Purdue Extension Plant Pathologist Kiersten Wise says wheat growers can take steps during harvest and in storage to control head scab, or Fusarium head blight, which 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, she says. "Farmers should know what they have in the field before they get to the elevator," Wise says. "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. If farmers know they have grain with head scab before harvest, Wise recommends they turn up the fan speed on the combine. The lightweight, scabby kernels will be blown out, leaving behind the healthy grain, she says.
She also says 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 says. "They can also blend it with other wheat to lower the amount of DON if they are feeding the grain to livestock."
In cattle, DON causes feed refusal and poor weight gain. The mycotoxin also can cause hormonal problems and uterine prolapse in swine, she says. "Livestock producers should have grain tested prior to feeding, especially if there was scabby grain present at harvest," Wise says. The Animal Disease Diagnostic Laboratory at Purdue will test for DON and other mycotoxins. More information can be found at http://www.addl.purdue.edu/.