Wheat streak mosaic (WSM), caused by Wheat Streak Mosaic Virus
(WSMV), is a common disease in many wheat growing regions in the U.S. and world. This is one of the few wheat diseases that can cause a total loss, although losses typically are much less. WSMV survives only in living plants: wheat, corn, and many other grasses. WSMV is transmitted by the wheat curl mite (Aceria tosichella
), which also transmits the High Plains Virus;
both viruses can be present in affected plants.
WSM symptoms vary based on the virus strain, the wheat variety, how old the plant was when it was infected, and weather conditions. Typically, infected plants are stunted, may be splayed on the ground, and do not tiller as well as unaffected plants. Foliar symptoms include a light green to yellow mottled mosaic; more advanced infections may develop yellow streaks running parallel to the veins. Tightly rolled and trapped leaves may also be evident and are the result of feeding damage that occurs when large numbers of wheat curl mites are present.