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Effect of Nematode Inoculum on Suppression of Root-Knot and Cyst Nematodes by the Nematophagous Fungus Hirsutella rhossiliensis. B. A. Lackey, Department of Nematology, University of California at Davis, Davis 95616-8668, Current address: Zeneca Ag Products, Richmond, CA 94804-0023; B. A. Jaffee, and A. E. Muldoon. Department of Nematology, University of California at Davis, Davis 95616-8668. Phytopathology 84:415-420. Accepted for publication 8 January 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-415.

The effect of pelletized hyphae of Hirsutella rhossiliensis on penetration of tomato roots by Meloidogyne javanica and cabbage roots by Heterodera schachtii was measured in cups containing 100 cm3 of field soil. The soil (50 pellets) was infested with egg masses or cysts when placed into cups on day 0 or with juveniles on day 14. Seedlings were planted on day 17, and roots were measured and stained on day 22. The fungus always was more effective in soil infested with juveniles than in soil infested with egg masses or cysts, but substantial variability among trials within experiments limited our quantitative inferences. Suppression of nematodes per centimeter of root averaged 42 or 98% in soil infested with egg masses or juveniles of M. javanica and 83 or 98% in soil infested with cysts or juveniles of H. schachtii. Hirsutella rhossiliensis did not suppress M. javanica in egg mass-infested loamy sand when nematode density, as determined by bioassay, exceeded 1,200/100 cm3 of soil but suppressed H. schachtii in cyst-infested loamy sand and loam regardless of nematode density.

Additional keywords: biocontrol, biological control.