Wheat streak mosaic complex was active in Kansas again during the 2026 season. Delayed harvest and frequent rainfall have led to high levels of volunteer wheat across the state. Now is a critical time to plan for wheat streak complex mitigation. In this article, we discuss key actions producers can take as they head into 2026 planting.
Overview of Wheat Streak Mosaic Complex - wheat streak mosaic complex consists of a complex of three viruses: wheat streak mosaic virus, Triticum mosaic virus, and High Plains wheat mosaic virus. When two or more of these viruses are present in the same field, yield losses can be synergistic. As a reminder, the wheat streak mosaic complex of viruses is vectored by the tiny wheat curl mite. We know that mite populations in the state were high again at the close of the 2026 season. Research has reported that up to 500 curl mites can be found on a single healthy wheat head, which can conservatively translate to more than 1 billion mites per acre at the end of the year.
Wheat curl mites can only survive ~4 days without a living host, so when the wheat crop dries down, mites will work their way to the top of plants and assume an “upright posture” to help them disperse by wind. Curl mites don’t fly, and they walk very slowly, so dispersal by wind is their only way to move from field to field. The period when mites are migrating off the mature wheat crop has been referred to as the “mite rain” period, as billions of mites are showering down in the landscape. When conditions are very windy, mites can be passively dispersed more than 10 miles. The highest risk place for curl mites to survive the summer is volunteer wheat that is present at or around harvest.
Conditions that favor grain shattering, such as preharvest hail or harvest delays due to windy storms (as in much of the 2026 Kansas wheat harvest), can increase the presence of preharvest volunteers. If mites are allowed to survive on this volunteer wheat or alternative hosts until the fall-established wheat crop is planted, there is a high likelihood of another outbreak in 2027. As a reminder, there are no recommended insecticides for wheat curl mite management, it is a mite, not an insect.
This article is the first in a multi-week series on wheat streak mosaic complex management. Next week’s article will address how essential volunteer wheat control will be in 2026 to set our wheat crops up for a successful harvest in 2027.
Stacy Campbell is a Crop Production Extension agent in the Cottonwood District (which includes Barton and Ellis counties) for K-State Extension. You can contact him by e-mail at scampbel@ksu.edu or by calling 785-628-9430.