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Fusarium Head Blight Taking Hold in Winter Wheat Fields
This year’s cool and damp spring is ideal for boosting kernel weight and maximizing grain fill in winter wheat. However, these also are prime conditions for Fusarium head blight, commonly called head scab.
Erick DeWolf, plant pathologist at Kansas State University, says the incidence of the disease seems to be higher this year than it has been over past years, showing up in parts of central Kansas in addition to eastern Kansas, where it has previously been more common.
In Nebraska, head scab is visible on susceptible varieties in the eastern part of the state, according to Stephen Wegulo, Extension plant pathologist at UNL.
Fusarium head blight is a fungal disease that affects the developing grain, and it can produce a mycotoxin that’s a threat to the health of animals and humans.
Visual symptoms of Fusarium head blight include large tan lesions encompassing large portions of the developing wheat head, DeWolf says. Close examination of the heads often reveals a chocolatey-brown color on the stem, and orange masses of fungal growth on the edges of the glumes.
At harvest, he adds, the kernels may be white and chalky, rather than a healthy amber color. The diseased grain is often shriveled and has a poor test weight.
“Many times, producers don’t realize they have a problem with it until they start harvesting their grain,” DeWolf explains. “People start asking questions when they see the discolored, shriveled kernels in their loads of grain.”
Unfortunately, DeWolf adds, nothing can be done to suppress the disease after flowering. In those fields where Fusarium head blight is present, the disease likely took hold in May. Wetter weather during that time could have contributed to its spread this year. In western Nebraska, Wegulo says applying fungicide at flowering could suppress head scab. There is still time to protect the crop in that part of the region.
However, as harvest moves northward, DeWolf says growers who are past the point of treatment need to shift gears to “…make the best of an otherwise difficult situation,” he says.
If your area has had scab this year, take note of DeWolf’s suggestions:
- Make fields planted to moderately resistant varieties a top priority. Early harvest will avoid any additional weathering of that crop, plus help preserve the test weight and quality of fields that were less at risk of Fusarium head blight.
- Adjust harvest equipment to remove as many lightweight, diseased kernels as possible. Adjust airflow on the combine to improve test weight, plus avoid discounts to harvested grain.
- If you have on-farm storage, separate the loads of grain to avoid mixing healthy wheat with the grain from fields with unacceptable levels of grain.
If you plan to plant wheat in head scab-infested fields this fall, be sure to use a wheat variety with strong resistance to head scab, or plan to rotate fields to a different crop altogether.