Mother Nature took a toll on Kansas winter wheat this season, with USDA rating the crop – at the harvest halfway mark earlier this week – at only 48% reaching good to excellent quality.
Beyond inclement weather, it was a small, cigar-shaped pest – the wheat curl mite – that delivered one of the harshest yield blows to the crop this year, according to Romulo Lollato, wheat and forages Extension specialist, Kansas State University (K-State).
The small pest is a vector of wheat streak mosaic virus (WSMV), one of the most destructive wheat disease complexes in the U.S. and around the world. The disease complex can be caused by several viruses, including wheat streak mosaic virus, Triticum mosaic virus, and wheat mosaic virus (High Plains).
The issue is widespread, well beyond Kansas. Other top wheat-producing states have the pest and WSMV, as well, including Colorado, Montana, Nebraska, North Dakota, Oklahoma and Texas.
Kansas was hit hard this season, Lollato reports.
“There are farm fields out here that got completely decimated,” he says.
Extension field test trial results show yield losses can range from 30% to 80% from WSMV. Fifteen percent yield losses in a single field are common, adds the Kansas Wheat Commission.
Weather Conditions Are A Factor
Lollato believes the warm fall in 2024 created ideal conditions for the mites to thrive and deliver the disease to wheat crops this season.
“If we think back on the conditions last fall, it was actually one of the warmest ones on the record here, and the mites really prefer temperatures at 70-plus degrees” he says. “The mites reproduce very quickly under those conditions.”
By early to mid-April this year, Lollato says the impact of the mites and WSMV complex was readily apparent in Kansas.
“We started to see that disease explode, and while it’s typically more localized in the western third of the state, this year, it really is across the entire state,” he says.
Control Volunteer Wheat And Other Crop Hosts
As wheat harvest finishes up this summer, what farmers do next will largely determine what happens in the 2026 season.
Lollato explains the pest survives on volunteer wheat and other host plants, contributing to what the wheat industry refers to as the green bridge effect during the post-harvest period. In the fall, the mites are carried by wind from volunteer wheat to newly emerged winter wheat crops, perpetuating WSMV.
Jeanne Falk Jones, multi-county agronomy specialist with K-State Research and Extension, writes that volunteer wheat needs to be addressed.
“It is critical that all volunteer wheat within one-half mile (of your field) be completely dead at least two weeks prior to planting (your next crop),” she advises. “Volunteer wheat can be controlled by working the ground or by herbicide application.”
Grazing volunteer wheat is not an effective option for control, she adds, because there is green wheat material left and the mites can be living in that material.
To address WSMV proactively, Jones encourages wheat growers to walk their wheat stubble this summer and check for volunteer wheat and then devise a control measure, if needed.
“It may save your (or your neighbor’s) wheat yields this next harvest,” she says.
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