The incidence and severity of this disease depends on the environment, vector survival, distribution and frequency of volunteer wheat plants which serve as a source of virus and haven for vector, and wheat cultivar susceptibility. However, the field pattern of wheat streak mosaic is related to the distribution and activity of the vector, the wheat curl mite, Aceria tulipae .
Leaves appear upright while the margins roll inward.
Wheat streak mosaic symptoms tend to become more severe as the weather warms, and severely affected plants may produce sterile heads or die prematurely. The wheat curl mite, Aceria tulipae , is the only means by which the virus is transmitted in nature. This mite thrives in lush young growth of wheat and other grasses. Thus, volunteer wheat in soybean fields harvested in the fall is a particularly good breeding ground for this mite and the virus. The wheat curl mite is approximately 0.03 mm long.