Field studies were conducted from 1996 to 1998 at Queenstown, MD to evaluate weed management programs utilizing single and multiple applications of glufosinate, with and without preemergence (PRE) and postemergence herbicides in both glufosinate-resistant (GR) corn and soybean. No herbicide treatment resulted in corn or soybean injury greater than 10% at 7 d after treatment (DAT). No injury was visible at 14 DAT for both GR corn and soybean. In corn, all treatments provided 72% or greater giant foxtail control 14 wk after planting (WAP). With soybean, in 1996 and 1998, few differences in giant foxtail control were observed, with all treatments providing at least 93% giant foxtail control 12 WAP. For common lambsquarters control in GR corn, there were no differences in control among treatments for 1996 and 1997. Over 80% common lambsquarters control was observed both years with all treatments 14 WAP. Glufosinate + atrazine at 0.4 kg/ha + 1.7 kg ai/ha, respectively, provided 100% season-long common lambsquarters control all three years of the study. For GR soybean, few differences in common lambsquarters control existed between treatments for all three years. Most treatments provided 72% or greater common lambsquarters control 12 WAP. Few differences in grain yield between herbicide treatments were observed for either GR corn or soybean. These studies illustrated that glufosinate, whether applied alone, sequentially, in tank-mixes, or as an overlay to a PRE program in GR corn and soybean is a viable herbicide program for the control of giant foxtail and common lambsquarters.

Experiments examining burcucumber management in glufosinate-resistant (GR) and imidazolinone-resistant (IMI) corn were conducted in 1997 and 1998 in southeastern Pennsylvania. GR corn was planted in 38- and 76-cm rows, and postemergence (POST) treatments of glufosinate and glufosinate plus atrazine were applied to corn at the V4 or V5 growth stage. In a second study, IMI corn was planted in 76-cm rows, and 15 preemergence (PRE) and POST herbicide programs were evaluated. Herbicide treatments included RPA-201772, CGA 152005, simazine, imazethapyr plus imazapyr, imazamox, chlorimuron plus thifensulfuron, nicosulfuron plus rimsulfuron plus atrazine, CGA 152005 plus primisulfuron, and combinations with atrazine. Burcucumber germinated throughout the growing season, with greatest emergence occurring in early June, gradually decreasing to minimal emergence by mid-July. Glufosinate alone controlled burcucumber 79 to 90% 7 weeks after planting (WAP) regardless of application timing or row spacing. By 10 to 13 WAP, control was 82% or less due to lack of residual control and new burcucumber emergence. Row spacing had little effect on burcucumber emergence or control and appears to have little impact on burcucumber management in corn. In general, PRE herbicide programs were less effective than POST programs, although PRE treatments containing atrazine equaled some POST herbicides. POST-applied chlorimuron plus thifensulfuron, nicosulfuron plus rimsulfuron plus atrazine, and CGA 152005 plus primisulfuron controlled burcucumber greater than 80 and 90% in 1997 and 1998, respectively. Imazethapyr plus imazapyr and imazamox applied POST controlled burcucumber 66% 10 WAP. Adding atrazine to POST herbicide programs did not increase control, with the exception of imazethapyr plus imazapyr.