Incidence and Pathogenicity of Phyllosticta vaccinii and Botryosphaeria vaccinii on Cranberry. G. J. Weidemann, Department of Plant Pathology, University of Wisconsin, Madison 53706. D. M. Boone, Department of Plant Pathology, University of Wisconsin, Madison 53706. Plant Dis. 67:1090-1093. Accepted for publication 6 April 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1090.

Botryosphaeria vaccinii and Phyllosticta vaccinii were compared on the basis of incidence and pathogenicity to cranberry leaves and fruit. P. vaccinii was associated with preharvest fruit decay and was pathogenic to leaves, shoots, and fruit in growth chamber tests. Maximum disease severity on leaves and fruit occurred when plants were incubated at 28 C following a 72-hr dew period at 24 C. B. vaccinii established latent infections on naturally infected cranberry leaves and fruit and caused postharvest decay in fruit stored at 24 C. Inoculated fruit developed fruit speckle symptoms or decayed in growth chamber tests. B. vaccinii was found in samples from all the production areas surveyed, whereas P. vaccinii was recovered only from New Jersey and Massachusetts.

Keyword(s): Guignardia vaccinii.