Populations, Pathogenicity, and Benomyl Resistance of Botrytis spp., Penicillium spp., and Mucor piriformis in Packinghouses. R. A. Spotts, Associate Professor, Oregon State University, Mid-Columbia Experiment Station, Hood River 97031. L. A. Cervantes, Experimental Biology Technician, Oregon State University, Mid-Columbia Experiment Station, Hood River 97031. Plant Dis. 70:106-108. Accepted for publication 8 August 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-106.

Populations of Botrytis spp., Penicillium spp., and Mucor piriformis were determined during two seasons in air and dump-tank water of nine apple and pear packinghouses. Populations of all fungi varied considerably among packinghouses. Spores of Penicillium spp. were more abundant in air and dump water than spores of Botrytis spp. or M. piriformis. Spores of Penicillium spp. and M. piriformis in dump water increased as the packing season progressed, suggesting that decaying fruit stored in bins and processed later in the season increased propagule levels more than did debris brought into packinghouses from orchards early in the season. Selected isolates were characterized for pathogenicity and virulence on Anjou pear fruit and resistance to benomyl. Sixty, 72, and 89% of Botrytis spp., Penicillium spp., and M. piriformis isolates, respectively, were pathogenic on pear fruit. The percentage of pathogenic Penicillium spp. isolates resistant to benomyl also increased later in the season. Benomyl-resistant isolates of Penicillium spp. were less virulent than benomyl-sensitive isolates. The percentage of Penicillium spp. isolates resistant to benomyl in the Mid-Columbia region has not increased during the last 5 yr.