Relationship of Apple Fruit Maturity and Inoculum Concentration to Infection by Glomerella cingulata. James P. Noe, Graduate Student, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602. Thomas E. Starkey, Assistant Professor, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602. Plant Dis. 66:379-381. Accepted for publication 21 July 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-379.

An inoculum concentration of 10⁷ conidia per milliliter resulted in 65% infection of mature apple fruit by Glomerella cingulata. The rate of infection dropped off rapidly to only 25% at 10⁶ conidia, and no infection occurred at 10⁴ or 10³ conidia per milliliter. Wounding did not affect the percentage of fruit developing lesions. Sucrose concentration and pH of extracted juice from apple fruit were not positively correlated with susceptibility to infection by G. cingulata. Apple fruit was susceptible at all stages of development.

Keyword(s): bitter rot, epidemiology.