Comparative evaluation of organic formulations of Pseudomonas fluorescens based biopesticides and their application in the management of bacterial wilt of brinjal (Solanum melongena L.)

Abstract

An experiment was conducted in the laboratory and farm of the Department of Biotechnology, Gauhati University, to explore the potentiality of various organic formulations of Pseudomonas fluorescens (Pf) and to manage bacterial wilt disease of brinjal (Solanum melongena L.) under local conditions. Different organic materials and adhesives were used in the formulation of Pf based biopesticides and stored at room temperature (30°C) and 4°C to evolve a suitable substrate carrier-adhesive based bioformulation on the basis of comparative longer shelf life of the biocontrol bacteria. Storage condition of 4°C was found to be more suitable as it yielded higher viable count of the biocontrol bacteria in all the organic formulations studied. The formulation CVPf was found to give highest viable count of 890.33 x 10⁸ cfu/g at 4°C and 45 x 10⁶ cfu/g at room temperature, at 120 days after storage. Five best organic formulations of Pf were selected for application by different methods in pot and field experiments to study their effectiveness in the control of bacterial wilt of brinjal. CVPf formulation and seed + root + soil method of application performed significantly better than others with 83.33% control of bacterial wilt of brinjal in field experiment conducted by completely randomized block design. Effective management of bacterial wilt of brinjal by P. fluorescens under local conditions signifies its potentiality and scope as a plant growth promoting rhizobacteria (PGPR) when formulated using effective substrate carrier and adhesive.

Key words: Bacterial wilt, substrate-carriers, bioformulation, biocontrol, plant growth promoting rhizobacteria (PGPR).