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Oak wilt
IPM scouting in woody landscape plants > oak wilt
Cause: Ceratocystis fagacearum (fungus)

Hosts: Oaks in the red and black group are the most susceptible; white oaks are less susceptible.

Symptoms: Trees in the red and black oak group undergo wilting and rapid death within a few weeks. Those in the white oak group usually experience the death of a few branches and may live for several years after infection. Water-stressed trees can show symptoms within a week of infection. Symptoms commonly develop in July but may be earlier or later depending on the amounts of rainfall.

How it’s spread: This fungus invades the vascular system of oaks. Oak wilt is transmitted by picnicbeetles (Nitidulidae), which carry spores from infected trees to wounds on healthy trees. Healthy trees may also be infected via root grafts with infected trees.
Wilting tree
Wilt symptoms usually begin in the upper branches of the tree and progress downward.
Management: Positive identification of this disease should be confirmed by sending twig samples to MSU Diagnostic Services. Samples must be from live branches (green or white tissue under the bark) not dead branches (brown or black tissue under the bark). Collect 3 twigs (at least 1 inch in diameter and 6 inches in length) from 3 different branches with wilting leaves. Grafts between infected and healthy trees should be mechanically severed. Avoid pruning until the dormant season. If pruning or wounding during the growing season becomes necessary, wounds should be sealed immediately with shellac or a water-based sealer. Red oaks infected with wilt cannot be saved. White oaks with less than 30 percent infection may benefit from fungicide injection by qualified arborists.
Oak wilt
Oak wilt		 Infected leaves
Brown streaking is visible in the sapwood of oaks infected by oak wilt, but the amount can be quite variable. Infected leaves wilt rapidly, turn brown around the edges of the leaves and usually remain attached to the tree. Browning begins at the leaf tip and spreads downward.

Additional information

  • Oak Wilt in Michigan, Extension bulletin E-2764
  • MSU Diagnostic Services for assistance in pest identification.
  • MSU Landscape Alert newsletters for information about the current growing season, pest concerns and plant advice.
This information was developed from A Pocket IPM Scouting Guide for Woody Landscape Plants by Diane Brown-Rytlewski. Purchase this in a pocket-sized guide for reference in the orchard from MSU Extension (publication E-2839).
The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
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Updated 10/11/07