Leaf blotches that are yellow, orange, or red will develop until entire leaves are involved. Plants along the edges of fields are usually affected first. Severely affected plants produce little or no grain. The virus can infect all cereal grains, corn, and grass weeds. This disease is spread by several species of aphids, which are more active under warm conditions in the late spring and summer.
Plants infected in the seedling stage are the most severely damaged.
Average planting date for oats in Iowa is April 20. If oats are planted in a cold, wet soil, they will be affected by seedling blights, but if the soil is dry enough, earlier planting will help reduce losses to crown rust and barley yellow dwarf. Some oat cultivars also have resistance to these diseases, and it is advisable to plant these cultivars in Iowa, because both diseases are potentially severe each year. See the Iowa Crop Performance Test - Oats for further information on resistance ratings to both diseases. This information subject to a usage policy .