Oak wilt is a fungal disease that is spreading among trees in Michigan and many other states. It has been confirmed in much of the Lower Peninsula and in the western U.P.
The disease is lethal to many oak species — including red, pin and black. It can be transmitted by insects moving to fresh wounds on trees, including those caused by pruning, and the fungus can also spread through root systems.
"Oak wilt initially causes wilting of leaves, ultimately killing otherwise healthy trees within a matter of weeks," DNR forest health specialist Roger Mech explained. "The effects can be dramatic and costly when mature trees die and are removed, especially in highly maintained landscapes, parks and recreation areas."
Grand Haven is one community that has seen the effects of the tree disease.
“Oak wilt is very serious,” City Manager Pat McGinnis said. “It continues to invade the forests in and around the city of Grand Haven.”
This includes areas in the city’s forest dune areas on the west side of town.
“At our cemetery, we’ve identified a stand of trees just up the hill from the (cemetery) office,” McGinnis said, noting that another area of concern in the cemetery area was near Henley Drive.
To help slow the spread of the disease at the cemetery, McGinnis said the city plans to perform root trenching and trunk girdling as a preventative measure.
Officials are keeping an eye out for oak wilt in other areas, as well.
“At Mulligan’s Hollow, by the ball field, we have some oak trees,” McGinnis said. “We’re having those looked at, as well.”
For home and private property owners, it is recommended that any tree trimming be done when the risk of oak wilt transmission is lowest.
The greatest risk to oak trees is from April 15 to July 15; the moderate risk is from March 15 to April 14 and July 16 to Oct. 31; and the safest period is from Nov. 1 to March 14.
“Anytime before that, you don’t want to trim any of your oak trees,” McGinnis said. “Any trimming during the (high-risk period) is probably a death sentence for oak trees.”
With the threat of oak wilt lurking statewide, the Michigan Oak Wilt Coalition has formed as a new partnership between private, nonprofit and governmental organizations to increase awareness about the threat of the tree disease. Led by the Arboriculture Society of Michigan, the partnership also includes representatives from the Michigan Association of Conservation Districts, Michigan Department of Natural Resources, Michigan Department of Agriculture and Rural Development, Michigan State University, ReLeaf Michigan, and various electric utility companies and tree-care companies.
The coalition’s goal is to coordinate and promote a unified information campaign describing oak wilt, its threat and impact in Michigan, and to provide science-based advice aimed at prevention and management.
Information will be developed and housed online at www.michiganoakwilt.org, and is for everyone from homeowners and landowners to foresters and tree-care professionals.
By coming together and creating a coordinated message about this tree and forest health issue, the Oak Wilt Coalition believes that Michigan’s citizens and the professional tree-care industry will be better informed to make proper management decisions helping to prevent the spread of this disease and ensuring the health of oak trees in Michigan.