Many state parks, recreation areas, state forest campgrounds and other state-managed land have been impacted by oak wilt. The deadly fungus can kill healthy trees within a matter of weeks. Oak wilt is spread by sap-feeding beetles, which are also known as "picnic beetles." To help prevent the spread of oak wilt, do not move firewood and do not prune oak trees during the growing season.
Like American elm in the 1950s and ash trees in more recent history, Michigan's red oak trees are facing potentially significant die-offs due to an exotic and largely invisible killer: oak wilt. A deadly fungus that can kill previously healthy trees within a matter of weeks, oak wilt is spread by sap-feeding beetles - also known as "picnic beetles" - that introduce the disease to freshly wounded trees. The fungus then quickly moves through the underground root systems that connect entire stands of oak trees, rapidly increasing the impact of one infected tree.
Oak wilt moves slowly on its own through root systems and travels short distances overland when new spores are moved by beetles from an infected tree to a freshly pruned or injured tree. Oak wilt can be moved long distances when people move infected firewood from one location to another. Look for red oaks that suddenly drop their leaves in the summer. The disease spreads, killing nearby oaks from one year to the next. Currently, oak wilt is generally distributed throughout the Midwest and Texas.
What could happen in Michigan?
Once established, if not treated, oak wilt will continue to spread, killing all red oaks in a forest, park and/or neighborhood. Oak wilt has already taken out tre
es in many state parks and recreation areas.
What can you do?
Use local firewood. Oak wilt is spread by the movement of infected wood. DO NOT prune oak trees during the growing season. If you need to prune oaks, DO NOT prune them between April 15 and July 15.