Cultural Characteristics and Pathogenicity of Glomerella cingulata Isolates from Apples in Alabama. A. J. Latham, Department of Botany, Plant Pathology, and Microbiology, Auburn University, AL 36849. J. C. Williams, Department of Research Data Analysis, Auburn University, AL 36849. Plant Dis. 67:1065-1068. Accepted for publication 11 April 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1065.

Apples inoculated with the perithecial type of Glomerella cingulata produced orange conidial masses on apple lesions that became gray and then black after 10–12 days of incubation at 28 C. Apples inoculated with the asexual chromogenic type produced orange conidial masses on apple lesions that became reddish brown after 12 days of incubation at 28 C. Monoconidial isolates from both types were found that produced few or no conidia on apple lesions. Results similar to those found in the laboratory occurred on apples naturally infected by G. cingulata under orchard conditions. The overall growth rate of apple lesions caused by perithecial types was significantly greater than those of the asexual chromogenic types; however, conidial mass ratings of the asexual chromogenic type were significantly larger than those of the perithecial type.