2018-04-19 / Life in Leelanau

Coping with oak wilt and working to keep our healthy forests


TRENCHING TIME. Corey Parshall, owner of Parshall Tree Service, works to cut trenches between trees infected with the oak wilt fungus. As oak wilt can spread from one tree to another through intertwined roots, trenching breaks the connection between the trees’ root systems and prevents oak wilt from spreading in this manner. TRENCHING TIME. Corey Parshall, owner of Parshall Tree Service, works to cut trenches between trees infected with the oak wilt fungus. As oak wilt can spread from one tree to another through intertwined roots, trenching breaks the connection between the trees’ root systems and prevents oak wilt from spreading in this manner. If forests could talk, they might be screaming for help right now.

Following damage to ash trees inflicted by flying beetles called the Emerald Ash Borer, Oak Wilt is taking a toll on another native tree species.

As a part of efforts to combat tree pests and diseases, Leelanau Conservation District forester Kama Ross last week presented a forum entitled, “Eyes on the Forest: How to be the Best Steward of Your Trees and Forest.”

About 20 Leelanau County residents attended at the Kasson Township Hall.

Education and understanding have become critical parts of maintaining the health of area forests.

“We are dealing with a lot already that we know how to handle,” Ross said. “It’s what we don’t know that’s coming.”

She added that most insects and diseases are discovered by landowners, not foresters. “Education and observation are key.”

Not a new problem, oak wilt has been in the U.S. since the 1940s and advanced to northern Michigan in the 1980s.

“So it is here and has been killing red oaks for some three to four decades,” Ross said. “It doesn’t move fast, though if you ask someone who has oak wilt they will not agree. An oak dies within a couple of weeks.”

The fungus is close to 100 percent fatal to northern red oaks. It’s deadly because red oaks have an open vascular system that allows the fungus to travel through the tree’s conducting tubes. Once it enters the tree’s system, it typically kills the tree within 14 days.

Oak wilt spreads in two ways: beetles and roots.

Commonly called a “sap beetle” or “picnic beetle,” the Nutidulid beetle has quite a sweet tooth that’s soothed by ingesting spore mat. The fungus becomes attached to the beetle, which unknowingly spreads the disease when moving from tree to tree.

Oak wilt is also spread through tree root systems that inter-twine, creating an underground “graft.”

What’s a landowner to do?

First, don’t turn your head.

“If you suspect oak wilt, it must be confirmed,” Ross said. The treatment varies by type of fungus, pest or disease.

Typically, anytime after June 1 is a good time to spot oak wilt. The tree will look “wilted” and under the bark there will be a spore mat, which causes the bark to have a raised patch that sounds hollow when tapped.

Once confirmed, oak wilt has three options for treatment:

• Perhaps the most effective treatment is a course of injections of propaconizole made directly into the tree. The option requires hiring a professional, which according to Ross might be most effective.

“I would definitely recommend thinking about that,” she said. Injections can cost between $10 and $12 per inch of a tree’s diameter and must be repeated three times over a six-year period.

• Another treatment focuses on a tree’s root system. Trenching separates roots between trees and will be effective for five to seven years. At $3 to $4 a foot, “it is the most cost-effective way to control an outbreak,” Ross said.

The last option is to create a chemical barrier between the root system of the infected tree and the others surrounding it. A herbicide is applied as a “line” to isolate affected trees.

• For healthy oak trees, only prune when safe. No pruning should be done from April through November. Oak trees should not be transported during this time, either.

As oak comprises 10 percent of the state’s forest volume, oak wilt results in a sizable loss of timber value, wildlife benefits, aesthetic value, property value and diversity of tree species in the forest. So containment is essential.

Currently, there are only four confirmed oak wilt sites in Leelanau County. These sites are under close supervision and monitoring.

One of these sites is located on Leelanau Point, north of Suttons Bay. Ross said treatment has included tree removal, trenching and fungicide for the past six years. “We believe we have the site under control,” Ross said. “But we have to be careful because of its setting by the lakeshore.

“We have a real opportunity to have an effect on oak wilt through education here in Leelanau County.”

What’s next in the lineup of tree fungus and pests? Based on information shared by Ross, Beech Bark Disease is headed here.

It can be devastating.

In fact, Beech Bark Disease is expected to wipe out 99 percent of area beech trees.

As one meeting attendee asked, “What will be left in the woods?” After all, ash, oak and beech trees are being attacked.

Ross said steps can be taken.

“Change is happening all the time in our forests but at an accelerated rate with the current pests we are dealing with,” she said. “We definitely need to think about the loss of acorns for wildlife food and see if we can plant other native species that might fill that gap. Beech are on their way to 99 percent loss, so maybe white oak, butternut, American hazelnut, American Chestnut and other mast producing trees and shrubs that lots of wildlife will eat.

“But we all know the trees we plant are not for us,” she added. “They’re for the next generation.”

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