How to Treat Fungus on a Tree

Your trees may become riddled with fungal disease without prevention.

Your trees may become riddled with fungal disease without prevention.

Fungal diseases account for many of the problems with deciduous trees. In many cases, proper cultural practices will prevent and sometimes even treat outbreaks of certain fungi. Fungicides will help control others, and still one fungal disease in particular, verticillium wilt, is untreatable. Knowing the tree and the fungi is the first step in dealing with the problem.


Identify the type of fungi infesting the tree. If you cannot identify it, send a sample to your local extension office for identification. Cankers often appear as darkened areas of bark sometimes sunken in. Verticillium wilt symptoms include early discoloring of leaves or whole branches dying with brown, wilted leaves attached.


Thin out the branches of the crown to allow more air circulation within the tree in late winter or early spring with loppers, a pruning saw or chainsaw depending on branch size. When thinning, cut branches back to the main trunk or to a joining branch. This helps prevent and control fungi such as leafspot and powdery mildew, two common fungal diseases.


Apply fungicides to the tree at specific times for the specific fungi. Fungicide labels include instructions for various types of fungal diseases. In most cases, an application every seven days is recommended until the problem is taken care of.


Destroy leaves infected with powdery mildew or leafspot to prevent the fungi from spreading.


Cut out any branches infected with fungal cankers such as hypoxylon, phomopsis or cytospora canker, at least 4 to 6 inches below the canker infection during dry periods or late winter.


Fertilize the tree in the early spring, and water as needed. Healthy trees are less prone to fungal and other diseases.

Things You Will Need

  • Fungicide
  • Loppers, pruning saw or chainsaw
  • Rake
  • All-purpose fertilizer or tree-specific fertilizer

Photo Credits

  • Siri Stafford/Lifesize/Getty Images
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