Trees provide our properties with shade, privacy, and natural beauty. These landscape landmarks seem so big and strong, it’s hard to imagine anything harming their health. But trees, like humans, get diseases. For instance, all oak trees are susceptible to a disease called oak wilt, but it’s most fatal for the red oak family, including scarlet and black oaks. Here’s what you need to know about this deadly disease.

How It Works

Oak wilt is a quick-spreading fungal disease. Sap-feeding beetles carry the fungus, Bretziella fagacearum, into the tree via open wounds or pruned areas. Once the tree is infected, one way that the disease spreads to other trees is when fungal spores travel through the sick tree’s root system to healthy trees nearby. The disease ultimately destroys a tree’s vascular system, blocking water and nutrients from traveling throughout the tree. Eventually, it kills the entire tree. The fungus, however, lives on and reproduces, and finds its way to other oaks.

Symptoms of Oak Wilt

Trees infected with the disease may die as quickly as three or four months after the first symptoms appear. Symptoms vary from tree to tree and different species, but the signs all occur in late spring through summer. First, foliage at the top of the tree wilts. The leaves begin to brown around the edges, eventually falling to the ground prematurely. Fungal spores form mats under the bark and cause the bark to split open. Dark streaks in the sapwood are another symptom that’s found by removing the top layer of bark on an infected branch. The symptoms of oak wilt are similar to other tree diseases, so it is wise to get a professional to properly diagnose.


There is no cure for oak wilt, therefore, prevention and early identification is important. Here are some helpful tips.

  • Don’t prune oak trees from mid-April through early October, during the growing season. Fresh pruning wounds attract sap beetles that could potentially be carrying the disease.
  • Immediately paint over open wounds that occur after a storm or branch breakage. This prevents beetles from being drawn to the tree by the smell of sap.
  • Properly clean pruning tools so diseases are not transmitted from one tree or shrub to another.

What to Do About Oak Wilt

Once a tree is infected with oak wilt, removal is inevitable to prevent the spread of infection. Identifying and treating tree disease is difficult and time is of the essence. Call in an expert as soon as possible if you suspect any issues. Contact Free Spray Lawn Care at 419-529-5296 and we’ll help you keep your trees and landscaping healthy and beautiful.