Establishment of Heterodera glycines in Three Soil Types

The establishment ofHeterodera glycines race 3, from soil plugs infested with population densities ranging from 0 to 10 eggs and second-stage juveniles per 10 cm(3) soil, was compared in three soils (Haynie sandy loam, Eudora silt loam, and Chase silty clay loam) that were either pasteurized or unpasteurized. Final population densities of H. glycines in soil and on soybean (Glycine max cv. Williams 82) roots were affected by soil type but not by soil pasteurization (P = 0.05). Higher numbers of H. glycines females and cysts were recovered from the sandy loam than from the silty loams after 8 weeks. The relationships between initial populations in infested soil plugs and the levels of recovery in the previously uninfested soils were described by sigmoidal Gompertz growth models. Estimated threshold levels for establishment were approximately 75% lower in the sandy loam than in the silty loams.