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Beech Bark Disease Spreading

Beach bark disease distribution as of 2005. The insect that causes the disease was introduced to North America in Canada in the 1890s. Map courtesy of the USDA Forest Service.

Bob Bultman of the Door County Invasive Species Team reports that it is not looking good for Door County’s American Beech trees.

Beech Bark Disease, caused by an interaction between an insect and a fungus, is gaining steam. The scale insect (like an aphid) that leads to Beech Bark Disease has been confirmed in Peninsula State Park and other areas in the county.

Linda Williams of the Wisconsin Department of Natural Resources reports in her latest Forest Pest Update that surveys are continuing in Door County for the insect and the Nectria fungus.

“Samples of the scale are being taken and sent to Madison for species verification. It appears that a very light infestation of the scale insect is spread over much of Door County, but so far only the area east of Sturgeon Bay is heavily infested with mortality occurring. There are no results of the fungal survey as of yet, and it will take some years for the scale populations to build up around the county to extremely heavy infestations.”

The scale insect was introduced to Nova Scotia, Canada by accident around 1890 and has slowly made its way west.

More info on beech bark disease can be found on the DNR Forest Health website at http://dnr.wi.gov/forestry/FH/exotics/exotic-bb.htm.