MON-13200 EARLY PREPLANT CONTROLS GIANT FOXTAIL (SETARIA-FABERI) SEASON-LONG IN NO-TILL SOYBEAN (GLYCINE-MAX)

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 rate s ranging from 224 to 448 g ai/ha applied up to 57 d before planting c ontrolled 97 to 99% of giant foxtail averaged over years. MON 13200 pl us imazaquin applied approximately 45 or 30 d before planting controll ed 92 to 99% of giant foxtail compared with 53, 64, and 65% and 61, 69 , and 78% in plots treated with alachlor, metolachlor, or pendimethali n plus imazaquin, respectively. Differences in control of giant foxtai l among the herbicides evaluated were minimal when applied 15 or 0 d b efore planting. Little or no soybean injury was observed in 1991; up t o 30% was observed in 1992 but final soybean height was not affected.