease control. Research on chemical control of this disease is currently in progress^{ref1, ref2}
• Sphaeropsis malorum (the imperfect stage of Botryosphaeria obtusa (Bo)) is common on dead or moribund wood of a wide range of hosts. In North America, Bo is reported to cause an important leaf spot, canker, and fruit rot of apple (black rot or frogeye leaf spot of apple), while in England and New Zealand it is chiefly a weak secondary pathogen associated with, but not necessarily the primary cause of, leaf spots, cankers, and fruit rots. It has been associated with various wood diseases of grapevines in several viticultural regions of the world. Frequently, it is found on tissues that have been damaged by physical factors or killed by primary pathogens. This species can be distinguished from other Botryosphaeria spp. by the large, dark brown, mostly aseptate conidia, and the distinctly annellate conidiogenous cells. It is probable that the disease is caused by a complex of species. Control of diseases caused by Bo is difficult, as information on disease control, especially chemical control, is very limited. Currently, there are no fungicides registered for use against Botryosphaeria dieback in South Africa (Nel et al., 1999). France is one of the very few countries in which a fungicide is registered for control of black dead arm caused by Bo, B. dothidea, and, in some cases, B. stevensii. Sodium arsenite is recommended and must be used under the same conditions as for the treatment of Esca disease. Good sanitation practice, specifically removal and burning of pruning debris, is recommended^{ref1, ref2,ref3, ref4}.
Other species of Sphaeropsis infect citrus. Disease management basically requires strict attention to sanitation in orchards and the use of an appropriate fungicidal spray regimen.
• Stenocarpella
• Stenocarpella macrospora occurs in maize crops in Uganda
• Stenocarpella maydis [Sm] (formerly Diplodia maydis)

=> maize ear rot in Spain, Israel : disease incidence can range from 1-80% of ears, and test weights can be reduced substantially. During the 1950s and early 1960s, maize ear rot was the most common ear rot disease of corn in the Corn Belt of USA. Disease management for maize ear rot includes crop rotation, conservation tillage to reduce soil erosion, and planting of
maize cultivars with a range of maturity dates
• Dothioraceae
• mitosporic Dothioraceae
• Aureobasidium
• Aureobasidium pullulans

in grapes
• Mycosphaerellaceae
• Mycosphaerella

=> Sigatoka leaf spot of bananas
• Mycosphaerella fijiensis (anamorph Pseudocercospora [formerly Paracercospora) fijiensis] (Pf)

=> black leaf streak disease / black sigatoka disease (BSD) is the most damaging disease of banana worldwide. It decreases photosynthesis, reduces fruit size and induces a premature maturation. It reduces leaf area, decreases yields by > 50% and causes premature ripening, which downgrades marketability of fruit. Unable to reproduce sexually, propagation depends upon cloning, using shoots from trees. Consequently, all banana cultivars are almost identical and are universally susceptible to the disease. According to FAO data from 2003, bananas rank 4th behind rice, wheat, and maize in worldwide production, measured in metric tons. Bananas and plantains (cooking bananas) are staple food crops for millions of people who produce the fruit in backyards and small plots in developing countries. The disease was 1st reported in Fiji in 1963 but was probably well established in southeast Asia and the south Pacific before that time. It was been reported in Honduras in 1972 and now is reported from Mexico south to Bolivia and northwestern Brazil and in the Caribbean region. It was reported in 1996 in Trinidad and Tobago porobably introduced from Venezuela. In 1998 it was reported in southern Florida, probably by introduction of infected suckers from elsewhere. It can be found all over the world with the exception of the Canary Islands, and its management and control have become a key concern of commercial banana producers. Disease management of large plantations is costly ($1000 per hectare), but is more costly in smaller plantations that cannot apply fungicides by air. Small farmers usually opt for other control measures of control such as removal of old infested leaves, intercropping with disease-resistant crops and planting in partial shade, which slows the development of the disease. Disease management involves application of protectant fungicides or systemic chemicals such as the sterol biosynthesis inhibitor, tridemorph, several sterol demethylation compounds, and systemic compounds such as propiconazole, methoxyacrylate, and azoxystrobin. There is a tendency for resistance or tolerance to systemic fungicides to be developed over time, and this is being countered by use of broad-spectrum, protectant fungicides such as the dithiocarbamates and chlorothanlonil. There is an intensive international effort to develop resistant hybrids for more long-term resistance to black sigatoka. Genetic engineering may be a possible means of producing resistant planting stock for disease control, but that will take some considerable time to effect^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9}
• Mycosphaerella graminicola
• Mycosphaerella musicola

=> yellow sigatoka disease is not as severe, although it infects plantains, dessert and cooking bananas.
• Mycosphaerella pini (a.k.a. Dothistroma pini infection)

=> red band needle blight. A number of countries in the Northern hemisphere, including the United Kingdom, France, and Canada are reporting an upsurge in the severity and distribution^ref. Milder and wetter weather conditions are partly to blame, as the spread of this pathogen is favored under moist, warm, light, and sheltered conditions. This disease has become particularly noticeable over the past 2 years and has apparently been increasing in frequency for 5 to 6 years. In the 2002–2003 period, > 25% of the trees were suffering serious defoliation in the East Anglia forest district, where large numbers of the highly susceptible Corsican pine are planted. New Zealand and Australia have been coping with widespread D. pini infection for decades and have been quite successful in protecting their pine forests. The fungus rarely kills the tree, but the percentage of pine needles infected is directly proportional to loss of wood yield, so D. pini can have a severe economic impact. One new approach that could be fruitful is to genetically engineer trees that inactivate, remove, or prevent synthesis of toxin dothistromin by the fungus, thought to be the primary cause of disease and is structurally related to the potent carcinogen aflatoxin. This similarity has enabled scientists to identify and isolate key genes involved in the synthesis pathway. One option would be to use non–toxin-producing strains as biocontrol competitors^ref with the toxigenic fungi in the field. Others include engineering trees that express dothistromin-specific antibodies in the needles or targeting destruction of the toxin in the plant tissue by enzymatic means. Another approach is the deployment of toxin transporter genes into host plants. These transporters are normally used by the fungus to allow secretion into plant tissue and to provide a self-protection mechanism against the effects of its own toxin. A candidate dothistromin transporter has already been isolated from D. pini that could be used in this way. Genetic modification of trees is not necessarily the best option for disease management, but in the long term, it may well be our detailed knowledge of the molecular biology of the pathogen and its toxin that will provide the basis for sustainable control
• Mycosphaerella graminicola (a.k.a. Septoria tritici)

=> Septoria leaf blotch of wheat
• mitosporic Mycosphaerellaceae
• Pseudocercosporella
• Pseudocercosporella albida

=> white leaf spot disease of dry red kidney bean (Phaseolus vulgaris L.). Corresponding with fungal growth, yellow, angular spots are observed on the upper leaf surface. In older leaves, lesions coalesce, covering most of their surface, while younger leaves are relatively free of symptoms. Heavily diseased plants senesced faster and defoliated earlier than nonsymptomatic plants. Identification of the pathogen is conducted by direct observation of infected plant tissues with light andelectron microscopes. Conidia are hyaline, filiform, rounded at their apex, and with no visible scar at their point of attachment to the conidiophore. Conidia have one to 4 septa, were 57-68 mm long, and approximately 2.4 mm in diameter. Conidia are produced at the tip of colorless, short conidiophores that emerge through stomata in groups of 5 or more.
• Pseudocercosporella capsellae

Brassica juncea has advantages over B. napus including more vigorous seedling growth, quicker ground-covering ability, greater tolerance to heat and drought, and enhanced resistance to the blackleg fungus, Leptosphaeria maculans. WLS survives on residues of infected plants. Under favourable autumn and winter conditions, it produces wind-borne conidia, which mainly cause leaf lesions. In turn, the conidia produced in these lesions are carried by wind and rain to cause secondary spread of the disease. WLS is also spread from infected seeds and from pieces of infected debris present with the seed. Optimum temperatures for WLS infection are 13-18°C, but high moisture levels are necessary for disease development. WLS disease usually develops after periods of high rainfall. It can be found in most plantings, but is not usually a cause of heavy yield losses. WLS can cause complete loss of leaves in highly susceptible varieties, with yield losses as high as 30% if the disease is severe. However, losses are unlikely to exceed 5-10% with current Australian cultivars. Nitrogen-deficient crops seem to be more severely affected by WLS. Disease management is similar to that of blackleg which means using crop rotation and good hygiene. Sow only cultivars expressing very high levels of resistance, and practice crop rotation. All varieties recommended for sowing in Western Australia have good adult plant resistance to blackleg. Canola fields should be in a rotation for at least 3 years to allow diseased residues to decompose and reduce the risk of ascospore infection. In recent years, some growers have successfully reduced this break period, but there is increased risk from this practice. If the seedling stage of crop development (cotyledon to 1- or 2-leaf stage) coincides with heavy airborne spore discharges from nearby stubbles, even adult resistant varieties can suffer substantial damage. If there is no erosion risk, destroy crop residues after harvest to reduce carryover of the fungus on infected
stems. Graze stubbles heavily to reduce fungus carryover. Canola should be planted as far as possible from previous canola crops to reduce the risk of infection by wind-borne ascospores. Do not plant in areas downwind from old stubbles where the prevailing winds are likely to blow air-borne spores^{ref1, ref2, ref3, ref4, ref5}
• Pseudocercospora
• Pseudocercospora angolensis (a.k.a. Phaeoramularia angolensis)

=> fruit and leaf spot disease of citrus was the main disease in western Kenya in the late 1990's. Application of various contact and systemic fungicides (triazoles and copper) were useful
• Pseudocercospora vitis [Pv]

=> grapevine leaf spot in several genera of Vitaceae (Ampelopsis, Cissus, Parthenocissus) and different species of Vitis are listed as hosts of Pv (Farr et al., 1989). Pv has been found in Brazil, Europe, India, Japan, North America, Korea, Pakistan, Saudi Arabia and South Africa (Ellis, 1971; Shin, 1997). Pv was reported in Argentina on European grapevine (V. vinifera) almost a century ago but no symptoms were described (Spegazzini, 1910). Mummified fruits (dried fruits) remaining from the previous fruiting season are the source of inoculum for the next crop season. Mummified fruit containing fruiting bodies (perithecia and pycnidia) overwinter on ground and vines. Fruiting bodies release spores which then infect nearby plants. Moisture is a critical element in disease etiology. Disease management involves use of preventative and curative fungicides, and removal of mummified fruit^ref.
• Eurotiomycetes
• Eurotiales
• Trichocomaceae
• mitosporic Trichocomaceae
• Penicillium
• Penicillium allii, rather than P.hirsutum or P. viridicatum, is the pathogenic species responsible for garlic crop losses during storage due to blue mold in Argentina. This is the 1st report confirming P. allii as a field pathogen of Allium sativum. The general problem of correct diagnosis of Penicillium species on onions and garlic is exemplified by this study. This plant disease in garlic is managed by storing bulbs with a minimum of bruising, wounding, or insect damage. Prompt curing of bulbs so the necks are dry and storing bulbs at temperatures of 41°F (5°C) or less with low relative humidity minimizes disease losses^{ref1, ref2, ref3, ref4}
• Leotiomycetes
• Erysiphales
• Erysiphaceae
• Erysiphe
• Erysiphe polygoni [Eg]

=> powdery mildew of sugar beet by Eg causes a serious fungal foliar disease resulting in sugar yield losses of up to 30%. Eg occurs world-wide in all regions where sugar beet is grown, and it also infects other edible beet crops, e.g. garden beets, Swiss chard, and fodder beet. Eg infection of sugar beet is especially damaging in arid climates, e.g. Mediterranean countries, the Middle East, Idaho, Colorado, Nebraska and California. The host range of Eg is specific to Beta species. Several powdery mildew fungicides are effective if applied in a regular preventative program commencing with the 1st signs of the fungus. Disease management depends upon the use of resistant cultivars, applications of registered chemical fungicides in rotation to delay evolution of resistant strains of Eg, crop rotation, removal of old plant debris, and deployment of a single monogenic form of mildew resistance in lines derived from Beta maritima. Sources of genetic resistance to Eg are available in cultivated, and wild, Beta germplasm and molecular markers developed linked to Eg, the only single major R gene described so far, and also to quantitative trait loci (QTL). Production of the perfect stage (teleomorph) of Pg and its over-wintering in western Nebraska is cause for concern for sugar beet producers, especially in terms of its survival as inoculum for long periods in soil^ref.
Eg grows on the surfaces of leaves and stems. Older infected leaves yellow and wither, and growth of heavily infected plants is diminished. The disease is favored by moderate temperatures. Eg produces airborne spores that facilitate spread of the disease. Moisture is not necessary for germination and infection, and is actually detrimental to the fungus^{ref1, ref2}
• Leveillula
• Leveillula taurica causes severe disease on pepper, aubergine, artichoke, and other vegetables in glasshouse and field production. Disease management involves use of fungicides. Bicarbonate solutions are also effective in reducing damage to leaves. Unfortunately, cultivars vary in their disease susceptibility
• Podosphaera
• Podosphaera phaseoli (Sphaerotheca phaseoli) => powdery mildew on cowpea (Vigna sinensis L.), Phaseolus spp., and Rhynchosia volubilis in Turkey. White, epiphytic mycelia and conidia, characteristic of a powdery mildew, are present on leaves, stems, and inflorescences. The plant tissue underneath the mycelial patches is purplish in colour. Mycelial growth was amphigenous, thick, forming irregular white patches, sometimes effused to cover the whole leaf surface and had a poorly developed nipple-shaped single appressorium. Simple straight conidiophores (115-190 x 10-13 mm) developed mostly singly from a hyphal cell, arising from the upper part of mother cells, and having the basal septum at the branching point of the mycelium with a sharp constriction. Each conidiophore has 3 to 8 barrel-shaped conidia formed in a chain. Conidia with fibrosin bodies are 28-42 x 15-18 mm in size and germinated below the shoulder by producing a simple germ tube. Dark brown ascomata, found on leaves and stems as embedded in the mycelial felt, are spherical, gregarious to subscattered and measured 85 to 105 mm in diameter. Appendages (6 to 15) are myceloid, arising from the lower half of the ascomata, brown, paler upward and 6 to 8 micrometers wide. The ascomata contained single ascus (65-95 x 55-67 mm). The ascus contained 8 ellipsoidal to ovoid ascospores (18-24 x 12-16 mm)
• Podosphaera xanthii (Px) (formerly known as Sphaerotheca fuliginea)
• race 1
• race 2
• race 3
• race 4
• race 5
=> cucumber powdery mildew is 1 of the world's most widespread and damaging cucumber diseases. Px consists of several races, some of which attack all cucurbits, while others have a host range restricted to certain types of cucurbits. 997 cucumber (Cucumis sativus L.) accessions from the U.S. National Plant Germplasm System (NPGS) collection were tested for resistance to powdery mildew. Plants were evaluated and classified for their resistance to Px. 3 susceptibility grades were used: susceptible (S), intermediate (I) or resistant (R). 94 of 977 accessions (9.6%) contained at least 1 I or R-type plant and 17 of the 20 most-resistant accessions originated in Asia. Disease management depends upon use of resistant cultivars and application of both systemic and protectant fungicides, alternating among systemic fungicides in at least 2 chemical classes and including a protectant fungicide in at least every other application. Resistant varieties are being developed and are becoming an increasingly important component of management programs. There is the danger, however, that strains may develop which could overcome the genetic resistance of some cultivars^{ref1, ref2, ref3}.
• mitosporic Erysiphaceae
• Oidium
• Oidiopsis taurica Salmon (Syn. Oidiopsis sicula Scalia) is usually found in its imperfect form, Oidiopsis taurica [Ot]. It was identified as the causal agent of a powdery mildew disease occurring on distinct Allium species in Brazil. This disease was initially observed in plastic house and field-grown garlic (Allium sativum) and leek (A. porrum) accessions in Brasilia (Federal District) and in field-grown and greenhouse onion (A. cepa) cultivars in Belem do Sao Francisco (Pernambuco State) and Brasilia, respectively. Typical Ot symptoms consisted of chlorotic areas on the leaf surface corresponding to a fungal colony. These lesions turn to a brownish color with the progress of the disease. Fungal morphology was similar to that described for Ot. Endophytic mycelium emerging through estomata, light pale conidia were dimorphic (lanceolate primary conidia and somewhat cylindrical secondary conidia), fibrosin bodies were absent, conidia formed predominantly single (not in chains), and appressoria were non-lobed. Its sexual stage, Leveillula taurica (Lev.) Arnaud, was not observed. Inoculations were performed with the Ot isolates from distinct Allium hosts. These isolates were also pathogenic to sweet pepper and tomato, indicating an apparent absence of host specialization. One bunching onion (A. fistulosum) accession was not infected by Ot, suggesting that this species might carry useful resistance alleles to this pathogen. This is the 1st formal report of a powdery mildew disease on species of the genus Allium in Brazil. Ot might become important on these vegetable crops, especially in hot and dry areas such as those in the Central and Northeast regions of Brazil. Genetic resistance is not well documented, but susceptible tomato cultivars are available. Since Ot also infects other hosts (e.g., eggplant (Solanum melongena) and tobacco, weed hosts such as nightshade), scouting of these hosts can be helpful to identify potential sources of inoculum. Chemical control is targeted at eradication of existing infections and protection of healthy tissues. Once disease is detected, the 1st sprays should be aimed at eradication. These are usually followed by sprays for protection. Eradicant sprays should be applied as soon as symptoms are first observed since early control is critical. Monitor and rotate the types of compounds used to avoid development of fungicide resistance in the powdery mildew population. Among the compounds registered for use are azoxystrobin, chlorothalonil, bicarbonates, cupric hydroxide, sulfur, and paraffinic (horticultural) oils^{ref1, ref2, ref3, ref4}.
• Helotiales
• Dermateaceae
• Neofabraea
Neofabraea alba (Na) (a.k.a. Pezicula alba; anamorph: Phlyctema vagabunda) There are many fungal pathogens affecting apple worldwide. With regard to those in Washington State, 4 species of the genus Neofabraea are known to cause bull's eye rot (BER) of apple. Na is the main pathogen causing BER in continental Europe, and also has been reported as a minor disease of apple in eastern North America
• Neofabraea malicorticis causes anthracnose canker / bull's-eye rotracnose canker of apple trees and is found principally in the more humid areas of the Pacific Northwest (PNW). It is an aggressive pathogen able to infect sound wood directly
• Neofabraea perennans causes perennial canker of apple trees. The pathogen requires wounds to infect the wood, and the fungus survives in cankers by infecting injured tissue at the border of old cankers.
N. malicorticis and N. perennans are considered a single species in Europe, whereas they have been regarded as distinct species in North America. A putative new species, yet to be described, has been recorded in Australia. It was recently recorded in a phylogenetic study of Neofabraea spp. causing tree cankers and apple BER. It was represented by one isolate from Nova Scotia, Canada, and one from Portugal. An undescribed species also has been identified recently in a molecular study in Australia. Another fungus, Cryptosporiopsis perenanns, causes similar chronic diseases of apple wood and fruit, respectively. Any factor that produces excess succulent growth -- such as high nitrogen fertilization or overirrigation -- or that weakens the tree increases the severity of perennial canker. Disease management involves removal of branches containing cankers, which helps to reduce inoculum of Neofabraea spp. and Cryptosporiopsis malicorticis in the orchard. Ziram (zinc bis(dimethyldithiocarbamate), applied within 2 weeks before harvest is recommended for control of BER in the Pacific Northwest. Any practice that helps to maintain trees in a healthy vigorous condition is critical for controlling the canker phase of the disease. Cankers generally develop only on stressed or weakened trees. Prune trees annually and maintain a balanced fertility program based on soil and foliar nutrient analysis. Cankers generally develop rapidly on winter-injured trees. The use of fungicides combined with good sanitation is beneficial for controlling the fruit rot phase of these diseases. Fungicides are not effective for controlling the canker phase of the disease on weakened trees. Commercial apple producers should consult the appropriate agencies for current information on recommended fungicides. Postharvest controlled atmospheres (CA) are used increasingly to supplement good refrigerated storage practices. In CA-controlled storage, a beneficial combination of reduced oxygen levels and increased carbon dioxide concentrations in the atmosphere are being combined with refrigeration^{ref1, ref2, ref3, ref4, ref5, ref6}
• Sclerotiniaceae
• Botryotinia
• Botryotinia fuckeliana (a.k.a. Sclerotinia fuckeliana, Botrytis cinerea)

=> Botrytis blight or gray mold (GM) is a fungus disease infecting many herbaceous annual and perennial crops. GM can be particularly damaging under continuous rainy, drizzly weather conditions for several days. The host range of GM is extensive (asparagus, bean, beet, crucifers, cucurbits, eggplant, grape, lettuce, onion, pepper, potato, tomato, turnip, and others). If cool, overcast conditions predominate, the disease progresses and a fuzzy grey mold develops. If conditions are warm and sunny, only ghost spots remain without any further disease progression. Cool, wet weather exacerbates disease expression. Fungicides can be used to prevent the spread of infection^{ref1, ref2, ref3, ref4, ref5}. Botrytis blight of peanut is a late-season disease that generally occurs in cool, wet weather. Infected tissues rapidly develop a water-soaked, brown appearance and are frequently covered by a greyish-brown mold. Although all currently planted varieties are susceptible to Botrytis blight, NC 17 appears to be highly susceptible to this disease. In the USA, Botrytis blight occurs predominantly in certain areas of West Texas. Symptoms of this disease closely resemble Sclerotinia blight. Disease management is best accomplished by harvesting in a timely fashion and avoiding plant injury so as to reduce symptom incidence and severity^{ref1, ref2}.
=> mango blossom rot : there is one reference indicating that Botrytis cinerea causes the disease in India. Another important disease of mango called blossom blight can be responsible for up to 94% losses depending on the cultivar. This disease is caused by a series of fungal pathogens. Although the cultivars "Awase" and "Alfonse" were found to be moderately susceptible and "Hendy Bezra" even less susceptible, specific fungicidal sprays are the accepted and widespread method of control^{ref1, ref2, ref3}. There are different varieties available in Andhra Pradesh state of India : table varieties are Banganapally (Benishan) Totapari, Neelum, Dashehari, Langra, Kesar; juice cultivars are Peddarasam, Chinnarasam, Cheukurasam, Navaneetham and Panakalu; and pickle varieties are Jalal, 2C Amani, Rajapuri, Royal Special, Bobbili Punasa, and Baramasi.
• Monilinia
• Monilinia fructicola [Mf]

=> brown rot (BR) is a major pathogen on stone fruits (peaches, cherries, plums, prunes, nectarines, and apricots) and wine grapes ( in Vitis vinifera) in France and China, affecting blossoms, fruit, spurs, and small branches : depending on weather conditions, can cause extensive crop losses. BR is most important on fruits just before ripening and during and after harvest. Under favorable conditions for disease development, the entire crop can be completely rotted. Peaches not kept in cool storage may rot in 2 to 3 days. Management of Mf is usually not a problem on early maturing cultivars. Application of fungicide sprays to reduce blossom and twig blight help minimize loss to ripe fruit rot at harvest. Removal of remaining fruit from trees soon after harvest will help reduce inoculum the following spring. Disease management involves use of phytosanitary measures (removal and destruction of rotted fruit, mummies, and neglected trees as possible inoculum sources); pruning of  cankers during the dormant season; and insect control to avoid  insects that feed on punctured or bruised fruit in the orchard or during harvesting and packing. Fruit should be cooled and refrigerated (as close to 0°C as possible) immediately after harvest^{ref1, ref2}. The fruit of the crop plant peach, Prunus persica, is susceptible to the disease brown rot both on and off the tree. Other species of Monilinia are known to rot peaches in Hungary, so this is not the first report of brown rot. The significance of the observation has to do with the fact that the pathogen is included in the EPPO A2 list of quarantine organisms for Europe. It was detected for the 1st time in Europe in 2001 (in France)^{ref1, ref2, ref3, ref4, ref5}
• Monilinia fructigena on apples, pears, and peaches; Europe, Asia, South America
• Monilinia laxa has been reported in China
=> brown rot of stones and pome fruits
• Sclerotinia
• Sclerotinia minor [Sm]

=> Sclerotinia blight [Sb] is a destructive mid-to late-season disease of peanuts. 1st discovered on peanut in Virginia in 1971, it subsequently spread to North Carolina, Oklahoma, and Texas. Sm survives in soil as sclerotia (resistant seed-like structures) and attacks plants near the soil line. Sm occurs worldwide, primarily in cool, moist regions. Its host range includes canola, sunflower, bean, sweet potato, cole crops, and soybean. In Oklahoma, yield losses in experimental plots infested with Sb ranged from 7% to 80%. Spread of the disease is limited because Sm does not Sm produce airborne spores during the cropping season. Sclerotia are the major means of long-distance movement. Sm is seedborne and is found as a contaminant in soils cropped by peanut. Infection by Sb can be very damaging and is difficult to control. Disease management basically depends upon preventing movement of contaminated soil to clean areas. Farm implements coming off contaminated soils should be washed thoroughly to remove soil and straw. A combination of cultural and chemical management practices will usually provide adequate control. New resistant cultivars have been developed recently by USDA^{ref1, ref2, ref3, ref4}.
• Sclerotinia sclerotiorum
• Sordariomycetes
• Hypocreomycetidae
• Hypocreales
• Clavicipitaceae
• Claviceps
• Claviceps africana
• Nectriaceae
• Calonectria
• Calonectria ilicicola (a.k.a. Cylindrocladium parasiticum)

=> Cylindrocladium black rot (CBR) was first found in 1965 in peanut in southwest Georgia and subsequently spread to Florida, in Alachua and Columbia counties. In the mid 1980s CBR was found in peanut in the panhandle section of Florida. Since 1975, CBR has been found in alfalfa, clovers, and soybean. Other crops reported to be susceptible to CBR are cowpea, bean and blueberry. Yield losses from CBR in some infested peanut fields in Florida have exceeded 50%. CBR has become a limiting factor for production of peanut in some fields in the panhandle area, particularly in Santa Rosa County. In general, CBR appears to be gradually increasing in severity in peanut throughout the peanut-producing areas of Florida. Management of CBR includes avoidance of susceptible crops, a crop rotation of 4-5 years, elimination or reduction of weeds such as hairy indigo (Indigofera hirsuta), beggarweed (Desmodium purpureum ) and coffeeweed (Sesbania exaltata). Soils should be well drained. Phytosanitary measures such as removal of soil and plant debris from tractor tires and implements before moving them to non-infested fields is advised. Some peanut cultivars possess low levels of resistance to CBR. Chemical control for CBR in peanut has provided some control. In Virginia, North Carolina, and to a limited extent in Georgia, preplant fumigation with metam-sodium has been used successfully, particularly if fumigation is coupled with use of a resistant variety. In Florida, CBR has been suppressed in peanut by means of post-plant sprays of approved fungicides at mid-season^{ref1, ref2, ref3}.
• Gibberella
• Gibberella avenacea (a.k.a. Fusarium avenaceum)
• Gibberella zeae (a.k.a. Fusarium graminearum (Fg))
=> Fusarium head blight (FHB), also known as scab or tombstone, is a disease of wheat, barley, oats and other small cereal grains and corn. It is caused by several Fusarium species, primarily Gibberella zeae, Gibberella avenacea, Fusarium culmorum andMicrodochium nivale. FHB causes severe production losses worldwide and may be as high as 50%. It is a major cereal disease in Manitoba, Saskatchewan and Alberta. Scab can cause significant yield and quality damage, as well as toxicoses in animals and humans. Damage due to scab in the USA was estimated to be more than USD one billion in 1993 and USD 500 million in 1994. In China, the estimate is that scab may affect up to 7 million ha, and 2.5 million tons of grain may be lost in epidemic years. Diseases related to fusarial mycotoxin in humans have been reported in China, India and Japan, whereas in animals, diseases have been reported in numerous parts of the world. FHB-infected kernels often contain a mycotoxin called deoxynivalenol (DON), also known as vomitoxin. It is a very mild mycotoxin. When present at high enough levels in the diet (>2 ppm), it causes a reduced feed intake in swine. DON is of limited concern to cattle producers because it is metabolized extensively in the rumen. DON belongs to a family of mycotoxins called tricothecenes. Tricothecenes are protein inhibitors, and it has been speculated that animals fed high levels of tricothecenes may have a weakened immune system. owever, DON is a very mild toxin compared to other tricothecenes. It is also extensively metabolized, poorly absorbed and rapidly cleared from tissues and fluids in ruminants. There is no evidence to support depressed immune function, even in pigs, which are much more sensitive to DON^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8}. These Fusarium species are all asexual forms that produce only conidia. The sexual stage is Gibberella zeae. Scab-infected wheat seed that is planted may develop root rot as well. These Fusarium fungi are ubiquitous and unfortunately can also cause a seedling blight and stalk, ear, and root rot of corn. A major concern is the presence of several important mycotoxins that can be produced in grain affected by scab. These toxins are produced by growth of the Fusarium fungi in the kernels, and ingestion of them can cause vomiting, nausea, dizziness, diarrhea, and muscle spasms in non-ruminant animals. Highly sensitive laboratory tests are currently used to detect mycotoxin contamination in grain. Thus, the chances of toxic compounds getting into human food is almost nil. The problem arises when farm livestock are fed uncleaned scabby wheat, oats or barley. > 3% scabby kernels in feed may be poisonous to hogs. Hogs fed > 10% scabby grain may vomit and refuse to eat the grain mixture. Cattle, sheep and mature poultry are much less susceptible to the mycotoxins. These toxins are quite stable and may remain in grain stored indefinitely. Disease management involves crop rotation with legumes or other non-cereal crops; planting only seed that has been thoroughly cleaned and treated with recommended fungicides; using deep plowing to completely cover crop residues so as to reduce head-blight infections; and planting less-susceptible wheat cultivars where possible
=> potato dry rot
=> infection of wheat and barley is epidemic in USA and is increasingly becoming a threat to the world's food supply due to recent outbreaks in Asia, Canada, Europe, and South America. Crop quality and yield have been adversely impacted. A major effect of Fg infection in cereals is contamination of seeds with trichothecene and estrogenic mycotoxins, making them unsuitable for food or feed. In Brazil, soybean crop residues in fields under conservation tillage have been found to be heavily infested with Fg. Although the fungus also reportedly grows on living soybean stems and seeds, many consider the fungus non-pathogenic to soybean. Recent surveys of soybean seed grown in Brazil also revealed infection by Fg. Fg strains from Brazilian soybean seed consistently caused pod rot and root rot disease on all soybean varieties, under all conditions tested. These same strains also caused FHB in wheat. Farmers who use a soybean/wheat crop rotation should be aware of a potential build-up of strains that infect both wheat and soybean, reducing the usefulness of the rotation. Brazilian strains, which also produce a novel mycotoxin known as 3-acetylnivalenol, have not yet been found in the USA In Argentina, a range of wheat cultivars are known to be infected by Fg^ref
• Nectria
• Nectria haematococca
• mitosporic Nectria haematococca
• Fusarium solani complex
• Fusarium solani
• Fusarium solani f. sp. glycines
• Fusarium solani f. sp. cucurbitae (Fsc)  causes necrotic lesions affecting the stem near the ground, eventually resulting in girdling of the stem. Plants become wilted and die rapidly during mid-season. The decay at the base of the stem is soft and mushy. Fruit lesions begin as small corky cracks that develop into sunken necrotic lesions. Internal tissue near the site of infection becomes off-color and corky. Fruit decay results in a firm, dry rot. A PCR-based technique has been devised to determine genome variability between Fsc isolates of Fsc isolates races 1 and 2. Fusarium crown and foot rot occurs sporadically in most areas, and disease severity is dependent on soil moisture and inoculum density. Because the fungus survives in the soil for only 2-3 years, a 4-year rotation is usually adequate for disease control. Planting fungicide-treated seed is also effective in reducing the incidence of disease initiated from infected seed. Additional measures would include use of resistant or tolerant cultivars if available and cleaning of farm machinery and tools so as to prevent soil-borne spread of the pathogen. A PCR-based technique has been devised to determine genome variability between Fsc isolates of races 1 and 2^{ref1, ref2,ref3}
=> sudden death syndrome (SDS) of soybean : Initially, the cause of SDS was elusive, with mechanical, cultural, environmental and biological factors all considered possible. Early studies involving soil fumigation indicated that the origin was biological. Subsequent work in Arkansas and Mississippi proved that SDS is caused by a strain of the common soil fungus Fusarium solani (FS-A). This result has been confirmed by work in Indiana and Missouri and is now generally accepted. Although FS-A is the primary organism associated with SDS, other pathogens may also be involved in disease development. The most studied of these is the soybean cyst nematode (SCN). Mississippi researchers found that while SCN is not required for severe SDS to occur, SCN at sufficient levels exacerbates foliar symptoms, leading to early and severe SDS. This finding is important, since the disease's timing and severity, relative to soybean development, determines how severely the yields are reduced. In addition to SCN, other soybean pathogens (foliar and root/stem infecting) are being studied for their potential role in SDS development. Preliminary data suggest that any stress factor (biological, mechanical or environmental) may magnify SDS symptom expression and cause SDS-affected plants to deteriorate earlier and
die prematurely. Other conditions that affect SDS severity are planting date and nematode injury. Early planted soybeans generally suffer more injury than those planted later. The positive correlation between soybean cyst nematode injury and SDS severity was noted by some of the first researchers to study the disease. While the presence of H. glycines tends to exacerbate problems with SDS, it is not required for successful establishment of F. solani f. sp. glycines in its host. The best way to avoid SDS in future cropping is to avoid early
planting, plant early to mid-season varieties, and plant varieties in SDS-prone fields which are not highly susceptible to SDS. True resistance to SDS is not yet available. However, avoiding planting highly susceptible varieties will usually help by delaying disease onset until the later stages of crop development. Roots of plants are
infected and become diseased during the vegetative stages of plant development. Then, typically as plants enter the pod development stages, foliar symptoms are expressed as a result of foliar sensitivity to one or more plant toxins produced by the fungus in diseased root tissue. In extreme cases, plants can die prematurely, with yields being dramatically impacted. In some years (such as 2004), plants will show symptoms early and later recover, with no impact on crop yield. In most years the response is somewhere in the middle of these 2 extremes. SDS is characterized by a rotting of the primary and secondary root system and a subtle brown discoloration of the stem tissue immediately inside the green exterior. Leaf symptoms that start as yellow spots and blotches between the veins of upper leaves (usually), leading to large areas of brown tissue between the veins, and eventual defoliation of the leaflets, but not the petioles. Abortion of flowers and young pods is common. Symptoms usually develop first in hot spots in fields of varying shapes and sizes. Entire fields may eventually become involved in severe instances, but even then, there are typically areas in fields where the disease is more severe than in others. At this time, there is nothing that can be done to make the disease less or more serious. The die is cast, as it were. SDS is in a race against time with the crop. If the crop reaches the R5-R6 stage before the disease is severe, then the yield prognosis will be excellent. Serious disease prior to the R5 stage, however, can result in substantial yield reductions. Typically the earlier the onset of serious SDS, the greater the impact will be on crop yield^{ref1, ref2, ref3, ref4}. SDS  has reached epidemic proportions in North and South America during the past decade. It causes interveinal foliar chlorosis and necrosis leading to defoliation of the leaflets but not the petioles. A molecular diagnostic test to rapidly detect and distinguish the 2 SDS pathogens is being developed by USDA scientists. Results of this study are important to plant pathologists, plant breeders and quarantine officials who need to know that soybean SDS is caused by at least 2 different pathogens. Factors affecting SDS include the choice of cultivar, planting date, growth state at the time of infection, and field environment. Selection of soybean varieties that are the most resistant  to SDS is crucial to maintaining a healthy soybean crop. Disease progress is reduced in mid-May through early June plantings, compared to those in early May, most likely because soil is warmer and drier in later plantings than in earlier plantings. Crop rotation on a regular regimen also lessens disease severity^{ref1, ref2}
• Fusarium tucumaniae
• Fusarium virguliforme
• Fusarium xylandoides

=> coffee wilt disease (CWD) / tracheomycosis / vascular wilt disease occurred sporadically in Africa but in the last decade or so it has become virulent, sweeping across Cameroon, the Congo and into Uganda. According to the Uganda Coffee Development Authority (UCDA), CWD mainly affects the native, lowland robusta variety and, since 1993, it has destroyed over 12 million plants. Uganda also grows arabica coffee, which constitutes only 10% of production, grows mainly in the highlands, and is unaffected by CWD. The entire plant is affected. Disease management was confined to burning uprooted plants, but the development of wilt-resistant coffee cultivars will be a major step in alleviating shortages due to CWD^{ref1, ref2}.
• mitosporic Hypocreales
• Fusarium
• Fusarium coeruleum
• Fusarium culmorum

=> Fusarium head blight (FHB)
=> potato dry rot [DR]. DR usually causes extensive tissue decay and collapse, and large holes are common in tubers. The amount of DR due to decay in storage depends upon the amount of fungus in the soil, the extent of mechanical damage to tubers during digging and harvesting, and on the susceptibility of the potato variety. Growers are advised to treat seed pieces with a recommended fungicide prior to planting, to make certain that tubers go into clean and disinfected storage bins, to handle treated seed with clean, disinfected equipment, to harvest tubers during cool dry weather, and to prevent bruising during harvesting, handling and grading operations. Note that F. graminearum was reported on soybean in Brazil last year (2004)^{ref1, ref2, ref3}
• Fusarium oxysporum complex
• Fusarium oxysporum f. sp. betae

=> Fusarium yellows (FY) or wilt of sugar beet has been reported from the Red River Valley of Minnesota and North Dakota, given the opportunity for propagules of the fungus to be distributed on windborne soil aggregates and by physical movement of soil on farm equipment. Disease management utilizes certified seed of Fusarium wilt-tolerant or resistant varieties, if available, treatment of seed or furrow with recommended fungicides to delay initial infection of seedlings by Fusarium spp. and other soil-borne pathogens, manage irrigation to eliminate moisture stress to the developing plant, avoid excess water which may deprive roots of oxygen, and dispose of sugar beet tare soil to avoid introduction of FY propagules (or new races) into the field^{ref1, ref2}
• Fusarium oxysporum f. sp. conglutinans

=> Fusarium wilt of canola is a disease that has only recently been discovered in western Canada, and little is known about the host/pathogen relationship. Canola varieties differ in disease susceptibility, and one of the first priorities has been to determine the amount of genetic resistance currently available in commercial canola cultivars. Varieties, inoculated with Fusarium oxysporum f. sp conglutinans, at the seedling stage in a greenhouse were classified as susceptible or resistant. A majority of varieties are resistant. Management of this disease should be possible by simply screening susceptible cultivars. In addition, field results from locations with natural incidence of fusarium wilt have correlated well with results from this artificial inoculation procedure, providing some validity to this method of testing. The fact that infected cultivars can be readily detected in fusarium-infested field plots will assist research in disease management^ref
• Fusarium oxysporum f.sp cubense

=> Panama disease (PD) / Fusarium wilt of banana. Banana and plantain are the most important agricultural products in the tropics, with annual production of over 100 [million] metric tons. Ladyfinger bananas are a special type of banana. Of the various pathogens encountered in the tropics PD is the most significant.  PD was considered a major threat to banana production in the 1940s-1950s, but planting of a PD-resistant banana known as the Gros Michel was a breakthrough. Over time, Gros Michel was replaced by the 'Cavendish-type' cultivar, which has remained in production to date. Recently a new variant of FOC, tropical race 4 (TR4), has been responsible for the Southeast Asian outbreaks. Unlike subtropical outbreaks that affect cold-stressed Cavendish in Australia, the Canary Islands, and South Africa, TR4 affects Cavendish in the absence of predisposing factors. Although it is found only in Southeast Asia, TR4 continues to spread in that region. The great fear is that FOC will spread to the Americas and Africa, where it could have a great impact on production of export bananas and plantains that normally resist PD. TR4 poses a serious threat to a multibillion-dollar industry and the food stability of millions of poor farmers. In another development, phylogenetic work on FOC has revealed that it has had at least 3 independent evolutionary origins. Different clades of the pathogen are distantly related, and one is more closely related to members of another forma specialis, F. oxysporum f. sp. melonis, than to other FOC clades. There are 4 races of the PD pathogen: Race 1 attacks Ladyfinger, Sugar and Ducasse bananas but not Cavendish; Race 2 attacks Bluggoe and Blue Java, but not other banana varieties; Race 3 attacks only Heliconia and is not a problem on bananas; and Race 4 attacks nearly all varieties of bananas, including the main commercial Cavendish variety. Effects range from reduced yields to death of the plants. The soil remains infested indefinitely so that only resistant varieties can be grown on that site in the future. These effects create costs for production. Disease management involves prompt detection and destruction of infected plants, which cannot be cured. Strict quarantine regulations have to be employed to prevent spread of infected material to clean areas through movement of soil, water or plant materials. Foremost among preventive measures is exclusion, supported by a general awareness of the characteristic external and internal symptoms of Panama disease, so that reporting can take place^{ref1, ref2, ref3}
• Fusarium oxysporum f. sp. lactucae

=> Fusarium wilt of lettuce (Lactuca sativa)
• Fusarium oxysporum f.sp. lycopersici [Fol]

=> Fusarium wilt of tomato, caused by 3 races   is one of the most important diseases of tomato. Races 1 and 2 are distributed worldwide, whereas race 3 has amore limited geographic distribution with no report thus far in Brazil. 7 Fol isolates were obtained from wilted tomato plants of race 1 and 2-resistant hybrids 'Carmen' and 'Alambra' in Venda Nova do Imigrante (State of Espirito Santo), Brazil. Results of virulence assays using a set of race differential cultivars showed that 'Ponderosa' were susceptible to all races, 'IPA-5' was resistant to race 1, 'Floradade' was resistant to races 1 and 2 and 'BHRS-2,3' was resistant to race 3. All isolates were highly virulent to 'Ponderosa', 'IPA-5' and 'Floradade' and were able to infect only a few plants of 'BHRS-2,3'. An additional virulence test was conducted including the same set of cultivars plus Lycopersicon pennellii 'LA716'. Identical results were obtained with L. pennellii displaying an extreme (immune-like) resistant response. These results indicated that all 7 isolates could be classified as Fol race 3. This new Fusarium wilt might became an economically important disease, since race 3-resistant cultivars adapted to Brazil are not yet available. This is the 1st formal report of race 3 in Brazil, extending the geographical range of this pathogen. Fol can be introduced into new growing areas via contaminated seeds. The presence of race 3 in geographically isolated tomato-growing areas in Brazil could be the result of either pathogen introduction via contaminated seeds or the occurrence of an autochthonous (indigenous) race 3 isolate. In fact, recent results indicate that new race 3 isolates could have originated from genetic changes in the local populations of native Fol isolates. Additional studies employing molecular fingerprinting systems and/or vegetative compatibility groups with a world-wide collection of Fol isolates could provide some indication of whether this pathogen is endemic to Venda Nova do Imigrante or if it was introduced and, if so, from which geographical area. This new Fusarium wilt might became an economically important disease since race 3-resistant cultivars adapted to Brazilian conditions are not yet available. In addition, screening trials searching for new sources of resistance seems to be necessary, since the genetic plasticity associated with selective pressures due to the use of race 3 resistant cultivars might cause the establishment of new pathogenic races of this fungus. These screening trials are already under way in Embrapa Hortalicas, and new resistance sources have been found. Management strategies for Fol include disinfestation of the soil and planting material with fungicidal chemicals; crop rotation for several years, but Fol is long-lived; planting non-hosts of Fol; and using resistant cultivars. Limit the spread of infested soil by cleaning farm equipment. Avoid root knot nematode infestations, because nematode feeding can overcome plant resistance to Fusarium wilt^{ref1, ref2, ref3, ref4}
• Fusarium oxysporum f. sp. melonis (Fom) causes a severe disease of melon (muskmelon and canteloupe) in many parts of the world. There are 4 races, 0, 1, 2 and 1,2. Disease management is predicated on the use of resistant cultivars, which in turn depends on fungal populations in the soil and the races present. Movement of farm equipment from Fom-infested fields to clean fields is to be avoided because chlamydospores remain viable for years. In addition Fom can be spread on tools, feet and in surface water contaminated with infested soil. Deposition of compost on clean fields is to be avoided since it contains Fom. Crop rotation can be helpful in lowering the amount of Fusarium in the soil, as part of an integrated management program using resistant varieties.  It is important to rotate to unsusceptible plant species, such as grasses or cereals^{ref1, ref2, ref3, ref4}
• Fusarium oxysporum f. sp. niveum

=> Fusarium wilt (FW) is the most common soilborne disease of watermelon : race 1 is uniformly distributed throughout watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) growing regions, but F. oxysporum f. sp. niveum race 2 has a limited known distribution in the USA (Texas, Oklahoma, Florida, Maryland, Delaware and Indiana). It has also been reported from Greece, Turkey, Spain and Cyprus. FW threatens watermelon production in the Northeast region of the USA, where triploid (seedless) watermelons are grown on nearly 50% of the acreage. Most triploid cultivars are highly susceptible to FW. Control of FW is difficult, because once the pathogen builds up in the soil, no effective rotation period will ensure a healthy crop. Host resistance to FW of watermelon is expressed in cultivars as a continuum from highly resistant to susceptible. However, even cultivars rated as resistant may sustain significant wilt when grown in highly infested fields. Soil fumigants are used in combination with host resistance to reduce FW in Maryland and Delaware. A 5-6 year rotation with non-cucurbits, also recommended for disease management, is not feasible in the mid-Atlantic region, where availability of fumigated land is limited. Use of multiple tactics, rather than cultivar resistance alone, appears to be most appropriate for management of FW of watermelon. Preliminary trials in the greenhouse and field indicate that hairy vetch (Vicia villosa) residue amended to Fon race 2-infested soil reduced FW and increased yield but did not reduce the Fon level in soil^{ref1, ref2,ref3, ref4}.
=> Lycopersicon esculentum seeds, Thailand, Israel
• Myrothecium
• Myrothecium roridum (Mr)

=> leaf spot, stem canker on melon, causing significant economic losses up to 30%. The disease is favored by wet weather conditions that also favor development of other foliar pathogens and can be controlled by the use of protectant fungicides. The disease occurs infrequently and has been observed mostly in the Lower Rio Grande Valley. Mr produces macrocyclic trichothecenes that are antibiotic/phytotoxic compounds produced by both fungi and plants. Some Mr-induced macrocyclic trichothecenes are identical to trichothecenes found in 2 species of the plant genus Baccharis. Production of macrocyclic trichothecenes by Mr has been implicated as a possible virulence factor in plant diseases caused by this fungus. However, the role of these compounds in the biology of Baccharis species is unclear. Mr, causes fruit rots, cankers on crowns and stems, and leaf spots. Hosts include cantaloupe and honeydew (Cucurbita melo) and cucumber (Cucumis sativus)^{ref1, ref2, ref3}.
• Microascales; Microascales incertae sedis; Ceratocystis
• Ceratocystis fimbriata is a pathogen reported on 31 plant host species representing 14 families (e.g. it causes black rot on lettuce); it was 1st detected in Place, VIC, Australia in 1987 on Syngonium sp. It has been reported on White Butterfly, White Knight, White Wings; as being well established in eastern States when 1st detected; common overseas; with taro importation intercepted in quarantine. It was introduced with Syngonium sp., possibly in tissue cultures, with taro tubers from Fiji. Other diseases include black rot (sweet potato and Araceae), Ficus wilt, mango wilt, coffee wilt and canker, xylem stain and canker (Bitternut hickory), and in Sycamore (California, North Carolina and Wisconsin)^ref
• Sordariomycetidae
• Diaporthales
• Valsaceae
•  Diaporthe
• Diaporthe phaseolorum

=> stem canker of  soybean, Glycine max, has been reported in Europe, South America and in most soybean regions of Canada and the USA. There are 2 different types of stem canker in USA :
• Diaporthe phaseolorum var. meridionalis [Dpm]

=> southern stem canker was first observed in the southern US in 1973, and by 1984, had been detected in all southern states, where losses of 100% have been reported. Southern stem canker arose as a problem in the southern USA in the 1970s and continues to be significant problem for southern soybean farmers.
• Diaporthe phaseolorum var. caulivora [Dpc]

=> northern stem canker : 1st reported in the late 1940s in Iowa, and by the 1950s, the disease had spread into the upper Midwest and Canada, causing losses of up to 50%. Northern stem canker caused severe losses in the Midwestern and North Central Regions of the USA and Ontario, Canada in the late 1940s and early 1950s. Yield losses have been reported to be as high as 50 to 80% in naturally infested fields. It became less significant as a problem when extremely susceptible varieties were removed from production. A resurgence of Northern stem canker may be related to the deployment of susceptible varieties, changes in agronomic practices, changes in the pathogen population, as well as seed sources.
There does not appear to be any overlap in geographical range of these 2 stem canker diseases. Both pathogens can overwinter in infested soybean residue and may be spread with infested seed. Stem canker is effectively managed by the combination of planting resistant cultivars and reducing infested crop residue on the soil surface by deep plowing prior to planting a soybean crop. Delayed planting may be helpful. Seeds that are to be used for planting should not be harvested from fields with a history of stem canker. Fungicides applied to the seed at planting can reduce the introduction of stem canker to a field but will not control infections in the field. Foliar fungicides can be effective when applied during vegetative stages; however, results are inconsistent, and in most cases, foliar fungicides would not be an economical management strategy^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8}
• Diaporthe phaseolorum var. sojae

=> pod and stem blight
• Leucostoma
• Valsa
• Valsa ceratosperma is the fungus that causes perennial canker disease in Cydonia oblonga, Malus domestica, Pyrus communis (pear).  Vc most likely is present in plants for planting, such as Cydonia, Malus and Pyrus where Vc occurs. Fruit crops such as pear, apple and quince are important for the EPPO region. In Asia, Valsa canker is mainly reported on apple, and, occasionally, on pear and quince. In Italy, it was only found on pear. (cv. Abate Fetel was the most affected, but other cultivars -- William, Decana, Kaiser, Passecrassane, Morettini, General Leclerc -- were also found susceptible). In Italy, high incidence in affected orchards and crop losses has been reported. Similar diseases are caused by species of Cytospora and Leucostoma. The pathogens over-winter in active cankers, or, in dead wood, thus perpetuating their life cycle. A controlled integrated pest management program (IPM) is required to maintain fruit production. Disease management includes control of other pathogens, such as the brown rot pathogen (Monilinia fructicola), and other pests such as insects, tree-borers, and rodents that cause injury to tree limbs. Eradication of the pathogen is one strategy, but it is effective only if affected limbs below the cankered area are removed and burned, especially in younger orchards^ref. Seen in Asia (China, Japan, Korea) and Italy (Emilia-Romagna (provinces of Bologna, Ferrara and Modena) and Lombardia (Schivenoglia (province of Mantova))) at low prevalence. The fungus causes elongated cankers on twigs, branches and trunks. Symptoms can easily be confused with other pathogens such as: Nectria galligena, Sphaeropsis malorum, Phomopsis mali, and Erwinia amylovora. When cankers develop, they can girdle twigs, branches, and even trunks, which then lead to desiccation and death of the distal part. Vc over-winters in infected wood and plant debris, and most new lesions appear in spring. The affected bark is swollen, water-soaked, and, in February, small dark pycnidia can be observed. In spring, under humid conditions, pycnidia release spores, which are responsible for new infection. The fungus penetrates through natural bark crevices and wounds (due to adverse climatic conditions or pruning). Ascospores are also formed in autumn/winter, but it seems that they only play a secondary role in disease spread. In the literature, it is mentioned that on apple, the disease may remain latent for 1 to 3 years. Within orchards, disease spread is ensured by the production of pycnidiospores in spring, and, to a lesser extent, by ascospores in autumn/winter. Over long distances, trade of plants, and, eventually, of wood can ensure dispersal of Vc. Control of canker diseases is usually difficult in practice. Mechanical removal of cankers is a possibility, but data is currently lacking on chemical products which may be effective against Vc^ref.
• mitosporic Valsaceae
• Cytospora
• Phomopsis
• Phomopsis sclerotioides (Ps) (an insidious, soil-borne fungus which overwinters as black sclerotia in soil and in thick root tissue that resist degradation

=> black root rot [Brr] is common in greenhouse crops planted into cold soil at temperatures as low as 10-12°C. The disease is uncommon in field crops. If Ps increases in glasshouse production beds over several years, growers are advised to switch to hydroponic production^ref
• Sordariales
• Sordariales incertae sedis
• Monosporascus
• Monosporascus ibericus
• Monosporascus cannonballus
=> Monosporascus root rot. First reported in Arizona in 1974, it has subsequently been reported from the EPPO region: Israel (as M. eutypoides [Me]), Italy, Libya (as Me) Spain and Tunisia; Asia: India, Iran (as Me), Japan, Pakistan (as Me), Saudi Arabia and Taiwan; and North America: Mexico, USA (Arizona, California, Texas) and Central America: Guatemala and Honduras; and South America : Brazil (as Mc). The fungus is oilborne, its ascospores are heavily walled and thus can remain viable for many years, and there are few resistant or tolerant cultivars. Management options include chemical soil treatment (which is becoming increasingly less popular because of environmental concerns) and grafting of susceptible melons and watermelon (Citrullus lanatus) onto rootstocks of some resistant hosts ( Cucurbita spp.)  or bottle gourd (Lagenaria spp.). Biological control is being attempted by infecting wild-type fungal isolates of the pathogen with hypovirulent isolates containing dsRNAs so as to convert wild type isolates to a less aggressive form.
• Sordariomycetes incertae sedis
• Calosphaeriales
• Calosphaeriaceae
• Togninia
• Togninia fraxinopennsylvanica (a.k.a. Ceratocystis fraxinopennsylvanica)

The gist of this piece is that Togninia fraxinopennsylvanica is the sexual stage (teleomorph) of P. mortoniae. Moreover, Togninia (Calosphaeriales) is confirmed as the teleomorph (sexual stage) of Phaeocremonium by means of morphology, sexual compatibility and DNA phylogeny. It occurs on esca (black measles)-diseased grapevines (Vitis vinifera) and declining ash trees (Fraxinus latifolia) in California. Petri disease (PD) (young esca) is a serious disease of vines in most areas where grapevines are cultivated^{ref1, ref2, ref3, ref4, ref5}. This disease is now known to be caused by multiple species of Phaeoacremonium including P. aleophilum, P. angustius, P. parasiticum, P. rubrigenum, and P. mortoniae. The teleomorph of P. aleophilum was confirmed recently as Togninia minima (Tul. & C. Tul.) Berl., but the teleomorph for the other Phaeoacremonium species are not known.
• mitosporic Calosphaeriaceae
• Phaeoacremonium
• Phaeoacremonium viticola

A group of Phaeoacremonium isolates, first distinguished by red pigmentation on the reverse of their colonies, is described as a new species, P. viticola, on the basis of molecular data. An intensive sampling in French vineyards affected by the Esca disease has shown that this species is rare compared to P. aleophilum and P. chlamydosporum and is often associated with symptoms on the fruits. Esca is a complex of diseases rather than a single pathogen causing symptoms associated with the disease. It is likely that different organisms cause specific but similar symptoms. Esca is primarily a disease of mature vines (10 years +). The definition of esca has been recently revised. The proposed definition reads as follows: Esca is the series of pathological events, the series start in the nursery, continues in the young vineyard and completes its development when the plant is mature. Similarly, young decline (commonly known as black goo) is caused by Phaeomoniella chlamydospora and other Phaeoacremonium spp. In Australia, the disease affects young and mature vines. Following discussions, it was decided that "Petri Disease" will precede the names "black goo", phaeocremonium grapevine decline, and young decline. That Phaeoacremonium viticola [Pv] can infect ash (Fraxinus latifolia) represents an alternative source of inoculum that may be of some significance in the epidemiology of esca^{ref1, ref2, ref3, ref4}
• Magnaporthaceae
• Magnaporthe
• Magnaporthe grisea (rice blast fungus) is responsible for rice blast, a disease that destroys enough rice to feed 60 million people each year, particularly in hot and humid countries such as Thailand and the Philippines. The genome was sequenced from 1998 to 2005, marking the completion of the first draft sequence of a plant pathogen. In combination with the DNA sequence of rice itself, which researchers established in 2002, the team hopes the code will facilitate the development of genetically modified rice capable of resisting the disease. The organism has 11 109 genes -- similar to other fungi that have been sequenced. Mg is believed to be able to secrete 739 proteins -- twice as many as in other sequenced fungal genomes -- in order to penetrate and infect its host. 8 genes alone are used to synthesize cuticle-degrading enzymes called methyl esterases that aid in disease expression. By identifying the genes of crop pathogens and seeing how they work, scientists can target ways of blocking them chemically or of breeding plants that are resistant to the invader. Ideally, these solutions will be cheaper and environmentally safer than spraying with expensive pesticides. The rice-blast fungus uses a new class of receptor to distinguish its target, rice, from other crops. These receptors are found on the infectious spores of the fungus, which can aggressively punch into the leaves of rice plants. At the moment, powerful fungicides are the only option for keeping M. grisea at bay. Some farmers have fallen ill through exposure to high doses of these fungicides. Genetically engineered rice would reduce the need for such toxic chemicals^ref. Worldwide, RB disease is one of the most devastating diseases of rice, the staple food for 2/3 of humanity. Crop losses associated with RB have been magnified in recent times due to intensification of rice production. Genetic resistance continues to be the major means of disease management for RB, but Mg is able to overcome this resistance rapidly. A gene has been isolated that controls cultivar-specificity of Mg with rice and has been identified with the corresponding disease resistance gene. Disease management involves several options, including manipulation of planting time and fertilizer and water management, early rather than late sowing of seeds after onset of the rainy season, avoidance of excessive fertilizer, especially nitrogen, which increases RB incidence, and water management practices in rainfed areas to lessen the likelihood of stress, which also aids RB control. Planting resistant varieties against RB is the most practical and economical way of controlling the disease and, if necessary, systemic fungicides such as pyroquilon and tricyclazone are possible chemicals for controlling the disease^{ref1, ref2, ref3, ref4}

Web resources : MagnaportheDB
• Phyllachorales
• mitosporic Phyllachorales
• Verticillium
• Verticillium dahliae :

=> Verticillium wilt : once a plant is infected, part of the leaflet lamina wilts in the shape of a "V". This is accompanied by inner vein yellowing, which begins unilaterally and is, in turn, followed by a desiccation of the leaves at the base of the plant. The vessels are coloured light brown or light gray. The affected plants do not die.  Inoculum source is normally from resting structures of the fungus (microsclerotia) in infested soil. Race 1 is common in Tunisia, and the local tomato varieties grown under protected structures (screenhouses/greenhouses) while resistant to race 1, develop Verticillium wilt when attacked by race 2.  Race 2 of V. dahliae, virulent on cultivars with the Ve gene that provides resistance to Race 1, was first detected in 1957 and later reported in North and South America, Europe, Africa and Australia. Until 2005 screenings of tomato germplasm have not revealed a reliable source of resistance to race 2, but a factor conferring resistance in the Veda line has been mobilized by conventional breeding and is dominantly inherited. Grafting of susceptible scions onto resistant rootstocks is one possible approach to managing this soilborne disease when soil sterilization/disinfection is not acceptable or practiced, which seems to be the case in Tunisia. Fungicidal treatment of infected plants is largely ineffective against Verticillium wilt of tomatoes. Eggplant cultivars grafted on rootstocks (Solanum torvum) resistant to root-knot nematodes (Meloidogyne spp.) are increasingly grown in Italy to reduce nematode infection, but the interaction with  nematodes and V. dahliae has apparently compromised the expected result of higher yield. Plant pathologists have studied antifungal activity of Iranian Actinomycetes isolates against a number of fungi including Verticillium dahliae. Biological control of plant diseases has received worldwide attention in recent years, mainly as a response to public concern about the use of hazardous chemicals in the environment. Soil actinomycetes, particularly Streptomyces spp., enhance soil fertility and have antagonistic activity against a wide range of soil-borne plant pathogens. In search for soil actinomycetes with activity against plant fungal-pathogens, 110 isolates were screened from which 14 isolates were found active at least against one of the tested fungi. Streptomyces plicatus strain 101, Frankia sp. strain 103 and Streptomyces sp. strain 44 had the widest antifungal spectra of activity. Antifungal genes from these strains may be proper candidates for genetic engineering of plants for increased tolerance against the tested cosmopolitan fungal pathogens^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9, ref10}
• Phyllachoraceae
• Glomerella
• Glomerella acutata (a.k.a. Colletotrichum acutatum)

=> postbloom fruit drop (PFD)  of citrus was first reported in Belize in 1979 and has since spread to Florida, the Carribean, and South America. Sweet orange and lime are susceptible, and substantial yield reduction has been
reported in Florida. In Australia, Ca has been widely recorded as causing a ripe fruit rot of many fruits including pawpaw (Asimina triloba) and strawberry. Disease management basically involves applications of systemic fungicides or copper fungicides
• Plectosphaerella
• Plectosphaerella cucumerina (a.k.a. Monographella cucumerina, Microdochium tabacinum, Fusarium tabacinum, Plectosporium tabacinum)

=> Plectosporium blight (Pb) is a new destructive disease of cucurbits in New England. Pb was found in Tennessee in 1988 and has since spread rapidly throughout the eastern United States, occurring on a farm in Massachusetts in 2000 and on at least a dozen farms in Connecticut and Massachusetts in 2003. In the fall of 2004, after 2 seasons of rainy weather, it was present in every field surveyed from Long Island Sound to Burlington, Vermont. Pb can cause significant damage to a wide variety of cucurbit crops in Europe and Asia, but the U.S. strain seems to primarily damage pumpkins, summer squash, zucchini and a few varieties of gourds. In wet years, which favor disease development and spread, crop losses in no-spray and low-spray fields can range from 50 to 100%. Fortunately, this disease is easily recognized and can be effectively managed. Recommended management strategies include a 3-year crop rotation, planting in sites with good air circulation to encourage rapid drying of the foliage,switching to trickle irrigation, scouting fields to confirm presence of Pb, applying fungicides, and plowing under crop residue after harvest. There are no known pumpkin or summer squash varieties, although differences in susceptibility do occur. Pumpkin varieties Sorcerer, Gold Standard and sugar pumpkins seem to be less susceptible than other varieties grown in the same fields^ref
• Xylariomycetidae; Xylariales; mitosporic Xylariales; Microdochium
• Microdochium nivale (a.k.a. Fusarium nivale)

=> Fusarium head blight (FHB)
• Saccharomycotina
• Saccharomycetes
• Saccharomycetales
• Dipodascaceae
• Galactomyces
• Galactomyces geotrichum (a.k.a. Oospora lactis, Endomyces geotrichum, Geotrichum candidum)
• Saccharomycetaceae
• Issatchenkia
• Issatchenkia scutulata
• Saccharomycodaceae
• Hanseniaspora
• Hanseniaspora uvarum (a.k.a. Hanseniaspora apiculata, Kloeckera apiculata)
=> sour rot of commercial peaches and nectarines in the field and postharvest situations in California. The disease has been found on 'Red Glo', 'Ruby Diamond', 'Zee Grand', 'Spring Bright', and 'Honey Blaze' nectarines and 'Elegant Lady' and 'Fire Red' peaches. G. candidum was isolated from peaches and other fruit in California and incited rot of 'Paloro' peach in 1960 and caused postharvest sour rot of peaches originating from Georgia, Pennsylvania, New Jersey, and North Carolina
• mitosporic Ascomycota
• Helminthosporium
• Helminthosporium solani

=> potato (Solanum tuberosum)
• Basidiomycota
• Hymenomycetes
• Heterobasidiomycetes
• Tremellomycetidae
• Tremellales (jelly fungi)
• Tremellaceae
• Filobasidiella
• Cryptococcus laurentii

=>
• Homobasidiomycetes
• Agaricales
• Schizophyllaceae
• Heterobasidion
• Heterobasidion annosum species complex
• Heterobasidion annosum can infect pine, fir and spruce trees. The disease can be contained by spraying anti-fungal agents onto exposed stumps or bark to block the fungi's point of entry into the tree. When conifers are pruned or thinned, their exposed surfaces can be treated immediately to lower the risk of infection. An American strain, imported by US troops during the Second World War when they set up camp on the Presidential Estate of Castelporziano shortly after capturing Rome in 1944, killed hundreds of Italian stone pine (Pinus pinea) in the estate, once home to 60 km² of native Italian flora
• Tricholomataceae
• Crinipellis
• Crinipellis roreri (a.k.a. Moniliophthora roreri)

=> frosty pod rot (FPR), a highly destructive cacao disease, currently found in 11 countries in South and Central America. In Belize, the disease was 1st detected during a field visit to a small farm in the village of Maya Mopan, Stann Creek District in September 2004. Symptoms characteristic of typical FPR included pod deformation, premature ripening and chocolate-colored pod lesions with creamy-colored mycelium becoming darker as the spores mature. Internal pod tissues showed a typical necrotic compact mass surrounded by a decayed watery substance. The presence of mummies (dehydrated, sporulated pods), the high disease incidence -- estimated at 60% of the pods affected -- and the extent of FPR within the plantation all suggested that FPR had been present for at least 6 months. 2 major fungal species, witches' broom [WB] caused by Crinipellis perniciosa and frosty pod rot [FPR] caused by Moniliophthora roreri (FPR), formerly Monilia roreri, have been advancing steadily through cacao plantations in the Americas and the Caribbean for over a decade. In an attempt to stop the spread and prevent transmission to Africa, an international team of cacao researchers is attempting to establish quarantine zones and creating new fungal-resistant varieties. WB shrivels them, and FPR leaves them swollen and white. However, the end result is the same: no cocoa beans to harvest. There is currently no effective control against these fungal diseases. Of the 2 fungi, FPR is the hardier species, with spores that can travel further in hot, dry conditions. When it entered Peru in 1991, it wiped out 75% of cacao production in less than 2 years, and it continues to invade new territories at alarming speeds and is now believed to have reached Brazil, where the World Cocoa Foundation estimates it could reduce production in the region by 20% in the next decade. To prevent the northern spread of FPR, attempts were made to establish quarantine zones in Central America, but unfortunately, it is now present in southern Mexico. In the absence of other solutions, these fungal diseases will continue to spread in the Americas until resistant material becomes available. But, with the right procedures in place, Africa should continue to FPR-free. Schnell says the quarantine systems are secure, and diseases like frosty pod and witches' broom are unlikely to make it through. Smuggling of plants is one possible way that FPR or witches' broom could spread. This is potentially disastrous because, as he notes, "It would take 6 months or a year for the disease to establish itself, and by then it's too late to do anything." The most economical way of controlling FPR spread is to eliminate inoculum sources, which are dead sporulating pods, with frequent harvests on regular cycles. Other practices should include reduction of tree height (maximum 3.5 m) to facilitate removal of diseased pods, biological control, and planting of resistant or tolerant cultivars as they become available^{ref1, ref2, ref3}
• Aphyllophorales
• Athelia rolfsii (a.k.a. Sclerotium rolfsii)

=> seedling blight in wheat (Triticum aestivum); a major pathogen on peanut (Arachis hypogaea), where it also causes seedling blight. This report of S. rolfsii on wheat in a single plot of experimental wheat is unusual, and the authors point out the possible threat to peanut crops from seedling blight were they to be planted on land that had grown infected wheat in a previous cropping period. A different seedling blight of wheat can be caused by the fungal pathogen Fusarium graminearum. Sclerotium rolfsii, is an omnivorous, soilborne fungal pathogen that causes disease on a wide range of agricultural and horticultural crops. Although no worldwide compilation of host genera has been published, over 270 host genera have been reported in the United States alone. Susceptible agricultural hosts include sweet potato (Ipomea batatas), pumpkin (Cucurbita pepo), corn (Zea mays), wheat (Triticum vulgare) and peanut (Arachis hypogea). From a global perspective peanut crops sustain higher losses than any other agricultural crop. In 1959, the United States Department of Agriculture estimated losses from USD 10 million to 20 million associated with S. rolfsii in the southern peanut-growing region, with yield losses ranging from 1-60% in fields in the NC coastal plains region. The fungus develops protective structures known as sclerotia, and these contain viable hyphae that can serve as primary inoculum for disease development. The sclerotia also serve as the principal overwintering structures and primary inoculum for disease. Persisting near the soil surface, sclerotia may exist free in the soil or in association with plant debris. Those buried deep in the soil may survive for a year or less, whereas those at the surface remain viable and may germinate in response to alcohols and other volatiles released from decomposing plant material. Thus, deep plowing serves as a cultural control tactic by burying sclerotia deep in the soil. Since S. rolfsii does not produce spores, dissemination depends on movement of infested soil and infected plant material. Use of contaminated equipment and machinery may spread sclerotia to uninfested fields. Cool, moist weather is required for southern blight, which usually appears during fall or late summer. There is a biosecurity issue associated with S. rolfsii, and it appears on lists of potential bioterrorism agents. Its broad host range, rapid action and general recalcitrance to fungicides make it an attractive candidate for such lists^{ref1, ref2, ref3}
• Ganodermataceae
• Ganoderma
• Ganoderma boninense

=> basal stem rot (BSR) disease has long been recognized as the most serious disease of field palms in South ast Asia, especially in replanted areas. The fungus is a saprophyte that can infect a living palm if there is a large enough inoculum. The fungus, which is soil-borne, initially invades one or more roots and from there gradually extends into the stem, causing a dry rot, especially in the base of the palm plant, that eventually leads to the death of the palm. The disease can kill up to 80% of the stand by the time the palms are halfway through their normal economic life span. It constitutes a major threat to sustainable oil palm production in SE Asia and affects palm oil production. As with most soil-borne diseases, it is extremely difficult to control once the disease has become established. The best approach for disease control is avoidance. All potential sources of infection from old stems and roots of oil palm and coconut should be destroyed, and fungicide should be used. Attempts to control this disease in the field with fungicides have been inconclusive, though some systemic fungicides seem to be promising. The methods of fungicide application include soil drenching, trunk injection, or combination of these 2 methods. None of the control methods practiced has satisfactorily controlled or inhibited the spread or occurrence of this fatal disease. This report emphasizes the importance of this disease to Malaysia now that it has not only reached epidemic proportions in coastal areas but has also made considerable inroads into inland soils. The article also notes that growers are so impacted by it that they are prepared to seek out virgin land, even in other countries. In this area, the destruction of natural rainforest to grow oil palm plantations is an issue of major environmental concern, and this issue will not be minimized by the expanding influence of basal stem rot on choice of planting areas^{ref1, ref2, ref3, ref4}. The African oil palm Elaeis guineensis was introduced into Malaysia as an oil crop in the early 1900s, and many large plantations of oil palms are now in this area, with Malaysia growing over 20,000 km². Malaysia claims that in 1995, it was the world's largest producer of palm oil with 51% of world production
• Ceratobasidiales
• Ceratobasidiaceae
• Thanatephorus
• Thanatephorus cucumeris (a.k.a. Rhizoctonia solani, black scurf of potato)
• Rhizoctonia solani f. sp. sasakii
=> potato (Solanum tuberosum)
• mitosporic Basidiomycota
• Macrophomina
• Macrophomina phaseolina (a.k.a. dry-weather wilt or summer wilt)

=> charcoal rot. It is a weak pathogen, but under drought conditions (27-35°C) Mp can induce severe stress It is a warm-weather pathogen, causing stress on crops under unfavorable environmental conditions. Mp is widely distributed, and the disease occurs worldwide. Under severe disease conditions, the disease reduces yields and seed quality. Mp has a wide host range and geographic distribution, infecting more than 500 crop and weed species (including corn and soybean). It is highly variable, with isolates differing in microsclerotial size and the ability to produce pycnidia. Microsclerotial morphology is a key taxonomic characteristic in its identification. Cultural and morphological characteristics can vary as a result of continuous sub-culturing. Plants moderately resistant to cvs. such as Delta-Pineland 3478, Hamilton, or Jackson II, or the tolerant cvs. Davis or Asgrow 715 are recommended. Select early maturing cvs. that do not have late reproductive growth stages that might coincide with periods of drought stress and high temperatures. Disease management involves reduction of plant stress (providing adequate moisture, optimum fertility, and proper spacing between plants), utilization of resistant cultivars, and crop rotation away from soybean for 2 years^{ref1, ref2, ref3}
• Urediniomycetes
• Urediniomycetidae
• Uredinales
• Phakopsoraceae
• Phakopsora
• Phakopsora pachyrhizi [Pp] (very aggressive, originates from Asia (hence its common name: Asian soybean rust [ASR]) but in recent years, it has spread to other continents)
• Phakopsora meibromiae [Pm] (weaker, found in limited areas in the Western Hemisphere, and is not known to cause severe yield losses in soybean)
=> soybean rust (SR) : both native to Asia, they have also been reported from Africa, Australia, South America (in 2001 : now occurs in Argentina, Brazil, and Paraguay), and Hawaii, but neither is currently found in the continental United States. Pp was recently found 5° (250 miles) north of the Equator, near Cali, Colombia. Colombian authorities have confirmed the presence of Pp in the country's Valle del Cauca region, north of the Equator : the fungus found in the Caloto, Buga and Obando municipalities is Pm, present in Colombia for several years. Pm is present throughout South and Central America and the Caribbean and was initially reported in Puerto Rico in 1976. Symptoms of Pm and Pp on soybean are identical. In addition to the cultivated soybean, Glycine max, there are many other leguminous host species that are susceptible to Pp and Pm. Yield losses from soybean rust are reported to range from 10 to 50% in the Eastern Hemisphere (Japan, southern China, Thailand). In Taiwan, yield losses have been reported as high as 90% in selected fields. As of November 2002, USDA scientists had screened 1000 of 4000 public and commercial soybean lines against a mixed Pr population of 4 isolates from Zimbabwe, Thailand, Brazil, and Paraguay. Most were susceptible, but a few show a resistant reaction type or reduced numbers of lesions on infected leaves. Fungicides appear to be the only workable disease management strategy at present. Several efficacy trials are underway in Africa and South Africa to select candidate fungicides for rust control. Only 2 effective fungicides are currently registered for use in soybeans. In trials conducted outside the USA, 4 additional products have been identified as effective against Pr, but are not currently registered for use in soybeans. Disease management will depend upon the use of chemical fungicides, because there are no resistant commercial soybean cultivars in the USA. The development of resistant cultivars is under way, but it will be several years before commercial cultivars are available. Classical plant breeding approaches, as well as DNA sequencing strategies, are being employed. The development effort is considerable. At least 20,000 soybean lines have been screened for resistance to SR. Some have been screened for a 2nd time, but < 300 appear to have some tolerance to SR, and none have broad spectrum resistance to all Pr isolates in the USDA collection. Effective disease management will be based on the use of chemical fungicides for control of SR, as has been demonstrated in Zimbabwe, South Africa, and Brazil. The most likely fungicide candidates appear to be the strobilurins (azoxystrobin), thylenebisdithiocarbamate (EDBC) fungicides, and triazoles (triadimefon, difenoconazole, tebuconazole). Several fungicidal products labeled for SR are available, but effective dosage rates and application methods must be determined. The USA is initiating cooperative efforts to conduct field trials in Africa and South America^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9, ref10}. Chlorothalonil based fungicides have provided fair to good rust control in dry beans when applied before infection. Preventative treatment will be critical once SR is actually present. Azoxystrobin based fungicides are in the relatively new strobilurins and are environmentally safer, according to results of foreign trials. Unfortunately, the strobilurins are a single, specific mode of action, so resistance management is a big concern if they are overused or misused. Triazoles will be very important in protecting the strobilurins from rust resistance. Resistance to azoxystrobin has been reported in the United States from 3 powdery mildew isolates^ref. Occurrence of the Asian strain of SR in Arkansas is unlikely to be a surprise to pathologists. Attention is now being drawn to the involvement of kudzu (Pueraria montana), which is common in the southern USA states, as a susceptible host for the SR pathogen. Moreover, in addition to kudzu, soybean, yam bean (Pachyrhizus erosus), and cowpea (Vigna unguiculata) are principal hosts of SR, all of which are found in Florida and presumably in contiguous states. Both Phakopsora pachyrhizi and P. meibomiae are autoecious (no alternate hosts) and microcyclic (with uredinial and telial spore stages), with the obligate pathogens surviving and reproducing only on live hosts. Officials in Brazil issued a phytosanitary alert to farmers in October 2004, identifying kudzu as a potential reservoir host for SR. Immediate measures to prevent further proliferation include application of chemical herbicides, followed by controlled burning to prevent possible regeneration of plants, and destroying SR-infected plants where detected. Confirmed soybean rust-infected areas in the southeast USA now stand at 16^{ref1, ref2}. In the absence of any commercial cultivars that are resistant to soybean rust (SR), farmers have only chemical fungicides for disease management. Early diagnosis and treatment are critical for soybean rust management. Currently, there is no effective resistance to Phakopsora pachyrhizi, the fungus that causes SR. Availability of SR-resistant soybean varieties in the USA is still many years away (5 to 7 years). The Canadian Food Inspection Agency (CFIA), USDA and the Ontario Ministry of Agriculture and Food (OMAF) are monitoring and assessing the extent of these infections and the likely size of the impacted area. If this confirmation leads to an over-wintering SR population in the southern US, SR spores could migrate in a similar manner that wheat rust and common rust of corn are spread into Canada from these regions and Mexico. The impact and potential losses will vary from year to year and will depend upon factors such as initial infection levels (mild versus severe), soybean crop stage, environmental conditions, and timing of fungicide applications^{ref1, ref2}. The report that ASR, is present in Argentina is significant, but not unexpected. Of more interest is that ASR, now that it is established on kudzu and perhaps other leguminous hosts in the southern tier of USA states, can be expected to spread northward by wind from these hosts, thus expanding the range of ASR in the country. Whether ASR teliospores survive winter conditions in these states remains to be determined. If ASR is established on susceptible hosts and teliospores remain viable, these hosts will almost certainly serve as potent inoculum sources for further spread northward. ASR, now that it is established in the USA, would be expected to cause significant crop losses and perturbations in commercial trade. ASR is present in Asia: Russia Far East, Korea, Japan, China, Taiwan, Philippines, Nepal, India; Australia; Africa: Nigeria, Mozambique, Rwanda, Uganda, South Africa, Zambia, Zimbabwe; South America: Brazil, Paraguay, Argentina; Oceania and the USA (several southern states)^{ref1, ref2, ref3}.
ASR has an extensive natural host range that includes several major food crops, including pigeon pea (Cajanus cajan), lima bean (Phaseolus lunatus), garden pea (Pisum sativum), azuki bean (Phaseolus angularis) and cowpea (Vigna unguiculata). The fact that ASR has appeared on common bean in South Africa would indicate that dry rust is likely to become a factor in dry bean production. Dry beans are the most important leguminous food crop in Africa. Africa is considered to be a secondary center for bean genetic diversity.  In Africa, women on small farms are the primary bean growers. Farmers plant about 3 million hectares of beans annually in eastern, central and Southern Africa, usually as a mixture of varieties. The common bean has been, and continues to be, the most important grain legume for direct human consumption in the world. Its total world production exceeds 12 million tons, of which some 7 million tons are produced in Latin America and Africa. This tonnage represents almost twice that of chickpea, which is the 2nd most important grain legume^{ref1, ref2, ref3, ref4, ref5}.
The 1st confirmed report of ASR on the African continent was made in 1996 from Kenya, Rwanda, and Uganda, and it then continued to spread to other African countries. ASR was first reported in Hawaii in 1994, but until very recently it was still absent from the continental part of USA. In South America, ASR was first detected in Paraguay in 2001, in a limited number of fields in the Parana River basin bordering Brazil. By 2002, ASR was widespread throughout Paraguay and in limited areas of Brazil bordering Paraguay, with reports of severe disease in some fields in both countries. During the 2003 growing season, ASR was detected in most of the soybean-growing regions of Brazil with significant yield losses (approximately 5% of the annual production). In Argentina, ASR was found in 2002 in a limited area in the north of the country. In 2004, it spread readily throughout most soybean-growing areas of northwest and northeast Argentina. In USA, ASR was first found in November 2004 in Louisiana, and later in other southeastern states. It is considered that the rust was transported from South America to North America by hurricane Ivan in September 2004. There are also recent reports of the disease in Bolivia and Uruguay. Although it is not entirely clear whether ASR would be able to survive in Euro-Mediterranean conditions (cold winter temperatures, lack of humidity), a CLIMEX study did not exclude the possibility that ASR could survive in southern Mediterranean countries. As this damaging rust of soybean is still absent from the Euro-Mediterranean region, the EPPO Secretariat decided to add it to the EPPO Alert List. On September 2005 it affected 52 counties in USA (22 in Florida, 20 in Georgia, 2 in Mississipi; 3 in South Carolina). Phakopsora pachyrhizi (Asian soybean rust) :
• why: the recent and rapid spread of ASR in the Americas attracted our attention. Although data is lacking on potential establishment in the Euro-Mediterranean region (tropical and sub-tropical pathogen), the EPPO Secretariat decided to add it to the EPPO Alert List.
• where:
• Asia: Cambodia, China, India, Indonesia, Japan, Korea, Malaysia, Nepal, Philippines, Russia (Far East), Taiwan, Thailand, Vietnam.
• Africa: Ghana, Mozambique, Nigeria, Rwanda, Sierra Leone, South Africa, Uganda, Zambia, Zimbabwe.
• North America: USA (Alabama, Arkansas, Florida (the 18 Florida counties with rust as of 12 Aug 2005 are: Escambia, Santa Rosa, Okaloosa, Holmes, Gadsden, Leon, Jefferson, Taylor, Madison, Hamilton, Columbia, Alachua, Marion, Hernando, Pasco, Hillsborough, Lee, and Dade), Georgia, Hawaii, Louisiana, Mississippi, Missouri, North Carolina, Tennessee).
• South America: Argentina, Bolivia, Brazil (Goias, Maranhao, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Parana, Rio Grande do Sul, São Paulo), Paraguay, Uruguay.
• Oceania: Australia, Papua New Guinea.
• on which plants : soybean (Glycine max) is the main cultivated host, but many other Fabaceae can host this rust, for example: Lupinus hirsutus, Medicago arborea, Melilotus officinalis, Phaseolus vulgaris, P. lunatus, Vicia dasycarpa, Vigna unguiculata, and the weed Pueraria montana var.lobata (kudzu). More data is needed on the range and economic importance of Pp.on legume hosts, other than soybean.
• damage : the most common symptoms of infection by ASR are tan-to-dark brown or reddish brown lesions (2 to 5 mm²) which are usually clustered along the veins. Lesions contain erumpent, globose uredinia. Urediniospores are released through the circular ostiole. The disease begins with small, water-soaked lesions, which gradually increase in size, turning from grey to tan or brown. They assume a polygonal shape restricted by leaf veins and usually coalesce to form larger lesions. As the plant matures and sets pods, the symptoms spread rapidly to the middle and upper parts of the plant. Lesions are found on petioles, pods, and stems but are most abundant on leaves. As rust severity increases, premature defoliation and early maturation of plants is common. In areas where the pathogen occurs commonly, yield losses up to 80% have been reported. Successful infection is dependent on the availability of moisture on plant surfaces. At least 6 h of free moisture is needed for infection, with maximum infections occurring with 10 to 12 h of free moisture. Temperatures between 15 and 28°C are ideal for infection.
• dissemination : over long distances, ASR is mainly spread by wind-borne spores (e.g. in USA, it is considered that Hurricane Ivan transported it from South America to Southern USA^ref). Trade of host plants cannot be excluded as a pathway (e.g. leafy vegetables, ornamentals, pods).
• pathway : plants for planting, ornamental cut foliage, vegetables of host plants may ensure dissemination of the pathogen.
• possible risks : soybean is an important crop in the EPPO region. ASR is considered as a serious rust disease in countries where it occurs. Control methods are available (chemical control, destruction of weed hosts) but more data is needed on their efficacy. Preliminary CLIMEX studies have showed that low winter temperatures and lack of humidity are limiting factors for the establishment of the pathogen, and therefore in Europe, only Southern Mediterranean countries may be at risk. However, more detailed studies on its potential for establishment would be needed for the EPPO region.USDA-APHIS. Pest Alert. Soybean Rust. Plant Management Network. Soybean Rust. ASR was reported on late crops of soybean and on kudzu (Pueraria lobata) in several southern states in 2004. In 2005, it has so far been reported only from Florida and Georgia.
ASR subsequently blanketed Uruguay and central Argentina, where much of that nation's soybean production occurs. Excellent preparation by farmers, agronomists, plant pathologists and others has helped them weather ASR. There are differences between the 2 countries. They have a different climate and wind patterns and we can learn from them. The growing climate of these countries more closely resembles that of the USA than does the steamy tropical environment of Brazil. It's more like Arkansas and Missouri, where frost occurs in the winter. Similarities also include spore arrival via wind. In the fall of 2004, hurricanes blew ASR spores northward into the USA. It was the opposite situation in Argentina and Uruguay, where northward winds blew spores in from the ASR hotbed of Brazil. Once ASR was initially detected in Uruguay and central Argentina, it quickly surfaced all over. Soybeans double-cropped after wheat in Uruguay were the most prone to infection, as they were in the R4 (full pod) and R5 (beginning seed) stages. These fields were more likely to be infected and treated than early-planted soybeans that were further along in the R6 (full seed) stage. Farmers treat infected fields with curative fungicides or a mixture of curative and preventive fungicides. These mixtures include fungicides from both the triazole and strobilurin families, which also are approved for use in the USA^{ref1, ref2, ref3}. Some of the top experts in North America have assembled a 60-page color booklet entitled "Using Foliar Fungicides to Manage Soybean Rust". It contains contributions from plant pathologists from the nation's leading land-grant universities, as well as experts from Canada. The manual is available through state extension offices or it can be downloaded chapter-by-chapter online.
• Pucciniaceae
• Puccinia
• Puccinia graminis f. sp. tritici, produces a rusty color on wheat stems (wheat stem rust (WSR)^ref and slowly destroys the plant. It was controlled in the late 1950's and 1960's through the groundbreaking work of Norman Borlaug, an American who won the Nobel Peace Prize in 1970 for developing high-yield grains that led to the green revolution. After the new WSR strain fungus emerged -- named Ug99, for Uganda 1999 -- it seemed to disappear for a couple of years. It re-emerged in Kenya in 2001 and in Ethiopia 2 years later. WSR spreads by wind-borne spores or on the clothing of travelers. The panel's report warns that urgent action is needed if the world's wheat producers are to be spared. A 10% reduction in global wheat yield would mean a crop loss of 60 million tons, worth USD 9 billion. It is only a matter of time before Ug99 reaches across the Saudi Arabian peninsula and into the Middle East, South Asia and, eventually, East Asia and the Americas. A Global Rust Initiative has been set up in Nairobi to monitor the progress of the disease and begin the process of breeding and disseminating new resistant wheat varieties. In the 1950's, wheat rust devastated crops in North America, affecting 3/4ths of some varieties. Since then, scientists have worked to develop high-yielding varieties that resist ever-emerging diseases. Wheat grown in East Africa had been resistant to the disease for the last 40 years. But the new strain has decimated local varieties. Industrial farmers grow most of Kenya's wheat, and they have been spraying their crops several times a year to control WSR. But wheat rust could have a devastating effect in countries like Ethiopia and India, where local farmers grow the bulk of the wheat, and chemicals might prove too costly. The International Maize and Wheat Improvement Center (CIMMYT) had compiled 165 000 different genetic varieties of wheat over the years, giving scientists a head start in searching for strains resistant to the new variety. The origin of strain Ug99  was not unexpected. Evolution of new strains of pathogens is a constant process, and the arrival of a new strain, Ug99, presents a challenge to wheat producers worldwide. The new strain was detected in a test group of about 30% of experimental wheat lines growing in Uganda, a "hot spot" notorious for rust diseases. The concern is that spores of Ug99 are undoubtedly destined to reach susceptible wheat cultivars in the Saudi Arabian peninsula and the Middle East, South Asia and, eventually, East Asia and the Americas. Wheat cultivars grown in East Africa have remained resistant to WSR for the past 40 years, but Ug99 has decimated local cultivars. WSR occurs wherever wheat is grown, and yield losses can range up to 70% over a large area, and infected fields can be totally destroyed. Damage is greatest when the disease becomes severe before the grain is completely formed. In areas favorable for disease development, susceptible cultivars cannot be grown. Grain is shriveled due to the damage to the conducting tissue, resulting in less nutrient being transported to the grain. Severe disease can cause straw breakage, resulting in a loss of wheat spikes during combine harvesting^{ref1, ref2, ref3, ref4, ref5, ref6, ref7}
• Puccinia recondita
• Puccinia recondita f. sp. tritici
=> leaf rust of wheat
• Puccinia striiformis [Ps] f. sp. tritici

=> wheat stripe, yellow or glume rust (WSR)^ref occurs worldwide at higher altitudes in wheat production zones of the southern and northern areas of temperate regions. As with rust diseases in general, Ps reduces plant vigour, limits seed maturing in adult plants, and is most damaging just before or during flowering. It is different from other rusts in that it does not have a sexual stage nor does it require an alternate host to complete its life cycle. The only spore form on wheat is the urediospore. Ps infects over 18 genera of grasses including rye and barley in addition to wheat. Of particular significance is that many perennial grass species can serve as reservoir hosts for Ps, thus providing a ready supply of inoculum. Yield losses can be considerable, ranging from about 40% to complete destruction of the crop. Survival of the fungus is threatened by high temperature and dry weather. It survives primarily in dormant mycelium and uredinia on infected volunteer wheat. It also infects some barley cultivars. Disease management involves the use of resistant cultivars, control of seeding dates, elimination of volunteer seedlings and use of chemical fungicides^{ref1, ref2, ref3, ref4}. A major development in the stripe rust situation in Australia was the arrival of a new race/strain of Ps from overseas in 2002. It is a problem for grain farmers in cooler climates and at higher elevations in Australia. The first outbreak of Ps in Western Australia in 2002 caused crop losses ranging from 30-50% with greater losses (65%) in some areas. 2 theories have been developed to explain the occurrence of the new strain. One suggestion is that Ps blew into Western Australia late in 2001 on wheat and the disease was not noticed until the 2002 crop year. High-altitude jet streams at speeds approaching 300 km/h are known to
carry rust spores to Australia from wheat farms in Europe, Asia, and North America. Another route could be via an air passenger from France whose Ps-contaminated clothing touched wheat plants in a wheat field. The impact of Ps-WA is that the fungus was blown onto eastern Australian wheat fields where it overcame stripe rust resistance in several popular wheat cultivars in eastern wheat fields. Presence of Ps-WA in eastern Australia means that the popular H45 wheat cultivar will have to be discarded along with advanced lines based on this cultivar. Provision of a new commercially acceptable resistant cultivar could take 5-10 years. Disease control measures (chemical control) applied at early stages of growth reduced crop damage considerably. A major concern is that the western pathotype/strain could spread to eastern Australia where the disease has been present since 1979. Partial and major resistance genes are present in the eastern wheat cultivars, which should provide some degree of disease protection. A popular cultivar, H45, which is susceptible to Ps and blotch caused by Septoria tritici, is likely to be withdrawn in favor of more resistant cultivars such as Bowerbird and Drysdale^{ref1, ref2, ref3}. Unusually cool and wet spring weather encouraged a scattered outbreak of WSR on susceptible varieties. WSR was 1st noticed on experimental wheat lines planted by the Institute of Food and Agricultural Sciences (IFAS) spring wheat breeder at North Florida Research and Educational Center (NFREC) in Quincy, Florida in early February 2003. Florida wheat breeders and growers have had little reason to be concerned about this rust in the wheat cultivars grown in Florida. In 2004, WSR infections in the southern US were less severe and extensive than last year and therefore will provide less inoculum for the northern wheat growing area. Yield losses can be severe if the rust appears at flag leaf (boot) or anthesis stage, since the flag leaf is known to contribute 30-40% of the grain filling (yield). Management of WSR in Florida is likely to be minimal, but only time will tell. Disease management will depend upon use of resistant varieties with multiple genes for both seedling and adult plant resistance, applications of EPA-approved foliar systemic and contact fungicides registered for WSR on wheat. If fungicides are warranted, application should begin at the 1st sign of disease. A last resort would be to remove wild hosts to reduce inoculum, especially that which over-winters^{ref1, ref2}
• Puccinia melanocephala

=> sugarcane brown or orange rust occurs in USA, Australia, Ecuador, Colombia, Mauritius and perhaps elsewhere. In Australia, the disease has been confirmed on sugarcane in most of the 18 sugarcane farms in the Ord district of the Kimberley region. The best means of disease management is to grow resistant cultivars, but resistance is often unstable in some cultivars, presumably because of variants of the pathogen. Farmers are encouraged to diversify their varieties to minimize damage. Sulfur is often used for control of rust on sugarcane, but that option is not effective in the long run. Another strategy is to avoid planting susceptible cultivars. The French plant research agency CIRAD is actively searching for candidate resistance genes.
• Puccinia triticina (brown rust, wheat leaf rust)^{ref1, ref2}. Most cereal rust researchers have agreed to discontinue the use of Puccinia recondita f.sp. tritici. Thus, brown rust and leaf rust are the same disease. The use of 2 names for the same disease does not help indexing and bibliographical search, but those names have been used for more than a century, and it would be difficult to drop one rather than the other. The report that the Lr 19 resistance gene for leaf rust no longer confers resistance against the fungus is cause for concern. Yield losses may reach 40% in susceptible cultivars, but it is generally in the range from 1-20%. The global leaf rust population varies in virulence and this variation may result from one or more factors. Development of genetic resistance to rust is the most efficient, cost-effective and environment-friendly approach to prevent the losses caused by rust epidemics. The use of cultivars with single-gene resistance permits the selection of mutations at a single locus to render the resistance effective in a relatively short time. However, due to selection pressure and evolution, new virulent races of the fungus appear, which increase the need to develop durable resistance. Hence the use of combinations of genes, irrespective of whether they are major or minor, has been suggested as the best method for genetic control of leaf rust. This can be achieved by pyramiding effective resistance genes, but they are difficult to monitor in the field for expression of individual resistance genes against the background of other resistance genes. With the advent of molecular marker technology it is now possible to tackle such complex problems. DNA-based molecular markers have several advantages over the traditional phenotype markers. They can be used for marker-assisted selection (MAS) to improve the efficiency of selection in plant breeding because the environment does not affect the expression of molecular markers. These markers can also be detected at all stages of plant growth, whereas phenotypic markers often can only be identified at a specific growth stage. Many resistance genes against leaf rust in wheat have been introgressed from wild relatives. The leaf rust resistance genes Lr19 and Lr24 have been introgressed from Agropyron elongatum. Scientists are to test the validity of the molecular markers and the correspondence between the molecular and the resistance tests for the leaf rust resistance genes Lr19 and Lr24 in some lines, and the use of combined tests to permit the identification of relevant resistance lines for pyramiding resistance genes^{ref1, ref2, ref3, ref4}
• Uropyxidaceae
• Tranzschelia
• Tranzschelia discolor (Td) (a.k.a. Tranzschelia pruni-spinosae)

Prunus cerasifera (Cherry plum; Myrobalan plum) produces abundant edible fruits. It causes economic losses in stone fruits (peach, nectarine, apricot, plum, and wild Prunus spp.) in regions with severe winters. Losses are potentially severe in orchards where orchards and nurseries are not sprayed regularly. Td is a cosmopolitan fungus, whereas T.pruni-spinosae is found in Europe and USA. In California, the disease is common on foliage of prune but rarely infects prune fruit. The fungus that attacks the foliage of prunes, but rarely prune fruit. Rust occurs most frequently in Sacramento Valley orchards because it is favored by wet conditions. Severe foliar rust can cause defoliation, which may reduce yields if defoliation occurs well before harvest. Disease management depends upon applications of fungicides or sulfur.
• Ustilaginomycetes
• Exobasidiomycetidae
• Exobasidiales
• Graphiolaceae
• Graphiola
• Graphiola phoenicis [Gp] Djerbi, 1983

=> graphiola leaf spot disease / false smut disease / palm leaf pustule : infection results in sub-epidermal spots on both sides of the pinnae (leaflets) and on the rachis, with small, black sori developing in abundance on old fronds. Once the spores have been disseminated, only the rough black craters of the sori remain. Severe infection reduces tree growth and date production through premature death of leaves. Sori are 1 to 3 mm in diameter, and occurred on both sides of the pinnae, typically more abundant in the apical regions. They superficially resemble a scale insect or mealy bug infestation, but closer examination revealed the exudation of powdery yellow spores on whitish filaments. The spores observed were spherical to ellipsoidal, 3-6 mm in diameter and had a thick, smooth hyaline wall. It is most common in Egypt (Delta region and Fayum) but absent in the less humid oases. In Saudi Arabia, it is abundant in Kattif, Demam and Jeddah, but absent in Iraq. Reports of this disease also originate from Algeria, India, Egypt and Brazil (CAB International, 2003), Libya (Edongali, 1996), Kenya and USA. Around the world it is the most common disease wherever the date palm is cultivated under humid conditions -- mostly marginal date-growing areas (Mediterranean coast) but also in the southernmost humid regions of Mali, Mauritania, Niger and Senegal. On a commercial scale, the Middle East and North Africa are the major date palm (Phoenix dactylifera) producing areas in the world. Control measures include leaf pruning coupled with treatment with Bordeaux mixture or any large-spectrum fungicide. Genetic tolerance has been found in some varieties (Barhee, Adbad, Rahman, Gizaz, Iteema, Khastawy, Jouzi and Tadala)^{ref1, ref2}
• Tilletiales
• Tilletiaceae
• Tilletia
• Tilletia barclayana [Tb] (a.k.a kernet smut) : Tb infects developing flowers of the rice plant, growing within the embryo "milk" until the kernel enters the soft dough stage. At this time, the vegetative hyphae of Tb turn into dark black teliospores that replace the internal rice kernel contents. The teliospores absorb moisture during the night and early morning hours and the black spore mass often exudes from the rice flower during the morning. As the spores dry, they are blown around the field and contaminate other plant parts, the soil and harvesting equipment. Tb is ubiquitous in mid-southern USA rice soils, where the teliospores can survive for > 2 years. When the field is planted to rice again, teliospores float to the surface of the irrigation water and eventually germinate, producing primary sporidia. The primary sporidia have not been observed to fuse, as is the case in Tilletia, but do produce 2 types of secondary sporidia. The allantoid-shaped secondary sporidia are easily airborne and probably are responsible for most infections. Only a few florets per panicle are infected in most fields, but the disease has caused up to 10% yield loss and reduced head rice yield by 6% in certain highly susceptible cultivars under favorable conditions. The cultivars 'LaGrue', 'Francis', 'Banks', 'Cocodrie', 'Priscilla' and 'Cypress' are considered susceptible to very susceptible, especially under conditions where excessive rates of nitrogen fertilizer have been applied. Heavily "smutted" rice cannot be parboiled, since it results in a grey product, so mills routinely discount for "smutty" rice. While teliospores contaminate rice seed and are moved geographically with them, seed treatments do not affect the disease, since it is primarily soilborne once established. Kernel smut is favored by extended periods of cloudy weather during heading, high humidity, long dew periods, and frequent but very light rainfall. Excessive nitrogen use at preflood and late planting strongly favor kernel smut  development. Heavy rainfall during heading can reduce the disease. Kernel smut can be minimized by early planting, use of recommended nitrogen rates, and propiconazole fungicide applied preventively during the booting stage^{ref1, ref2, ref3, ref4, ref5}
• Tilletia indica (a.k.a. Neovossia indica)

=> karnal bunt [Kb] was first reported in the Karnal district of India in 1930 and has since been reported in Afghanistan, Pakistan Nepal, Iraq, Iran and Mexico. The disease was also reported in Arizona and California in regions adjacent to Mexico in March 1996. Diseased grain bears a fishy odor, which downgrades the grain but does not adversely affect quality.This long-simmering problem seems to be resolved, although not to the satisfaction of all concerned. CSL was selected to test the samples because it currently has 88 procedures within the Food Safety & Quality, Microbiology and Pesticides Veterinary Medicine Groups accredited to the ISO/IEC 17025 standard by the United Kingdom Accreditation Service and is a world-renowned expert laboratory in testing for Kb. In addition, the Australian Department of Fisheries Forestry and Agricultural has independently tested over 100 samples of current seasons grain from throughout Australia's entire wheat belt and no Kb was found
• Tilletia caries (wheat bunt fungus, stinking smut of wheat, Tilletia tritici)

=> common bunt of wheat
• Tilletia laevis (a.k.a. Tilletia foetida)

=> common bunt of wheat
• Ustilaginales
• Glomosporiaceae
• Thecaphora
• Thecaphora solani (a.k.a. potato smut)

=> potato smut (PS) is 1 of the most destructive fungal diseases affecting potato (Solanum tuberosum) in the Andean region of South America, producing yield losses of up to 85%. It is also recorded from areas of Panama and Mexico, but there are no reports of PS elsewhere worldwide. PS affects various cultivated species of Solanum, such as S. tuberosum, S. andigenum (Andigena), and S. stoloniferum. It also has been reported on tomato (Lycopersicon), and on some common weeds such as Datura stramonium. T. solani survives in soil or in tuber debris, and its spores are thought to be long-lived, though it is not known how long they are viable. Pathogen incidence is increased in the absence of crop rotation and is favored by high humidity and saline soils. Field observations indicate that seed tubers transmit the disease. PS has a very low natural dispersal potential. The most likely way in which PS could enter un-infested areas would be with potato tubers. It has been intercepted by the USDA in 52 consignments of tubers of Solanum tuberosum and S. stoloniferum, almost all from Mexico, since 1946 (USDA Lists of Intercepted Plant Pests). Soil from infected areas could also introduce the fungus. PS is reported to be serious, accompanied by losses of up to 80% in the very susceptible cultivar Peruanita. In Peru field trials, methyl bromide and dazomet, used as soil dis-infestants against T. solani, reduced the weight of hypertrophied tubers considerably (but did not eliminate the fungus). Susceptibility to infection varies, some cultivars being resistant. Resistance screening is actively being pursued at CIP (International Potato Center) in Peru. General control measures recommended are: use of resistant cultivars, planting of smut-free seed potatoes, long rotation, elimination of the weed Datura stramonium (also reported as a host), and removal of smutted galls^{ref1, ref2}
• Ustilaginaceae
• Sporisorium
• Sporisorium scitamineum (a.k.a. Ustilago scitaminea)

=> the crop plant sugarcane, Saccharum officinarum, develops symptoms of the disease smut when infected by the fungus. Sugarcane smut was 1st noted in South Africa in 1877. The disease is sometimes referred to as "culmicolous" smut of sugarcane because it affects the stalk of the cane. At one time or another, sugarcane smut has been important in nearly every sugarcane growing country in the world. Australia has been a major exception, since the disease was present only in western Australia, a minor production area. The current report extends the distribution to Queensland and therefore eastern Australia, the major sugarcane production area. This will be considered a serious new problem for their industry. Sugarcane smut does not always pose a serious problem where it occurs. However, smut may remain unnoticed for years, then quickly devastate large areas of susceptible varieties. Smut can cause significant tonnage losses as well as juice quality losses. Disease development is dependent on the environmental conditions and the resistance of the sugarcane varieties grown. The use of resistant varieties is the best approach to smut control. There is a strong genetic basis for resistance, and resistant varieties have been readily available and used to control outbreaks of smut in several countries. Using disease-free seed cane is also very important for disease control. Care should be taken, because this disease can be latent and show up only after planting^{ref1, ref2, ref3}
• ?

=> apple core rot [ACR] is caused by many different fungal species. ACR is characterized by infection within the locules (the cavity of the ovary or seed cavity), without penetration into the fruit flesh. External symptoms on the fruit are quite subtle, and, typically, the disease goes unnoticed until the fruit is cut open. External symptoms may include premature ripening and fruit drop. ACR has been recorded in the United States, Australia, New Zealand, Canada, the United Kingdom, South Africa, and the Netherlands. The most common fungi associated with ACR are Alternaria, Stemphylium, Cladosporium, Ulocladium, Epicoccum, Coniothyrium, and Pleospora herbarum. Many cultivars of apple are
affected, including Delicious, Golden Delicious, Gravenstein, and Idared. ACR fungi species colonize the flower parts as soon as the blossoms open, allowing the pathogens to enter the developing fruit through an opening in the calyx. ACR is primarily a problem during years with light fruit set or in years when dry weather in early summer is followed by heavy rains in late summer. In addition, wet weather during bloom may cause conditions favorable for the fungi to produce
spores. Apple cultivars vary in their susceptibility to ACR. This difference is primarily related to the presence of the sinus opening at the calyx end of the fruit. "Delicious," "Gravenstein," and "Idared" are susceptible cultivars and should be avoided in areas prone to ACR problems. In some studies, fungicides used during bloom have been successful in controlling ACR, but the results are erratic, and fungicides are rarely recommended. Cultural practices, such as tree training and pruning (which open up the tree canopy and allow good airflow and light penetration), will help to promote fast drying of plant surfaces, reducing the potential for spore development. These practices should help to reduce the incidence of ACR^{ref1, ref2, ref3}
• stramenopiles
• Oomycetes
• Peronosporales
• Peronosporaceae
• Plasmopara
• Plasmopara australis => Luffa cylindrica, known as smooth loofah, sponge gourd, dish-cloth gourd, and vegetable sponge (local name: bucha) is a member of the Cucurbitaceae that is native to tropical Asia, possibly India. It was an important crop before the Second World War because of its use as a biological filter. In Brazil, loofah is a subsistence crop for small farmers. A downy mildew, caused by Pseudoperonospora cubensis, is one of the most important diseases for this crop, but although this fungus is a common cucurbit pathogen worldwide and also in Brazil, it has never been recorded on loofah in Brazil. The presence of P. australis in Brazil was recorded for the 1st time in May 2005. Based on the information at hand, it is difficult to assess the effect of the pathogen on the host. There is not much information about downy mildew disease on this particular crop^ref
• Plasmopara halstedii (Ph)

=> sunflower downy mildew (DM) is found in most parts of the world wherever sunflower is grown, although it is absent from Australia. Disease loss can be severe. Epidemics have been regularly observed in Bulgaria, Romania, Moldavia, Hungary and in the Mediterranean and western parts of the European continent. In China, yield losses have ranged from 5 to 80%, and losses in Iran have been recorded up to 40%. DM has spread throughout the entire American continent, and is now in Europe, including Russia where cultivars with high oil content have been developed. The classification of Ph races have been recently reorganized. The major ones are 300, 700, 377, 730, 770, 330, 710 and 403 correspond to the former races 1, 2, 3, 4, 5, 7, A, B, respectively. French races 700 and 300 were formerly named C and D, respectively. Race 100 is found in some countries of Europe and Africa but not in USA, while Race 300 is primarily found in USA, Africa and France. Moreover, extensive exchanges between scientists in Europe and North America have contributed to distribution of Ph isolates. Unfortunately, Ph oospores remain viable in soil for up to 8-10 years, making it almost impossible to eradicate the fungus. Hybrid races evolve, overcoming resistant cultivars, with the result that yields are depressed. Strategies for disease management include planting of pathogen-free seed produced on fields free of Ph, seed treatment with recommended fungicide (metalaxyl and oxadixyl or related compounds), monitoring of fields previously seeded for 2-3 years and roguing of infected plants. Any plants found should be tested for race identification and, if found to be a non-indigenous, the field should not be used for sunflower production^{ref1, ref2, ref3, ref4, ref5}
• Pythiales
• Pythiaceae
• Phytophthora
• Phytophthora capsici (Pc) infects tomato (Lycopersicon esculentum), cucumber, pumpkin, summer and winter squashes, zucchini, bell pepper, chili pepper, eggplant, and watermelon (Citrullus lanatus). Pc spores can survive for years in soil. High soil moisture predisposes plants to infection. Disease management involves avoiding the planting of crops susceptible to Pc, use of crop rotation to include maize or small grains, application of copper fungicides, and implementation of phytosanitary regimens to minimize spread of the pathogen to equipment. Use of pathogen-free transplants is recommended. In hydroponics operations, strict management of the circulating nutrient solutions is essential to avoid introduction of the pathogen.
• Phytophthora erythroseptica [Pe]

=> pink rot (PR) symptoms are typically observed in tubers (potato (Solanum tuberosum)), but severe infections may develop foliar symptoms such as wilting, yellowing, and aerial tubers. Infected tubers exude a clear, watery liquid and potato tissues remains intact, but are rubbery. Affected tubers are susceptible to bacterial diseases, especially soft rot caused by Erwinia carotovora. Pe lives in soil and can infect any below-ground part of the plant. Disease management strategies include avoiding irrigation in the late growing season, particularly if temperatures stay above 75°F. Irrigation management and humidity control are crucial to disease control. Potatoes must be sorted so
as to isolate infected tubers from healthy ones. Early curing conditions should be 45-50°F during drying. Continuous air flow in storage bins is essential during this period. Resistance of Pe to chemical fungicides such as metalaxyl (Ridomil) and mefenoxam has been reported from several locations in the US and Canada, but the majority of the population remains sensitive. Resistance to PR has been noted from Idaho to Maine and east to New Brunswick^{ref1, ref2}
• Phytophthora infestans [Pi] (a.k.a. potato late blight agent or fungus)
• late blight on potatoes (PLB) and tomato (Lycopersicon esculentum). Managing potato crops involves forecasting for PLB, which depends upon the probability of weather conditions that will favour PLB and assumes the existence somewhere in the area of a primary source of infection; the actual level of inoculum present at any time is unknown. Many spraying decisions will be made in the light of -- and before the onset of -- deteriorating weather. The Smith Period is used to identify periods of high risk of disease spread, i.e., when the temperature and humidity favour blight. Smith Periods are defined as: 2 consecutive 24-hour periods in which the minimum temperature is 10°C or above and in each of which there are > 11 hours with a relative humidity > 90%. In practise, the occurrence of a Smith Period provides a wake-up call. Management of PLB has traditionally relied on copper, which is a broad-spectrum fungicide which protects against disease. It has been superseded by modern systemic fungicides, such as metalaxyl and furalaxyl. However, PLB overcame these plants because new strains (physiologic races) developed. New cultivars were developed that have "polygenic" or "field" resistance to the PLB pathogen. Combinations of several "minor" genes, none of which gives absolute resistance, are now used, and together they impede the rate of fungal development and enable the plant to tolerate infection^{ref1, ref2, ref3}. PLB is the most important disease affecting the potato crop in Ireland (involved in the Irish potato famine in the 1850s). The 1st reports of late blight in 2004 indicate that outbreaks are occurring a little earlier than usual. Normally, the 1st outbreaks are recorded in the south coastal areas, followed by outbreaks on the east and north coasts, and, finally, by outbreaks in the midlands. The la strain/haplotype of Phytophthora infestans (originated in the Andes Mountains in South America (as opposed to the prevailing theory that the pathogen originated in Mexico) was the causal pathogen of late blight disease in the 1840s^ref1,ref2. If a protectant fungicide has not been applied in the past 7-10 days is to put on an immediate application of fungicide. For those who have applied a protectant fungicide, the recommendation is stay on a 7-10 day fungicide spray schedule. General strategies for disease management include forecasting and reporting programs to predict late blight incidence, cultural control (strict adherence to sanitary regimens to bury and compost culls, removal of volunteer plants, avoidance of over-fertilization with nitrogen, avoidance of solanaceous crops such as tomato, pepper and eggplant in any crop rotation, and use of certified seed). Unfortunately, there are no resistant cultivars, although some cultivars such as Kennebec, Sebago and others express some resistance and are being used in breeding programs. Compost teas made from horse or cow manures in combination with beneficial bacteria are being investigated as possible alternative fungicides^ref. There is little to no blight resistance in tomato, but scientists in Oregon have developed the cultivar "Legend," which is resistant to it^ref. Pi has been a problem for over 150 years. Many approaches have been developed to control it, but the fungus still poses a major threat. It has evolved to overcome most of the measures that were introduced over the years. Several management strategies can be deployed :
• control of Pi has traditionally relied on copper-based fungicides such as Bordeaux mixture, but copper is potentially phytotoxic, so disease forecasting was developed to enable growers to predict when the environmental conditions were highly conducive to spread of Pi. Forecasting methods for PLB differ in different countries, but in Britain they are based on the "temperature-humidity rule" devised by Beaumont. Copper is a broad-spectrum protectant fungicide which must be applied to prevent disease. It has been superseded by modern systemic fungicides, which move within the plant and can both protect and eradicate existing infections. The acylalanine fungicides such as metalaxyl and furalaxyl act specifically on the RNA polymerase of Pi and closely related fungi. However, resistance to these chemicals can develop quickly in the pathogen population -- it requires only a single gene mutation leading to a minor change in the RNA polymerase molecule. In many parts of the world, Pi is now resistant to these fungicides.
• destruction of foliage : if Pi becomes established on potato foliage, sporangia can be washed down into the soil to infect tubers, or tubers can be contaminated with sporangia during crop harvesting, thus leading to rotting of the tubers during storage, and carry-over of inoculum from one season to the next. Destruction of the foliage (the haulm) with sulphuric acid or herbicide 2-3 weeks before the tubers are lifted is a recommended strategy
• resistance breeding : the cultivated potato (Solanum tuberosum) originated from the Andean region of South America, where there are several other species of the genus Solanum. Solanum demissum proved to be an important source of resistance, and by conventional plant breeding this resistance was bred into commercial potato cultivars. 4 major resistant genes (R genes) were discovered and were introduced successively into commercial cultivars. However, within a few years of each R gene being widely introduced into potato cultivars, resistance was overcome by new strains (termed physiologic races) of Pi that developed in response to selection pressure imposed by the specific R genes. Many plant breeders now prefer to develop cultivars that have "polygenic" or "field resistance" to the pathogen. Such plants have combinations of several "minor" genes, none of which gives absolute resistance, but together they slow the rate of development of the fungus and enable the plant to tolerate infection.
Emergence of new pathogenic strains through sexual crossing : like many members of the Oomycota, Pi has 2 mating types (A1 and A2). It can undergo sexual reproduction only if both mating types are present in a population. Both mating types occur in Mexico, near the centre of origin of Solanum and thus presumably of its pathogen P. infestans. In Europe only the A1 strain was [originally] known to occur -- presumably because it was introduced by chance on potatoes imported from elsewhere. The A2 mating type was discovered in Britain in 1978 and is now common in much of continental Europe^{ref1, ref2, ref3}
• foot rot of tomato (Lycopersicon esculentum)
Symptom development is restricted to lower plant parts with severe rotting of the entire root system and dark lesions girdling the stem base. No symptoms of disease are observed on the foliage or upper stems. Cross-sections of the stem base revealed brown discoloration of internal tissue, including the vascular tissue and pith. Dark brown lesions also occurred on the roots. It is unusual that there were no disease symptoms associated with the foliage or upper stems. The fact that the internal transcribed spacer (ITS) region of the glasshouse isolate of Pi is identical to that of a wide array of Pi isolates suggests a mutation in another region of the fungal genome. Unusual environmental conditions may have contributed to this anomaly. Pi has been around for a long time, and we are now aware of a new facet of its biology
• Phytophthora megakarya

=> black pod disease / Phytophthora pod rot has been reported in all cacao-producing regions. Annual crop losses worldwide are about 45%. Pm is present in West Africa, the main producing region, and total losses occur in some areas. Much of the cacao crop in Ghana is currently infected, and the fungus has been reported in Cameroon and Nigeria and is suspected in Cote d'Ivoire. Disease management involves cultural control (reduction of humidity and sources of inoculum), application of topical copper-containing fungicides and systemic compounds, and experimental use of antagonists. Breeding for resistance is a priority in West Africa. Development of a genetic finger-printing technique for identifying black pod will facilitate distinguishing species^{ref1, ref2, ref3}.
• Phytophthora ramorum (Sudden oak death agent, ramorum blight)

Genomics : 65 million-long sequence of DNA base pairs that make up 15,000 genes
=> invades plants through the bark and cuts off the flow of food from the leaves to the roots. Eventually the roots die, causing the upper tree and limbs to die from lack of water. The disease kills several species of oak and beech in this way. It can infect at least 40 other species, including shrubs like rhodedendrons and camelias, which spread P. ramorum through spores on their leaves. Currently, it can be impossible to detect the pathogen until a tree shows symptoms a year or more after infection. An existing treatment involves spreading a chemical over the entire bark of tree twice a year, but is not effective on all trees. This fungus that has killed thousands of California trees was exported from Asia, perhaps China, aboard rhododendron plants (Garboletto, Molecular Ecology)
• soilborne fungi such as Phytophthora cactorum, P. cambivora and P. cryptogea are occasional but serious problems for many orchardists who grow these tree fruits. These pathogens are especially severe on apple trees that are grown on Malling Merton 106 (MM106) rootstocks. Collar rot is most frequently associated with areas of the orchard having heavy, poorly-drained soil. Phytophthora crown rot attacks the lower trunk just at or below the soil surface. In addition to good water management, fungicide applications are suggested for those areas of the orchard likely to have collar rot problems. Because collar rot occurs so sporadically and the cost of chemical treatments is prohibitive, growers should consider only spot treatment of blocks with susceptible rootstocks growing in poorly drained areas. Chemical control can be an effective option, but must be applied before symptoms become obvious, because by then the tree is usually girdled. Fungicides containing mefanoxam are labeled for use on bearing apple and stone fruit trees. They are best applied to apples in the fall after harvest^{ref1, ref2, ref3, ref4}
• Pythium
• Pythium irregulare
• Pythium tracheiphilum

=> wilt and leaf blight on lettuce (Lactuca sativa) in Spain. Disease management includes crop rotation (3 years) and good drainage. In contained nursery operations, avoid contamination of the nutrient solution with soil. Avoid allowing dirty hands or tools to come in contact with the plants or nutrient solution. Ultraviolet sanitizing units for water are effective in destroying Pythium spp. and are available for installation into hydroponic operations. However, these systems are of little value if the disease-causing organism is present in the nutrient troughs and substrate.
• Pythium ultimum
They are common pathogens that affect many crops, causing damping-off diseases (including stunted, chlorotic, and partially defoliated lentils (Lens culinaris Medik)). Yield losses can be very high, especially in soils with heavy moisture-holding capacity. Prevention of diseases under field conditions is a priority, but that is easier said than done -- because once infestation occurs, oospores can remain viable for several years. Disease management depends upon planting of high-quality seeds and treatment of seed with approved fungicides. Infection of wheat by P. irregulare in the Pacific Northwest USA may be more common than we know.
• Synchytrium endobioticum

=> potato wart disease (PWD) has spread from the South American Andes to most potato-growing countries in Europe and has been recorded in the Canadian provinces of Newfoundland and Prince Edward Island. PWD was eradicated from several states in USA and is now considered free of the pathogen. PWD has spread to most regions of the world where potatoes are cultivated. Synchitrium endobioticum affects cultivated potato and a number of wild Solanam. It was once the most serious disease of potato in the UK but has now been controlled by statutory measures and the development of "immune" varieties. It still poses a serious threat to potato production, because the spores of the fungus can remain viable in contaminated soil for many years. New strains of the fungus, capable of attacking potato varieties that were previously resistant, have developed in several European countries. Preventing spread of these strains to the UK is especially important^{ref1, ref2}. The most likely way PWD entered Turkey was by an accidental introduction of wart-infected potato or by contaminated soil or equipment.
• Metazoa; Eumetazoa; Bilateria
• Pseudocoelomata; Nematoda
• Chromadorea; Tylenchida
• Paratrichodorus
• Paratrichodorus teres

=> stubby root nematodes are becoming of increasing importance to the potato industry in Washington State, because they are vectors of Tobacco rattle virus (TRV), the causal agent of Corky Ringspot disease. In addition to the presence of Paratrichodorus allius (Pa) in Washington State, a 2nd morphologically similar stubby root nematode species (Paratrichodorus teres, Pt) has been identified. The current method for determining if the nematodes are viruliferous for TRV takes several weeks, because it requires a glasshouse bioassay. Therefore, a rapid molecular assay has been developed using RT-PCR to identify viruliferous nematodes. The technique can detect TRV in as few as 5 nematodes. Corky ringspot disease (CRS) in potatoes is caused by tobacco rattle virus (TRV), which is vectored by stubby root nematode species (Paratrichondorus, Tricondorus spp.). Both virus and vector have wide host ranges, leading to persistence of the disease in spite of the use of expensive chemical control agents. Use of resistant varieties can be a key factor for managing this disease. However, it is difficult to confirm resistance of parents and selected progeny genotypes due to erratic incidence and symptom expression in field screening plots. Screening nurseries require many replications and large plots, but escapes are still common. Recent work at Scottish Crop Research Institute (SCRI) (Xenophontos et al., (1998) Potato Research, 41, 255-265; Dale et al., (2000) European Journal of Plant Pathology, 106, 275-282) has shown that some potato cultivars, (Wilja and King Edward), can become persistently systemically infected with TRV without developing spraing symptoms (reddish brown spots, rings, or arcs in tuber tissue), and that such plants can serve as sources for virus acquisition by vector nematodes. Stocks of these cultivars can become chronically infected, and show effects on yield and quality, with the production of smaller tubers with extensive secondary growth and growth cracking. Preliminary experiments suggest that more cultivars than the 2 mentioned above are affected in this way^{ref1, ref2, ref3, ref4, ref5}
• Tylenchina; Tylenchoidea;
• Anguinidae
• Ditylenchus in soil machinery
• Ditylenchus destructor (a.k.a. potato tuber nematode, potato rot nematode (PRN)) has been reported in areas of Idaho, California and Wisconsin. PRN has also found in widespread areas in many potato-growing areas in Europe and the Russia, in some areas of South America, South Africa and the Mediterranean region. PRN cannot be eradicated from any cropland with any conventional farm chemical or management practice, but sanitation and some management practices help prevent the nematode's further spread. Only certified potato seed that originated from a limited generation program is to be planted; year-out or eliminator plants should not be planted. Resistance among recently released potato cultivars has not been determined, but all older cultivars are considered susceptible. Do not store potatoes if PRN is detected during harvest, because the nematode can grow and develop under normal storage conditions. Potatoes must not be planted in infested fields for 4 to 6 years and a cereals and grasses rotation is suggested for inclusion in the scheme. All contaminated storage facilities, and cultivation and handling equipment that have come in contact with contaminated potatoes must be disinfected. Infested soil or potatoes on cropland must be properly disposed of and fields should be free of weeds. Application of approved nematicides according to label recommendations is presently the best management method for reducing PRN populations in the soil^{ref1, ref2}
• Ditylenchus dipsaci in Allium sativum
• Heteroderidae
• Heteroderinae
• Globodera (genus since 1975) (a.k.a. potato cyst nematodes (PCN))
• Globodera rostochiensis [Gr] (a.k.a. golden nematode, potato cyst eelworm, potato nematode, potato root eelworm or nematode) is now believed to be the more dominant species, and is distributed widely in Europe, India, North Africa, Asia, many countries of South America, and North America (parts of Mexico, on Long Island in New York State and in Canada only in Newfoundland and the central Saanich Peninsula of British Columbia, where it was found in 1965). Of all the crop pests worldwide, Gr is one of the most difficult to control. Once established, it is difficult to eradicate, because the nematodes survive for up to 30 years as eggs protected by the durable cyst wall. Gr can survive in soil for 20 years in the absence of any potato crop. The strategy for limiting spread, once the potato cyst nematodes are introduced, is to integrate control measures, in particular, the use of pesticides, resistant varieties, and crop rotation^{ref1, ref2, ref3, ref4, ref5} . Potato cyst nematodes are major pests of the potato crop in cool-temperate areas. More recently, crop rotation has been supplemented by use of resistant potato cultivars and nematicides (fumigants or granular systemic compounds). Methyl bromide is being gradually phased out in favor of other fumigants. There is no known single alternative fumigant, chemical, or other technology that can readily substitute for methyl bromide in efficacy, low cost, ease of use, wide availability, worker safety, and environmental safety below the ozone layer. Research by USDA indicates that multiple alternative control measures will be required to replace the many essential uses of methyl bromide. For pre-plant uses, such measures include combinations of fungicides, herbicides, and insecticides; other fumigants; and non-chemical alternatives, including cultural changes in cropping systems, resistant crops, and biological control^ref.
• Globodera pallida [Gp] (white or pale potato cyst nematode)^ref
=> globoderosis; potato cyst nematodes attacks potato roots, causing very significant yield reduction (up to 70%) over time, particularly in Europe. The cysts can remain viable for up to 30 years in some instances. They are worldwide in distribution and are considered one of the most difficult plant diseases (pests) to manage. In Scotland, one ton/acre is lost for every 20 eggs/g soil. Continuous cropping of cultivars resistant to Gr selects for pathotypes of Gp. Disease management utilizes nematicides and resistant cultivars. Seeds of 3 varieties segregating for resistance to 2 pathotypes of Gr (Ro1 and Ro2) and 2 pathotypes of Gp (Pa2 and Pa3) have been released by Cornell University and USDA/ARS. The resistance is suitable for North American production. It was developed in anticipation of the eventual introduction of pathotypes of Gp, prevalent in many other potato production areas of the world, into North America. The combined resistance in this germplasm is from S. tuberosum ssp andigena and S. vernei^{ref1, ref2}. Together they are rstimated to result in annual losses in European potato production valued in excess of 200m BPS [USD 349 million]. A recent survey of soil samples taken by growers revealed that up to 60% of the land cropped with potatoes in the UK is infested with PCN. Annual loss to the UK potato industry as a direct consequence of PCN has been estimated at approximately 9% of crop value, worth around 43m BPS [USD 75 million]. Disease management is traditionally by crop rotation, as it is recognized that several years in the absence of potato cultivation will reduce the population of nematodes to a significant degree; 7 years without potatoes is a common recommendation. More recently, crop rotation has been supplemented by use of resistant potato cultivars and nematicides (fumigants or granular systemic compounds). An integration of these methods can be used to keep the nematode population levels below economic thresholds. Control on tomatoes is chiefly by soil fumigants. Both species of potato cyst nematode are A2 quarantine pests for EPPO (OEPP/EPPO, 1978; 1981). They are also of quarantine significance for APPPC and NAPPO. In addition, G. rostochiensis is a quarantine pest for CPPC and IAPSC. The nematodes are already established in most or all areas in the EPPO region that are important for the cultivation of potatoes for consumption or the production of starch; therefore, regular attention to control is needed in such areas. Where domestic legislative measures are in force, import regulations are justified to ensure comparable standards for imported material. It is essential that areas of seed potato production be kept as free as possible from these nematodes^{ref1, ref2, ref3}
• Heterodera
• Heterodera glycines [Hg] (a.k.a. soybean cyst nematode (SCN))

=> soybean cyst, one of the most important diseases of soybeans. Yield losses can range up to 30%, mainly because fewer pods are produced on infected plants. Moreover, soybean yield is directly related to the numbers of nematodes feeding on soybean roots. SCN-infected soybean is also more susceptible to infection by brown stem rot of soybean, caused by the fungal pathogen Phialophora gregata, in both resistant and susceptible soybean cultivars. Unfortunately, SCN cannot be eliminated from affected fields. The tough cyst, besides providing long-term protection for eggs and juveniles, allows for possible long distance dispersal. Cysts are found in "soil-peds" (aggregates of soil) which adhere to anything that moves through an infested field. To restrict spread of SCN to uninfested areas, and to control populations in known infested fields, the following management practices are necessary; decontamination of farm implements and footwear, controlled movement of infested plants, weed control, crop rotation, and use of resistant cultivars. A new bioassay for Hg has been developed and is described in the links below. The gist of the new test is that a low FI means the field's SCN population reproduces poorly on that line. A high number means a high rate of reproduction and that a variety from that line would be a bad choice for planting^{ref1, ref2, ref3, ref4}. Each nematode can contain about 250 eggs. When they drop off, they can remain viable in the soil for up to 12 years in the absence of a host. Heterodera glycines, the soybean cyst nematode [SCN] is a major limiting factor in Michigan soybean production. First detected in Michigan in 1987, it is known to exist in almost all of Michigan's major soybean-producing counties. SCN infestations can result in poor stands, stunted plants, yellow foliage and low soybean yields. Losses can range from 5% to 90% of the yield potential. Michigan soybean growers need to have a well-developed strategy to avoid SCN problems or to minimize impacts if SCN is already present. It is a problem for soybean producers as well as a regulatory concern for growers wishing to export seed or plant material to other states or countries, many of which will not accept seed or plant material unless it is certified SCN-free. It is important that growers using land that has been previously planted to soybeans have their fields sampled routinely if they wish to export seed or plant material. SCN has 3 major life stages: egg, juvenile, and adult. Juvenile stages feed on roots as they continue to develop into either adult males or females. Affected plants express above-ground symptoms such as plant stunting and yellowing. SCN females can be observed on the root systems of soybeans around 45 days after planting. They are small white spheres about the size of the head of a pin and are found attached to the roots of the host plant. As the females mature, they turn brown and become a protective cyst for their eggs that can remain viable in the soil for many years. Each cyst may contain up to several hundred eggs that will eventually hatch when a suitable host is present. SCN hosts are mainly legumes such as soybeans, dry beans, and snap beans but it has also been known to survive on some winter annual weed species. Monitoring for SCN is an essential part of nematode management. All fields in Michigan should be routinely sampled for nematodes, preferably every fall before soybeans are planted. Early detection is critical to avoid drastic yield losses and high population densities of SCN. Sampling for SCN and other plant-parasitic nematodes is described in Michigan State University [MSU] AG Facts Bulletin E-2199, Detecting and Avoiding Nematode Problems. Samples consisting of roots, soil or both can be submitted to Diagnostic Services at MSU for nematode analyses. Lateral movement of SCN is slow, about an inch a year on its own. However, SCN can be transported over long distances in soil associated with crop transplants (e.g., tomato, strawberry, ornamentals), on machinery, animals, and with seed. Movement of soil should be minimized. Fields without SCN should always be worked and harvested before infested fields. To minimize the spread of SCN, equipment should always be washed free of soil after working in SCN-infested fields. Reduction of SCN is the strategy used for minimizing risks in SCN-fields. Once a field is infested with SCN it is virtually impossible to eradicate it. If SCN is present in a field, the objective in most situations is to reduce the population density. This can be achieved by growing non-host crops, maintaining good weed management, and incorporating SCN-resistant soybean varieties into cropping schemes. Currently, there are a very limited number of nematicides registered for control of SCN, and the economics of nematicide use for control of SCN in Michigan have not been justified. Recommendations for SCN management will vary depending on population densities and the production needs of the grower. When samples are submitted to Diagnostic Services at MSU, a nematode diagnostician will provide recommendations to growers to assist them in implementing appropriate SCN management strategies. Apparently no SCN has been detected in the Upper Peninsula region of the state as of May 2004^{ref1, ref2, ref3, ref4, ref5}.
• Heterodera latipons (cereal cyst nematode) in wheat
• Meloidogyninae
• Meloidogyne

Root-knot nematodes have been detected regularly in greenhouses throughout Europe, while in the field it is restricted to the southern parts of Europe. They cause extensive damage to roots by their feeding activity, exacting a heavy toll on producers. Root knot nematodes cause crop yield reductions by interfering with nutrient flow in the xylem. Infected plants are less vigorous than healthy plants and are susceptible to wilting at high temperatures. Disease management utilizes several strategies: weed control because they are often hosts; resistant host cultivars; rotation with resistant varieties and non-host crops; and soil fumigation using broad-spectrum fumigants to reduce fungi and nematode populations^{ref1, ref2}. Both nematodes are involved with other pathogens in disease complexes. Root-knot  nematodes, especially M. incognita [Mi], M. arenaria [Ma] and M.  javanica [Mj], cause serious damage to cucumber, melon, watermelon, pumpkin and squash. The finding of M. arenaria [Ma] in Jordan is certain to cause considerable yield losses in important food crops. Ma is considered one of the "major" Meloidogyne species due to its worldwide economic importance. It is commonly encountered in warmer regions and is seldom found in areas where average monthly temperatures approach freezing. It is the most morphologically and cytologically variable of the Meloidogyne species. 2 host races have been differentiated, one that reproduces on peanut (race 1), and race 2 which does not. Differences in field resistance to Meloidogyne spp. among 21 melon cultivars and breeding lines have been reported in Florida, but good resistance in muskmelon or other cucurbits is not available. A high level of resistance to the 4 major root-knot nematode species is present in the African horned cucumber (Cucumis metuliferus), but attempts to develop interspecific hybrids with cucumber cultivars have failed. Resistance to Mj and Ma races 1 and 2 occur in Cucumis sativus var. line 90430, and cucumbers resistant to these species or races currently are being developed at North Carolina State University. Resistance to Mi, Mj and Ma has also been identified in the West Indian gherkin (C. anguria) and other wild Cucumis spp. Disease management involves use of nematicides for high-value crops such as peanuts, tobacco, and peach. Where available, resistant cultivars provide the most economical and environmentally benign means of control. A PCR-based system has been developed using species-specific DNA fragments, and it identified all 4 major species present in South Carolina, but further refinements are required to maximize its potential. The research has provided a foundation to develop an accurate root-knot nematode species identification system (based only on a single 2nd stage juvenile) that can be integrated into a nematode management system. Rotation experiments are underway
to test the modified PCR-based system when reliability can be improved^{ref1, ref2, ref3, ref4}
• Meloidogyne arenaria [Ma]
• Meloidogyne chitwoodi [Mc] (EPPO A2 list)
• Meloidogyne ethiopica Whitehead originally described from Tanzania is also distributed in South Africa, Zimbabwe, Ethiopia, and Slovenia. Although this species is a relatively unknown root-knot nematode, M. ethiopica parasitizes several economically important crops, such as tomato, cowpea, bean, cabbage, pepper, pumpkin, tobacco, lettuce, and soybean. This species can be morphologically confused with M. incognita (Kofoid & White), and therefore is probably easily overlooked. Recently, characteristic esterase isozyme patterns were described for this species, which provide a more reliable identification.
• Meloidogyne fallax [Mf] (EPPO A2 list)
• Meloidogyne floridensis (Mf) : previously unnamed and assumed to be "race 3" of Meloidogyne incognita. Mf was isolated from nematode-resistant Nemaguard and Okinawa peach rootstocks in Gainesville, Fla. This explains why nematodes were infesting and reproducing in these root knot nematode resistant rootstocks. Scientists found the pest's penchant for nematode-resistant rootstock characteristic, which stimulated further research. Morphological, cytological, molecular and host-range studies conclusively determined the taxonomic position of the nematode. Using scanning electron microscopy, it was demonstrated that differences between Mf and M. incognita were recognized. Mf did not exhibit the same host affinities as M. incognita. Mf reproduced abundantly on Nemaguard and Guardian peach rootstocks, whereby M. incognita did not. Alternately, Mf does not reproduce in peppers as does M. incognita. Molecular studies confirm the uniqueness of Mf from M. incognita and other root-knot nematodes^ref
• Meloidogyne hapla [Mh] (northern root knot nematode) occurs in temperate regions and at higher elevations in warmer regions worldwide and has an extensive host range that includes many vegetables. Mh management requires clean planting material, crop rotations seeded to non-host crops such as grasses and cereals, and use of resistant cultivars
• Meloidogyne incognita [Mi] occurs primarily in thetropics and warmer regions. Meloidogyne incognita is able to parasitize > 700 plant species and varieties, including the majority of our economically important crops. Its hosts include vegetables, cereals, sugarcane, and potatoes. Disease management for Mi involves use of nematicides and host-plant resistance
• Meloidogyne javanica [Mj]
• Pratylenchidae
• Nacobbinae
• Nacobbus
• Nacobbus aberrans [Na] (a.k.a false root-knot nematod) : in South America and Mexico, Na has been reported to cause crop losses as high as 65% on potato and 36% on bean (Phaseolus vulgaris). Na is spread through soil debris, poorly sanitized bare root propagative plant material and edible roots or tubers. It is ranked in the "top 3" nematode pests of potato in the Andean regions of Peru and Bolivia (Anon., 1973), along with the potato cyst nematodes Globodera rostochiensis, G. pallida (EPPO/CABI, 1996) and root-knot nematodes (Meloidogyne spp.); in some areas, e.g. Puno Department of southern Peru, it is the most important.  Most potato fields in southern Peru and Bolivia are heavily infested (Jatala, 1979). Na populations can be decreased by nematicides, fumigants (Stone & Burrows, 1985b) and crop rotation over a 4-6 yr period. Recent work has demonstrated that antagonistic fungi and bacteria (Zuckerman et al., 1989) may be useful biological control measures. Breeding for resistance has shown some promising preliminary results (Finetti Sialer, 1990), but resistant potato cultivars are apparently not yet available^{ref1, ref2}.
• Pratylenchinae
• Pratylenchus in soil machinery
• Rotylenchus in soil machinery
• Enoplea; Enoplia; Dorylaimida; Dorylaimina; Longidoroidea; Longidoridae; Xiphinema
• Xiphinema rivesi

It is present in the EPPO region (France, Germany, Portugal and Spain). It may be an introduction from North America (Lamberti & Ciancio, 1993). It is widespread in USA and is possibly present in South America. The distribution of European populations of X. rivesi is illustrated by Alphey & Taylor (1986). X. rivesi is a vector of Tomato ringspot nepovirus^ref
• Coelomata; Protostomia; Panarthropoda; Arthropoda; Mandibulata; Pancrustacea; Hexapoda; Insecta; Dicondylia; Pterygota; Neoptera; Paraneoptera; Hemiptera; Sternorrhyncha; Aphidiformes; Aphidomorpha; Phylloxeroidea; Phylloxeridae; Daktulosphaira
• Daktulosphaira vitifoliae [Dv] (a.k.a. grape phylloxera), is a worldwide pest of grapevines. During the later part of the 1800s, phylloxera destroyed 2/3rds of Europe's vineyards. The pest arrived in California about the same time, either from its native range in the eastern United States or from Europe. Its life cycle has sexual and asexual portions with forms that feed from leaf and root galls. Not all forms occur throughout the insect's range. Root forms predominate on grapevines (Vitis vinifera) cultivars; leaf forms predominate on other Vitis spp.characteristic of the American native range. Other conditions influence expression of the life cycle. Hosts and conditions similarly affect life table performance. Damage to grapevines is by secondary soilborne pathogens attacking feeding sites and by physiological interaction of Dv with the grapevine, though the latter has not been well studied. Resistant rootstocks derived from native American Vitis are the primary control tool. Dv varies genetically and relative to performance on hosts. Use of insecticides is limited in effect, and other control methods are not proven. More research on the biology, ecology, and management of Dv is needed. What is interesting is the involvement of Dv in spreading the soilborne fungus, Fusarium oxysporum, in vineyards where it overpowers resistant cultivars. These fungi are spread by phylloxera as they taste and probe among feeder roots and older storage roots of the grapevines, leaving the roots more vulnerable to fungal decay.Interestingly, Fo strains isolated from declining areas in vineyards are far more aggressive than isolates from non-impacted vineyards or soils when tested by root assays in the lab, greenhouse and field. Soil compaction (increase in penetration resistance) is the natural result of multiple passes of heavy equipment down vineyard rows. The use of farm equipment with narrow tires exacerbates the problem as the weight of the vehicle is spread over a very small area. Using wider set of tires on heavy vehicles can, in part, alleviate this problem^{ref1, ref2, ref3}
There are 4 classes of plant virus transmission by Homopteran insects :
• non-persistently transmitted (styletborne NP)
• semi-persistently transmitted (foregutborne SP)
• circulative-persistent (CP)
• propagative-persistent (PP)
Unknown etiology :
• citrus blight (CB) was 1st reported in Brazil in 1977 in Sao Paulo State, it was later detected in other states and is now found in all production areas of the country. It has been an important disease in Florida for over 100 years. Similar diseases have been described in other parts of the world, but their etiologies remain unknown. It causes a chronic decline of citrus and is now responsible for the removal of nearly 10% of the trees from production annually. No causal agent has been identified, but CB has been root-graft transmitted to healthy trees, suggesting that the causal agent is infectious. First detected CB is the main cause of low longevity of orchard groves, accounting for 5% of tree deaths annually. The high mortality rate is due to the use of Rangpur lime (highly susceptible to the disease), because that rootstock is used in > 90% of the groves. Some pathologists suggest that CB is an abiotic disease (that is, nutritional and pH-related issues), while others think it is a biotic disease (that is, some fastidious organism or virus-like agent). Several nutritional and pH-related studies are under way to examine abiotic factors. Efforts are underway to search for and characterize any organisms associated with the CB syndrome. Host genes that relate to CB-induced proteins are being examined to help determine the cause. USDA/ARS scientists at Ft Pierce, FL are examining nutrition issues and genetics, and University of Florida researchers are examining molecular biology and virus-like organisms. CB is one of the most serious economic problems for citrus growers in Florida and Brazil. Millions of trees are lost annually, and yearly losses are pegged at 4 to 7% in affected groves. In Florida, about 500 000 citrus trees are removed annually^{ref1, ref2, ref3}.
Laboratory examinations :
• local lesion assay is a technique to estimate the relative virus or viroid concentration, which involves rubbing variously diluted aliquots of a preparation onto leaves of a hypersensitive host plant that reacts to infection with the production of vivisble chlorotic or necrotic spots, the number of which is directly related to the virus or viroid concentration
• several versions of PCR are at the cutting edge in the development of sensitive methods for detection of plant pathogens. Examples include: tests for detecting inoculum, especially airborne spores, in low concentrations; specific detection of pathogen DNA to assess disease progress in a crop before expression of visual symptoms;

real-time PCR to provide precise estimates of disease levels in plant tissues in advance of developing epidemics; and PCR to identify specific mating types in fungal populations so as to predict presence of infective spores at the start of a cropping season^{ref1, ref2, ref3, ref4, ref5}.
Prevention : transgenic crops bearing insecticidal genes
Therapy : phage therapy has been used successfully against bacterial blotch of mushrooms caused by Pseudomonas tolaasii. In studies notable for the employment of phage host-range mutants, phage therapy has also been employed against bacterial blight of geraniums and bacterial spot of tomatoes, both caused by pathovars of Xanthomonas campestris. Though seemingly effective in certain situations, it is likely that phage therapy against bacterial plant pathogens will not prove to be a magic bullet in all cases. The natural interactions between phages, bacteria, and plants are still not well understood. While phages that attack pathogenic bacteria can help improve plant health, other phages may attack the bacteria that affect the root nodulation of plants such as soybeans, which are necessary for normal plant growth.
Web resources :
• Descriptions of Plant Viruses (DPV) by John Antoniw and Mike Adams at Rothamsted Research
• European and Mediterranean Plant Protection Organization (EPPO)
• Plant Pathology Internet Guide Book (PPIGB) at University of Hannover
• Usenet sci.bio.phytopathology
• Plant Parasitic Nematodes
• Global Crop Pests
• Canadian Plant Disease Survey (CPDS)
• Agricultural Research Service (ARS)of the U.S. Department of Agriculture (USDA)
• Forest and shade tree pathology
• the economic damage caused by episodic outbreaks of forest-defoliating insects has spurred much research, yet why such outbreaks occur remains unclear. Theoretical biologists argue that outbreaks are driven by specialist pathogens or parasitoids, because host–pathogen and host–parasitoid models show large-amplitude, long-period cycles resembling time series of outbreaks. Field biologists counter that outbreaks occur when generalist predators fail, because predation in low-density defoliator populations is usually high enough to prevent outbreaks. Neither explanation is sufficient, however, because the time between outbreaks in the data is far more variable than in host–pathogen and host–parasitoid models, and far shorter than in generalist-predator models. Insect outbreaks can be explained by a model that includes both a generalist predator and a specialist pathogen. In this host–pathogen–predator model, stochasticity causes defoliator densities to fluctuate erratically between an equilibrium maintained by the predator, and cycles driven by the pathogen. Outbreaks in this model occur at long but irregular intervals, matching the data^ref
• when researchers mulch with a layer of mown vetch instead of the conventional black plastic, tomato plants live longer and develop less fungal : in years with sufficient rainfall, the vetch-treated fields yielded a Sunbeam tomato crop bigger than that of fields receiving conventional treatment. Although the plastic mulch provided the crop a little sooner, the vetch mulch offered other benefits, including reduced erosion, decreased signs of fungal disease on leaves, and delays in plant aging. These benefits appeared during 2 seasons but not in a third, when there was a severe drought. Among the genes that kick into higher activity in vetch-mulched fields are 2 for plant defense (chitinase and osmotin) and 2 for regulation of aging (receptors for cytokinins). The vetch system has been around for decades among farmers practicing environment-friendly agriculture : over the winter, the farmers grow hairy vetch, a member of the bean family, and they mow it in the spring, they then set out tomato plants in the matted vetch, which discourages weeds and boosts nutrients in the soil.
• genetically modified plants : plant biotechnology relies on 2 approaches for delivery and expression of heterologous genes in plants: stable genetic transformation and transient expression using viral vectors. Although much faster, the transient route is limited by low infectivity of viral vectors carrying average-sized or large genes. Agrobacterium-mediated delivery of constructs for the efficient delivery of RNA viral vectors as DNA precursors results in gene amplification in all mature leaves of a plant simultaneously (systemic transfection). This process, called 'magnifection', can be performed on a large scale and with different plant species. This technology combines advantages of 3 biological systems (the transfection efficiency of A. tumefaciens, the high expression yield obtained with viral vectors, and the post-translational capabilities of a plant), does not require genetic modification of plants and is faster than other existing methods^ref. Scientists may have developed a potentially less controversial way to bioengineer plants, by replacing a marker gene normally borrowed from bacteria with a gene from weeds. The new technique could make genetically modified crops less contentious in places such as Europe^ref. Modern technology allows experts to mix and match DNA from different organisms to enhance favourable crop properties; a gene from fish, for example, can make tomato plants frost resistant. Most transgenic crops also contain a bacterial gene, which helps researchers distinguish between plants that have successfully picked up foreign genes and those that haven't during crop development. The 2 genes, one for the favourable trait and one for antibiotic resistance, are tacked together and inserted into seeds. When the growing plants are then doused with antibiotic, those that haven't picked up the foreign genes die off.  The marker gene typically comes from the Escherichia coli bacterium. But critics of the technology have pointed out that the code for antibiotic resistance could hop, in a process known as horizontal gene transfer, from the bioengineered food we eat into the bacteria that live in our gut, thereby creating a superbug and a health menace. Some companies take an extra step to remove the antibiotic-resistant gene before marketing their seeds. But this doesn't always happen. A more foolproof way to eliminate this threat involves scrapping the E. coli gene and using one from a plant instead. A gene called Atwbc19 in the well-studied weed Arabidopsis thaliana also confers antibiotic resistance; when this gene is expressed at unusually high levels it helps to capture and squelch antibiotic compounds. Stewart and Mentewab designed a piece of DNA including this gene and another that codes for blueish pigments, making plants that pick it up easily identifiable. The Atwbc19 gene is 3 times larger than the antibiotic-resistance gene from bacteria. Both the large size of the gene and the fact that it comes from plants makes it less likely to hop into microbes. To test whether the Arabidopsis gene worked, they incorporated the linked genes into tobacco plants; the tobacco seedlings with the Arabidopsis gene continued to grow when blasted with antibiotics. The study could calm fears about GM crops, particularly since the plant gene simply can't be expressed by bacteria. It produces a gene which, if displaced by horizontal gene transfer back into bacteria, would never be able to confer resistance to antibiotics. The technique could be adopted in parts of the world that have remained skeptical about bioengineered foods. There would be some interest, especially in Europe, to move away from a bacterial gene towards a plant gene. But further testing is needed. Scientists must demonstrate, for example, that the protein made from the weed gene has no negative effect in humans.
• genetically modified plants for industrial uses :
• GM potatoes which contain high amounts of a type of starch that can be used in paper production. Byproducts from the starch extraction would be used for animal fodder and fertilizer. It's not a food potato. It has already been cultivated on a trial basis by a Plant Science Sweden, a company in southern Sweden
• phytoremediation
• genetically modified crops to ...
• ... better meet our needs (phytopharming, the production of protein biologicals or other kind of phytonutrients in recombinant plant systems), ie increase ... :
• amino acid composition of proteins in basic grains
• specific vitamin contents such as vitamin A or vitamin E
• specific components such as caffeine or phytic acid conceivably can be eliminated in the source plant, negating the need for processing steps that add cost and that lessen flavor and nutrition
• scFv
• edible vaccines
• GM tomatoes :
• carotenoids, flavonoids, and lycopene, both of which are highly beneficial for human health. Overexpression of genes encoding biosynthetic enzymes or transcription factors have resulted in tomatoes with improved carotenoid or flavonoid content, but never with both. Suppressing an endogenous photomorphogenesis regulatory gene, DET1, using fruit-specific promoters combined with RNAi technology significantly increased both carotenoid and flavonoid contents, whereas other parameters of fruit quality were largely unchanged^ref
• quercetin glucoside : introduction of a highly expressed chalcone isomerase leads to a 70-fold increase of the amount, which is a strong anti-oxidant in tomato^ref
• prevent ripening :
• 'Flavr Savr' tomato introduced in the United States in 1994 contains a resistance gene for the antibiotic kanamycin (kan^r) and a gene construct for the inhibition of fruit ripening and softening (antisense polygalacturonase)
• a yeast S-adenosylmethionine decarboxylase gene (ySAMdc; Spe2) fused with a ripening-inducible E8 promoter to specifically increase conversion of putrescine into higher polyamines (permidine and spermine) in tomato fruit during ripening. This leads to an increase in lycopene, prolonged vine life, and enhanced fruit juice quality. Lycopene levels in cultivated tomatoes are generally low, and increasing them in the fruit enhances its nutrient value. Furthermore, the rates of ethylene production in the transgenic tomato fruit are consistently higher than those in the nontransgenic control fruit^ref
• GM sugar beet engineered with the first enzyme involved in fructan synthesis, the sucrose sucrose fructosyltransferase (isolated from Jerusalem artichoke) shows a dramatic change in the nature of the accumulated sugar, 90% of the sucrose being converted into fructan^ref.
• GM potatoes which contain :
• a feedback insensitive bacterial gene involved in biosynthesis of aspartate family amino acids leads to a 6-fold increase of the lysine content. Because the use of a bacterial gene could appear to be controversial, introduction of a mutated form of the plant key enzyme of lysine biosynthesis (dihydrodipicolinate synthase) leads to a 15 times increase of the lysine content of potato. This increase of the essential amino acid lysine influences the nutritional value of potato, which normally has low levels of several essential amino acids^ref.
• 250 times more zeaxanthin than found in conventional potatoes were produced by the University of Karlsruhe's Institute of Food Process Engineering in a project which started in 1999 after receiving a grant of around &euro; 10 million (USD $13.2 million) under the government of the previous chancellor, Helmut Kohl. Kohl supported GM research more than the current government of Chancellor Gerhard Schroeder, whose SPD party relies on the support of the Greens party to maintain a parliamentary majority. Past studies have indicated that higher dietary levels of zeaxanthin reduce the risk of age-related macular degeneration, a frequent cause of vision loss in the elderly^ref. In the spring of 2003, seed potatoes developed by a University of Frankfurt team were planted in a test field by a research team headed by Gerhard Wenzel from the Technical University of Munich. But as has often been the case in Germany, the test field was destroyed by anti-GM activists, throwing the project a year behind schedule. Last spring, the team installed &euro; 23,000 (USD $30,400) worth of security cameras before planting a fresh test field, which survived until harvest, yielding 2 metric tons of GM potatoes this past autumn. The first batch of potatoes was to have been analyzed by the Federal Research Center of Nutrition and Food in Karlsruhe. But funding for the center and most other project participants ended in October, and the 2 tons of GM potatoes are now in storage. About half a million euros is needed to complete the project, which would include a second test field planted next spring.
• GM rice engineered with human genes to produce lactoferrin and lysozyme : on Mar 29, 2004 the California Department of Food and Agriculture (CDFA) has approved Ventria Bioscience's proposal to grow up to 120 acres in 10 Californian counties away from the state's primary rice fields. In a second blow to Ventria, the USDA on Monday (April 12) decided not to renew the firm's permit to plant its genetically modified rice on a separate 120 acres in northern California, saying that it would be located too close to crops intended for human consumption. The planting season lasts from April to July, and since the standard review process can take months, Ventria went on a fast-track process to avoid delaying plans until next year, among the protests of the Union of Concerned Scientists, the Consumers Union and  The Center for Food Safety
• GM canola which are otherwise exactly like regular canola plants produce seed with oils a) that are modified in average fatty acid carbon chain length, b) that are modified in content of saturated fatty acids (both lower and higher), or c) that contain structured lipids. In principle, although the gene target may not be obvious, the relative amount of lipids compared to other nutrients can be decreased or increased in foods like peanut or soybean. The oil content of some food products might be modified to enhance levels of medium chain triglycerides or to contain "fish oil" fatty acids--without the cost or olfactory disadvantages^ref.
• GM corn plants
• that express the protein trypsinogen
• whose flowers produce a hormone that enables both florets to survive and to be pollinated. The resulting corn kernels contain 2 embryos and a smaller, squashed endosperm. Consequently, the corn packs double the normal amount of protein and fat and half the carbohydrate. It could be used by :
• crowd following low-carbohydrate diets, for whom standard sweetcorn is not allowed
• supplement protein-deficient diets in Africa and South America
• farmers who want high-energy corn for their pigs and chickens
> 70% of US corn is used to feed livestock, 20% to make the corn starches or oils that find their way into numerous foods, and around 5% is milled for dry products such as corn chips. The sowing of GM corn on 30 small farm fields in 7 German states for mostly research purposes has unleashed a political uproar that appears likely to grow even louder in coming weeks. Research coordinators and the 3 seed companies involved—Monsanto, Pioneer Hi-Bred International, and the German-based firm KWS SAAT—did not publicly announce the project until after the GM seeds to resist corn borer were safely in the soil, to protect them from activists. Since announcing the project recently, project coordinators, seed companies, and government officials have steadfastly refused demands from the environmental organization Greenpeace and opposition politicians to reveal locations of the farm fields—26 of which are owned by private farmers, with the remaining 4 fields on public land. A total of about 300 hectares of GM corn had been planted. The prime research goal is to determine if GM corn has any effect on neighboring non-GM corn fields : each GM field is surrounded by 60 m of conventional (non-GM) corn, meaning that in total between 900 and 1000 hectares of land is involved in the project. All corn involved in the project will be used as animal feed, adding a commercial dimension to the project. The seed companies hope to collect scientific evidence that demonstrates that GM corn will not contaminate nearby conventional corn fields, she said, adding that some opponents of the technology in Germany have demanded laws that require GM fields to be up to 2 kilometers from conventional fields. In recent years, environmental activists in Germany have destroyed GM corn fields and harassed participating farmers and their families. To avoid disruptions from anti-GM activists, coordinators and seed companies decided not to reveal privately owned field locations to government officials or other public officials who might be legally required to release the information. Earlier this spring in Germany, agribusiness firm Syngenta had to replant a GM wheat test field damaged by activists. But activists hit the replanted field again on May 4, canceling this year's field test. Keeping the location of GM farm fields secret could be a violation of European GM crop regulations : non-GM farmers have the right to know the location of GM farm fields. The GM planting on 26 of the 30 farm fields was a private matter between the seed companies and participating farmers, who he said had paid full price for the GM corn seeds and who received no other compensation for participating in the project. The seed companies signed contracts prohibiting them from revealing the locations of farm fields without approval of the respective farmers. The seed companies have contributed &euro; 110,000 toward the estimated &euro; 300,000 needed to finance project research. The idea of GM foods in general creates unease in Europe, and for the past 6 years, there has been a moratorium on selling GM foods. But that may soon end, according to a report in the New York Times, which stated that European Commission spokesmen said commissioners were expected to approve an insect-resistant sweet corn developed by Syngenta at its weekly meeting on Wednesday (May 19). The approval would be for human consumption only, allowing imports of the corn from outside the European Union.
• GM cress enriched in w-3 and w-6 polyunsaturated fatty acids (PUFAs)^ref could be consumed directly by humans, or enter the food chain after being fed to animals. British supermarkets have recently begun marketing PUFA-rich chicken eggs, produced by poultry fed on cereal rich in w-3. Poultry and eggs are good sources of w-6; cereals and cold-water fish such as salmon, halibut and sardines yield w-3. PUFA-rich plants could have another important benefit: they might make cows belch less. As food ferments in the animal's stomach, hydrogen is produced, which reacts with carbon to produce methane. The fatty acids help block methane production in cow stomachs, and could help reduce greenhouse gas emissions if used in animal feed. Although the exhaled gas accounts for < 3% of total greenhouse gas emissions in fossil-fuel burning countries, such as Britain and the United States, it makes up nearly 40% of emissions in agricultural New Zealand.
• ... increase resistance to :
• pests and diseases : cotton and maize are the only commercial crops engineered with Bt genes. In 2004 these crops were grown on 22.4 million hectares worldwide. After 8 years of extensive use, there have been no reports of crop failure or insect resistance in the field to genetically modified Bt crops. Still, several insects have developed resistance to Bt toxins in the lab, and recently, cabbage loopers, a moth whose larvae feed on plants in the cabbage family, have shown resistance to Bt sprays in commercial greenhouses. Diamondback moths used in this study have also developed resistance to Bt toxins in the field. In greenhouse studies, the researchers used 3 types of GM broccoli plants: 3 types of plants each expressed a different Bt toxin, and a third, known as a pyramided plant, expressed both toxins. First, the researchers bred moth populations in which a low percent of the moths were resistant to a single Bt toxin. The insects were then released into caged growing areas with either single-gene plants, dual-gene plants or mixed populations and allowed to reproduce for 2 years. They found that the insects living in the greenhouse with single-gene and dual-gene plants housed together damaged all the plants after 26 generations, because more insects developed resistance to the plants' toxins overtime. However, in the same 2-year time frame, all or almost all of the insects died when exposed to pyramided plants alone. It's easier for an insect to develop resistance to a single toxin. If an insect gets a jump on one toxin, then it becomes more rapidly resistant to that same toxin in a dual- gene plant. While single-gene Bt plants are most prevalent, industry trends suggest that pyramided plants may be favored in the future. In the USA, companies introduced dual-gene cotton in 2003, but single-gene varieties remain on the market. Single-gene Bt plants have provided good economic and environmental benefits, but from a resistance management standpoint they are inferior to dual-gene plants. US regulatory agencies should consider discontinuing the use of those single- gene plants as soon as dual-gene plants become available. And industries should be encouraged to create more dual- gene plants^ref
• GM tomatoes
• overexpression of Prf activates the Pto and Fen pathways in a pathogen-independent manner and leads to the activation of systemic acquired resistance (SAR)^ref
• expressed a wide range of randomly chosen sequences of the tripartite tomato spotted wilt virus (TSWV) RNA genome or its complement^ref
• expression of 2 animal antiapoptotic^ref genes (worm ced-9 and human bcl-xL ) can better fend off a molecular parasite of cucumber mosaic virus (CMV) called D satRNA (which when present together with CMV, kills tomatoes) and cold temperatures (no necrotic lesions forming in these plants at 4°C and still able to bear fruit at 7°C, while non-transgenic plants were not)
• CystX, a patented technology owned by Purdue Research Foundation, offers broad-based Hartwig-type resistance to soybean cyst nematode (SCN) in that it prevents the pest from reproducing on the plant's roots. SCN feed on the roots of young plants, which prevents roots from taking up vital nutrients. The result is a drop in yields and economic losses. The best management tool to control SCN populations is to sample fields with a history of problems and rotate resistant varieties based on relative egg counts. Yield loss threshold of SCN begins at 200 eggs per cup of soil. At 2,000 eggs per cup of soil, most susceptible soybean varieties suffer significant economic losses. At 5,000 eggs per cup of soil, growers should avoid growing soybean varieties altogether, even resistant varieties. The technology is a good way of controlling soybean cyst nematode populations but other management practices, such as soil sampling and crop rotation, should not be forgotten.
• virus resistance based on the expression of single-chain Fv fragments (scFvs) against a conserved domain in a plant viral RNA-dependent RNA polymerase (RdRp), a key enzyme in virus replication. The selected scFvs inhibited complementary RNA synthesis of different plant virus RdRps in vitro and virus replication in planta. Moreover, the scFvs also bound to the RdRp of the distantly related hepatitis C virus. T₁ and T₂ progeny of transgenic lines of Nicotiana benthamiana expressing different scFvs either in the cytosol or in the endoplasmic reticulum showed varying degrees of resistance against 4 plant viruses from different genera, 3 of which belong to the Tombusviridae family^ref.
• insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are revolutionizing agriculture. Bt, which had limited use as a foliar insecticide, has become a major insecticide because genes that produce Bt toxins have been engineered into major crops grown on 11.4 million ha worldwide in 2000. Based on the data collected to date, generally these crops have shown positive economic benefits to growers and reduced the use of other insecticides. The potential ecological and human health consequences of Bt plants, including effects on nontarget organisms, food safety, and the development of resistant insect populations, are being compared for Bt plants and alternative insect management strategies. Evolution of resistance to the genetically engineered toxins in the target insects could threaten such gains. Reducing acquisition of resistance by insects can be achieved by :
• the use of crops bearing 2 different toxin genes in the same plant (pyramiding) (by far the most efficient method)
• the use of 2 different transgene plants grown sequentially, in mosaics or by mixing genetically engineered seeds
US Environmental Protection Agency (EPA) guidelines on the planting of non-transgenic “refuges”—areas in which a non-transgenic crop is grown to allow survival of susceptible insects—adjacent to genetically modified (GM) crops could actually increase the risk of pests acquiring resistance to the GM crops. Bacillus thuringiensis (Bt) toxin Cry1-Ab is a benign pesticide that does not affect mammals, birds, or fish : it's a very useful pesticide especially for organic farmers. If growers planted wall-to-wall corn that had Bt bred in, we would expect that insect resistance would evolve rapidly : the use of refuges can slow resistance down considerably. If you plant the non-Bt refuge too close to the Bt crop low to moderate levels of Bt toxin were detectable in ears of non-transgenic maize growing up to 31 m away from the GM crop. At least 43% of the levels found in the transgenic crop were found in the closest planted rows, with levels decreasing with distance, which implies that pollen-mediated transgene flow from Bt maize caused contamination of non-Bt maize refuge plants. Pests eating the kernels of the contaminated refuge plants would not be exposed to the very high level of Bt toxin found in the transgenic crop, but to an intermediate level : insects heterozygous for a resistance gene would not be expected to be as resistant as a homozygote^ref. Yet because they may encounter conditions under which they can survive in the contaminated refuge, the potential risk of resistance developing to an appreciable frequency in the pest population is definitely increased. The current EPA recommendations for the minimum separation distance between the transgenics and the refuge is only about 4 m. The marketing of seed mixes, proposed to be an alternative to managing refuges as distinct areas for crop in developing countries, would mean there will always be a proportion of non-transgenic plants within the crop : this phenomenon which the authors describe in the paper however almost excludes seed mixes as a tactic
• 2 42-d experiments compared the nutritional value of YieldGard Rootworm corn (MON863; experiment 1) and YieldGard Plus corn (MON810 x MON863; experiment 2) to their respective nontransgenic controls and 6 commercial reference corn hybrids when fed to growing broilers. For each experiment, a randomized complete block design was used with 8 dietary treatments in each of 5 replicated blocks of pens. In experiment 1, no differences among diets were observed (P > 0.05) for final live weights and feed conversion. Broilers fed diets containing MON863 corn had adjusted feed conversion similar to the nontransgenic control and the population of control and commercial diets. On a weight basis, there were no differences among diets for chill, fat pad, and thigh, drum, and wing weights. Differences (P < 0.05) between MON863 and commercial corn diets were noted for breast meat, chill and thigh, drum, and wing weights on a percentage of weight basis. No differences were observed (P > 0.05) in the percentage of moisture, protein, and fat in breast meat or thigh meat across treatment diets. In experiment 2, there were no significant differences among diets for all broiler performance and carcass parameters evaluated. Broilers overall performed consistently and had similar carcass yields and meat compositions when fed diets containing MON863 corn or MON810 x MON863 corn as compared with their respective nontransgenic control and commercial diets, supporting a conclusion of similar feeding values among diets^ref.

2 studies were conducted to evaluate the effect of a glyphosate-tolerant (event nk603) and a corn rootworm protected (event MON863) corn hybrid on feed intake and milk production compared with the nontransgenic hybrid and two reference hybrids. In Experiment 1, 16 multiparous Holstein cows were assigned to one of four treatments in replicated 4 x 4 Latin squares with 28-d periods. Diets contained 40% (dry matter [DM] basis) of either 1) glyphosate-tolerant corn silage (GT), 2) nontransgenic control corn silage, or 3) two nontransgenic reference hybrids which are commercially available. Each diet also contained 23% corn grain from the same hybrid that supplied the silage. At ensiling, rapid drying conditions prevailed and the GT hybrid was the last to be harvested which resulted in greater DM content at similar physiological maturity. The 4% fat-corrected milk (FCM) yield and DMI were reduced for cows fed the GT corn diet due to the higher DM content of the GT silage (37.1 vs. 33.2 kg/d and 4.05 vs. 3.61% of BW, respectively). There was no effect of the GT diet on milk composition or efficiency of 4% FCM production that averaged 1.43 kg/kg of DM intake for all diets. In Experiment 2, 16 multiparous Holstein cows were assigned to one of four treatments in replicated 4 x 4 Latin squares with 21-d periods. Diets contained 26.7% (DM basis) corn grain from either 1) corn rootworm protected (event MON863) corn hybrid, 2) nontransgenic control corn hybrid, or 3) the same two nongenetically enhanced reference hybrids used in Experiment 1. The 4% FCM yield (34.8 kg/d) and DM intake (4.06% of BW) were unaffected by diet. Efficiency of FCM production (average 1.32 kg/kg of DMI) was not affected by diet. In summary, these two studies indicated that insertion of a gene for glyphosate tolerance or corn rootworm protection into a corn hybrid did not affect its nutritional value (as measured by efficiency of milk production) for lactating dairy cows compared with conventional corn hybrids^ref.
Supplemental analysis ofselected findings on the rat 90-day feeding study with MON863 maize. ReportMSL-18175 revealed Statistically significant increases in white cell counts (+20.4%), lymphocyte counts (+22.1%), and serum glucose levels (+9-10%), and decreases in reticulocyte counts (-51.8%), kidney weights (-7.1%) and renal tubular mineralization^ref. This study from Monsanto details the further details on subchronic toxicity data for rats fedMON863 requested by the French Competent Authorities. MON863 is a GE Bt corn, whichexpresses the Cry3Bb1 protein. However, it is different to the more common GE Bt (Cry1Ab) corn, as a different Bt protein is produced. The target organisms for the protein in MON863 (Cry3Bb1) iscorn rootworm (Coleopteran (beetles and weevils), Diabrotica sp.), whereas the Cry1Ab protein (asproduced by, e.g. MON810, Bt11, Bt176) is toxic to the European corn borer (Lepidopteran (butterflies and moths), Ostrinia nubilalis). According to the study, 10 groups of 20 genetically standardised rats (specially bred for this type oftesting) were fed feed containing 33 % maize. Four trials were conducted, allowing 2 comparisons were made between rats fed no GM maize and a low dose MON863 (11% of the feed, with another 22 % from conventional maize) and between rats fed no GM maize and a high dose MON863 (33% of the feed, with no conventional maize). Separate control groups were used for each comparison (low - 11% and high – 33%).
• Arabidopsis thaliana has been genetically engineered with a strawberry gene that made the weed produce sweet-smelling chemicals called terpenoids that attracts protective insects. The idea could help plant breeders select for crops that produce a high amount of such chemical smells, reducing the need for pesticides.  Many plants emit scents as a kind of SOS signal to attract predatory mites when attacked by parasites. The terpenoids helped the weed attract the carnivorous mite Phytoseiulus persimilis, a bug that preys on plant parasites such as spider mites and so can act as the plant's bodyguard. The transgenic plants attracted up to twice as many predatory mites as normal Arabidopsis. The researchers say they are now close to identifying a gene that does the same job in cucumbers. This will enable them to use traditional breeding techniques to select varieties of this vegetable that naturally produce stronger scents. Spider mites are a widespread problem. The parasitic mites affect over 300 plant species including cucumbers, cotton, strawberries, beans, apples and roses. They suck out the contents of plant cells, sometimes killing the entire plant. The research team, led by Iris Kappers and Asaph Aharoni of Plant Research International, a research company based at the Wageningen University and Research Centre in the Netherlands, chose the weed Arabidopsis thaliana for their work because it does not normally produce 'SOS' scents to attract these mites. This enabled them to test the function of a gene from strawberries that was thought to code for an enzyme involved in scent production. To create plants that produce enough attractive terpenoids, the team used a trick: they fused a sequence to the gene that directs the resulting enzyme to mitochondria, the energy factories inside the plant's cells. The mitochondria harbour a terpenoid precursor called farnesyl diphosphate (FPP), a substance the enzyme needs to produce the scent compounds. Identifying the equivalent gene in cucumbers isn't as easy as it sounds, because the cucumber has > 10 very similar genes. But once the correct gene is identified, the researchers will aim to select for cucumber variants that express it more strongly. The team also plans to investigate the possibility of introducing such genes into plants that do not normally have them. But they note that plants that naturally express the gene have an advantage over GM crops, in that the protective chemicals are only produced when the plants are infested by the herbivorous parasites, rather than continuously. That would be like you calling the fire brigade all the time. Making plants produce more of the protective scent might cause another problem too: it could make the crops smell. Altering smells as protectants may have to be limited to plants and parts of plants we don't care to consume. That's something we should take into account. But there's always the chance it might make the crops smell better^ref.
• environmentally benign herbicides
• glyphosate : this means that weed-killer can be sprayed later in the growing season, allowing weeds more time to develop so that their rotting matter and seeds can feed birds and creepy crawlies. Glyphosate inhibits the enzyme enolpyruvylshikimate-3-phosphate synthase (EPSPS) in the plant chloroplast-localized pathway that leads to the biosynthesis of aromatic amino acids. Because the target pathway is not present in animals or insects, glyphosate is nontoxic to them. In addition, glyphosate is rapidly broken down in the soil and does not contribute to groundwater contamination. The use of glyphosate tolerant crops has resulted in a dramatic increase in the use of no-till cropping systems, which improves nutrient retention in the soil, increases soil organic matter content, and reduces soil erosion
• Monsanto's Roundup Ready GM crops
• Roundup Ready GM canola : on April 13, 2004, China approved safety certificates for imports until April 6, 2007. China accounts for 30% of Canada's total canola export market. China now joins an extensive list of countries that include Japan, Korea, Taiwan and the Philippines
• Roundup Ready GM wheat : by using Roundup herbicide together with transgenic wheat farmers can boost their yields by 5-15%. On May 10 2004, Monsanto announced that it is discontinuing development of its GM herbicide-resistant wheat. Instead of going forward with the commercialization of the wheat strains, developed with the help of the federal government's Agriculture Canada, Monsanto said it would monitor the progress other biotech companies make in developing traits that would make GM wheat more commercially viable. In 1997, Monsanto began developing wheat that allows farmers to treat fields with Monsanto's Roundup herbicide without damaging the crop. In 2003 alone the Missouri-based company has spent almost US$5 million on the project. But industry groups fear that the hostility to transgenic food, particularly among European consumers, will damage the lucrative export market. In 1999-2000, around half of the 5.5 million tonnes of US wheat exports went to Europe and Japan. Depending on the year, Canada ranks second or third in the world in wheat exports, with about 15 million tons per year of overseas sales. The Wheat Board maintains that most sales would be endangered if importing countries suspected that GMO grains “contaminate” Canadian exports. A University of Manitoba study indicates that the costs of rotating Roundup Ready wheat with Roundup Ready canola would be greater than the benefits, because additional herbicides would have to be introduced to clear away leftover or “volunteer” seeds from previous plantings^ref. The economic benefit of Roundup Ready wheat is much less than that of Roundup Ready canola or soybeans because controlling weeds in wheat fields is relatively easy compared with other GM crops. The University of Saskatchewan is on the verge of commercializing herbicide-resistant wheat developed the old fashioned way—by breeding it over generations^ref. Since 1997, the amount of land devoted to spring wheat in the United States and Canada has declined by 25%. Monsanto says that it will now "realign" its US$500-million annual research and development budget to accelerate development of its transgenic crops to be marketed predominantly in the United States and the developing world :
• Roundup Ready GM cotton
• Roundup Ready GM maize
• in the UK's Farm Scale Evaluations (FSE) 75% of non-GM maize was treated wtih atrazine, this led to the result that herbicide tolerant GM maize allowed more weeds and bugs to thrive in the environment than conventional crops. But around 33% of GM maize's biodiversity benefits will be cut if the common herbicides that were used on the conventional crops (triazines, including atrazine) are no longer approved for use by EU farmers by 2006 because they harm wildlife^ref. The House of Commons Environmental Audit Committee (EAC) has concluded that the triazine ban will invalidate the results of the Farm Scale Evaluations and that the trials should be repeated^ref.
• Roundup Ready GM oilseed rape
• an isoform of Bacillus licheniformis glyphosate N-acetyltransferase (GAT) obtained by directed evolution (11 generations of DNA shuffling) is capable of detoxifying doses of the heavily used herbicide glyphosate nearly 10,000 times higher than the original parents when expressed in Escherichia coli : transgenic plants show no setback in growth and that could help corn, soybeans, and other crops benefit from the herbicide later than before in the growing season without affecting flower and seed development. Globally, Roundup Ready glyphosate tolerance is the number one transgenic trait, occupying most of the 122 million acres of transgenic herbicide-tolerant crops grown in 2003. Currently, Roundup Ready plants do not detoxify glyphosate, but rather overproduce EPSPS to resist lethal glyphosate levels: however, the potential for such enhanced herbicide resistance genes spreading to wild cousins to create superweeds is a serious concern. The transgene proved less effective in crop plants than in bacteria even though the GAT is hyperactive (maybe because the site of action of the glyphosate is EPSPS, which is compartmentalized within plastids, but the authors did not target their enzyme to the chloroplast or because these genes originated from B. licheniformis, a prokaryote which is not efficiently translated in a eukaryotic environment, like BT genes that needed codon optimization), but transgenic corn expressing the best GAT enzymes were tolerant to 6 times the usual lethal field rate of glyphosate, while showing no visual damage or growth setback.
• a 4-year study, called Botanical and Rotational Implications of Genetically Modified Herbicide Tolerance (BRIGHT), involved 5 different agricultural research stations around Britain. The researchers alternated between transgenic sugar beet or winter oilseed rape and conventional wheat or barley on the same plots of land. Farmers use these patterns of crop rotation to preserve nutrients in the soil or disrupt pest life cycles. The scientists found that the number of weed seeds on the plots, a measure of biodiversity, increased over the four years in all cases. This shows, they argue, that although weed plants themselves can be controlled, transgenic crops do not necessarily damage diversity. This partly echoes the message of the British government's Farm Scale Evaluations (FSE), the results of which were published last year, but which gave mixed reports as to whether transgenic crops deplete diversity. BRIGHT also assessed which farming strategies were best at killing weeds. On 50% of study plots, growing oilseed rape that had been engineered to resist the wide-ranging herbicide glyphosate, also called Roundup, gave the lowest weed numbers throughout the four years. Using such rape could make it easier and cheaper for farmers to keep weeds down, the BRIGHT team said at a press conference in London on 29 November. However, it cautions that in other fields, neither conventional nor transgenic crops were consistently better for battling weeds^ref. Transgenic crops could potentially represent a cheap option. Weedkillers for conventional oilseed rape cost £60 (US$113) per hectare, compared with £16 for the Roundup-tolerant crop and £40 for a different transgenic strain that is resistant to the herbicide glufosinate : these figures do not include the costs of seeds (transgenic strains, if approved, are likely to be subject to technology costs set by the manufacturers). The results underline the fact that it is the way the crop is farmed, not the crop itself, that determines its effect on biodiversity.  The BRIGHT team does warn that seeds left over from transgenic sugar beet would be impossible to separate from normal sugar beet grown subsequently on the same land. Farmers would therefore struggle to stay under the 0.9% contamination limit required for a crop to be sold in Europe as 'not genetically modified'. The team hopes that European governments will take notice of their work when deciding how to regulate transgenic crops. Despite a recent European Union directive calling on member states to impose regulations on the crops, France has declared that it will not draft any legislation until 2005 spring. Meanwhile, Germany is embroiled in a dispute between opponents of transgenic crops and advocates of the technology. Opponents have welcomed legislation approved by the German parliament on 26 Nov 2004 that will hold GM farmers liable for any contamination of their non-GM neighbours' fields. But advocates counter that such stringent regulations will foment anti-GM feeling and are unnecessary, citing researchers' claims made at a press conference two days earlier that transgenic corn fields can 'coexist' alongside conventional ones without significant contamination

Web resources :
• Rothamsted Research in Harpenden, UK
• Broom's Barn
• transgenic potato and rice plants were generated by the introduction of human P450 species, CYP1A1, CYP2B6, CYP2C9 and CYP2C19, which metabolized a number of herbicides, insecticides and industrial chemicals. The transgenic potato plant T1977 co-expressing CYP1A1, CYP2B6 and CYP2C19 genes showed remarkable cross-resistance to several herbicides with different structures and modes of action due to metabolism of these herbicides by the P450 species expressed. The transgenic rice plant 2C9-57R2 expressing CYP2C9 gene showed resistance to sulfonylureas, and the transgenic rice plant 2C19-12R1 expressing CYP2C19 gene showed cross-resistance to certain herbicides with different structures and modes of action. These transgenic plants appear to be useful for herbicide resistance as well as phytoremediation of environmental contaminants. In the first modification of its kind, Japanese researchers at the National Institute of Agrobiological Sciences in Tsukuba have inserted the CYP2B6 gene from the human liver into rice to enable it to digest 13 different herbicides, so that they are not harmed when fields are sprayed to kill weeds : this would mean that weeds could be kept down by constantly changing the chemicals used^ref.
• herbicide-resistant plants can be engineered by designing an herbicide and expressing a catalytic antibody that destroys the herbicide in planta. First, a carbamate herbicide that can be catalytically destroyed by the aldolase antibody 38C2 was devloped. This compound has herbicidal activity on all 3 plant species tested. Second, the light chain and half of the heavy chain (Fab) of the catalytic antibody were targeted to the endoplasmic reticulum in 2 classes of Arabidopsis thaliana transformants. Third, the 2 transgenic plants were crossed to produce an herbicide-resistant F₁ hybrid. The in vitro catalytic activity of the protein from F₁ hybrids corroborates that catalytic antibodies can be constitutively expressed in transgenic plants, and that they can confer a unique trait^ref.
• rice : a new GM variety is heavy with seeds, but not so tall that it will fall over in the rain. The work is expected to help increase yields of rice, which is the staple grain for the majority of the world's population. The many-seeded variety is less likely than others to bend double in high winds or rain, and this keeps the tops out of the water and reduces their chance of rotting. The new plant was made possible through a mix of modern and old-fashioned techniques. First, the recent availability of the rice genome allowed the researchers to investigate areas of the plant's DNA that influence productivity. A gene in one particular area of DNA, for example, produces an enzyme that degrades a seed-production hormone (cytokinin oxidase). If this gene isn't very active, and produces only a small amount of the enzyme, then the hormone builds up and encourages the plant to pump out more seeds. This was confirmed by genetically altering individual plants to express this gene to varying degrees. Armed with this knowledge, the team then produced an improved variety of rice the old fashioned way - through traditional breeding. They selected 2 breeds: one well known for producing lots of seeds, and one that tends to be short. They then screened successive generations of rice plants for the areas of DNA they knew to influence these traits, in order to select the best plants to cross with each other^ref. The researchers stress that although their plants are not genetically engineered, genetic engineering may be a useful tool to improve crop yields. Their approach is one of the powerful methods. However it is not all-powerful. Genetic engineering might one day be employed to move useful areas of DNA from rice into other crops, such as wheat and soy. The variety makes 25% more seeds than the popular Koshihikari type, which was one of its parents. Such high-yield plants may be in the fields in the very near future. Rice breeders could use the information about which portions of DNA affect productivity immediately.
In 1996, the first year  were commercially available, about 4.3 million acres were under biotechnology cultivation. Genetically engineered crop plantings increased 15% in 2003 despite continued consumer resistance in Europe and elsewhere, according to a group that promotes use of the technology in poor countries : 7 million farmers in 18 countries grew engineered crops on 167.2 million acres last year, compared to 145 million acres in 2002. In all, some 18% of the world's 3.7 billion acres (i.e. > 67 million hectares) under food-crop cultivation are biotech. The leading growers of biotech crops are the United States, Argentina, Canada, China, Brazil, and South Africa. These countries account for 99% of the global biotech crop area. The greatest increases in 2003 were in China and South Africa, which both planted 33% more biotech hectares than in 2002. The remaining four places in the top 10 biotech crop–cultivating countries are taken by Australia, India, Romania, and Uruguay. In the most significant change in Europe, Spanish biotech cultivation grew 33% due to increased production of genetically engineered maize. No new biotech crops have been approved for growth in the European Union since the de facto moratorium began in 1998. The ISAAA predicts that within the next 5 years, 10 million farmers in 25 or more countries will plant 100 million hectares of biotech crops. It expects the global market value of biotech crops to increase from approximately $4.5 billion this year to $5 billion or more by 2005^ref. 60% of soya bean products collected from Taipei City's supermarkets, convenience stores, food stands and night markets in Taipei are GM, but none of them bear clear labeling : some of the samples were even found to contain > 80% of GM components.
Unintended releases of GM crops in the USA :
• in 2000 a Bt corn known as StarLink was inadvertently planted for human consumption. Because of possible allergic reactions, StarLink had been approved for use only in animal feed. Recall of StarLink corn cost the food industry an estimated US$1 billion and lent impetus to global concerns about the safety of GM food.
• 2001-2004 : a strain of GM corn that does not have regulatory approval has been distributed by accident over the past 4 years : Syngenta, one of the world's largest agricultural biotechnology companies, revealed the mistake to US regulators at the end of 2004. Although the crop is believed to be safe, the fact that it was sold for years by accident raises serious questions about how carefully biotechnology firms are controlling their activities. The corn (maize) was modified with a gene from the soil bacterium Bacillus thuringiensis (Bt), which is inserted into the crop to act as a pesticide. Syngenta has approval to sell a variety of the transgenic crop called Bt11, which has been used successfully for many years in the USA and elsewhere. The strain has been approved for consumption in the European Union, for example, and may be one of the first food crops approved for cultivation there. But between 2001 and 2004, Syngenta inadvertently produced and distributed several hundred tonnes of Bt10 corn - a different genetic modification that has not been approved. Since the release was discovered in late 2004, US government scientists have assessed the Bt10 corn - which differs from Bt11 by only a handful of nucleotides on a section of the gene that does not code for the protein toxin - and have concluded that it is safe to eat and poses no environmental threat. What makes this somewhat unique is that Bt10 and Bt11 are physically identical and the proteins are identical. Syngenta promptly reported the mistake to regulators after the discovery : this shows that the system is working as it should do. Company officials also note that the release was relatively small. About 150 km² of the crop was planted over the 4 years, which is 0.01% of all corn planted in the USA during that period. As Bt corn seed has to be bought every year, rather than being gathered from the previous year's crop, the problem should not escalate. The release reflects the absence of a thorough monitoring system for GM products in the US food supply : this will raise questions in the minds of countries that import food from the USA about whether they have adequate controls in place. It will provide ammunition for critics of GM food - and it may provide incentives for countries to look at non-GM varieties. Syngenta discovered the mistake when one of its seed manufacturers, which was attempting to use the corn seeds in plant-breeding experiments, informed it that the seed was not Bt11. Syngenta then told the Environmental Protection Agency (EPA), the Food and Drug Administration and the US Department of Agriculture (USDA), which are jointly responsible for approving GM crops. Regulators and the company have since been involved in months of discussions over what should be done about the error, and how and when information should be released to the public. White House officials have also been involved in these sensitive talks, partly because the USA and the European Union are locked in a fierce trade dispute over whether tough European rules to trace the flow of GM crops are scientifically necessary. Syngenta officials declined to list the countries that accidentally received the Bt10 seed. The EPA says that it is investigating whether the Federal Insecticide, Fungicide, and Rodenticide Act has been breached, and that the USDA is looking at possible violations of the Plant Protection Act
See also risks for human healthand concerns for loss of biodiversity.
Web resources :
• Nature Focus : GM crops
• Technology Platform on Plant Genomics and Biotechnology by the European Commission
• European Plant Science Organisation (EPSO)
• European Association for BioIndustries (EuropaBio)
• Plants for the future: a European vision for plant biotechnology towards 2025
• Committee of Agricultural Organisations in the European Union (COPA)
• European Consumers' Organisation (BEUC)
Web resources :
• Advisory Committee on Releases to the Environment (ACRE), UK
• GM at Department for Environment, Food and Rural Affairs (DEFRA), UK
• International Service for the Acquisition of Agri-biotech Applications (ISAAA)
• Friends of the Earth Europe
• the effects of global warming on crops are complex. Although increased CO₂ - a nutrient for plants - generally stimulates growth, climate change is expected to alter everything from the amount of nitrogen in the soil to the amount of rain. Although ozone slows plant growth by 20%, the beneficial effect of the CO₂ more than compensates for this effect, allowing an increase in soy yields of 13% by 2050 (US farmers currently plant about 150 million acres of soybean a year). Climate change is likely to increase summer temperatures and cut rainfall in the mid-west, both of which will hit yields. Overall, climate change will bring about slight increases. Heat-sensitive cameras show that the tops of the experimental plots are about 2.5 °C higher than surrounding crops, probably because the leaves absorb less water when the pores narrow. If the plants increase their temperature and pull less water out of the atmosphere, they could influence rainfall patterns right across the USA
• kudzu (Pueraria montana var. lobata) is an invasive plant that is being subjected to aggressive attempts to eradicate it. Kudzu-infested states are the following: AR, CT, DC, DE, FL, GA, IL, IN, KY, MD, MO, MS, NC, ND, NJ, OR, PA, SC, TN, TX, VA, and WV^ref. It is obvious that a large area of the USA is infested with kudzu, and I suspect that many farmers are concerned about native plants being crowded out. The 3rd and 4th links deal with a map of kudzu-infested states and links to kudzu sites^{ref1, ref2, ref3, ref4, ref5}. There are a number of management options to control kudzu. Herbicides, grazing, prescribed burning, and disk harrowing can be used as eradication or containment treatments. Kudzu patches can be eradicated with persistent treatments or they can be contained and managed with other treatment options. For eradication, every kudzu plant in and around a patch must be killed or the spread from any surviving plants can make all prior efforts and investments useless. This means that all landowners sharing a patch must treat together. Landowners often find herbicide applications the easiest means for eradication and containment, but herbicides should only be applied according to exact label instructions, requirements, and prohibitions. Read, understand, and follow herbicide labels completely before and during use. Commercial applicators can be contracted to perform such applications, but the landowner must give directions in most cases to be successful and cost-effective. On open patches on level ground, most herbicides will brown kudzu leaves and vines, but few will result in root control. Tordon 101 Mixture and Tordon K (see table at URL above for common names and manufacturers) are the most cost-effective herbicides of the 25 tested on kudzu over an 8-year period. Both herbicides are applied as sprays to the foliage and then must be washed from the leaves by rainfall to the roots for uptake. Both of these are restricted-use herbicides because they are very water-soluble and can leach through sandy soils into streams and ground water, nearby trees with roots in the area can be killed or injured, many crops are very sensitive to these herbicides, and they are relatively persistent and may injure or kill plants introduced into the area too soon. Because of this, a permit for purchase is issued by your county agent or state regulatory agency in the USA after proper use procedures are reviewed. Kudzu is a legume, and Tordon herbicides are very effective on leguminous plants. With respect to biological control of kudzu, there is some information. 6 fungal pathogens have been identified by collaborators at South China Agricultural University (Jiang et al., 2000). One Phycomycete (Synchytrium puerariae P. Henning) Miyabe (Chytridiaceae) may hold some potential as a biological control agent. This pathogen has been reported on several Pueraria species from Japan, New Guinea, Java, the Philippines, India, China, and California (specimen at U.S. National Fungus Collection, Beltsville, Maryland) (Karling, 1964), but further investigations are necessary to confirm its host specificity. Preliminary host range testing with soybean and peanut were begun in the summer of 2000. As far as possible, initial host testing will be conducted in China, where quarantine facilities are not required for these native insects. In the later screening stages, extensive testing of American plants and crops will be conducted in U.S. quarantine facilities to ensure host specificity before any insect can be released.

Biological control using pathogens native to the USA :
• Pseudomonas syringae pv. phaseolicola : this bacterium is the causal agent of "halo blight" of bean and kudzu, causing a small necrotic leafspot surrounded by a bright halo of chlorotic tissue. Zidak and Backman (1996) reported that the bacterium could kill 8- to 10-week-old kudzu seedlings, but produced few, if any, secondary infections under fairly dry conditions in the field
• Myrothecium verrucaria (Moniliales) : this fungus has a fairly broad host range. Yang and Jong (1995) reported good control of leafy spurge and 8 other Euphorbia species using isolates of this fungus. Walker and Tilley found that an isolate from sicklepod (_Senna obtusifolia_ [L.] Irwin and Barneby) affected a number of important crops, ornamentals, and weeds, representing 6 different families. Sprays directed to soybean stems and lower leaves did not reduce soybean dry weight (Walker and Tilley, 1997). It was patented for sicklepod biocontrol, and, although originally isolated from sicklepod, it is even more effective against kudzu.  2 years of testing in Mississippi demonstrated that the fungus attacks leaves and stems, with greater activity at 25 to 40 deg C than at 10 to 20 deg C. Field tests demonstrated that 95 to 100% control could be achieved within 14 days of inoculation by girdling runner stems with this fungus, which produces asexual spores in a sporodochium, with a matrix suggesting dispersal by splashing rain. In inoculation studies, a surfactant was needed for good infection (Boyette, 2000). A patent for kudzu control has been applied for.
• Colletotrichum gloeosporiodes (Sphaeriales) : a strain of this widely-distributed pathogen was isolated from kudzu in Houston County, Georgia, and its virulence was increased by repeated selection for growth on Czapek Dox medium amended with kudzu extract. Field inoculations showed a synergistic effect was achieved by inoculations of spores together with 20% of the recommended rate of dicamba. The fungus attacks both leaves and vines, and produces asexual spores in a pycnidium (Farris and Reilly, 2000)^{ref1, ref2}
• Web resources:
• Bionatics : digital tree simulation
• UBC Botanical Garden
• Journals
• The Plant Cell [free at PubMedCentral : archive starts with Vol. 12(12); 2000]
• Plant Physiology[free at PubMedCentral : archive starts with Vol. 116(1); 1998]
• New Phytologist
• Bibliography
• Bremer, K. 1994. Asteraceae: Cladistics and Classification. Timber Press.
• Dressler, R.L. 1993. Phylogeny and Classification of the Orchid Family. Dioscorides Press.
• Griffiths, M. 1994. Index of Garden Plants. Timber Press.
• Mabberly, D.J. The Plant-Book. 1987. Cambridge University Press.
• Staff of the Liberty Hyde Bailey Hortorium. 1976. Hortus Third. MacMillan Publ.
• Trehane, P. 1989. Index Hortensis. Vol. 1: Perennials. Quarterjack Publishing.
• Greuter, W. et al. 1994. The International Code of Botanical Nomenclature (Tokyo Code). Koeltz Scientific Books.
• PQR (4.3 - June 2004) is a database on geographical distribution and host plants of pests listed by EPPO and the European Union. It also contains data on many other quarantine pests of interest to other regions of the world, and information about NPPOs. This new version contains updated information on quarantine pests and is provided on CD-Rom^ref

Copyright © 2001-2005 Daniele Focosi. All rights reserved | Terms of use  | Legal notices
About this site  |  Site map  |  Acknowledgements | Open forum  |  Tell a friend about this site  |  Current link partners
 Abbreviations and acronyms  |  Medical terminology  |  Add a link  |  Translate this site into your favourite language  |  Softwares

---