Oak wilt cases reported in Cass, Crow Wing counties

Oak wilt is easy to prevent but left unchecked it is deadly.

Trees with oak wilt. Photo courtesy of the Minnesota Department of Natural Resources

Invasive oak wilt is progressing northward in Minnesota into Cass and Crow Wing counties.

To prevent the spread and loss of oak trees to this deadly disease, the Minnesota Department of Natural Resources is urging residents and visitors in these counties to report suspected oak wilt now through mid-August.

Homeowners, landowners, and resort and tourism operators are on the front lines of oak wilt prevention, and are encouraged to report possible oak wilt through a new website created by the Department of Natural Resources and University of Minnesota-Extension as a part of an invasive species community science project.

While all Minnesota oak species are under threat from oak wilt, those in the red oak group are especially susceptible. Reporting will center on red oaks - oaks with pointed leaf lobes - because oak wilt is easier to identify on these trees. The website contains guidance on identification. Reports with a clear photo of the tree, branch and leaves are most helpful.

“As its name suggests, the telltale sign of oak wilt is when oak trees suddenly lose all their leaves, notably in midsummer,” Rachael Nicoll, forest health specialist in Brainerd, said in a news release. “The bad news? Oak wilt is deadly if left unchecked. The good news? Oak wilt is easy to prevent.”


Early detection is the best defense against oak wilt because it allows for proper prevention and management techniques.

“Public reporting will be the key to protecting the uninfected forests in Cass and Crow Wing counties,” Nicoll said.

Reports will be verified by staff with the DNR and the Minnesota Department of Agriculture, upon which submitters will receive an email notification.

Nicoll also cautions summer campers and recreationists not to move firewood. Moving oak firewood can spread oak wilt over long distances.

To learn more about detecting and managing oak wilt, visit the DNR’s oak wilt webpage .

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