VIEW ARTICLE

Ecology and Epidemiology

Microbial Activity and Biomass in Container Media for Predicting Suppressiveness to Damping-Off Caused by Pythium ultimum. W. Chen, Graduate student, Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691, Present title and address: postdoctoral research associate, Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge 70803; H. A. J. Hoitink, and L. V. Madden. Professor, and associate professor, Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. Phytopathology 78:1447-1450. Accepted for publication 5 July 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-1447.

Predictive guidelines, based on general microbial activity and biomass, were developed for the formulation of container media suppressive to cucumber damping-off caused by Pythium ultimum. Disease severity correlated negatively with microbial activity, based on the rate of hydrolysis of fluorescein diacetate, and with microbial biomass, based on extractible phospholipid phosphate content in the container media. A preliminary mathematical model for predicting Pythium damping-off severity, based on both microbial activity and biomass, is proposed, and possible applications and potential limitations are discussed.