Now that it’s April, experts say don't prune oak trees until after July…if you want to keep them safe from the oak wilt pathogen. Oak wilt is a deadly fungus that gets transmitted through tiny sap beetles.
DNR Forest Health specialist Brian Schwingle says oak wilt works in a similar way as Dutch elm disease, which devastated North American elm populations in the 20th century. Both are fungal diseases spread through beetles. But Schwingle says out of the two, oak wilt is much easier to prevent.