Effect of chemical and soil amendment for the control of bacterial wilt of potato in Nepal caused by Ralstonia solanacearum.
Management to control bacterial wilt of potato caused by R. solanacearum (RS) race 3, biovar II was carried out by amending infested soils with stable bleaching powder (SBP) and a mixture of urea and lime (urea-lime) at different concentrations and combinations under glasshouse and field conditions in Nepal. Soils infested with RS were treated with either SBP or urea-lime mix 2 weeks before planting healthy seeds of the highly susceptible potato cultivar Kufri Jyoti. The SBP treatment at 25 kg/ha provided effective disease control in both glasshouse and field conditions; suppression of plant infection was 66.96% and 71.87%, respectively, and that of tuber infection was 76.94% and 88.89%, respectively, in the glasshouse and field. Tuber yields of the SBP treatment at 25 kg/ha were 121.5 g/plant in the glasshouse and 13.54 kg/plot in the field which were not significantly different from the treatment of SBP at 12 kg/ha + urea-lime mix at 428 kg/ha urea and 5 ton/ha lime. The RS population was reduced in all treatments except in the non-treated control. Treatment with SBP at 25 kg/ha resulted in the lowest RS population of 3.01 and 2.06 log c.f.u./g dry soil at 120 days after amendment in glasshouse and field experiments, respectively. The results indicated that the use of SBP at the rate of 25 kg/ha was more effective and suitable than the other treatments for the control of bacterial wilt in infested soils under glasshouse and field conditions. Alternatively, soil amendment with 428 kg/ha urea and 5 ton/ha lime can be used to effectively control bacterial wilt disease where SBP is not available.