Oak wilt is killing Michigan oak trees

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By: Lia Kananipuamaeole Kamana
Ingham County Chronicle staff writer

Tree dying of oak wilt. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

Tree dying of oak wilt. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

Michigan oak trees don’t have to worry just about getting cleared out for the construction of neighborhoods, homes, businesses and schools anymore. These days an oak tree’s biggest concern is a fungus known as oak wilt that constricts the water-conducting vessels.

According to Steve Martinko of Michigan Organic Tree Care, the first kind of infection occurs in the leaves and spreads through the branches, trunks and roots.

 

“The roots take the pathogen and disperse the infection like cancer,” said Martinko.

Once oak wilt infects a tree, there is no cure and the best thing to do is start protecting nearby trees from getting infected.

Infected oak leaf. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

Infected oak leaf. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

“Worst thing you can do is cut down a tree that has oak wilt without protecting other trees,” said Martinko.

One way for oak wilt to spread is through reverse osmosis. According to Martinko, reverse osmosis is when the water from the root system of the infected tree moves to the water system of the nearest tree. This can occur when an oak tree is cut down. Trenching can prevent it.

“People need to know that they need to trench around the diseased tree before they cut it down. That is where most of the problems lie,” said Martinko.

Open wound due to pruning on an oak tree. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

Open wound due to pruning on an oak tree. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

The second way for oak wilt to spread is through sap beetles. According to Martinko, sap beetles’ job is to patch up and heal open wounds caused by pruning.

“The beetles come to these trees for the sap and get the spores of the disease on their feet and spread it pretty readily,” said Ron Murray of the Michigan Department of Natural Resources.

According to Martinko, sap beetles are dormant throughout the winter and the times one has to worry is during those warm summer months.

“Best thing people can do is not prune their tree between April 15 and July 15,” said Murray.

Murray said that most tree-trimming companies are aware of this oak wilt time frame, but that the state Department of Natural Resources send letters out to remind people anyways.

The Sierra Club of Mid-Michigan is teaching people about oak wilt and trying to find ways to prevent the spreading of oak wilt in the state of Michigan.

Trees that were killed by oak wilt. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

Trees that were killed by oak wilt. Photo courtesy of Roger Mech, Michigan Department of Natural Resources.

“We have been encouraging local governments on the city and county level to learn about the threat of oak wilt to our precious oak trees. Sierra Club is actively seeking legislation that will adopt a ban on cutting and pruning Michigan Oaks statewide from April through July,” said Mark Muhich of the Mid-Michigan Sierra Club.

“Oak trees are the ‘keystone species’ of the forests and urban landscapes of southern Michigan,” said Muhich. “Losing our oak trees to oak wilt, as is happening in Wisconsin and Minnesota, would be a catastrophe for Michigan.”

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