Whether to spray for fusarium: flowering period is key

Whether to spray for fusarium: flowering period is key

Wet weather in eastern Saskatchewan and much of Manitoba means farmers likely have fusarium head blight risk on their minds. But cereal grades are only at stake risk if environmental risks match up with flowering, a crop pathologist says.

Vikram Bisht, field crop pathologist with Manitoba Agriculture, Food and Rural Development, says two or three days of rain the previous week, combined with humidity and moisture on the heads adds up to high environmental risk.

“If it matches the flowering period, when it is peak flowering, that is when the risk is high,” he says.

“And if the risk is high and in the area there is a history of carrying head blight, it is worth protecting the heads because in many cases the loss of grade is worth applying the fungicide.”

Manitoba Agriculture publishes a FHB risk map that is updated nearly every day. Farmers in eastern Saskatchewan can reference the western part of Manitoba’s FHB risk map, Bisht says, “and probably draw some conclusions on the relative risk in their area.”

Manitoba farmers faced extremely high FHB risk earlier this summer. Winter wheat, which is particularly susceptible, “got caught with lots of flowering at extreme risk periods. So everyone was spraying their wheat (in Manitoba),” says Bisht.

Farmers in southeastern and east-central Saskatchewan also sprayed for fusarium, according to the latest Saskatchewan Agriculture crop report.

Manitoba farmers often face higher fusarium head blight risk, Bisht says. And the majority of fusarium in Manitoba is 3ADON, which has a higher mycotoxin level than 15ADON, he adds. Saskatchewan and Alberta doesn’t see as much 3ADON, Bisht adds.

“The tolerance for fusarium diseased kernels in Manitoba will be lower because of this strain which produces more toxin,” he says.

A recent news release from BASF notes timing is key to control FHB. Farmers protecting oats, wheat and rye should apply when 75 to 100 per cent of the main stem heads are fully emerged, BASF states. Between 40 and 50 per cent of the main stem heads should have started flowering. Fungicide can be applied to barley up to three days after the head has fully emerged, the company notes.

But hot, windy conditions have dropped FHB risk in Manitoba for now, Bisht says. “And in the mornings you don’t have much dew on the heads for long. And that has reduced the risk for the head blight.”

Given the lower FHB risk, some Manitoba growers have opted to skip FHB fungicide right now, instead protecting the flag leaf with a foliar application, he adds.

“It is a sound strategy in the sense if your peak flowering period is going to be during the low fusarium head blight risk, why take a chance and waste money while you can protect your flag leaf?”

 

Lisa Guenther

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