Wheat streak mosaic is one of the most economically devastating wheat diseases in Kansas and the Great Plains.
In 2017, this disease caused a conservative $76.8 million in direct losses to wheat farmers, a loss of 19.2 million bushels of wheat. This year's loss was 5.7% yield loss, up from an average 1.5% loss.
In 2017, central and western Kansas had above average disease intensity.
There are basically only three ways to control the spread of wheat streak mosaic:
- Timely removal of volunteer wheat and other grassy weeds. 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 removed with herbicides or tillage, but it’s absolutely essential to allow time for herbicides to work.
- Avoid early planting; plant after the hessian fly-free date. By avoiding early planting, Kansas wheat farmers are able to avoid times when wheat mite populations are the highest in late summer and to decrease the interval between planting and fall freeze events. "When we say avoid early planting, we’re not talking about planting outside of the window for success of your wheat crop,” said KSU Plant Pathologist Erick De Wolf. “We’re encouraging you to plant on the later side of the recommended planting dates."
- Plant varieties with moderate or high levels of resistance to WSMV.
- Joe, Clara CL and Oakley CL are current varieties with moderate resistance to WSMV. Unfortunately, the WSM2 resistance genes in these varieties is less effective at temperatures above 75 degrees Fahrenheit.
- TAM 112, Byrd and Avery varieties slow the development of mite populations.
- At this point in time, there are no chemical options such as insecticides or pesticides that are effective at controlling the wheat curl mite.
Research is headed down the path of genetic resistance, and Kansas wheat farmers should know that help is on the way. However, there are only a few varieties with moderate resistance at the current time.
The WSM3 gene, which was discovered by Bernd Friebe at the Wheat Genetics Resource Center (WGRC) at Kansas State University, comes from wild relatives of wheat and is resistant to not only Wheat Streak Mosaic Virus, but it also provides protection from Triticum Mosaic Virus and High Plains Mosaic Virus as well. Another benefit of WSM3 is that it is not temperature sensitive, which has been a weakness in the current sources of resistance. This research is being partially funded by Kansas wheat farmers through the Kansas Wheat Commission’s two-penny wheat assessment. The WGRC is housed at the Kansas Wheat Innovation Center in Manhattan.
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.
To learn more about this disease, how to control it and about research projects being done at Kansas State University, visit the links below.