Inoculum Availability and Pathogenic Variation in Botryosphaeria dothidea in Apple Production Areas of North Carolina. T. B. Sutton, Department of Plant Pathology, North Carolina State University, Raleigh 27650. J. V. Boyne, Department of Entomology, North Carolina State University, Raleigh 27650. Plant Dis. 67:503-506. Accepted for publication 8 November 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-503.

Ascospores and conidia of Botryosphaeria dothidea were trapped in rainwater at four orchard monitoring sites in the mountains and Piedmont of North Carolina in 1976 and 1977. The relative proportion of B. dothidea ascospores and conidia trapped in rainwater varied by location and growing season. All isolates collected from wood or rotting fruit were pathogenic on apple fruit. Isolates of B. dothidea collected within various production areas in the Piedmont and mountains of North Carolina varied in pathogenicity, but the amount of variation generally was consistent from location to location. White rot disease of apple fruit may be more severe in Piedmont growing areas than mountain growing areas because of the warmer mean temperatures during the growing season or prior to harvest.