Wheat producers face enough challenges without pesky diseases, but identifying and treating them when possible helps.
That was an assessment of Kelsey Andersen Onofre, an assistant professor and a wheat and forage Extension specialist at Kansas State University.
Kansas producers have heard plenty about wheat streak mosaic and stripe rust recently.
Vance Ehmke, a Dighton, Kansas, wheat grower noted in early May in a story he wrote for hpj.com posted recently that he has seen and heard reports from farmers about diseases including wheat streak mosaic.
“Once the plant is infected with the virus, there is nothing you can—there is nothing you can spray on the crop like a fungicide,” Ehmke said. “And the penalty can be severe—it can range from a mild 10% loss on up to the entire crop. Too, infections frequently occurred last fall when the wheat curl mite moved from neighboring fields of volunteer wheat to the newly planted crop. Often the symptoms don’t show up until the spring. The virus is easily controlled by simply killing volunteer wheat back in the fall. But some farmers don’t do that.”
Stephen Wegulo, an Extension plant pathologist at the University of Nebraska-Lincoln, reported the mosaic virus complex emerged as a threat in 2025.
The predominant disease in the surveyed fields in a report issued May 9 was the wheat streak mosaic virus disease complex. The complex consists of three viruses (WSMV, Triticum mosaic virus and High Plains wheat mosaic virus) found from trace levels to 100% incidence and severity.
A portion of a field in Kearney County, Wegulo reported, was completely destroyed by the virus complex.
Wheat streak mosaic virus can be confused for nitrogen deficiency, Andersen Onofre said. “When infections are severe, it can cause substantial yield loss,” she said.
The virus is transmitted by a curl mite that can thrive most notably in volunteer wheat and in other grassy environments, she said. The curl mites are difficult to detect. In warmer temperatures, they can survive about eight to 10 days, but in colder temperatures they can survive more than three months. The female can lay about 12 to 20 eggs a day, and the population explodes around harvest time.
“How do we stop wheat streak mosaic? We need to break the ‘green bridge,’” Andersen Onofre said. In other words, farmers need to eradicate volunteer wheat within two weeks of planting the fall crop.
“Prevention is the best way to break the disease cycle and control wheat streak,” Andersen Onofre said. “There is no silver bullet for management.”
Wegulo said use cultural practices to break the green bridge (volunteer wheat and other grassy hosts of the mites and viruses) and avoid early planting of winter wheat. In no-till systems, practicing crop rotation will help in controlling volunteer wheat and other green bridge hosts. These practices, when combined with planting resistant varieties, will significantly reduce losses caused by the WSMV disease complex.
Andersen Onofre said there were several varieties that are more resistant to the virus, and growers who have dealt with it should consider looking into those seed varieties.
Triticum mosaic virus, also spread by curl mites, is a related virus that wheat farmers need to scout for. It can also severely impact yields. Triticum mosaic virus was first found in western Kansas but in recent years has moved eastward into the central parts of the state.
Ehmke has received several reports of it in west-central Kansas.
Other diseases
Andersen Onofre said Kansas producers also need to pay attention to barley yellow dwarf virus, which is caused by aphids.
Stripe rust is another disease that is harmful, she said. This fungal disease starts in Texas when wind carries spores from infected leaves. When conditions are right, the spores travel northward into Oklahoma and then to Kansas.
Stripe rust can drastically reduce yields, she said. “If it gets to flag leaf, it can cause up to a 40% yield loss.”
In dealing with stripe rust control, Andersen Onofre said the timing of fungicide application can help ease concerns. Research has shown that proper treatment of a susceptible variety results in a 10 to 15 bushels per acre increase at harvest, which represents about a 30% hike in production when compared to untreated wheat. K-State Extension annually publishes a guide with variety ratings for stripe rust and other diseases.
Other challenges
In southcentral Kansas, growers reported cases of white heads and the death of tillers, she said. The causes were the interaction of drought and fusarium foot rot. Andersen Onofre said early season moisture was unfortunately followed by an extended dry period in the spring. Fusarium foot rot causes tillers to turn white later in the season due to compromised root systems. This disease can be more pronounced in wheat after wheat rotations.
Andersen Onofre also discussed common bunt (also known as stinking smut), which has shown up in Kansas and Oklahoma. Bunt diseases are some of the oldest known in the United States. Several have been traced back into the 1800s, with some of the earliest reports in the Pacific Northwest and Great Plains. In 1890, in Kansas, wheat crop losses were estimated at about 25 to 50% with bunt being cited as the primary cause. Elevators today give a discount for smutty grain or can reject severely infected grain lots. The disease is caused by a fungus that replaces the starch of the grain with black masses of spores.
Stinking bunt looks similar to dwarf bunt, but it has global trade implications because China will reject wheat imports that have levels of this disease above a certain threshold.
The good news is fungicide seed treatments have proven very effective, Andersen Onofre said, adding that now is the time to consider fungicide seed treatments.
Wet conditions and soil temperatures between 40 and 60 degrees Fahrenheit are ideal for bunt disease propagation, she said.
Dave Bergmeier can be reached at 620-227-1822 or [email protected].
