Other Michigan Trees Threatened

October 23, 2007
| By Pete Daly |
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The emerald ash borer isn’t the only evil weevil loose in the Michigan forest.

“There are more on the radar,” said Nancy A. Carpenter, executive director of the Arboriculture Society of Michigan.

Two threats in particular are the hemlock wooly adelgid and beech bark disease.

Beech bark disease is established in Michigan forests now, and it “really does a number on big, old American beech trees,” said Michigan State University professor Deborah McCullough, who holds a dual doctorate in entomology and forestry.

Beech scale is a tiny insect that causes beech bark disease to spread — which it is doing across the Upper Peninsula and in parts of the Lower Peninsula.

“It probably came from Europe. We’re not sure how it got into Michigan,” said McCullough. It has been in Nova Scotia since 1890, she said, but wasn’t discovered in Michigan until 2000.

According to Roger Mech of the Michigan Department of Natural Resources, the state stands to lose an estimated 800 million board feet of beech lumber. Although not at the top of the list of valued hardwoods, beech lumber does have some industrial uses such as factory flooring.

Many large beech trees that are dying of the disease have already been cut by the state, including some at Ludington State Park and at Tahquamenon Falls in the U.P.

Mature beech trees produce nuts that are a critical food source for many deer, black bear, squirrels, grouse, ducks and other birds and animals prized by hunters. Beech scale “is a disaster for animals,” said McCullough.

The hemlock pest is not established in Michigan yet, “but we’ve dodged a couple of bullets,” said McCullough. It is established on the East Coast and in Pennsylvania and West Virginia. Hemlocks are one of the most common trees in Michigan’s northern forests. Last summer, a landscape company in Michigan brought home some West Virginia hemlocks that turned out to be infested. The trees had to be destroyed. Native hemlocks in that area have been treated with insecticide and are being monitored by the Michigan DNR and Department of Agriculture, plus other agencies.

“If this becomes established in Michigan, we expect to lose most of our mature hemlock trees. It’s really going through the Smoky Mountain National Park right now, just clobbering them,” said McCullough.

Hemlock plays a major role in Michigan forests. Deer rely on the young hemlocks for food, and hemlocks also help prevent erosion along forest streams.

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