Emerald ash borer mitigation effective so far

Pictured is an adult emerald ash borer with its wings spread. (Special to The Globe)

WORTHINGTON — Since the Minnesota Department of Agriculture confirmed the presence of the invasive emerald ash borer in Worthington last summer , local and state officials have set a plan in motion to slow the spread of the destructive beetle.

Immediately following the discovery, MDA placed a quarantine on Nobles County, meaning that residents are not allowed to transport hardwood out of the county. That quarantine is still in place.

"Not moving firewood is the most important message for everyone, especially those living in known infested areas," said Jonathan Osthus, an MDA research scientist. "Insects can emerge from firewood more than a year after being cut."

Another way officials have minimized the beetle's spread is by removing ash trees. Worthington Public Works Director Todd Wietzema explained that the city has a plan to remove 10% (150 trees) of its ash trees each year over a 10-year period in an effort to spread out the cost of the tree removal.

So far, mitigation efforts have been effective.


"We haven't seen a large expansion of the (infected) area," Wietzema said.

Osthus agreed that the emerald ash borer has stayed confined to one local area, adding that "this will change over the next five or so years as the population builds up and new satellite infestations begin to fester miles from the original location."

Osthus explained that MDA had planned to host local field workshops in March to help public works employees, private tree care companies and interested members of the public to learn about EAB management, but the COVID-19 pandemic made in-person workshops impossible. MDA will try to reschedule those for winter of 2021, he said, but if meeting face-to-face still doesn't work, the events will go virtual.

Ongoing research is hopeful, Osthus added, but for now, "our best path forward is to try and slow the advance of EAB throughout the state."

Both state and local officials will continue to monitor the insect's spread, and they ask that local residents help by adhering to the quarantine.

Pictured are the holes generated by emerald ash borer. They must have a flat bottom, or "D" shape. (Special to The Globe)

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