Use of Pseudomonas fluorescens as a biopesticide for management of bacterial wilt disease caused by Ralstonia solanacearum 97

Virulent cells of bacterial antagonist P. fluorescens strain PfD-1 were used to prepare a biopesticide mass multiplied in organic substrates like Vermicompost, Farm Yard Manure (FYM) and Mustard oil cake (MOC). The substrate based biopesticide showed effective results in suppression of bacterial wilt (c.o. Ralstonia solanacearum) incidence in tomato (Lycopersicon esculentum) in fields of Assam during 2004-06. Quantitative aspects of population dynamics of P. fluorescens at different days of storage were also made and showed that the antagonist maintained a steady population count up to 250 days of storage at room temperature. Substrate based biopesticide of vermicompost, P. fluorescens, carboxy methyl cellulose (CMC) and mannitol was found to be most efficient on the basis of the mean population recovery (105.56 x 108cfu/ml) at different days after storage. Application of vermicompost, P. fluorescens, CMC and Mannitol as a seed treatment, root application and soil application at transplanting followed by soil application 30 days after transplanting (DAT) showed minimum wilt incidence (8.83%), maximum yield (72 kg /plot = 360 q/ha) and highest population count (58.93 x 108cfu/ml) of P. fluorescens in the crop rhizosphere. A negative correlation between the population dynamics of P. fluorescens and per cent wilt incidence, a negative correlation between per cent wilt incidence and yield and a positive correlation between the population dynamics of P. fluorescens and yield were recorded.