Control of Root Rot of Peppers Caused by Phytophthora capsid with a Nonionic Surfactant. M. E. Stanghellini, Department of Plant Pathology, University of Arizona, Tucson 85721. D. H. Kim, S. L. Rasmussen, and P. A. Rorabaugh, Department of Plant Pathology, University of Arizona, Tucson 85721. Plant Dis. 80:1113-1116. Accepted for publication 20 June 1996. Copyright 1996 The American Phytopathological Sociely. DOI: 10.1094/PD-80-1113.

Motile zoospores were identified as the sole infectious propagule of Phytophthora capsid responsible for spread of the pathogen in a recirculating rock wool cultural system. Amending the nutrient solution with a nonionic surfactant resulted in the elimination of zoospores and 100% control of the spread of the root pathogen from a point source. In the absence of the surfactant, all of the pepper plants within the cultural system, irrespective of plant age, died within 2 weeks following hypocotyl-inoculation of a single plant, which served as the source of secondary inoculum. The potential significance of surfactants for the control of polycyclic soilborne diseases attributed to Phytophthora spp. and other Zoosporic pathogens is discussed.

Keyword(s): pathogen dispersal, polycyclic diseases, Pythium aphanidermatum