Spray planes are still flying in northeastern Alberta but most residents feel confident the worst of the bertha armyworm infestation is behind them.
Paradise Valley was hardest hit, with Vermilion and Wainwright also affected, said Josie Van Lent, UFA crop production specialist for the northeast.
Bertha armyworms numbered as high as 120 per sq. metre on canola fields around Paradise Valley, she noted.
Van Lent predicted some fields would see yields reduced by 10 to 15 bushels per acre.
She said 40 percent of crops were at the threshold for spraying. Most were sprayed before they were seriously damaged. The bugs also fed on alfalfa and pea crops.
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The Canola Crop Watch Report also reported infestations around Eaglesham and Wanham in Alberta, at Lloydminster, Laird and Neilburg in Saskatchewan and in the Swan River Valley and Roblin areas in Manitoba.
Wet weather in the last two weeks hampered Alberta’s spraying operations, Van Lent said, citing the more than 125 millimetres of rain that fell last week.
“For the most part, (farmers) did a pretty good job of getting to them,” she said.
Wainwright farmer George Poruchnek, who sprayed four of his fields three weeks ago, said there are few insects left, if any.
“It looks good, I got them all,” he said.
Fixing equipment on Aug. 29 in preparation for swathing, he said he first noticed the green worms during a routine scouting trip that also uncovered lygus bugs.
He chose to act rather than “overwait,” he said.
“Canola isn’t a high price crop and nobody wants to put more money out but on the other hand, (doing) something is still absolutely better than nothing,” he said.
Poruchnek figures he spent $12 an acre to control the bugs in a canola crop worth about $25 an acre at harvest.
He rated this insect outbreak as “fairly bad” when compared to previous ones.
“Just about all of us are having to spray,” he said of the neighbouring communities north of Highway 14.
Early-seeded canola fared better against the pests than those seeded later, said Poruchnek, who seeded his canola around May 21.
Agricore United in Wainwright reported strong sales of chemicals to combat bertha armyworms.
Brad Birn, AU manager, cited badly chewed fields around Irma, Edgerton and Vermilion.
He said the bugs, which change from green to black as they mature, strip the plants, eating the leaves, stems and pods.
“We had some hilltops out there that were completely bare.”
He said farmers have to do routine inspections, checking for worms on plants, on the ground and under the leaves. He recommended walking into the fields because many insect “hot spots” were detected in the centre.
“You had to go in quite a ways to pick them out,” he said.
High clearance sprayers or spray planes are effective ways to control infestations, he noted.
Van Lent said it’s difficult to predict the hit-and-miss cycle of these insects, which generally peak every three years.
Their numbers can spike quickly, with an individual female able to lay 1,000 or more eggs.
