A new and simple baiting technique for easy isolation of Phytophthora palmivora Butl. from bud rot affected tissue of coconut

Abstract: Earlier studies using different methods of isolations revealed that it is extremely difficult rather impossible in certain cases to isolate the pathogen, Phytophthora sp. from bud rot disease of coconut due to the presence of high population of other microorganisms like bacteria and fungi in the rotten tissue. Hence, it was very much imperative to develop an easy technique for isolations of Phytophthora sp. from samples collected from various locations. In the modified baiting method, different treatments were given to infected tissues before baiting with susceptible healthy plant tissues. Among the different treatments given to infected tissue, the treatment of keeping infected tissue in carbendazim (Bavistin 50 WP) 125 ppm + rifampicin 200 ppm solution was found to be better for successful infection of baits and successive isolation of Phytophthora palmivora (Mean 30%) irrespective of the baits used. Out of the seven types of baits used in this treatments, rachillae of young unopened coconut inflorescence, leaves of Loranthus parasiticus (L.) Merr. and leaves and young fruits of badam tree (Terminalia catappa L.) were found to be superior to others (with 33-37% success in isolation) and they were statistically on par. Tender leaves of badam tree yielded the highest percentage (37) of isolation of P. palmivora, when used as bait in the treatment carbedazim + rifampicin solution containing rotten bud tissue of coconut palms. Hence it can be used for large scale isolation of P. palmivora.