Effect of Soil Water Potential on Survival of Meloidogyne javanica in Fallow Soil

Abstract

A natural infestation of Meloidogyne javanica in an aggregated Oxisol declined at an exponential rate when aliquots of the soil were stored for 72 days in polyethylene bags at various soil water potentials ([psi]). Time periods required for reduction in soil infestations by 50% were 2.7, 4.9, 110, 10, and 2.6 days at [psi] of -0.16, -0.30, -1.1, -15, and -92 bars, respectively. In the wetter soils, at [psi] of -0.16, -0.30, and -1.1 bars, the predominant stage recovered was the second-stage larva. In the drier soils, at [psi] of -15 and -92 bars, both eggs and larvae were recovered with neither stage predominating. Incidence of coiled larvae was inversely related to the [psi] value of the soil, a greater incidence occurring in the drier soils. After 15-32 days, percentages of coiled larvae were 13, 27, 55, 65, and 88% in soil at [psi] of -0.17, -0.60, -1.9, -15, and -82 bars, respectively. Key words: nematode extraction, quiescence, coiling.