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Tree-killing invasive species found in Oconto, Shawano counties

Wisconsin officials impose statewide ash borer quarantine
Posted at 11:23 AM, Sep 16, 2020
and last updated 2020-09-16 12:23:02-04

LITTLE SUAMICO/SHAWANO (NBC 26) -- Emerald ash borer, an invasive insect that kills ash trees, has been found in Oconto and Shawano counties, the Wisconsin Department of Natural Resources confirmed Wednesday.

The DNR said forestry staff have confirmed the presence of the insect in the town of Little Suamico in Oconto County and the city of Shawano in Shawano County.

A DNR forest health specialist estimates emerald ash borer has been present in the area for at least three to four years. The DNR says emerald ash borer kills all varieties of ash trees, but is not known to affect any other Wisconsin tree species.

The DNR said more than 99% of Wisconsin’s ash trees are expected to die. Once infested, ash trees generally die in four to six years, the DNR says.

Signs of EAB infestation includes woodpecker damage, thinning of the tree crown from the top, 1/8-inch D-shaped exit holes, and branches sprouting low on the trunk.

The DNR says Oconto and Shawano county woodland owners who own 10 or more wooded acres are encouraged to meet with their local DNR forester. Click here to set up an appointment.

EAB was discovered in Green Bay in 2009 and was also spotted in Marinette County in 2017.

Measures to help slow the spread of EAB include not moving firewood. If yard trees are close to houses or garages, the DNR says it is best to plan for removal or protection now. Trees on private property can be protected through the use of systemic insecticides on an annual or biannual basis.

For questions on residential trees, homeowners are encouraged to contact a certified arborist at