Weed Control in Soybean (Glycine max) with Lactofen Plus Chlorimuron

Field experiments were conducted over a 3-yr period at three locations to evaluate lactofen at rates of 110 to 220 g ai ha−1applied POST in combination with chlorimuron at 9 g ae ha−1for weed control in soybean. At St. Joseph in 1989 and Baton Rouge in 1990, lactofen at 110, 150, and 170 g ha−1in combination with chlorimuron controlled prickly sida (3 to 5 cm) and entireleaf and pitted morningglory (5 to 13 cm) comparable with the full rate of lactofen at 220 g ha−1plus chlorimuron and the standard treatment of acifluorfen at 280 g ae ha−1plus bentazon at 560 g ae ha−1. Entireleaf morningglory and sicklepod control at Alexandria with lactofen at 110 to 170 g ha−1plus chlorimuron was comparable with that from the full rate of lactofen plus chlorimuron and better than with acifluorfen plus bentazon. Weed control was reduced when soil moisture was deficient at treatment time or when prickly sida height was more than 5 cm and entireleaf morningglory, pitted morningglory, and sicklepod more than 15 cm. In related studies at St. Joseph, a reduced rate of lactofen (170 g ha−1) in combination with chlorimuron controlled prickly sida 98%, pitted morningglory 93%, and entireleaf morningglory 90% in 1988, which was comparable with the control from the full rate of lactofen plus chlorimuron and with acifluorfen plus bentazon.