The past few years have been good ones for the wheat midge.
But the memories haven’t been so sweet for farmers who must contend with the larvae of the mosquito-sized orange pest.
From the numbers of midge counted in the soil, this year might be no different.
Prairie bug scientists have come up with a risk map showing areas where, with a cool, damp spring, wheat midge have a good chance of coming out of the ground en masse to lay eggs in young heads of wheat.
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“We have a situation where all we really need is some ideal weather conditions and the populations could get to the point where growers are going to be pretty hard-pressed to keep abreast of the outbreak,” said Ian Wise of Agriculture Canada’s cereal research centre in Winnipeg.
“In the past, you had to have really perfect conditions for the midge to have a chance of building up,” Wise said. “We don’t need that this year.”
Soil surveys in Manitoba show extensive numbers of midge in the main wheat-growing areas. The pest is also concentrated in pockets in the heavier soil zones in Saskatchewan.
But Wise said midge, which can fly at least seven miles per year, are also moving into some new southern areas.
“It has actually expanded its territory quite noticeably in the last few years,” he said.
With a hot, dry spring, midge will likely only pop up in the most heavily infested areas, Wise said. But they can stay dormant in the soil and wait for better conditions next year.
An agrologist with the Saskatchewan government in Weyburn said the risk map last year accurately predicted where wheat midge problems were likely to pop up.
But Elaine Moats said growers worried about the bug should look at the way they plan their rotations, as well as looking at the map.
“If you’re cropping wheat on wheat stubble, you will quite likely have to spray for midge,” Moats said.
Late seeding a problem
Moats noted heavy snow may lead to late seeding, exposing wheat fields to more risk of midge infestation.
“The other side of the coin, of course, with wheat prices being down a little compared to some of the other crops, I think there’s more interest by producers in growing crops other than wheat this year,” she said.
But Wise said growers worried about the pest shouldn’t panic.
“There’s no area of the province where I’d say, ‘Don’t grow wheat because of the wheat midge,’ ” said Wise, referring to Manitoba.
Wise suggested growers in midge-prone areas take several precautions:
- Seed as early as possible in the spring.
- Start checking for adult midge in July, especially when the crop is starting to head.
- Count the number of midge compared to the number of heads at several points in the field.
- Consider spraying when there is more than one bug for every three or four heads. It must be done within four days of sighting to catch larvae before they get into heads.
