Control of bacterial wilt of potatoes in naturally infested soils by bacterial antagonists

Antagonistic abilities of different bacterial strains were investigated as possible methods of control for bacterial wile of potatoes caused by Pseudomonas solanacearum. Out of 54 bacteria isolates procured from different sources or isolated from potato rhizosphere soil, only three Bacillus spp., i.e., B. subtilis (S1, B5), B. cereus(B4) and an avirulent strains of P. solanacearum (BCA) exhibited antagonism against the bacterial will pathogen both under culture and glasshouse conditions. Te test their antagonistic activities in field, a randomized block experiment was carried out in naturally infested soils at Bhowali (1500 m above sea level, masl) in Kumaon hills of Uttar Pradesh, India, including five treatments and five replications. The experiment was repeated at three locations. Healthy seed potatoes bacterized with B4, B5 and nea brought down the incidence of wilt to nearly one third in case of B4, and B5 and one fourth ill case of BCA compared to control. Reduction in brown rot infection in harvested potato tubers was brought down to be nearly one third by B4, one fourth by B5 and one sixth by BCA From that of control. Substantial increases in per cent yields of 22.72, 46.47 and 62.27 were obtained compared to the control, when healthy tubers before planting were treated with B4, BS and BCA respectively. Strain S1 of B. subtilis did nor prove effective in controlling bacterial wilt when tried in the field even though it did inhibit P. solanacearum under culture and glasshouse conditions.