Emerald ash borer found in trees near Caledonia
Brianna Jett, bjett@postbulletin.com
CALEDONIA— At least 20 trees have been decimated by the latest infestation of the emerald ash borer beetle near Caledonia in Houston County. The infestation is within an area already quarantined by the Minnesota Department of Agriculture. “I wouldn’t say it was a big surprise,” said Mark Abrahamson, a state entomologist who confirmed the infestation.
The beetle burrows into ash trees and eats the tree’s food supply, eventually killing it. The insect is not native to the country and has killed tens of millions of trees in 18 states since its accidental introduction. “This is as close to Caledonia as it’s come,” said Valiree Green, a forester with the Minnesota Department of Natural Resources.
Adult emerald ash borers can fly to new locations but are often transported when people buy and move firewood.
“By itself, the bug doesn’t move very far — it’s people moving the wood,” Green said. “For us, the biggest thing is to remind people you have to be careful about firewood,” Abrahamson said.
Minnesota Department of Agriculture officials strongly caution the public to only buy and use local firewood. This is especially true for quarantined areas that are already home to confirmed infestations.
Houston County has been under quarantine since 2009. Other quarantined counties in the state include Hennepin, Ramsey and Winona. The new site is 10 miles from the closest infestation area, which Abrahamson called a “big jump.”
Although he said distribution of the insects is spotty, he expects many more trees to die between the two sites. “There are probably other ones no one has come across,” he said.
Abrahamson said the beetles spend most of their lives in wood. They’re able to live in firewood for years, emerging as late as two years after the tree is first cut into logs. “Cutting the tree into pieces doesn’t kill the insects,” he said.
Instead, there are two ways to deal with an infestation. In the city, Abrahamson said officials will often cut down and destroy infected trees, killing the insects. They can also use insecticide.
Green said emerald ash borers can be devastating to small towns with many ash trees. She recommends that homeowners with healthy ash trees start work to prevent fatality. “People who have high value, healthy ash trees should treat them,” she said.
When the beetles are found in natural areas the process is different. “This will be another opportunity for us to look at biological control,” Abrahamson said about the recently confirmed site.
Biological control is when officials use natural predators to attempt to solve the problem. In this case, the federal government has identified an Asian wasp that kills the beetles. The wasps have been researched and released around the country, Abrahamson said. “We don’t know yet how much of an impact they’ll have on the EAB population,” he added.
