VIEW ARTICLE

Disease Control and Pest Management

Mushroom Brown Blotch: Effects of Chlorinated Water on Disease Intensity and Bacterial Populations in Casing Soil and on Pilei. 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. Phytopathology 70:902-905. Accepted for publication 7 March 1980. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-70-902.

Severity and incidence of brown blotch caused by Pseudomonas tolaasii (= P. fluorescens) in the cultivated mushroom (Agaricus bisporus) was reduced by routine waterings with chlorinated water. Both disease severity and incidence were closely correlated with the occurence of P. tolaasii on mushroom pilei, but not with numbers of P. tolaasii in the casing soil. Furthermore, bacterial populations in the casing soil were not correlated with those on the surface of mushroom pilei. Thus, control of brown blotch apparently is due to protection of pilei rather than reduction of bacterial populations in casing soil. The efficacy of chlorinated water was not significantly increased by acidification (pH 3.5) with hydrochloric acid.