BYDV is carried to small grains by several species of aphids, including greenbugs, English grain aphids, and oat birdcherry aphids. In Kansas, the vector-nonspecific PAV strain is most common. The source of aphids may be local, or aphids may migrate great distances from southern states. Infection may take place in the fall or the spring. Random samples taken along a transect give a more accurate percentage.
Losses also depend strongly on time of infection.
If plants are infected after heading, losses are minimal. The primary control is to avoid early planting. Early planting allows maximum time for aphids to infect the plants in the fall. Plant after the Hessian fly-free date to minimize the risk of BYD infection. The Hessian fly-free date works well against BYD unless there is a very mild late fall which allows aphids to survive longer than usual.