Evaluation of Ethiopian isolates of Pseudomonas fluorescens as biocontrol agent against potato bacterial wilt caused by Ralstonia (Pseudomonas) solanacearum

Abstract

A total of 50 fluorescent pseudomonas were collected from different potato growing areas in Ethiopia isolated and characterized, and evaluated on king’s B medium for their antibiosis towards Ralstonia solanacearum the pathogen of bacterial wilt of potato. Out of the 50 isolates only three i.e., Pf S2, Pf Wt3 and PfW1 showed inhibition against the growth of the pathogen. To test their antagonistic effect under greenhouse condition an experiment was conducted using sterilized soil. Tubers of bacterial wilt susceptible potato clone CIP 383031.15 were used. The potato tubers were dipped into 48 hrs old culture suspension of the three isolates i.e., Pf S2, Pf Wt3, PfW1 and Pfri (Indian reference strain) for 1 hr and planted in pots containing sterilized soil. Bacterization of tubers with isolates Pf S2, Pf Wt3, and PfW1, significantly reduced by 59.83% the incidence of bacterial wilt compared to the pathogen-inoculated control and increased plant growth (plant height and dry weight) by 59.83%, 76.89% and 28.44%, respectively. This suggests the importance of the studied isolates as plant growth-promoting rhizobacteria.