Barley Yellow Dwarf Virus

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Winter barley infected with barley yellow dwarf virus.  Plants along center pivot tire tracks are often the most severely infected.  Photo by Juliet Marshall.

New UI Extension publication on Barley Yellow Dwarf Virus available

Barley yellow dwarf (BYD) is a serious and widely occurring viral disease of cereal crops and other grasses.  Spread by aphids that colonize grassy host plants like wheat, barley, oats, and corn, BYD may affect both winter and spring cereals, but often is a greater concern in winter crops. 

Several species of aphids may carry and transmit the BYD virus, including bird cherry-oat aphid and English grain aphid.  Greenbug and corn leaf aphid also may transmit the virus, but they are less efficient vectors than bird cherry-oat and English grain aphids.

Juliet Marshall, UI Extension Cereals Specialist, reported that some fields of winter barley and winter wheat with BYD virus symptoms were evident this spring. She noted that “BYD virus typically is a problem in areas where corn production is highest, due to the fact the corn is a ‘silent host’ for BYD virus - in other words, corn hosts the virus but does not show symptoms or yield declines. Aphids coming off of maturing corn in the fall will then fly to emerging wheat and barley fields, carrying the virus with them”. 

Symptom expression of BYD virus in wheat and barley can vary widely.  The most characteristic symptom of the PAV strain of BYD virus is yellowing and/or reddening of leaves starting at the leaf tip and moving toward the base and inward from the margins.  BYD-affected plants exhibit stunting of both foliar and root tissues.  Affected plants produce relatively small, irregular heads; seed size is also reduced, resulting in low test weight.

Yield loss due to BYD can approach 70 to 100% when early fall infections occur immediately following winter wheat emergence.  However, such high yield losses are unusual.  Yield reductions of 10 to 20% are more common, so it often is economically feasible to maintain the current crop rather than plow it under and replant.

Although there are no known BYD virus resistant varieties among Pacific Northwest wheat cultivars, information on cultural and chemical practices that reduce the risk of BYD virus can be found in the new UI Extension publication, Barley Yellow Dwarf Virus in Idaho Cereal Crops, CIS #1210, available at


Dr. Juliet Marshall, UI Extension Cereals Specialist, Idaho Falls, (208) 529-8376(208) 529-8376,

Dr. Arash Rashed, Entomology Research and Extension Specialist, Aberdeen, (208) 397-4181(208) 397-4181,