Department of Natural Resources advises oak tree pruning
The Department of Natural Resources reminds Minnesotans to prune oak trees before April 1 to prevent new oak wilt infestations. "The best time to prune oak trees is during the winter months when the beetles that carry the oak wilt fungus are dormant," said Ryan Blaedow, DNR forest health specialist.
Beetle activity usually peaks between April and June; however, oak wilt can be transmitted any time during the growing season when it is warm enough for the beetles to feed on the sap of wounded oaks.
"The key to keep oak wilt from spreading is to remove diseased trees before spore mats form and by preventing the transfer of spores to healthy trees," Blaedow said. "If your oaks need to be pruned, get the work done before April 1, otherwise wait until fall. Unfortunately, people who prune their oaks in the spring find their tree is dead by the end of the summer."