Characterization of Phytophthora capsici on diverse hosts, its survival and management

A cooperative research project of the University of Florida and the University of Puerto Rico investigated the occurrence, epidemiology, and management of the oomycetic pathogen, Phytophthora capsici. Significant losses due to this disease consistently occur in bell pepper and summer squash production in south Florida. Other vegetable crops affected include tomato, eggplant, cantaloupe, cucumber, pumpkin, and watermelon. In Florida, isolates of P. capsici from different production regions were compared on the basis of characteristics such as pathogenicity, mating type, and resistance to mefenoxam. The variation in the pathogenicity of P. capsici isolates was examined in four vegetable hosts: pepper, summer squash, tomato and watermelon. The pathogen's ability to survive in the soil type and agricultural system of south Florida was examined and our data suggest that the survival of oospores and other propagules easily spans the short summer fallow period. Phytophthora capsici was recovered from tailwater and retention ponds in southwest Florida, thus suggesting another potential source of inoculum. Field sampling of common weeds found two species which harbored the pathogen. Control of the disease by chemicals is difficult because of the rapid rate of development of the disease, especially under ideal environmental conditions, and insensitivity to fungicide. Components of an integrated, multi-tactic management program including cultural, chemical, and biological control methods were examined in field studies. Results obtained in Florida are serving as the basis for similar research in Puerto Rico. This project has led to a greater understanding of the variability, survival and management of this disease.