Herbicide programs for red rice (Oryza sativa) control in soybean (Glycine max)

A study was conducted in 1994 and 1995 at two Mississippi locations to evaluate preplant incorporated (PPI) and preemergence (PRE) applications of alachlor, clomazone, SAN 582, metolachlor, pendimethalin, and trifluralin, and postemergence (POST) applications of AC 263,222 and imazethapyr alone or followed by clethodim late postemergence (LPOST) for red rice control in soybean. Applications of 110 g ai/ha clethodim increased red rice control when following any earlier herbicide application at one location that harbored a high natural infestation. In 1 yr at one location, red rice seedhead suppression from PPI and PRE herbicide applications alone was greater than 95% due to high activity from herbicides and drought conditions during red rice seedhead development. Early postemergence (EPOST) applications of 30 g ae/ha AC 263,222 suppressed at least 95% of red rice seedheads, regardless of year, location, or clethodim LPOST application. At one location, any treatment where 110 g/ha clethodim followed an earlier herbicide application suppressed red rice seedheads at least 95%. Compared to the nontreated control, only AC 263,222 injured soybean (30%) and reduced soybean yield (200 kg/ha).