Effect of Culture Filtrates of Streptomyces spp. on the Mortality and Hatching of Root-Knot Nematode, Meloidogyne javanica

Six isolates of Streptomyces spp. were isolated from the rhizosphere of tobacco fields in Andhra Pradesh and Karnataka. Culture filtrates of all six isolates of Streptomyces spp. showed lethal effect against M. javanica at different levels. Percentage mortality and inhibitory effect on hatching of M. javanica were directly proportional to the concentration of culture filtrates and exposure period of each filtrate. Rate of mortality was low in the first 24 h but it appreciably increased with the increase in exposure period. Different dilutions of Streptomyces culture filtrates of all the isolates were hatch inhibitors to a varying degree. Isolate 2 was found to be more effective among all isolates followed by isolate 5 in both mortality and hatching inhibition. There was a relative decrease in larval emergence with the corresponding increase in the concentration of culture filtrates.