Identification and Thermal Sensitivity of Two Bacterial Pathogens of Agaricus bisporus. D. J. Royse, Assistant Professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. P. J. Wuest, Professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Plant Dis. 64:455-457. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-455.

The bacterial blotch pathogen was recovered from horticultural grade peat moss treated with aerated steam for 30 min at 52.2 C (126 F). A 30-min treatment with aerated steam at 52.5 C eliminated the bacterial blotch pathogen from mineral soil and the pathogen of mummy disease from artificially infested soil. In general, as the treatment temperature increased from 43.8 C (111 F), the number of bacteria recovered from soil or peat decreased. Both bacterial species were eliminated at 55 C (131 F), regardless of substrate, when moisture contents were maintained at field capacity before and during the treatment. Our studies resulted in a technique whereby these two pathogens can be quantified in mushroom casing, either soil or peat moss.

Keyword(s): Agaricus brunnescens, mushroom diseases, Pseudomonas tolaasi, P. fluorescens biotype Va, selective medium.