It is serious in very wet springs. By far the most important virus disease of barley is barley yellow dwarf virus. This disease is prevalent in Missouri on wheat, oats and many forage grasses. But barley is especially susceptible, and BYDV can be devastating to barley survival. Infected plants are often stunted and turn a golden yellow.
Heads fill poorly.
About a dozen aphid species transmit the virus. Oatbird cherry aphid, corn leaf aphid and greenbug are common vectors in Missouri. Fall infections of BYDV are much more serious than spring infections. Yield reductions of up to 15 percent from fall infections result from fewer heads and smaller head size. Loose smut replaces all the kernels of the head with masses of smut spores that are released at the time of flowering, causing new infection in the field.