A beech scale nymph. Image: USDA Forest Service
A beech scale nymph.
Wisconsin State officials are cutting down trees in Whitefish Dunes State Park in Door County that are infected with beech bark disease.
The park has lots of beech trees and those that are infected pose a safety hazard, said Linda Williams, a Wisconsin Department of Natural Resources forest health specialist. Weakened limbs and trunks can snap off or fall over during strong winds. The idea is to remove dead trees before they harm visitors or staff.
Infected trees that are within 75 feet of park trails are targeted, said Arnie Lindauer, a program analyst for the park.
This is the first year the park has performed a cutting, said Jerry Leiterman, district park supervisor for northeastern Wisconsin.
The disease is caused by beech scales, an invasive insect that feeds on beech sap. The scales poke holes in the trees to reach the sap. A type of fungus called neonectria later infects the trees through these holes and cut off nutrients, killing the trees.
Not much else can be done. “When you have a large forest area, there’s no feasible way out there to combat the spread of the fungus,” said Leiterman.
Distribution of beech scales in Michigan in 2011. Image: Michigan Department of Natural Resources
Beech bark disease spread to Wisconsin after it was found in Michigan in 2000. The disease has almost spread throughout the entire eastern Upper Peninsula and much of the Lower Peninsula, said Robert Heyd, a forest health specialist for the Michigan DNR.
To reduce the number of infected trees in Michigan, state officials cut them down from mid-July to early winter. The DNR also advises people not to move infested wood that has been recently cut at state parks.
“Besides that, there’s really not much else we can do to stop it,” said Heyd.
The disease was found in Door County in 2009. There have been no other Wisconsin counties infected, said Williams.
Some trees are resistant to beech bark disease. The Michigan DNR is working with a laboratory of the U.S. Department of Agriculture Forest Service’s Northern Research Station in Delaware, Ohio, to tag them for further study, said Heyd.