Oak Wilt Disease Discovered in Leelanau County

Foresters in Leelanau County are trying to tamp down another outbreak of tree disease. It’s just the latest in a series of problems disrupting forests in northern Michigan and experts are calling for some heavy-duty responses.

Kama Ross spotted the first outbreak of oak wilt disease in Leelanau County just east of Lake Leelanau in Bingham Township. As the forester for three county conservation districts, including Benzie, Grand Traverse and Leelanau Counties, she’s seen it before.

“It’s been confirmed in all the other surrounding counties,” said Ross. “But this summer we did take two lab samples down to the MSU laboratories and the second sample came back positive.”

Oak wilt disease is caused by a tree-killing fungus spread by beetles. It’s also transferred from tree to tree through the roots. The disease is particularly deadly to red oaks.

Ross said these trees will need to be cut down and carefully removed or buried on site. After that, the sites will need to be contained by a five-foot trench.

Oak wilt is only one of several diseases changing the entire forested landscape of northern Michigan. Ross said over 90 percent of white ash trees will succumb to the Emerald Ash Borer within a few years. And now beech bark disease has begun to kill most of the beech trees as well.

The Leelanau Conservancy helps manage many tracts of forested land throughout the county. Executive Director Brian Price said the loss of so many trees throughout Leelanau is highly visible and a growing concern for forest managers.

“Everybody knows there’s significant forest change underway,” said Price. “Most anybody that has their eyes open as they drive up and down the roads has some sense that we are losing … whole species of trees from our forest component.”

And it could get worse. A report issued by the U.S. Forest Service in March said climate change could make invasive pests and diseases even more damaging.

Stephen Handler is the report’s lead author. He said a warming climate is changing things for both for the trees and the bugs, including the beetles that spread oak wilt.

“As winters become shorter and growing seasons extend, beetles are likely to become active earlier and may become active later into the season as well,” said Handler. “Some of these pests and these disease agents may become even more damaging if they interact with trees that are already stressed from weather or climate.”

Handler said there are things people can do, like growing trees that are common farther south – trees that are adjusted to a warmer climate such as white oak and hickory.

But the key is keeping forests diverse. A diverse forest, he said, includes many different species of trees and different age ranges – young, mature and older trees.

Handler said property owners need to be aware of the risks posed by climate change to make the right choices for the future of northern Michigan’s forests.

“It’s not like growing an agricultural crop where you have the ability to reset every year,” he said. “We’re making decisions now that we will live with for decades.”

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