If winter wheat is sown near unharvested spring wheat, infected mites can be blown onto winter wheat completing the disease cycle. Development of this disease depends on the population of mites, the presence of virus-infected wheat plants, and sufficient moisture for good plant growth and rapid mite reproduction. Severe outbreaks occur when there is a build-up of mites and virus on volunteer spring wheat in fields next to winter wheat that was planted early. Symptoms of Damage Winter wheat rarely shows symptoms until spring. These symptoms appear on the leaves as dashes, streaks or yellow stripes parallel to the veins.
Leaves become increasingly mottled until the green areas disappear and the leaves die.
Wheat spot mosaic virus, which is similar to wheat streak mosaic virus, is spread by mites, has a comparable life cycle, and may sometimes be present in winter wheat. Wheat infected at an early tillering stage stops growing and produces few to no heads. Infection at late tillering to early jointing stages results in head formation but the flowers may be sterile. With late season infection during jointing to boot stage, the flowers are fertile but kernels are reduced in size. Fall-infected winter wheat plants do not produce grain the following season.