Barley Yellow Dwarf Virus: Treating Yellow Dwarf Virus Of Barley Plants
By: Mary H. Dyer, Credentialed Garden Writer
Barley yellow dwarf virus is a destructive viral disease that affects grain plants around the world. In the United States, yellow dwarf virus affects primarily wheat, barley, rice, corn and oats, often reducing yield by up to 25 percent. Read on to learn about barley yellow dwarf control.
Signs of Yellow Dwarf Virus of Barley Crops
Symptoms of barley yellow dwarf virus vary depending on the crop, but the primary signs of disease are stunted growth and discoloration. Older leaves of wheat plants may turn yellow or red, while corn turns purple, red or yellow. Diseased rice plants turn orange or yellow, and barley with yellow dwarf becomes a distinctive shade of bright, golden yellow.
Yellow dwarf virus of barley can also cause water-soaked areas on the leaves. The disease is often mistaken for mosaic or other plant diseases, and the symptoms often mimic nutritional problems or environmental stress. Stunting may be mild or significant. Kernels may be small or unfilled.
Causes of Barley with Yellow Dwarf
Yellow dwarf virus of barley is spread by certain types of winged aphids. The disease can be localized, or the aphids can travel from field to field with the help of strong wind. Symptoms generally show up a couple of weeks after an aphid infestation. Barley yellow dwarf virus is favored by warm falls followed by mild winters.
Barley Yellow Dwarf Control
There’s not much you can do about treating barley yellow dwarf virus, but the following tips may help:
It’s always a good idea to start with disease-resistant seeds, but resistance varies depending on the plant. Keep weeds and wild grasses in check, along with volunteer wheat, barley or oats. Grassy plants may harbor the virus.
Timing is critical. Plant spring cereal crops as early as possible to get ahead of aphid infestations. On the other hand, fall seeding should be delayed until the aphid population declines. Your local cooperative extension is the best source of information regarding optimal planting dates.
Insecticides aren’t recommended for control of aphids, and are generally not economical unless the infestation is extremely severe. Although insecticides have proven to be of little use, they will decimate populations of lady beetles and other natural predators, thus allowing aphids to thrive unchallenged. Systemic insecticides may help limit spread if applied when aphids are feeding on the plant. Unfortunately, fungicides have absolutely no effect on barley yellow dwarf virus.
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Barley Yellow Dwarf Viruses (Luteoviridae)☆
Barley yellow dwarf disease (BYD) is one of the most economically important virus diseases of cereals, and is found in almost every grain growing region in the world. Widespread BYD outbreaks in cereals were noted in the United States in 1907 and 1949. However, it was not until 1951 that a virus was proposed as the cause of the disease. The causal agents of BYD are obligately transmitted by aphids, which probably delayed the initial classification of BYD as a virus disease. Subsequently, BYD was shown to be caused by three species of Barley yellow dwarf virus (BYDV), a species of Cereal yellow dwarf virus (CYDV) and a species of Maize yellow dwarf virus (MYDV). Depending on the virulence of the virus strain, infection may contribute to winter kill in regions with harsh winters, induce plant stunting, inhibit root growth, reduce or prevent heading, or increase plant susceptibility to opportunistic pathogens and other stresses. Yield losses to wheat in the United States alone are estimated at 1%–3% annually, exceeding 30% in certain regions in epidemic years. The effects of BYD in barley and oats typically are more severe than in maize and wheat sometimes resulting in complete crop losses. The existence of multiple strains and species of viruses that are transmitted in strain-specific manner made the viruses model systems to study interactions between viruses and aphid vectors in the circulative transmission of plant viruses. In addition, the compact genomes of the viruses have provided useful insights into the manipulation of host translation machinery by RNA viruses.
Transmission is in a circulative, non-propagative manner by specific aphid vectors. Viruses are acquired by phloem feeding, enter the hemocoel of the aphid via the hindgut (e.g., BYDV-PAV) or posterior midgut (e.g., PLRV) by a receptor mediated transport process, circulate in the hemolymph and enter the accessory salivary gland by a second receptor mediated transport event. Inoculation results from introduction of viruliferous saliva into the phloem tissues via the salivary duct during aphid feeding. PEMV-1 is readily transmitted mechanically, a property dependent on its multiplication in cells co-infected with PEMV-2 (Umbravirus).
Barley Yellow Dwarf Virus in Wheat
Barley Yellow Dwarf Virus
(cereal yellow dwarf, yellow dwarf, red lead)
Barley Yellow Dwarf Virus is reported to be the most widely distributed and most destructive virus disease of cereals.
Damage by BYDV varies with cultivar used, virus strain, time of infection, and environmental conditions. Infections are most widespead in the spring in areas where aphids overwinter in winter wheat, autumn infections are most damaging.
Primary symptoms of Barley Yellow Dwarf virus include plant stunting, reduced tillering, and yellowing and purpling
Barley yellow dwarf yellowing symptoms
of tips and margins of upper leaves. Leaf discoloration usually starts along the leaf margins and moves toward the leaf base and midrib.
Infected plants frequently occur in small, random groups which are evident as saucer-shaped depressions of yellow plants in otherwise green fields. Large portions of fields or entire fields can be affected in severe cases.
Virus-infected plants generally do not follow a row pattern. When affected plants do follow row patterns or appear to be associated with high or low areas of the field, look for environmental causes, nutritional problems or chemical injury. Symptoms generally take 2-4 weeks to develop, but at higher temperatures may not even develop. Definitive diagnosis of Barley Yellow Dwarf requires laboratory tests such as the ELISA (enzyme-linked immunosorbent assay) test.
The Barley Yellow Dwarf virus is transmitted to wheat by several species of cereal aphids. The aphid vectors the disease from one plant to another. In Kentucky, the primary aphid transmitting BYDV is the oat bird-cherry aphid. Plant discoloration and stunting is evidence of transmission of the virus in the fall to seedling. Plant discoloration, but no stunting, is evidence of spring transmission of BYVD by the aphid vectors. Spring infections usually become evident anytime from flag leaf emergence through head emergence. Fall infections, on the other hand, are frequently noted as early as crop greenup in the spring. Serious yield loss is likely to occur where stunted and discolored plants are widely distributed in a field. Plants showing these symptoms may yield about 25 - 50% less than their non-stunted counterparts.
The best control for potential fall infections of BYVD is to avoid planting wheat before the Hessian fly-free date, mid October in Kentucky (avoid late-summer, early autumn seeding). Delayed planting will have little effect on spring infections. Plant wheat varieties with at least some tolerance or resistance to BYDV. Highly resistant or tolerant varieties are not yet available. Insecticide treatments aimed at controlling the aphids which transmit BYVD are inconsistent and unpredictable, and are often not recommended. Aphidicide treatments made to wheat already showing symptoms of BYDV will be of no value.