REGINA – Wheat midge populations in Saskatchewan have increased dramatically and farmers are urged to monitor their fields daily.
Agriculture Canada research scientist Owen Olfert said the population is greatest in an area east of Highway 11 and from Blaine Lake north of Saskatoon down to Carlyle in the province’s southeast corner. Numbers are expected to increase for several more days as crops move into the heading stage.
“Where you have one wheat midge per six or seven wheat heads you should be looking at an application of insecticide,” Olfert said.
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In Manitoba, spraying has been under way for several weeks mainly in an area south of Winnipeg. Only light populations have been reported in the Lloydminster area of Alberta.
Larry Gramiak, soils and crop agrologist in Saskatoon, said he has not heard any complaints of shortages of either applicators or chemicals.
“Dow Elanco (which manufactures Lorsban) has told us that won’t be a problem,” he said, adding, “We had lots of forewarning of this situation.”
But Gramiak said spraying only began in earnest a week ago after midge levels soared July 14 and it is likely some crops won’t be sprayed when farmers want them sprayed.
“Applicators are going to be taxed and I personally believe it’s inevitable that there will be a shortage of applicators,” he said.
This could happen as a result of the compressed spring seeding period. Most of the wheat crop was seeded within a seven-day period, which means it is all at roughly the same stage of development.
“We recommend that producers monitor their fields from the time the head emerges from the boot until flowers are visible on the head of the first tiller,” Gramiak said. “Once it flowers and if you haven’t reached economic levels (which determine whether spraying should be done) you are basically out of the woods.”
He also said there is a relatively short period when spraying can be done to eliminate both adult midge and eggs. Greater use of high clearance ground sprayers, equipped with light bars for night spraying, will ease the pressure on aerial applicators.
Olfert said producers are urged not to apply insecticide if their wheat crops have already flowered. It is not economical and it can hinder a parasitic wasp which lays its eggs in wheat midge larvae and emerges in spring instead of the midge.
He said in Manitoba last year nearly half the wheat midge infestation was brought in check through the parasite, compared to between 20 and 25 percent in Saskatchewan.
Meanwhile, moth counts to determine Bertha army worm infestations are showing a couple of hot spots in Saskatchewan.
Olfert said an area between Moose Jaw and Assiniboia had particularly high counts, as did an area near Estevan.
The area of infestation will likely be from southwestern Manitoba near Brandon, through southeastern Saskatchewan up to Regina and Moose Jaw and farther north to Saskatoon. Olfert said moth counts in east-central Saskatchewan are not high.
He said producers will be advised when the moth flight is over and they should start looking for larvae.
“We’ve got some lead time here,” he said. “It takes two to three weeks for the larvae to get large enough to cause real damage.”
The weather will also play a role because hot, dry conditions encourage Bertha army worm development.
