Evaluating weed control in dicamba, glyphosate, and glufosinate-resistant sugar beet in the western United States

Abstract Sugar beet with three-way resistance to dicamba, glufosinate, and glyphosate may provide sugar beet growers with additional herbicide options for management of glyphosate-resistant (GR) weed species such as Palmer amaranth and kochia. Field trials were conducted near Scottsbluff, Nebraska; Lingle, Wyoming; Kimberly, Idaho; and Ontario, Oregon in 2023, to compare the effectiveness of dicamba (549 g ae ha −1 ) + glyphosate (1,260 g ae ha −1 ) applied preemergence, and postemergence combinations of dicamba + glyphosate, glyphosate, and glufosinate (656 g ai ha −1 ) to manage weeds in sugar beet crops. Common lambsquarters, redroot pigweed, and GR kochia were present at the Idaho, Oregon, and Wyoming locations; and common lambsquarters and GR Palmer amaranth were present in Nebraska. Dicamba + glyphosate applied preemergence reduced common lambsquarters, redroot pigweed, and GR kochia compared with glyphosate applied alone. Common lambsquarters density was higher in plots where glufosinate had been applied early postemergence compared with dicamba + glyphosate and glyphosate applied alone. Glufosinate and dicamba + glyphosate applied early or late postemergence reduced GR Palmer amaranth density relative to glyphosate alone applied early or late postemergence. Postemergence applications had no significant effect on redroot pigweed or GR kochia density. Based on the findings of this research, sugar beet with three-way resistance to dicamba, glufosinate, and glyphosate will bring two additional sites of action to be used both preemergence and postemergence, providing improved weed control compared to currently available technology.