Overview
A lethal fungal disease that affects all oak species, with red oaks dying within weeks of infection. It spreads through root grafts between neighboring oaks and via sap-feeding beetles. White oaks are more resistant but not immune.
- Type
- Disease
- Severity
- CRITICAL
- Source
- USFS
Symptoms
Rapid wilting from the top of the canopy downward in red oaks, leaf discoloration with browning at margins, defoliation within weeks of symptom onset, fungal mats under bark that crack the bark open
Affected Species
Geographic Spread
Treatments
Root Graft Disruption (Trenching)
Mechanical severing of root connections between infected and healthy oaks using vibratory plow trenching to a depth of 4-5 feet. The primary method to stop underground spread in oak groups.
Propiconazole Fungicide Injection
Macro-infusion of the fungicide propiconazole (Alamo) into root flares of high-value oaks as a preventive or therapeutic treatment. Provides 1-2 years of protection.
Avoid Pruning During Risk Period
Do not prune oaks from April through July when nitidulid beetles that carry the fungus are most active. Paint all wounds immediately if pruning is necessary during risk period.
Recommended Products & Tools
Helpful supplies for managing Oak Wilt. Always read and follow label directions, and confirm a diagnosis before treating.
Seal oak wounds immediately if pruning in the growing season.
Protectant spray for many bacterial and fungal diseases.
For the rare case sealing is advised (e.g., oaks in oak-wilt season).
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Frequently Asked Questions
What is Oak Wilt?
A lethal fungal disease that affects all oak species, with red oaks dying within weeks of infection. It spreads through root grafts between neighboring oaks and via sap-feeding beetles. White oaks are more resistant but not immune.
What are the symptoms of Oak Wilt?
Rapid wilting from the top of the canopy downward in red oaks, leaf discoloration with browning at margins, defoliation within weeks of symptom onset, fungal mats under bark that crack the bark open
Where is Oak Wilt currently found?
Oak Wilt is currently active in Iowa, Illinois, Indiana, Kansas, Michigan, Minnesota, Missouri, North Carolina, Nebraska, New York, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Wisconsin, West Virginia. It has been reported in 18 total states across the United States.
What plants are affected by Oak Wilt?
Oak Wilt affects Red Oak, Live Oak, White Oak. Susceptibility varies by species.
How do I treat Oak Wilt?
Treatment options for Oak Wilt include: Root Graft Disruption (Trenching), Propiconazole Fungicide Injection, Avoid Pruning During Risk Period. Treatment approaches may include chemical, biological, cultural, and mechanical methods depending on the severity and context.
Compare with Similar Ailments
Not sure if it's Oak Wilt? Compare it side-by-side with similar ailments.