Environmental Factors Affecting Conidial Survival of Five Pear Decay Fungi. R. A. Spotts, Associate Professor, Oregon State University, Mid-Columbia Experiment Station, Hood River 97031. Plant Dis. 69:391-392. Accepted for publication 19 November 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-391.

The survival of conidia of Botrytis cinerea, Mucor piriformis, Penicillium expansum, Pezicula malicorticis, and Phialophora malorum on pear fruit surfaces in the orchard and under selected temperature-relative humidity combinations was determined. Under controlled conditions, survival half-life (T₅₀) of B. cinerea and Penicillium expansum often exceeded 1 mo, but the T₅₀s of M. piriformis and Pezicula malicorticis often were less than 2 wk. Survival of these fungi decreased as temperature increased from –1.1 to 30 C. The T₅₀ of Phialophora malorum varied from about 2 to 6 wk and was less at 20 than at 10 or 30 C. Conidial survival in the orchard was about 20–40% of that at similar temperature and relative humidity in controlled environments, and the T₅₀s in the orchard of B. cinerea, Penicillium expansum, and M. piriformis were 14.4, 6.1, and 4.2 days, respectively.