Prairie growers on lookout as insects seize opportunity

Dry conditions, delayed seeding lift pest counts

Cutworms. (Photo courtesy Canola Council of Canada)

MarketsFarm — With most Prairie growers’ newly seeded crops already up against dry conditions, growers remain on the lookout for insects which further threaten the health of those seedlings.

Considering the high prices of many crops this season, the potential damage would be more costly.

John Gavloski, entomologist for Manitoba Agriculture, said there is a greater risk for flea beetles in canola crops.

“We’ve had chronically high populations in recent years and what’s making the risk even greater this year is anything that keeps the plant in the seedling stage for a prolonged period will increase the risk,” he said.

“So (because of) the dry conditions we’ve been having, if the crop emerges but isn’t advancing quickly, it makes it a lot more susceptible to flea beetle feeding.”

Cutworms, which can feed on a wide variety of field crops, are also appearing in higher-than-normal populations, Gavloski said. Certain types of grasshoppers can also feed on crops, but dense, lush vegetation outside of fields can prevent them from encroachment.

Those grasshoppers who fly before June, that have hind wings visible in flight or make noise are not considered pests. Other beneficial insects include ladybugs, ground and rove beetles, aphids and flies.

“We encourage farmers to only use broad-spectrum insecticides when needed, because you’re killing off all the good bugs and sometimes the good bugs will help keep some of the potential pests in check,” Gavloski said, adding that growers should adhere to an economic threshold.

James Tansey, insect and vertebrate management specialist for Saskatchewan’s Ministry of Agriculture, said dry conditions and delayed seeding are helping increase insect populations in farmers’ fields.

While grasshoppers and flea beetles are still major threats across the Prairies, another pest to watch out for is wheat midge, an orange fly which can reduce yields and grades of non-resistant wheat varieties.

“We have a lot of heavy populations stacked up in different parts of the province,” Tansey said. “(However), this is an animal who doesn’t do well in hot, dry conditions. It needs 25 millimetres of rain before the end of May. Otherwise, its emergence gets interrupted.”

The pea leaf weevil is also a pest of interest, according to Doug Macaulay, acting provincial entomologist for Alberta Agriculture and Forestry. The insect, as a larva and an adult, feeds on peas and other legumes and is concentrated in areas surrounding Edmonton and Lethbridge.

“The wintering adults are now starting to show up in fields now that the peas are popping out of the ground,” he said. “If there’s a heavy population and (growers) don’t have treated seed, it’s going to be very hard to control them.”

Macaulay also cautions growers to watch for wheat stem sawfly, which feeds on wheat, rye and certain types of barley, but can be attacked by the parasitic wasp Bracon cephi.

He also urges growers to scout early and act quickly against pests.

“The earlier you can take action on any insect, the better,” Macaulay said. “Smaller, younger nymphs and larvae are more susceptible and it takes less insecticide to deal with them.”

— Adam Peleshaty reports for MarketsFarm from Stonewall, Man.

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