Chestnut Blight
Cryphonectria parasitica
Overview
A devastating fungal disease that virtually eliminated the American chestnut from eastern North American forests in the early 20th century. The fungus kills the above-ground portion but roots may survive and resprout.
Symptoms
Sunken, orange-brown cankers on bark that expand and girdle branches and trunks. Orange-yellow fungal fruiting bodies (stromata) erupt through bark. Wilting and death of branches above cankers. Epicormic sprouting below cankers.
Environmental Conditions
Humid
Prevention
Plant blight-resistant hybrid chestnuts. Avoid planting American chestnuts in areas with the pathogen. Hypovirulence (biological control with virus-infected fungal strains) shows promise in Europe.
Management
Hypovirulence treatment (inoculating cankers with virus-infected fungal strains). Mud-packing cankers. Plant resistant hybrids (American x Chinese crosses). Support breeding programs for resistant American chestnuts.