Control Volunteer Wheat to Stop the Wheat Streak Mosaic Virus

Wheat Streak Mosaic was detrimental to the western Kansas wheat crop this year.

On average, WSMV causes $75 million in losses to Kansas wheat farmers every year, but this year’s losses were much higher. Wheat Streak Mosaic can cause a yield loss of more than 80 percent. If we take preventative measures now, future yields will improve exponentially. Prevention is the only method, so Stop the Streak now.

The virus is spread by the wheat curl mite, which feeds on wheat and other grasses.

The best way to prevent the spread of the wheat streak mosaic virus is to remove volunteer wheat and other grassy weeds. Volunteer wheat must be completely dead and dry for two weeks before planting a new wheat crop. Volunteer wheat and other grassy weeds can be killed with herbicides or tillage.

A second management practice to limit the spread of the virus is to avoid early planting. Plant wheat after the “hessian fly free date” for your area. In some areas in western Kansas where there is no Hessian fly-free date, farmers should choose to wait until late September or October to plant their wheat. Planting after these dates will reduce the risk for the new wheat crop and reduce wheat curl mites from moving to new locations of wheat.

In addition, there are a few wheat varieties with moderate resistance to this devastating disease. Hard white wheats Joe and Clara CL as well as hard red winter wheat Oakley CL have performed well in areas with wheat streak mosaic.

Kansas Wheat Commissioner Jason Ochs, who farms in Hamilton County, says his area was hit particularly hard this year with WSM. However, Ochs plants exclusively hard white wheat, and his fields were mostly spared.

“Two hard white wheat varieties that performed well for my farm this year were Joe and Clara CL,” said Ochs. “By planting these resistant varieties and making the choice to plant later, we weren’t hit as hard by Wheat Streak Mosaic Virus as many of my neighbors were."

“It is absolutely essential to control volunteer wheat. Because of the weather conditions, there’s likely to be more volunteer this fall than last year. Even though money is tight in wheat right now, we are limiting future profits if we don’t get rid of it for two full weeks before planting. Our choices are to spend a little bit of money this fall, or lose a lot of money next harvest.”

This resistance is not perfect and these plants may still be susceptible to triticum mosaic or high plains mosaic. The resistance to wheat streak mosaic is less effective at temperatures above 75 degrees Fahrenheit. Therefore, planting these varieties early for grazing can place fields at risk for disease-related yield losses.

Researchers at Kansas State University are developing a trait, Wsm3, that is highly resistant to both wheat streak mosaic and triticum mosaic viruses. Bernd Friebe, a research professor with the Wheat Genetic Resources Center in the Department of Plant Pathology said the Wsm3 gene is just the third gene known to provide resistance to the virus – and the first that can do so at outdoor temperatures of 75 degrees Fahrenheit and higher.

The first two genes known to provide resistance to the virus were Wsm1 – identified by Kansas State University about 25 years ago – and Wsm2, which was discovered by researchers at Colorado State University.

But those two genes only provide protection in lower temperatures. Used in combination with Wsm1 or Wsm2, the warm-weather friendly Wsm3 could become part of a breeding mix that can give farmers’ much-needed relief, Friebe said.

The new Wsm3 germplasm has been released through the Kansas Agricultural Experiment Station. It is currently available to breeders through the National Science Foundation’s Industry/University Cooperative Researcher Centers program – whose members have immediate access to the germplasm – but will also be available to public breeding programs in two years.

Through traditional breeding processes, it can take several years before resistance genes show up in varieties available for planting. A new variety with the Wsm3 gene should be released for Foundation seed in about three years, making it available to farmers the following year.

For more information, visit kswheat.com/stopthestreak.