Nematicidal activity of some strains of Pseudomonas spp.

Culture filtrates of strains of Pseudomonas spp. were able to produce juvenile mortality of Meloidogyne javanica, the root-knot nematode in vitro. Seed treatment or soil drench with Pseudomonas sp. (strain 82 and 51) and Pseudomonas aeruginosa (strain-78) significantly reduced nematode population densities in soil and subsequent gall formation due to M. javanica in mungbean, under glasshouse conditions. P. aeruginosa strain-78 multiplied on talc powder and applied in soil reduced root-knot development and nematode population density under field conditions in mungbean used as first crop or succeeding crop. Strain-78 used with either Paecilomyces lilacinus or Bradyrhizobium japonicum suppressed root-knot disease compared with either antagonist used alone. Strain-78 applied in the soil amended with a brown seaweed (Sargassum tenerrimum) also inhibited root-knot development. The toxic principles of the strain-78 were partially characterized. The active factors were heat labile, sensitive to extreme pH values, polar in nature and having a molecular weight of less than 8000 MW.