Outbreaks of wheat scab have already been reported in south Georgia this year, and now the disease is being seen throughout Alabama.
In north Alabama, the window for applying a fungicide to wheat to prevent scab has closed, says Austin Hagan, Auburn University Extension plant pathologist.
“In this region of the state, nearly all the good wheat was treated with Prosario fungicide,” says Hagan. “Buying points ware looking for scabby wheat and probably will dock the price considerably or refuse to purchase the wheat.
Hagan says he has seen more wheat scab in Baldwin County near Alabama’s Gulf Coast, but not much in the wheat variety trials in Brewton and in the Field Crops Unit at E.V. Smith Research Center in east-central Alabama.
“In Baldwin County, the early varieties got blasted, but the later varieties did not. Historically, scab has caused serious losses in the Tennessee Valley and not in the southern half of Alabama. It’s possible that colder winter and cooler spring weather pushed the risk zone for scab further south.
“Recent heavy rains also have played a role as well. Wheat in north Alabama has just finished flowering, so it’s too late as I noted above for fungicides treatments. There was very little scab earlier this week in the wheat variety trials at the Tennessee Valley substation.”
According to the Fusarium Head Blight Prediction Center, there was a high risk of scab at or around flowering in most parts of Alabama over the past month, says Hagan.
“While it’s not the most accurate model, keep an eye on it. Weekly scab updates for Alabama are posted at that website along with information on other diseases,” he says.
When harvesting scab-damaged wheat, Hagan recommends following these guidelines:
- Separately harvest and handle seed from portions of fields with the highest level of scab-damaged heads.
- Choose higher combine air speeds to blow out the small, shriveled, mycotoxin-contaminated kernels and chaff. At minimum, “scabby” wheat will be heavily discounted by elevators.
- Dry harvested grain quickly to 13-percent moisture to prevent further fungal growth and mycotoxin concentration.
- Post-harvest cleaning of scab-damaged wheat to remove low-test weight, mycotoxin-contaminated kernels.
- Test wheat grain samples from scab-damaged fields for vomitoxin and zearalenone. Commercial labs will test for mycotoxins in grain and feed products.