Biocontrol of Meloidogyn javanica Inducing Olive Root-Knot under Green-house Conditions and by use of Fluorescent Pseudomonads

Rhizosphere soil samples were collected from olive orchards of Golestan, Guilan, Zanjan and Qom provinces. Fluorescent pseudomonad strains were isolated from the collected samples on King’s B medium and their phenotypic features characterized as based on the standard bacteriological methods. For all the tested strains oxidase reaction, fluorescent pigment, growth at 4˚C and arginine dihydrolase were positive while tobacco hypersensitivity reaction, levan production on 5% sucrose and pectolytic activity on potato slices were proved negative. Most of the tested strains reduced nitrate while liquidizing gelatin. Based upon the phenotypic features of the tested strains most were identified as P. fluorescns while a few identified as P. Putida. Nematicidal activity of the cultural filtrate of the Psudomonas strains was tested on fresh hatched juvenile of Meloidogyne javanica under laboratory conditions. They caused nematode mortality ranging from 13.33 to 100% while showing significant differences. Efficacy of the representative strains along with fenamiphos on nematode egg productions, juvenile and mature nematode activity on olive root were studied under green-house conditions. Significant differences were observed among the applied treatments. The highest and lowest nematode juvenile and mature formation on olive seedling roots were observed for control plants and plants treated with fenamiphos respectively. The most effective strains on the different nematode life stages were P. fluorescens strains CHAO as well as strain 208. The highest and lowest nematode egg production on olive seedling roots were observed for control plants and plants treated with strains CHAO vs. strain 99 respectively. Some strains proved to be more effective than fenamiphos in nematode egg production on olive seedlings roots. This is the first report of the biocontrol of olive root knot nematode using flourescent pseudomonads.