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Don't prune your oak trees in spring

Posted at 2:17 PM, Apr 12, 2018
and last updated 2018-04-12 14:17:06-04

Spring is finally here and that usually means spring clean up in the yards.

The Michigan DNR wants to let residents know that if you've got an oak tree on your property - don't prune it.

They say that to keep it healthy, it shouldn't be pruned from mid-April through the summer.

This is because that's a key time for oak wilt, which is an infection that can weaken white oak trees and kill red oak ones.

"Oak wilt, caused by a fungus, has been reported throughout the Midwest, including Michigan," said Ryan Wheeler, invasive species biologist with the Michigan Department of Natural Resources.

Symptoms most often appear from June until September, but the highest risk of infection happens between April 15 - July 15.

"Affected trees will suddenly begin to wilt from the top down, rapidly dropping leaves, which can be green, brown or a combination of both colors," Wheeler said.

If you suspect your oak trees have this disease: 
• Get help from an oak-wilt qualified specialist. 
Visit for a listing and more information. 
• Michigan State University’s Diagnostic Clinic can verify infection. 
Find instructions at or call 517-355-4536. 
• Report infections to or by phone at 517-284-5895; you also can use the MISIN website or mobile app.