The Wheat Curl Mite is able to feed on many different plants including wheat, corn, and other grasses such as barnyard grass. Wheat streak mosaic is favored by conditions under which more volunteer wheat is present because it allows both the wheat curl mite and virus to reproduce, and by longer and warmer fall temperatures that allow the mite to spread the virus from the volunteer to the newly planted winter wheat crop. Wheat curl mites spread by wind and consequently, wheat streak mosaic typically starts along field borders as mites move into the field. Wheat curl mite require living plants to survive, so they move from maturing grain crops or weedy hosts to nearby green hosts. Because of this behavior the virus is more common in areas where spring and winter wheat overlap, a situation known as the “green-bridge.” Early planted winter wheat is particularly susceptible as the mite can move in from late-maturing crops and volunteer plants or grassy weeds into the newly planted crop as it emerges.
Disrupting the green-bridge to prevent mites moving into the emerging crop is critical to controlling wheat streak mosaic. Destroying volunteer wheat and other grain or grass crops with tillage or herbicides at least 2 weeks prior to planting is very effective. Grassy weeds should likewise be controlled prior to planting. Avoiding very early seeding and delaying a week or two later than is usual for the area is also effective. There are no chemical insecticides, either foliar or seed treatments, that are recommended for control.
To confirm WSMV a sample must be tested for the virus. The WSU Plant Pest Diagnostic Clinic is available to test plants for WSMV as well as other wheat viruses. To submit a sample visit the WSU Plant Pest Diagnostic Clinic website.