Effect of crop rotation and cultivar resistance on bacterial wilt of tomato in Nepal

The effect of crop rotation and cultivar resistance on bacterial wilt of to mato (Lycopersicon esculentum), caused by Ralstonia solanacearum (biovar 3 and race 1), were studied from 1994 to 1996 in a field experiment in Chitwa n, Nepal. Corn (Zea mays), lady's finger (Abelomoschus esculentum), cowpea (Vigna unguiculata), and the partially resistant tomato line CL1131-0-0-43- 4 (CL1131) were rotated with susceptible tomato in different combinations. The susceptible tomato cultivar Pusa Ruby was used as an indicator plant to assess wilt severity (percent leaves wilted) in each plot after rotation. Wilt severity was significantly (P < 0.05) reduced by rotation with corn, l ady's finger, cowpea, or resistant tomato compared with continuous tomato. The onset of bacterial wilt was delayed by 1,3 weeks and wilt severity was reduced by 20-26% when susceptible tomato was grown after corn, lady's fing ers, cowpea or resistant tomato. Lower area under the disease progress curv e (AUDPC), based on wilt severity, and higher yield were observed in the pa rtially resistant tomato line CL1131 than in the susceptible tomato Pusa Ru by. Crop rotation to corn, lady's finger, or cowpea, and cultivar resistanc e appeared to be useful management strategies to control bacterial wilt of tomato in Nepal.