Michelle Grabowski, UMN Extension Educator
It is now the high risk period for oak wilt in Minnesota. Gardeners in the area of the state where oak wilt occurs should not prune oaks until next fall.
Oak wilt is a fatal disease that can affect all oak trees. Red oaks can wilt and die in as little as 4 weeks. White oaks often slowly decline over several years. Protecting trees from wounds and pruning cuts during the high risk period is critical in preventing new oak wilt infections.
The good news is sap beetles can not infect an oak tree without a wound. Bark is the best protection. If an oak tree must be pruned during the high risk period, the surface of the pruning cut should be immediately covered with water based paint or shellac.
It is now the high risk period for oak wilt in Minnesota. Gardeners in the area of the state where oak wilt occurs should not prune oaks until next fall.
Oak wilt is a fatal disease that can affect all oak trees. Red oaks can wilt and die in as little as 4 weeks. White oaks often slowly decline over several years. Protecting trees from wounds and pruning cuts during the high risk period is critical in preventing new oak wilt infections.
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An oak wilt spore mat revealed below the bark of an infected oak. M. Grabowski UMN extension |