WEST LAFAYETTE, Ind. — Wheat growers can take steps during harvest and in storage to control head scab in the crop.
Disease development
Head scab, or Fusarium head blight, develops in humid, wet conditions and moderate temperatures when the plant is at flowering.
If wheat has scab, elevators may not accept it or might offer a lower price because head scab produces a mycotoxin called deoxynivalenol, also known as vomitoxin or DON, that is harmful to humans and livestock.
“Farmers should know what they have in the field before they get to the elevator,” said Purdue Extension Plant Pathologist Kiersten Wise.
“Even if they have scabby grain in the field, there are a few things they can do to prevent problems.”
Diseased grain will appear shriveled and have a bleached or light pink color. The kernels are also more lightweight than healthy ones, she said.
Harvest
If farmers know they have grain with head scab before harvest, Wise recommended they turn up the fan speed on the combine. The lightweight scabby kernels will be blown out, leaving behind the healthy grain.
She also said all wheat should be stored properly to prevent the fungus from growing.
“Farmers should store wheat at low moisture to keep any potential fungus from growing and producing more DON,” Wise said. “They can also blend it with other wheat to lower the amount of DON if they are feeding the grain to livestock.”
Cattle
In cattle, DON causes feed refusal and poor weight gain. The mycotoxin can also cause hormonal problems and uterine prolapse in swine.
“Livestock producers should have grain tested prior to feeding, especially if there was scabby grain present at harvest,” Wise said.
The Animal Disease Diagnostic Laboratory at Purdue will test for DON and other mycotoxins. More information can be found at www.addl.purdue.edu/. There are also private companies that test wheat samples, Wise said.
