Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 11/12/2005
Publication Date: 3/27/2006
Citation: Kousik, C.S. 2006. Managing mefenoxam-tolerant isolates of phytophthora capsici on bell peppers. Phytopathology. Posted online March 27, 2006.
Technical Abstract: Phytophthora capsici is an important pathogen of bell peppers in southern Florida. In a recent survey, over 51% of P.capsici isolates in Southeastern Florida were tolerant to mefenoxam (French et. al., Phytopathology 95:S31.2005). Since 2003, we have been testing Ranman 400SC (cyazofamid) to manage P. capsici isolates that are tolerant to mefenoxam. In detached leaf experiments where mefenoxam-tolerant isolates were used as the inoculum, Ranman 400SC at 2.75 fl oz/a sprays provided about 70% disease reduction compared to nontreated or Ridomil Gold EC (1 pt/a) sprayed controls. Experiments also were conducted in commercial fields where mefenoxam-tolerant isolates were prevalent. Drenching field plots with Ranman 400SC or combinations of Ranman plus Ridomil Gold Copper (2.5 lb/a) at transplanting, followed by sprays of the same treatments, provided nearly 98% reduction compared to nontreated control against root and leaf infections. Root and collar infections also were significantly reduced by combinations of Omega 500F (fluazinam) drench (1.5 pt/a) followed by sprays of Ranman 400SC or Ranman+Ridomil Gold Bravo.