HEMP DOGBANE (APOCYNUM-CANNABINUM) AND WILD BLACKBERRY (RUBUS-ALLEGHENIENSIS) CONTROL IN NO-TILLAGE CORN (ZEA-MAYS)

Hemp dogbane and wild blackberry have become significant weed problems in no-tillage com production in Maryland. Nicosulfuron (31 to 62 g ha-1) plus crop oil concentrate (COC) gave 67% or more hemp dogbane and wild blackberry control. There was no difference in hemp dogbane or wild blackberry control between 31 and 94 g ai ha-1 nicosulfuron. Tank mixtures of 2,4-D or dicamba with nicosulfuron gave 72 to 100% hemp dogbane and wild blackberry control. Hemp dogbane control following applications of 560 g ha-1 2,4-D was 97% in 1989 and 63% in 1990. Wild blackberry control with 2,4-D was 40% both years. Dicamba at 280 g ha-1 gave 70 and 55% control of hemp dogbane and 75 and 65% control of wild blackberry in 1989 and 1990, respectively. Triclopyr plus 2,4-D provided 72 to 98% hemp dogbane control and 92 to 98% wild blackberry control. However, triclopyr plus 2,4-D applied at 280 plus 560 g ha-1 injured com, and com yields were reduced compared with weedy controls in 1990.