Summer Cropping Effects on the Abundance of Meloidogyne arenaria Race 2 and Subsequent Soybean Yield.

A summer-planted crop of alyceelover significantly (P < 0.05) increased the soil abundance of Meloidogyne arenaria race 2 juveniles by 3.7-fold when measured in the following spring. Maize, sorghum, and soybean had no significant effects on residual nematode numbers over the same period. Summer plantings of aeschynomene, cotton, hairy indigo, tespedeza, millet, peanut, and sorghum-sudangrass were as efficient as fallow in reducing root-knot nematode population levels. Soybean yields (averaging 2,156 kg/ha) were significantly increased over that of monocultured soybean (1,179 kg/ha) when grown in soil previously fallowed or planted to aeschynomene, hairy indigo, peanut, and sorghum. No significant differences in yields were achieved from soybean when grown in soil previously cropped to alyceclover, cotton, lespedeza, maize, or sorghum-sudangrass. Nematode numbers, which average 2,140 juveniles/100 cm(3) soil following the second year of cropping with soybean, were not related to previous cropping history and had increased an average of 9.3-fold over the course of the study.