(BYDV) is a member of the luteovirus genus and is closely related to cereal yellow dwarf virus. It is the most common viral disease of cereal plants and has a serious economic impact, reducing yields from infected crops by 2%–79%. Th e virus aff ects barley, wheat, oats, maize, and rice, and also infects wild grasses, which serve as year-round reservoirs of the virus and can trigger new outbreaks. It is transmitted through the saliva of aphids, which feed by piercing the phloem (vascular tissue) of the plant. Symptoms of the disease include yellowing of leaves, reduced height, reduced root growth, delayed heading, and yield reduction. Younger plants are most susceptible, and the only current mechanism of control is through application of insecticides to remove aphids from the crop.

Studies show that BYDV infection results in a reduction of kernel plumpness and higher proportion of thin seeds. In brewing practice, this can lead to higher total protein, higher wort protein, and lower extract. Th e virus is found worldwide, with diff erent species prevalent in diff erent areas. Transgenic plants expressing resistance genes have been produced under research conditions and show sustained resistance to viral infection.