Chestnut Blight
CRITICALCryphonectria parasitica
Overview
A fungal disease that functionally eliminated the American chestnut as a canopy tree species in eastern forests by the mid-20th century. Once numbering in the billions, mature American chestnuts are now exceedingly rare. Root sprouts survive but are re-infected.
- Type
- Fungus
- Severity
- CRITICAL
- Source
- USFS
Symptoms
Sunken orange-brown cankers on bark, yellowish-orange fungal fruiting bodies on cankers, wilting of foliage above canker, sprouting below canker, bark splitting around canker margins
Affected Species
Geographic Spread
Treatments
Hypovirulence Biological Control
Introduction of a virus (Cryphonectria hypovirus) that weakens the blight fungus, allowing trees to compartmentalize cankers. Has shown success in Europe but limited efficacy in North American forests due to fungal diversity.
Backcross Breeding Programs
The American Chestnut Foundation's breeding program crosses American chestnuts with blight-resistant Chinese chestnuts, then backcrosses to recover American traits. Producing potentially blight-resistant trees for restoration planting.
Recommended Products & Tools
Helpful supplies for managing Chestnut Blight. Always read and follow label directions, and confirm a diagnosis before treating.
Broad-spectrum protectant for many fungal leaf and bark diseases.
Preventive spray for needle cast, leaf spots, and blights.
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Frequently Asked Questions
What is Chestnut Blight?
A fungal disease that functionally eliminated the American chestnut as a canopy tree species in eastern forests by the mid-20th century. Once numbering in the billions, mature American chestnuts are now exceedingly rare. Root sprouts survive but are re-infected.
What are the symptoms of Chestnut Blight?
Sunken orange-brown cankers on bark, yellowish-orange fungal fruiting bodies on cankers, wilting of foliage above canker, sprouting below canker, bark splitting around canker margins
Where is Chestnut Blight currently found?
Chestnut Blight is currently active in Alabama, Connecticut, Delaware, Georgia, Illinois, Indiana, Kentucky, Massachusetts, Maryland, Maine, Michigan, Mississippi, North Carolina, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, Vermont, Wisconsin, West Virginia. It has been reported in 25 total states across the United States.
What plants are affected by Chestnut Blight?
Chestnut Blight affects American Chestnut. Susceptibility varies by species.
How do I treat Chestnut Blight?
Treatment options for Chestnut Blight include: Hypovirulence Biological Control, Backcross Breeding Programs. Treatment approaches may include chemical, biological, cultural, and mechanical methods depending on the severity and context.