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What is Oak Wilt?
Oak wilt is a deadly fungal pathogen disease that has spread throughout much of the oak range in Michigan and across the eastern United States. Oak Wilt has the potential to impact the 149 million red oak trees across the forested land in Michigan.
Symptoms of Oak Wilt
An infected tree is often first noticed due to a sudden drop or browning of leaves in the summer months. Leaves tend to brown from the tip to the stem. Often the leaf tips and edges will be brown while the leaf base will remain green. Oak death from oak wilt occurs rapidly, beginning at the top of tree and proceeding downward. Complete leaf loss and tree death can happen within two to three weeks.
How is it Spread?
Spread of oak wilt occurs when the fungus travels through the roots of infected and healthy trees. Once a single tree is infected, the disease will spread to other oaks through their grafted root network.
Tree Trimming Tree Wounds
Oak tree trimming, pruning and harvesting during the warmer months, April – July, can result in more new tree infections.
It is this time of year when certain sap-feeding beetles have the potential to spread oak wilt spores overland from oak to oak.
Moving firewood from symptomatic oaks is one of the most common ways oak wilt is spread to new areas. Oaks that die this year will be especially hazardous next year.
Treatment and Removal
Should injury to oak trees occur, tree wounds should be immediately coated with a latex-based paint. This is one of the few cases where tree paint is recommended.
Infected areas and oak wilt symptomatic trees require special disposal care and tree stump removal and treatment by certified arborists. Trees already infected with oak wilt cannot be saved.
Do not prune, harvest or thin oak trees during the warmer months, April – July.
Spore mat on tree with oak wilt, feeding ground for beetles
Red Oak leaves with oak wilt
Resources: MSU Extension Publication “Understanding Oak Wilt” May 7, 2018
MSU Extension Publication “Worried About Oak Wilt” April 5, 2019