Population of the olive root nematode (Meloidogyne javanica) was reduced by application of fluorescent pseudomonad strains isolated from rhizospher. Soil samples from olive roots planted in north, north-east and central of Iran were collected randomly and bacterial strains were isolated on King’s B medium. Liquid culture filtrate of some bacterial strains showed nematicidal activity when they applied on fresh-hatched M. javanica larva under laboratory condition in a randomized design. Tested bacterial strains showed significant differences in their nematicidal activity and more than 80% larva mortality was recorded. Representatives of bacterial strains and nemacur were applied on nematode under green-house condition in a randomized block design and the population of nematode as well as fresh root and top height of olive were recorded. Results indicated that bacterial strains showed significant difference in their effects on olive growth factors and nematode population. They reduced M. javanica population up to 63.5% and increased olive fresh weight and height. Phenotypic features of the effective Pseudomonas strains were as follow: They grew at 4 and 41°C, oxidase, arginine dihydrolase and fluorescent pigment production on King’s B medium were positive and levan formation on 5% sucrose, potato rot and tobacco hypersensitivity reaction were negative. Based on these characteristics most of them were identified as Pseudomonas fluorescens and a few as P. putida.
