What will bug prairie farmers most in the spring of 2007?
Although it’s an early forecast, the list of insects farmers should prepare for in the coming growing season is shorter than it has been in recent years.
In 2007, producers should expect to find the same pests they had in their fields at the end of last year, but a few are expected to dominate the Prairies.
Bertha armyworm
David Vanthuyne of the Canola Council of Canada said agronomists and farmers hope bertha armyworm populations have peaked and will soon be on their way down.
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“For some it may have peaked. For others they are just reaching the peak or it has yet come,” he said.
In pockets across the West, but worst in east-central Saskatchewan, the larvae turned some fields white last season, damaging what was for many canola growers a larger than average crop.
Scott Hartley of Saskatchewan Agriculture said the bertha problem won’t likely go away soon.
“It usually peaks for two or three years. So producers who have had one or two bad years need to vigilant (when it comes to scouting),” he said.
John Gavloski of Manitoba Agriculture said the need to scout fields and regularly watch for reports by provincial entomologists, can’t be understated.
In 2006, experts warned of the bertha population rise based on adult moths caught in pheromone-baited traps across the Prairies.
The decision on whether or not producers should spray to control the larvae must be made a on field by field basis, said Kevin Blair of Blair’s Fertilizer in Lanigan, Sask., in the heart of a region that has seen some of the highest bertha populations.
“You need to scout and then decide whether you’ve reached the economic threshold and whether the timing is right to spray,” he said.
Vanthuyne said maximizing yield from the current crop is the choice producers will have to make based on projected yield, the price of the crop and level of damage they can expect from the insect.
Gavloski said scouting must be done at the right time to paint a true picture of the pest.
“Larval monitoring should begin about two weeks after the adult populations in the traps have peaked in your area.”
In Alberta, Scott Meers of Alberta Agriculture in Brooks said the insects did damage near Edmonton, Drumheller, Foremost and Taber.
“Outside of the Peace country, this year no part of the province is safe,” he said.
Cabbage seedpod weevil
A perennial pest in southern and central Alberta, the cabbage seedpod weevil entered western Saskatchewan in 2000.
Hartley said this insect prefers canola, not a widely planted crop in the southwest. But it will invade mustard.
“There was some spraying in the Maple Creek, Gull Lake and Webb areas in canola crops,” he said.
He said there is no economic threshold established for the pest in the region so each infestation is assessed on a case-by-case basis. The canola council recommends control at three to four insects per sweep of a net in the early bloom stage of canola.
In Maple Creek, four to five were reported in June of 2006.
“This is one to watch for this year and going forward as it moves east,” he said.
The insect isn’t a problem in Manitoba, say entomologists.
In Alberta it remains a problem in southern Alberta from west of Leth-bridge to Medicine Hat and south of Calgary.
Wheat midge
The wheat midge is expected to rear its wings almost universally in cereal-growing regions across the Prairies.
Last year, midge populations resulted in crop damage north of the Trans-Canada Highway in Alberta and in most of Saskatchewan and Manitoba.
The midge is tough to monitor because of the need to wash soil samples and do pupae counts.
Hartley said midge has increased in numbers since 2005 and Canadian Grain Commission reports indicate potential for damage in areas north of North Battleford, Sask.
Southern Manitoba is at risk as well with pockets of high populations across the region.
Hartley said control is the difficult issue.
“There is a small window of control. It’s susceptible from the time the (wheat) head becomes visible until the anthers emerge,” he said.
Once the anthers are fully emerged it is too late to spray, he said.
Spraying at that point only kills the parasitic insects that prey on the midge.
“It’s a double economic whammy then. You waste your money on the midge and kill its natural enemies to boot,” he said.
Manitoba may see new populations of soybean aphids depending on weather systems pushing them in from southern Minnesota.
Other pests
Cutworms and wireworms too will likely be in significant numbers in areas where they were a problem last year. However, insects such as grasshoppers are not expected to have a widespread impact after several wet years before the last half of 2006.
Wheat stem sawfly has reached across Saskatchewan to the Estevan area, but parasitic wasps have been reducing the damaging insects’ populations.
The widespread planting of the solid stem spring wheat, Lillian, also played a role in failing to provide habitat for the sawfly.
“It’s less of a threat than it has been, but if you’ve had it, you should consider having a plan to avoid it or swath early, just in case,” said Hartley.
