Oak Wilt destroying Clare County trees

Photos of dead and dying oaks were taken on M61 in Hatton Township. Above is a leaf from a diseased tree.

Photos of dead and dying oaks were taken on M61 in Hatton Township. Above is a leaf from a diseased tree.

By Pat Maurer

“It’s definitely a big issue and people need to know about it,” said Nia Becker, Conservation District Forester for Clare and Gladwin Counties.
Becker was talking about Oak Wilt, which is killing oak trees all over the county. “You can see what it is doing east of Harrison’s airport and in the Cranberry Lake Road area,” she added.

In a spring release, Becker said, “Oak Wilt is a fungal disease that affects oak trees. Red oaks (pointed leaf edges) are most vulnerable, while White Oak (rounded leaf edges) are more resistant.”

She said an infected Red Oak can die within weeks or months. “As the tree is infected, leaves will turn brown and wilt from the top down. Within four to six weeks, all the leaves will fall. The following spring after the tree has died, you may be able to see a mass of fungus underneath the bark.”

She continued, “This disease can be spread in two ways. First it can spread from tree to tree though underground root connections. It can also be spread by “picnic beetles.” When a picnic beetle feeds on an infected tree, then moves to a healthy tree, it will spread the fungus.” She said the beetles are attracted to open wounds, which is why it is so important to avoid pruning from April to July.

9-8-17 Oak Wilt Wilted trees along street

“I’m worried about accidents that could take place when the dead trees come down in a windstorm,” said Celeste Przystrup, who contacted the newspaper to say that she has already had many of the trees in her yard removed because of the fungus infection and the danger of the dead and dying trees.

“I just had ten trees removed that are dead or dying and I will have to take down about 20,” Przystrup added. “I first noticed it in May. Trees up to 120 feet tall in the woods behind my property have no bark about half way down. It’s dangerous especially near homes. And it’s not just my area, it is happening all over Clare County.” She lives in Lake of the Pines near Farwell.

A University of Michigan release said, “During the year that the tree wilts and dies, the fungus produces special mat-like structures, called pressure pads. These pads form between the bark and wood splitting the bark. They are covered with the spores of the fungus.”

The release added, “To determine whether a Red Oak has died from Oak Wilt, examine the bark for cracks and splitting. Remove the bark near cracks to examine the wood beneath for fungal pads.”

Becker said the only treatment for Oak Wilt is preventative – a fungicide injection annually to healthy trees. “This must be done by an arborist and is usually only use for high value trees,” she said.

9-8-17 Oak Wilt tree2

She said an infected tree can spread the fungus, either through the root connections with nearby oaks or by the beetles who feed on the sap under the bark of an infected tree and take the spores to another tree.

Once infected, the trees, and their roots must be removed and disposed of carefully, so the fungus doesn’t spread. Once cut, Becker recommends covering the wood by a tarp, which increases the temperature of the wood and destroys the beetles that feed on the fungus and spread the infection. She said she recommends that infected trees be removed professionally if possible.

She cautioned that moving firewood (from an infected tree) can also spread the fungus. “Do not move firewood and always use local wood to minimize the spread of Oak Wilt and other forest pests.”

Treatment (tree removal) should be at the end of the growing season. Oak trees nearby also should be cut. She said the formula for determining which trees could be infected by a connected root system is determined by how far away healthy trees are and how big the infected tree is.

She urged again, “Don’t prune from April through July. “In March Michigan saw one of the strongest windstorms in the last 20 years. Thousands of trees across the state were toppled or damaged. Wind damage to oak trees can leave them vulnerable to infection by Oak Wilt, a deadly disease. Fortunately the beetles that spread Oak Wilt are not active until April.

The Michigan Department of Natural Resources Forest, Mineral and Fire Management said, “Prevention is critical. It is much easier, cheaper and more effective to practice prevention than to try to stop the disease once it is established.”

Becker said, “There are hundreds, or possible thousands of trees that are dead or dying. A Red Oak tree can die in weeks. A White Oak dies one branch at a time over a longer period.”

She said oak trees make up ten percent of Michigan’s forest trees and that Oak Wilt is very similar to Dutch Elm disease, which is also a fungus.

For more information on Oak Wilt or other forest issues, contact Clare Conservation District Forester Nia Becker at (989) 539-6401 or by email at nia.becker@macd.org.

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