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Disease Control and Pest Management

Biological Control of Meloidogyne javanica with Bacillus penetrans. G. R. Stirling, Senior research officer (Nematology), Department of Agriculture, Loxton, S.A., 5333, Australia, Present address: Department of Primary Industries, Plant Pathology Branch, Meiers Road, Indooroopilly, Queensland, 4068, Australia; Phytopathology 74:55-60. Accepted for publication 22 June 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-55.

Tomato roots containing females of the root-knot nematode, Meloidogyne javanica, infected with Bacillus penetrans were air-dried and finely ground to produce a powdery material heavily laden with spores of B. penetrans. When this material was incorporated into root-knot-nematode-infested field soil at rates of 212- 600 mg per kilogram of soil, galling of tomato roots and the number of nematodes in the soil at harvest was reduced significantly. Nematode control was similar to that usually obtained with nematicides. Before the tomatoes were planted, treated soils were bioassayed for B. penetrans by adding juveniles of M. javanica and counting the number of juveniles encumbered with spores 24 hr later. Control was obtained in the field when at least 80% of the bioassayed juveniles were encumbered with 10 or more spores per nematode. Laboratory experiments showed that spore-encumbered juveniles were less able to invade roots than were unencumbered juveniles. Numbers penetrating roots decreased with increasing spore concentration and as the distance juveniles moved in soil increased. Spores of B. penetrans did not always germinate after adhering to juveniles and more than five spores were required per nematode to ensure infection. In pot experiments with grapes, there were significantly fewer root-knot nematodes in vineyard soil infested with B. penetrans than in similar soil without the pathogen, suggesting that B. penetrans increased naturally in vineyards to levels sufficient to reduce root-knot nematode populations.