Management of bacterial wilt of solanaceous vegetabbles using microbial antagonists

Abstract

Studies on 'Management of bacterial wilt of solanaceous vegetables using microbial antagonists' was conducted at the College of Horticulture, Vellanikkara during 2000- 2002. The major objective was to find out effective microbial antagonists against bacterial wilt ofbrinjal, chilli and tomato. Estimation of population of R. solanacearum showed the maximum in Vellanikkara than Ozhalapathy. The total rnicroflora was higher in Ozhalapathy than Vellanikkara and resistant varieties of the three crops recorded better association of microflora than susceptible ones. In in vitro evaluation , rhizosphere organisms isolated from the low wilt incidence area (Ozhalapathy) exhibited better antagonism against R. solanacearttm than those isolated from Vellanikkara. Among them, fungi were more effective than bacterial and actinomycete antagonists. The major fungal antagonists belonged to Trichoderma spp. and Aspergillus spp. T. viride (Ozhalapathy), T. pseudokoningii (forest soil) and Aspergillus niger (Eruthyampathy) were the most effective ones against R. solanacearum. Among the bacterial antagonists, P. aeruginosa and B. subtilis (Vellanikkara) were promising one. All commercial antagonists viz. T. viride, A. niger (Varanasi), A. niger (AN 27) T. harziamtm, B. subtilis and P. fluorescens were also effective against R. solanaeearum. Of the culture filtrates tested, T. virens and.E. subtilis (commercial) showed the maximum inhibition of the pathogen. The antagonists which were found most effective in laboratory condition performed well in pot culture studies also. Among the different methods of application of antagonists adopted, either seed treatment + soil drenching or root dipping were effective in reducing the wilt incidence and in delaying the wilt appearance. Use of antagonists in highly susceptible varieties did not give a promising control of bacterial wilt under field condition. In field trial, using a moderately resistant variety Mukthi, antagonists showed some effect in controlling bacterial wilt indicating that, an integrated effect by combined use of host resistance and microbial antagonists can provide a better control of bacterial wilt pathogen in the field.