IN VITRO EFFECT OF PSEUDOMONAS FUORESCENS ON CAPSULE ROT OF CARDAMOM (ELETTARIA CARDAMOMUM MATON) CAUSED BY PHYTOPHTHORA MEADII

Abstract

Capsule rot disease of cardamom incited by Phytophthora meadii Mc Rae is a major threat in cardamom plantations during the monsoon period. Integrated management strategy has already been developed for the management of the disease at field level where Trichoderma species are being used as the biocontrol component. In the present study, in an attempt to isolate natural biocontrol agents for Phytophthora from cardamom capsules, a species of fluorescent pseudomonas was obtained in culture which is found to be inhibiting the growth of Phytophthora under in vitro conditions. In order to exploit the biocontrol potential of these bacteria for the management of capsule rot infection, a laboratory experiment was laid out using culture suspensions and filtrates. The experiment consisted of 10 treatments and 2 replications with different forms and periods of inoculation of p•fluorescens and P.meadii zoospores. The treatment includes spraying the panicles with Pseudomonas culture suspension and culture filtrate before and after infecting by spraying with zoospore suspension of Phytophthora meadii, dipping the culture suspension in culture filtrate for 24 hours and then spraying with zoospore suspension. The result clearly indicated that spraying 48hr old culture suspension on panicles prior to inoculation with zoospore suspension of Phytophthora and spraying with culture filtrate from 20 day old culture are effective in checking the infection. Hence this can be exploited as a management strategy for the field management of capsule rot infection, where either the fresh bacterial culture can be sprayed before the onset of monsoon or spray culture filtrates from stored cultures, after getting infected which could prevent or reduce the infection of capsules by the pathogens.