INTERACTION OF FENSULFOTHION AND PHORATE WITH PREEMERGENCE HERBICIDES ON SOYBEAN PARASITIC NEMATODES

Abstract

The herbicides alachlor, linuron, vernolate and metribuzin were applied to plots treated with the nematocide fensulfothion or the insecticide phorate and planted to soybean in 2 locations in North Carolina [USA]. In 1976, treatment with fensulfothion + alachlor or vernolate, phorate + alachlor or metribuzin resulted in greater nematode population densities than no treatment or treatment with either fensulfothion or phorate alone. In 1977, fensulfothion and phorate alone and in combination with the preemergence herbicides effectively controlled Tylenchorhynchus claytoni. Late season population resurgence of Heterodera glycines occurred in fensulfothion + alachlor treated plots. Correlation coefficients for H. glycines vs. yield were -0.48 (P = 0.05) and -0.46 (P = 0.05) for 30 and 68 days after planting, respectively.