Avoid pruning or wounding oak trees to prevent the spread of oak wilt disease

Media Contact: Allison Sandve, University of Minnesota Extension, office 612-626-4077ajsandve@umn.edu

ST. PAUL, Minn. (4/17/2015)—To help prevent tree loss caused by oak wilt disease, Minnesota homeowners and forest landowners should avoid pruning or wounding oak trees from now through early summer.

Spring weather promotes the activity of sap-feeding beetles that can carry the fungus that causes oak wilt disease from tree to tree, said Matt Russell, University of Minnesota Extension forest resources specialist. It also can be transmitted via root grafts spreading from an infected tree.

“Oak wilt poses a significant threat to Minnesota trees,” Russell said. “It can set in rapidly during high-risk season. If a wound is unattended for more than 15 minutes, the probability of infection rises dramatically.”

The disease is a serious problem in the Twin Cities metro area and in southeastern Minnesota. All species of oaks can become infected in Minnesota, but red oak species like northern red oak, black oak, and pin oaks, are more seriously affected and can show immediate symptoms. Symptoms in red oaks are the rapid wilting of leaves which can be seen as quickly as two to six weeks after infection.

Homeowners can be proactive against the diseases by avoiding any pruning or construction activities near oaks. Any fresh wound found on an oak tree is attractive to the sap-feeding beetles that transmit the fungal disease. If pruning is absolutely necessary, seal the wound immediately with shellac or a water-based paint. It is also important not to move any firewood from oaks that may have died from oak wilt off your property.

For more information on oak wilt from the University of Minnesota Extension: z.umn.edu/oakwilt


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