MSU Extension:

Fresh pruning wounds of oak trees attract beetles that spread oak wilt. It is critical to not prune oaks from April 15-July 15 in Michigan.

Oak wilt is an aggressive disease that affects many species of oak (Quercus spp.). It is one of the most serious tree diseases in the eastern United States, killing thousands of oaks each year in forests, woodlots and home landscapes. Oaks in the red oak group, distinguished by oak leaves with pointy lobes (Photo 1), are much more susceptible to the disease than white oaks, distinguished by oak leaves with rounded lobes. However, all oaks can be affected.

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