Control of root rot of peppers caused by Phytophthora capsici with a nonionic surfactant

Motile zoospores were identified as the sole infectious propagule of Phytophthora capsici 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.