Oak wilt in Minnesota: updated fact sheet and resources

Tree care professionals, woodland owners, and urban natural resource managers are greatly concerned with managing oak wilt across Minnesota. Oak wilt is responsible for killing large numbers of oaks annually across the state. A recent confirmation of oak wilt in Morrison County near Little Falls makes it the most northwestern find in Minnesota. Researchers and forest health specialists from the US Forest Service, MN Department of Natural Resources, and University of Minnesota Extension recently published an updated fact sheet on oak wilt in Minnesota.

Former or current oak wilt locations in Minnesota are shown as red dots (July 2015; courtesy MN Department of Natural Resources; CLICK to enlarge). Data are compiled from confirmed oak wilt locations obtained from the University of Minnesota’s Plant Disease Clinic.

Oak wilt occurs in 24 states in the eastern United States. In Minnesota, the disease is currently found in an area bounded on the north by Pine County, on the west by Stearns and Nicollet counties, and south to the Iowa border. Oak wilt is most severe in red oak group species such as northern red oak and northern pin oak.

The fact sheet represents an assessment of the current status and trends of oak wilt across Minnesota, highlighting tree symptoms and the biology of the oak wilt fungus. Management strategies and best practices are presented for managing and mitigating the spread of oak wilt throughout the state.

Interested readers can find the updated fact sheet here. There is also a printer-friendly (PDF) version of the fact sheet. Keep up-to-date on the current risk period of the disease by visiting MyMinnesotaWoods’ oak wilt risk page.

Matt works on issues related to forest ecosystem health. He's based in St. Paul.

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  1. I am the caretaker of a cemetery in Sauk Centre, and have noticed numerous white oaks that are losing leaves suddenly and have dead branches. One looks dead already. They have areas of leaves that are turning brown. I am concerned about losing the trees and also the cost of removing them if they do die. I understand that oak wilt isn’t supposed to here yet but it sure seems to have like symptoms. Is there a way to verify what is going on with these oaks. If it isn’t oak wilt what else could be causing the problem? I see plenty of oaks in the area with like symptoms.

  2. Your map “Current Oak Wilt Locations in Minnesota” is not the result of a survey, it’s more of a collection of “reported cases.” You’re not seeing it in, say, Morrison County not because it isn’t there, but mostly because there are fewer residential, high value trees there, and no one reports a dead oak tree in the woods. True of false? How are these data points collected?