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Oak wilt #922909

Asked December 16, 2025, 2:09 PM EST

In your opinion, what is the latest date we should prune our giant 200 + year-old oak tree this year in 30/6 to assure it will not get oak wilt or any other diseases I may not be familiar with. It’s an absolutely gorgeous tree and I don’t want to do anything to jeopardize it. But there is one branch hanging over our roof that needs to be taken back at the crux of a major fork branch.

Osceola County Michigan

Expert Response

Hello Pam,

It is wise to consider the time of year before pruning your oak tree. In order to prevent oak wilt disease, the best time to prune is during the winter months, between November 1 and March 14; the worst time is between mid-April to mid-July. Read the attached for more information: https://www.canr.msu.edu/resources/smart-gardening-to-prevent-oak-wilt

And here: https://www.michiganoakwilt.org/

You can use a pruning sealant but if the trees are pruned in the right time frame, it is not necessary.

To find an arborist who is an expert on oak wilt and pruning oak trees go to: https://www.michiganoakwilt.org/oak-wilt-qualified-vendor-directory

Good luck with your oak trees.

Thank you for contacting Ask Extension.


An Ask Extension Expert Replied December 18, 2025, 2:47 PM EST

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