Rainy days may advance disease in sunflower crop

Sunflowers wait to be harvested in a field southwest of Carman. Photo: Lorraine Stevenson

Manitoba’s sunflower producers are hoping to see more of their crop’s namesake, as wet weather hinders harvest preparations in some areas of the province.

“It’s been pretty good other than this weather we’ve got right now — we had rain here the other day, and again today, so we’re just waiting ’til we can get going again,” said Blair Woods, who has 380 acres of sunflowers near Elgin.

Most producers are still at the desiccation stage and haven’t yet begun to harvest their crop, said Devin Toews, a vice-president with the National Sunflower Association.

Most farmers will apply desiccant as soon as weather conditions permit aerial spraying. Given wet conditions, desiccation will be needed to help stop the spread of disease this fall, he said.

“Some of the fields are starting to get some disease, and there is some concern about that,” Toews said. “Head rot and sclerotinia, pretty much everything is coming in right now. It’s been so wet for the last month, it has infected a lot of fields.”

The last survey of Manitoba fields, done on Sept. 11, found one-third had signs of head rot, said Khalid Rashid at Agriculture and Agri-Food Canada in Morden.

“But the incidence or severity was not very high,” he said. “Maybe one to five per cent.”

That level of head rot is about normal, or even a little below normal, he added. But weather can change that quickly.

“What happens sometimes is you get a small infection on the head but you are faced with dry weather so it does not develop,” said Rashid. “Now if it gets wet and humid or muggy, a small tiny infection — given one or two weeks — might consume the whole head.”

That happened in 2004, when a wet September resulted in some fields having head rot rates as high as 90 per cent.

“Those fields were just plowed under,” said Rashid, adding it’s unlikely to happen this year despite rising disease levels.

Desiccation helps control disease, as well as hastening harvest, noted Toews.

“You can get away without desiccating, but you’ll probably be combining in December. It does speed up the drying and can kill the disease too, or stop the disease from spreading further,” said the MacGregor-area producer.

Ideally, moisture levels are around 10 per cent during harvest.

“We prefer to take it off dry,” Toews said. “But it all depends on what the weather looks like… last year, we took it off when it was basically snowing and it was still around 13 per cent.”

Toews, who planted 250 acres of confection sunflowers this year, expects Manitoba yields to be average and below 2012 levels.

“Last year they were so strong with how much heat we had, and yet no drought… and August was so dry we had no signs of disease either,” he said.

“They’re looking really good,” said Woods. “We just have to get them in.”

About the author


Shannon VanRaes is a journalist and photojournalist at the Manitoba Co-operator. She also writes a weekly urban affairs column for Metro Winnipeg, and has previously reported for the Winnipeg Sun, Outwords Magazine and the Portage Daily Graphic.



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