Identification of root-knot nematode suppressive soils

In three of 12 soils obtained from agricultural fields in California, population density development of Meloidogyne incognita under susceptible tomato was significantly suppressed when compared to identical but methyl iodide (MI)-fumigated, M. incognita re-infested soils. When the 12 soils were infested with second-stage juveniles (J2) of M. incognita and the juveniles were extracted after 3 days, significantly fewer J2 were recovered from 9 of the 12 non-treated soils than from the MI-fumigated equivalents. In one of the 12 soils, infestation 3 weeks before planting resulted in lower nematode population densities than infestation at planting in both MI-fumigated and non-treated soil. The combination of infestation 3 weeks before planting with infestation at planting did not alter the occurrence or degree of root-knot nematode suppressiveness. (C) 2002 Elsevier Science B.V. All rights reserved.