Symptoms appear in late February or March as stunted yellow plants. Upon close examination, leaves usually show a yellow-green mosaic pattern. In some fields disease will be limited to wet areas. However, under Arkansas conditions, the entire field may be affected. Both viruses survive in association with their fungus vector.
Infection usually occurs in the fall during periods of high soil moisture.
The most severe symptoms occur when seedlings are infected shortly after emergence. The viruses multiply in plants during cool weather. Optimum temperature is about 60 F Virus multiplication stops at temperatures above 70 F. Usually infected plants will green up by the end of March as temperatures increase. However, infected plants usually have fewer tillers, are shorter and yield less than healthy plants. Resistant varieties are the only means of control.