Small bugs are costing potato growers big bucks in Manitoba.
Colorado potato beetles flourished last year and it appears they are poised to chomp even harder in the coming crop year, prompting growers across the Prairies to become concerned.
Derek McLaren estimates his family spent close to $250,000 last year to combat potato beetles and late blight on their 900-acre farm near Carberry, Man. Besides spraying, they hired a field scout last summer to monitor for the bugs and blight.
McLaren suspects a mild winter will translate into a good survival rate among potato beetles. The pest insects like to overwinter in the soil or in thick shrubbery.
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May get worse
“Last year they were quite bad,” he said. “I think we are going to have even more of a problem this year.”
Controlling the potato beetles is becoming a tricky task on the Prairies. There’s evidence that Colorado potato beetles have developed widespread insecticide resistance in Manitoba. Evidence suggests they have moderate resistance in Saskatchewan and Alberta.
In a recent survey, the Lethbridge Research Centre found that more than 90 percent of populations (11 out of 12 samples) from Manitoba were totally or highly resistant to one or more insecticides. Three of the 13 populations tested from Alberta and one of the four populations tested from Saskatchewan showed high resistance. The remaining populations had low levels or no resistance.
The findings, based on prairie-wide sampling, pro-mpted a warning last week to potato growers in Western Canada. In a news release, the research centre noted that growers may soon be without an insecticide defence against “the most destructive insect pest of potatoes worldwide.”
The Colorado potato beetle is controlled almost exclusively with insecticides, said Christine Noronha, an entomologist and researcher who helped analyze the samples.
“If the same chemical is used over and over again, the potential is there for (resistance) to become a problem.”
There is no one cure-all for the problem of insecticide-resistant potato beetles, said Noronha. She said the best solution is integrated pest management, where a variety of tools are used against potato beetles.
Besides alternating the families of insecticides applied to a field, the research centre advises growers to rotate potato crops, use insecticides sparingly with targeted applications and include new genetically modified resistant potato varieties in rotations.
John Gavloski, a Manitoba Agriculture entomologist, said growers in his province are already taking precautions to slow the problem of insecticide resistance. But he said the situation in Manitoba is becoming critical.
“It’s nothing that can be prevented,” Gavloski said. “What you have to do is slow it down.”
Some people feel Ottawa is too slow in approving more pesticides for use in Western Canada’s potato fields. Among them is Garry Sloik, of the Keystone Vegetable Growers Association.
We want it too
Sloik said American potato growers have access to pesticides not yet registered for Western Canada. “We need some of these chemicals approved PDQ,” said Sloik.
The Lethbridge Research Centre is also investigating the merits of using the insect pathogenic fungus, Beauveria bassiana, against overwintering potato beetles. Once ingested, the fungus grows inside the beetles and kills them.
The fungus is already being used in the United States, Noronha said, “and seems to be working well.”
But she said it will likely be years before a decision is made about including the fungus in the arsenal of methods used against potato beetles in Canada.
