Extreme cold can help slow spread of invasives

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Extremely cold temperatures can help slow the spread of invasive species like Emerald Ash Borer, but one Minnesota DNR forest health specialist doesn’t expect this cold snap to have much of an impact.

Eric Otto said when it gets to -10, EAB has about a 30 percent mortality rate. When temperatures get to -30, 90 percent can die off. But there’s more to factor in.

"It’s important to note that the Emerald Ash Borer overwinters under the bark, its larvae, so it does have some insulation there. And then more so if that tree is covered by snow, that’s an extra layer of insulation," Otto said.

He doesn’t expect the current cold snap to have too much of an impact.

"You really aren’t going to have an impact unless you have like a polar vortex in 2019 that we had where temperatures were -30, -40," he said.

According to Otto, EAB has been found in Duluth, but it hasn’t popped up yet in the forests outside the city. He said the DNR continues to monitor for it.

"They’re always going to be here. You can’t eradicate them with cold weather, unfortunately," he said. "But the population can be decreased."

People should not transport logs that are in quarantine areas. So if an ash tree is cut down in Duluth, it shouldn’t be taken outside the city because Emerald Ash Borer larvae can live under the bark and spread to live ash trees.