Prevent Oak Wilt by Pruning Oak Trees in the Winter

lschultz • November 19, 2020

Wilt pattern in oak leaves. Photo by Joseph O’Brien, USDA Forest Service.

Oak wilt is a fungal disease that is carried to oak trees by small beetles that feed on the sap produced from fresh wounds to the tree (i.e. pruning, storm damage). The spores of the fungus then move through the vascular system of the infected tree, which is responsible for transporting water throughout the tree. Once the tree detects the infection, it tries to mitigate the further spread of the fungus by plugging infected cells. This in turn leads to the browning of leaves and the wilting of branches on the oak tree. Oak wilt disease is prevalent throughout the Lower Peninsula and in regions of the Upper Peninsula along the Wisconsin border and it primarily impacts red oaks.

Although the spring season is usually the ideal time for many people to complete yard work, oak trees benefit greatly from being pruned during the winter months instead.  Oak trees are far less likely to become infected with oak wilt disease when pruned in the winter since the beetles that carry and spread the disease to the trees are almost completely inactive during the cold winter months. Thus, those who intend to prune their oak trees are encouraged to do so in the winter instead of the high-risk period from April 15-July 15 when the beetles are most active.

Firewood is also a known contributor to the spread of oak wilt disease, and oak firewood should not be moved to prevent the chance of healthy oak forests being impacted by firewood that is host to oak wilt disease. If you suspect your oak firewood to be infected, the Michigan Department of Natural Resources (DNR) recommends the wood be burned, debarked or chipped before April. Or, once the wood has dried for a year and the bark has loosened, the oak firewood is unlikely to spread disease.

If you’re interested in learning more about oak wilt disease and what you can do to prevent it, please review the Michigan State University Extension article on the topic HERE . More information is also available from the Michigan DNR HERE .

Recent Posts

By Justin Tomei June 30, 2025
FOR IMMEDIATE RELEASE MUCC Submits Public Comment in Support of Line 5 Tunnel Project Lansing, MI — Michigan United Conservation Clubs (MUCC), the nation’s largest statewide conservation organization, has submitted formal public comments urging the U.S. Army Corps of Engineers to approve the Enbridge Line 5 Tunnel Project. In a letter submitted today, MUCC emphasized the need to move this critical infrastructure forward to protect the Great Lakes while maintaining safe, reliable energy transportation. “MUCC supports the tunnel project as the best available alternative to reduce the risk of an environmental disaster in the Straits of Mackinac while continuing to deliver essential energy products to Michigan families and industries,” said Amy Trotter, CEO of MUCC. “We believe the tunnel project strikes a balance between protecting the environment and maintaining energy security.” MUCC’s position is backed by a formal resolution passed by its membership, which includes thousands of hunters, anglers, trappers, and outdoor enthusiasts across Michigan. The resolution supports the tunnel as a long-term solution that replaces the aging and exposed pipeline segment currently crossing the Straits, offering greater environmental safeguards through secondary containment. The organization cited the Draft Environmental Impact Statement (EIS), which acknowledges the tunnel’s benefits, including reduced spill risk and a controlled, buried environment for transporting light crude oil and natural gas liquids. MUCC also rejected the "no action alternative," which would allow the existing line to remain in operation without any new protective infrastructure. “Other alternatives, like transporting fuel by truck or rail, are inefficient and carry greater environmental and safety risks,” Trotter added. “Allowing the current line to operate exposed on the lakebed indefinitely is simply not acceptable.” MUCC’s comment stresses that the organization is not weighing in on the type of energy transported, but rather on the environmental risks and safety benefits of the tunnel itself. Originally approved by the Michigan legislature and governor in 2018, the Great Lakes Tunnel Project represents a once-in-a-generation investment in infrastructure and environmental protection. MUCC urges the U.S. Army Corps of Engineers to issue the necessary permits and move forward with construction without further delay. For Media Contact: Justin Tomei jtomei@mucc.org 517-346-6488 #####
By Olivia Triltsch June 26, 2025
Since its inception, MUCC has made great strides in the conservation of natural resources through advocacy, habitat, youth education, and communications.
By Katelyn Helsel June 25, 2025
On Saturday, June 21, 2025, MUCC’s On the Ground program partnered with the Pierce Cedar Creek Institute (PCCI) for a native plug planting day in Barry County. Located on 850 acres, the institute offers both environmental education opportunities and serves as a biological field station for conducting research. Many diverse native communities from wetlands to prairies are present at PCCI, and many rare or threatened species in Michigan like the eastern box turtle call the institute home. 
More Posts