Colonization of Delicious Apple Fruits by Alternaria spp. and Effect of Fungicide Sprays on Moldy-Core. M. A. Ellis, Assistant Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster, and Ohio State University, Columbus 43210. J. G. Barrat, Professor, Division of Plant and Soil Science, West Virginia University Experiment Farm, Kearneysville 25430. Plant Dis. 67:150-152. Accepted for publication 8 July 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-150.

Fourteen genera of fungi were isolated from the core region of Delicious apple fruits. Alternaria spp. were the most commonly isolated fungi. Alternaria spp. colonized flower parts during and shortly after bloom and later moved (presumably through the open calyx tube) into the receptacle or core region of the fruit. During 2 yr of testing in Ohio, Alternaria was recovered from the core region of almost 100% of all Delicious fruits tested at harvest. The mean percentage of fruit with moldy-core (visible mycelia in the core region at harvest) was 38 and 65% in 1980 and 1981, respectively. A variety of fungicide spray programs had no effect on the rate of flower and fruit colonization by Alternaria spp. or on the incidence of moldy-core at harvest.