Exploitation of epiphytic microorganisms and organic preparations for the management of Choanephora pod rot of cowpea

Abstract

Exploration of epiphytic microorganisms from different plant parts and their exploitation for the management of plant pathogens is a relevant approach in view of greater awareness of pollution free environment. The aim of the present study was to analyze the microbial communities with special focus on antagonists isolated from the fructosphere of cowpea (Vigna unguiculata L. Walp.) and the use of organic preparations such as panchagavya, jeevamruth, compost tea, vermiwash and fish amino acid for suppression of Choanephora cucurbitarum, the pathogen inciting pod rot in cowpea. A collection of six isolates of bacteria and fungi were isolated through serial dilution technique, and their efficacy in suppressing the pathogen were tested under in vitro conditions. Among the six isolates, the bacteria and fungi with maximum inhibitory activity against the targeted pathogen were selected for further identification and in vivo assay. Based on the cultural, morphological and biochemical characters, the bacterial and fungal antagonists were identified as Pseudomonas fluorescens and Trichoderma virens, respectively. In vitro assay of the organic preparations revealed that vermiwash (5% and 10%), jeevamurth (10%) and panchagavya (10%) completely inhibited the growth of pathogen. Application of effective dose of organic preparations and the selected antagonists on the excised cowpea pods revealed that, among organic preparations jeevamurth (10%) exhibited maximum suppression of pod rot by 60.64%, however the selected bacterial antagonist, i.e., P. fluorescens gave complete suppression of the pathogen. Under in vivo conditions, jeevamurth (10%), vermiwash (5%), T. virens (106cfu/ml), and P. fluorescens (106cfu/ml) showed the maximum suppression of the pathogen and the percentage suppression was recorded as 87.33, 75.22, 75.27 and 72.31% respectively. Therefore, the present study revealed that the organic preparations such as jeevamurth (10%), vermiwash (5%), and the indigenous species of Pseudomonas fluorescens and Trichoderma virens obtained from the fructosphere can be used in integrated disease management strategies against Choanephora pod rot of cowpea.