Published online by Cambridge University Press: 12 June 2017
Field studies were conducted in 1991 and 1992 to evaluate the duration of giant foxtail control in no-till soybean with MON 13200 alone and with imazaquin applied up to 2 mo prior to planting. MON 13200 at rates ranging from 224 to 448 g ai/ha applied up to 57 d before planting controlled 97 to 99% of giant foxtail averaged over years. MON 13200 plus imazaquin applied approximately 45 or 30 d before planting controlled 92 to 99% of giant foxtail compared with 53, 64, and 65% and 61, 69, and 78% in plots treated with alachlor, metolachlor, or pendimethalin plus imazaquin, respectively. Differences in control of giant foxtail among the herbicides evaluated were minimal when applied 15 or 0 d before planting. Little or no soybean injury was observed in 1991; up to 30% was observed in 1992 but final soybean height was not affected.