In Monday’s Crop Progress Report, 14 percent of Michigan’s wheat is headed. In this next stage of development, growers are going to need to keep an eye out for fusarium head blight, or head scab.
Christopher Bauer, Pioneer agronomist, says growers need to ask two questions before they spray an application.
“Is the environment conducive for the disease? And what is the genetic resistance of the variety I planted?”
When looking at the environment, check for free moisture on the head at flowering.
“If you think about the conditions for head scab, it likes air temperatures around 75 to 85 degrees, and then it likes free moisture,” said Bauer. “If we get rain with 75 to 85 degrees or if we have a heavy dew or heavy fog in the morning during pollination, that’s causing the environment to be conducive for the infections.”
Bauer said Pioneer has been able to select new varieties of wheat that have improved scab resistance.
“Our scores on our wheat varieties scale from one to nine—one being low, nine being really good,” he said. “Ours range from a four to a seven. In a really heavy infection year or a really conducive environment, even a score of a seven will not be enough to keep the crop free of scab.”
That genetic tolerance is seen as a bonus, but for high-management growers, they will still spray a fungicide.
“In a low to mild scab infection year, a seven may be good enough, but the tough part is we usually don’t know the exact level of infection until after it happens,” said Bauer.
There are two fungicides Bauer recommends to fight head scab.
“Miravis Ace has an application timing of 10.3 to 10.5, so it’s around 50 to 55 percent head emergence to almost complete flowering, which is about a five- to eight-day window,” he said. “The Prosaro timing for head scab is right at early flowering. When anthers are protruding from the middle of that head, you want to get that application on right at that timing, so you have a two- to three-day window.”
Bauer is expecting the majority of Michigan’s wheat to start flowering over the weekend and into next week. Warmer temperatures and chances for rain is in the forecast. He says to watch conditions and use the Fusarium Risk Tool.
