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Incidence of Chestnut Blight and Survival of American Chestnut in Forest Clearcut and Neighboring Understory Sites. G. J. Griffin, Professor, Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061. . Plant Dis. 73:123-127. Accepted for publication 27 July 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0123.

In 1985 and 1987, chestnut blight incidence and survival of American chestnut sprout clusters (groups of stems sprouting from a single stump) were assessed in Virginia and West Virginia forest clearcut sites, 1319 yr after clearcutting, and in understory sites. Overall, sprout cluster blight incidence averaged 96.3% in 17 clearcuts and 37.1% in 13 understory sites; chestnut sprout cluster survival averaged 55.7 and 94.2% in clearcut and understory sites, respectively. In the 1987 survey, mean chestnut survival (49.8%) in 12 clearcut sites was significantly less than mean survival (93.7%) in 12 adjacent understory sites. Chestnut survival was 0% in three 13- to 19-yr-old clearcut sites, but 100% chestnut survival was found in one 13-yr-old clearcut site. Among clearcuts, chestnut survival greater than 0% was associated with a relatively open canopy. Superficial cankers, assayed by canker dissection, were found in 15 of 30 clearcut and understory sites, and had a greater frequency on sprout clusters with canopy or subcanopy stems than on clusters with small stems.

Keyword(s): Cryphonectria parasitica, Endothia parasitica, hypovirulence.