Written with contributions by Emmanuel Byamukama, former SDSU Extension Plant Pathologist, and Marie Langham.
Wheat streak mosaic disease caused by Wheat streak mosaic virus (WSMV) is an economically important disease of wheat in the Great Plains. This virus is especially problematic in the Great Plains mainly due to the availability of native grasses which serve as good hosts for the virus as well as the vector, the wheat curl mite (WCM). First reported in Nebraska in 1922, WSMV is now widely spread throughout the wheat-producing areas in the United States. In South Dakota, WSMV can cause significant yield losses especially when infections occur in the fall.