Improvement of bio-efficacy of bacterial antagonists by using bleaching powder and resistant cultivars to control bacterial wilt of tomato

Abstract

In present investigation, two bacterial antagonists Bacillus subtilis DTBS-5 and Pseudomonas fluorescens DTPF-3 were tested for their bio-efficacy against Ralstonia solanacearum causing bacterial wilt of tomato in combination with chemicals, viz., bleaching powder, calcium chloride, sodium carbonate and sodium bicarbonate under in vitro conditions. Sodium carbonate (0.1%) with P. fluorescens inhibited the maximum growth of R. solanacearum (10.4 cm2 inhibition zone) followed by sodium bicarbonate with B. subtilis (7.23 cm2 inhibition zone). Bleaching powder and calcium chloride in combination with the bioagents significantly increased growth inhibition of R. solanacearum as compared to bioagents alone. Bleaching powder along with resistant cultivar Arka Abha and susceptible cultivar Pusa Ruby were taken under this investigation to improve the bio-efficacy of bacterial antagonists under glasshouse conditions. Six treatments, viz., bleaching powder (0.01%) B. subtilis DTBS-5, P. fluorescens DTPF-3, bleaching powder (0.01%) + B. subtilis DTBS-5, bleaching powder (0.01%) + P. fluorescens DTPF-3 and control (only R. solanacearum) without chemical and bioagents were taken. Minimum wilt disease incidence 19.0 and 29.6% was found in combination of bleaching powder (0.01%) + B. subtilis DTBS-5 followed by 19.6 and 31.6% in bleaching powder + P. fluorescens DTPF-3 after 30 days of inoculation of R. solanacearum in Arka Abha and Pusa Ruby tomato, respectively. Integration of antagonistic bacteria, bleaching powder (0.01%) and Arka Abha reduces bacterial wilt incidence and improved bio-efficacy under glasshouse conditions.