Abstract of Centennial Session Presentation

Plant Pathology in 1908/2008

Recent advances in research and management of chestnut blight on American chestnut. G. Griffin. Dept. of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University. Phytopathology 98:S7.

Several approaches have shown promise for American chestnut restoration since the killing of about 3.5 billion canopy American chestnut trees by chestnut blight after 1904. Using the backcross breeding method proposed by C. Burnham, and hybrid trees having blight resistance from Chinese and/or Japanese chestnuts, highly blight-resistant chestnut trees have been recovered in the second cycle of backcrossing. Resistant trees from a third cycle are being produced. Low levels of blight resistance have been identified in some large, surviving American chestnut trees and their intercross progeny. Second-generation intercross progeny are being evaluated for resistance. The technology needed to produce a blight-resistant, transgenic American chestnut has been developed. Natural or introduced hypovirulent strains of the blight fungus, infected with hypoviruses, have yielded some blight control on susceptible American chestnuts in forest sites. A large body of fundamental research information has been produced to aid hypovirulence research. Hypoviruses from Italy have helped produce a high and durable level of blight control on grafted large, surviving American chestnuts 25 years after inoculation. Forest management practices and environmental factors have influenced blight resistance and the durability of chestnut blight control.