By Trish Svoboda

The wheat streak mosaic virus, which is spread by wheat curl mites living in volunteer wheat, presents challenges for farmers and requires control measures, said Kelsey Andersen Onofre, a wheat disease expert at Kansas State University.

The wheat streak mosaic virus family includes three types of viruses. Wheat curl mites, which live in leftover wheat from previous crops, known as volunteer wheat, carry these viruses. The number of mites depends on the quantity of this leftover wheat.

“If you had some wheat in a neighboring field that survived after harvest, or maybe it was hidden in some double crop field nearby, that’s where those curl mites survive. They can then blow into your field in either the fall or the early spring and that’s typically when we start to see damage,” Onofre said.

Producers have the option to get their wheat samples officially tested at the K-State plant pathology diagnostic laboratory. If wheat streak mosaic is detected in a producer’s wheat crop, it is recommended by Onofre to assess the potential yield of the crop. The Kansas Wheat Variety Guide can be used as a reference to accurately determine the crop yield.

She said that when symptoms occur in the fall or early spring, it’s likely to see more yield loss. Warm weather triggers the manifestation of wheat streak mosaic in fields. Although plants can be infected in winter, the virus’s symptoms are activated by heat. The 2023 harvest saw increased moisture and other weather events, leading to more volunteer wheat and favorable conditions for the wheat streak mosaic virus in the current season.

Kansas growers are also urged to look out for other wheat diseases, such as wheat soilborne mosaic virus, wheat spindle streak mosaic virus, barley yellow dwarf, and stripe rust.