Effect of Preharvest Pear Fruit Maturity on Decay Resistance. R. A. Spotts, Associate Professor, Oregon State University, Mid-Columbia Experiment Station, Hood River 97031. Plant Dis. 69:388-390. Accepted for publication 19 November 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-388.

Quantitative monthly changes in resistance of attached and detached Anjou, Bartlett, and Bosc pear fruits to several decay fungi were determined. During the last month before harvest, susceptibility to decay caused by Mucor piriformis increased in Anjou and Bartlett and susceptibility to decay caused by Botrytis cinerea and Penicillium expansum increased in Anjou. Susceptibility of Bartlett to B. cinerea and P. expansum appeared to increase gradually during the growing season. Fruits inoculated 3 or 4 mo before harvest with B. cinerea, M. piriformis, and P. expansum were highly resistant to decay. However, fruits were susceptible to Pezicula malicorticis 4 mo before harvest, and susceptibility continued throughout the growing season. This pattern of decay resistance also was evident in detached fruits. Detached fruits inoculated with P. malicorticis and Phialophora malorum and incubated at 20 C were not infected, but severe decay occurred when fruits were incubated at –1.1 C.