Evaluation of Pseudomonas fluorescens for biological control of wheat crown and root rot disease (Fusarium culmorum)

Crown and root rot diseases of wheat caused mainly by Fusarium culmorum and F. pseudograminearum are important diseases of wheat world wide including Iran. In this study, 60 strains of pseudomonad fluorescent bacteria were obtained and isolated from wheat rhizosphere in Tehran, Ghazvin, Golestan, Ardebil, Zanjan, Markazi and Esfahan provinces and their efficacy in biological control of F. culmorum was investigated. According to biochemical, physiological and morphological characteristics of the bacteria, the strains were very similar to biovars І, ІІІ and V of Pseudomonas fluorescence and P. protegens. Antagonistic activities of pseudomonad fluorescent strains against F. culmorum were then evaluatedResults showed that 11 isolates along with CHA0 were the most effective strains. In order to determine competition and colonization abilities of the selected stains in the soil and wheat rhizosphere, the strains were tested on four wheat cultivars for three continuous growth cycles, each which was 42 days long. The results indicated that Niknejad cv. had the highest bacterial population density after three cycles, followed by Zagross cv. The over all results of this study showed that the bacterial strains 19 and 27 (both belonging to P. progegens) had a very good antagonistic ability and have the potential for biological control of F. culmorum.