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 Ralstonia solanacearum (RS) (Syn. Pseudomonas solanacearum) 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 of Nepal. Soils infested with RS were treated with either SBP or urea-lime mix two weeks before planting with the highly susceptible and healthy potato seeds cultivar Kufri Jyoti. The SBP treatment at 25 kg/ha provided an effective disease control for both glasshouse and field conditions in which disease suppressions in glasshouse and field experiment were 66.96 percent and 71.87 percent for plant infection and 76.94 percent and 88.89 percent for tube infection as compared to nontreated control, respectively. 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 nontreated control in which the treatment SBP at 25 kg/ha demonstrated the lowest RS population of 3.01 and 2.06 log cfu/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 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 the bacterial wilt disease where SBP is not available.