Barley yellow dwarf
Area of impact: Leaf
Description: Tips and margins of upper leaves turn yellow and purple; discoloration normally starts on the margins and moves inward toward the leaf base. Other symptoms include stunted growth and reduced tillering. Plants will usually be infected in small random groups which will appear as saucer-shaped depressions of yellowed plants. In severe cases entire fields can be infected.
Pathogen involved: Virus
Timing/Conditions: Infection occurs in spring or fall and is transmitted by cereal aphids. Plant discoloration with stunting are signs of fall infection; discoloration without stunting indicates a spring infection.
Contributing factors: At high temperatures symptoms might not develop.
Management practices: Plant resistant varieties. To avoid fall infections try to plant after the Hessian fly–free date. Insecticides for controlling the relevant aphids are inconsistent and not recommended.