Leaves of plants infected with wheat streak mosaic have a bright yellow streaking. Symptoms are often most severe near the leaf tip. The virus that causes wheat streak mosaic survives in volunteer wheat and is spread by wheat curl mites. The disease is often most severe in areas of a field that are closest to these sources of the disease and mites. Commonly, plants infected with wheat streak mosaic also are infected with High Plains disease and Triticum mosaic. The symptoms of these diseases are nearly identical. Disease severity is greater when plants are infected by more than one virus.