Alberta growers tackle army of insects

Midge, flea beetles and cabbage seedpod weevils wreaked havoc in wheat and canola fields

It was the year of the insect in Alberta.

Central Alberta saw an outbreak of bertha armyworms, while pea leaf weevils and cabbage seedpod weevils rebounded to higher numbers. As well, cutworms were a major problem in a few areas, Scott Meers said in his annual Alberta Crop Insect Update 2012.

Wheat and canola insects will continue to be problems as farmers focus mostly on those two crops, said Meers, Alberta Agriculture’s insect specialist.

“As you have less diversity, it means more insect and disease issues.”

He said farmers can expect to see more wheat midge next year and recommended growing wheat midge tolerant varieties to lessen the problem.

“It’s a very difficult insect to scout effectively for and it’s easily missed if you’re not scouting effectively,” Meers said. “I do believe we have to be more diligent about making disease and pest control decisions. We need to make decisions on what is happening in the field.”

Meers said larger farmers are hiring agronomists to scout for disease and insects in the summer because of the amount of time needed to effectively do the job.

In oilseeds, cabbage seedpod weevil numbers were above economic thresholds for spraying throughout southern Alberta. Spraying was common south of the Trans-Canada Highway. It’s now considered normal to scout and spray for the insects in southern Alberta.

Bertha armyworm numbers were very high in central Alberta and found in pheromone traps throughout most of the province. Larvae were found in high enough levels to warrant spraying in northeastern and central Alberta.

Serious infestations resulted in severe damage to some crops. More than 100,000 acres were sprayed this year.

Meers said farmers will need to be cautious for at least one more year. Bertha armyworm larvae also attacked several fields of silage corn.

Diamondback moth numbers were very strong but seemed to have disappeared by the time the canola started to bloom. There is no clear answer to why.

Striped and crucifer flea beetles caused damage in parts of the Peace, but damage was minimal in the rest of the province. Reports of high flea beetle numbers this harvest may be a foreshadowing of things to come next year.

Lygus bugs were found in moderate to high numbers in early flowering canola in southwestern Alberta.

The numbers increased as swathing approached and farmers sprayed a lot of acres for the pest. More acres should likely have been sprayed based on threshold numbers.

Leafhoppers were more numerous in canola fields this year, including aster leafhoppers, which created the high number of aster yellows in many fields this year.

Root maggots were common throughout the province, and zebra caterpillars were discovered in one field near Brooks. Western white larvae were found in canola but are not considered an economic issue.

Cereal growers seemed to have fewer problems with wireworm, likely because of better chemical control.

Wheat stem sawfly damage was low in much of southern Alberta.

Orange wheat blossom midge occurred in increased numbers, but little spraying took place. Meers is expecting an increase in midge numbers next year.

Cereal leaf beetle has established itself in southern Alberta. A beneficial wasp continues to keep numbers low.

Cutworms were not as common this year, but damage was reported across all cereal producing areas.

The pea leaf weevil was the main pulse crop insect. Damage was more severe than in previous years.

Warm weather likely favoured early flights of over-wintered adult weevils.The alfalfa weevil caused concern in alfalfa and hay crops.

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