Identifying and preventing Ohio's deadly Oak Wilt disease

Right now the state of Ohio is under a full-on fungal assault of its oak trees. The culprit, Oak Wilt Disease, is a deadly fungus that effects every oak species and has been found in the majority of Ohio’s 88 counties. This disease can kill infected trees in a matter of a few weeks.

If your or your neighbors have oak trees on your property, the best defense against is to be proactive. Here is how to identify, prevent and treat Oak Wilt Disease:


  • Leaves in the canopy of the tree wilt or whither.

  • Whole branches or portions of a tree’s crown turn red-brown.

  • Spore-bearing fungal mats may split the tree’s bark, causing it to fall off. While there are many wilting diseases that affect trees, this symptom is specific to Oak Wilt.

Proper disease diagnoses by a certified arborist is recommended, as symptoms of Oak Wilt are similar to other types of wilt.


  • Oak Wilt is spread overland by sap-feeding beetles (Nitidulids); and underground, through neighboring root systems.

  • Overland spread occurs when Nitidulids, which are attracted to fungal mats, carry the disease to other healthy trees with fresh wounds. This can be prevented by making sure your Oak Trees don’t sustain wounds between April 15 and July 1. In other words, don’t trim or prune at all during this time period.

  • Underground spread can be prevented by severing diseased or potentially diseased root contacts between unhealthy and healthy oaks. This technique requires trenching or cutting through the soil to reach the roots, and is best left to professionals.


  • After consulting with a certified arborist, chemical treatments may be used to prevent the spread of Oak Wilt if underground spread is likely.

  • The only fungicide proven to prevent Oak Wilt, Propiconazole, is injected into the tree’s root flares.

  • The treatment is recommended in the early spring but should be used as soon as a tree is deemed at risk.

If you have concerns about Oak Wilt on your property, contact Ripley Tree Service for a free consultation. We are an independent family business with three certified arborists on staff, serving northeast Ohio since 2001

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