Abstract

The in vitro efficacy of different aqueous extracts of vermicompost prepared from leaves of Azardirachta indica, Lantana camera, Parthenium hysterophorous were tested for the management of the pathogen. Vermicompost was prepared by mixing the respective substrates with cow dung slurry (9:1 ratio w/w) independently. Among the three aqueous extracts, vermicomposted neem was found to be superior to that of vermicomposted Lantana and Parthenium in suppression of growth of X.campestris. Based on the results of the in vitro studies field studies were taken up as a combination of seed treatment with vermicompost extract and soil application of vermicompost.The seeds of tomato were soaked for one hrs in different aqueous extracts of vermicomposts before sowing. The seedlings were raised in separate nursery beds of size 1m x 1m to which vermicompost was applied at the rate of 5 tons ha-1. From the nursery beds seedlings were transplanted to plots and each plant received 250g of vermicompost (spot application) in two split doses. Since the aqueous extract of vermicomposted neem showed better suppression of the pathogen in in vitro studies, the same vermicompost was used for soil application. The results showed that the best treatment for suppression of bacterial spot in tomato was seed treatment (1 h) with 10% aqueous extract of vermicomposted neem coupled with application of vermicomposted neem to the soil both during sowing as well as on transplantation. This treatment reduced the incidence of bacterial spot by 98% and resulted in maximum yield of 15.4 t ha-1. Bioagent like aqueous extract of vermicomposted neem along with the soil amendment with the same vermicompost is essential for the management of the pathogen in affected soils. Use of such alternate materials which are non-polluting, cost effective, non hazardous and do not disturb ecological balance can reduce the use of copper based bactericides, leading to elimination of copper entry into the soil system.