PO Box 88, Manistee, Mi 49660

231-723-6996 or 231-845-2500 jamesscarlata@hotmail.com

Is it Oak Wilt?

photo credit: Joseph O'Brien, USDA Forest Service
Wilt pattern in oak leaves


photo credit: Bill Radtke, Michigan DNR Forest Health Program
Oak wilt mortality after firewood introduced

Why we care

Oak wilt kills healthy red oaks. White oaks can also be affected but are more resistant and less vulnerable to mortality from the disease. Once a red oak becomes infected with the oak wilt fungus, the tree will die, and there is no treatment to save the infected tree. Once an oak wilt infection is confirmed, however, treatments are available to save surrounding oaks and stop the spread of this disease.


What is at risk?

All red oaks are susceptible to oak wilt. Red oaks are common urban and suburban landscape trees. The loss of these trees can have a significant

negative impact. In the forest, red oaks are also an important producer of acorns for wildlife habitat. Using 2011 Forest Inventory and Analysis data along with the current average stumpage price for red oak sawlogs, it is estimated that the value of red oak timber in Michigan is approximately 1.6 billion dollars.

The threat

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 neighborhood or a forest.

What can you do?

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. DO NOT move firewood. Oak wilt is spread by the movement of infected wood.