Evaluation of corn herbicide programs with and without atrazine

Abstract

AbstractAtrazine is a foundational herbicide in corn (Zea mays L.) because of its broad‐spectrum weed control and utility for pre‐emergence or postemergence applications. Extensive atrazine use has led to traces in groundwater, surface water, and aquifers. This research explored corn herbicide regimes with little or no atrazine. Pre‐emergence herbicide treatments [S‐metolachlor (0.955 lb acre–1); saflufenacil (0.054 oz acre–1) plus dimethenamid‐P (0.473 lb acre–1)] and postemergence herbicide mixtures [bicyclopyrone (0.040 lb acre–1) plus mesotrione (0.161 lb acre–1) plus S‐metolachlor (1.429 lb acre–1); thiencarbazone‐methyl (0.013 lb acre–1) plus tembotrione (0.067 lb acre–1), thiencarbazone‐methyl (0.033 lb acre–1) plus isoxaflutole (0.082 lb acre–1); acetochlor (0.964 lb acre–1) plus mesotrione (0.103 lb acre–1) plus clopyralid (0.065 lb acre–1)] were applied alone or combined with atrazine at 0.50 lb acre–1 to glyphosate‐ or glufosinate‐resistant corn. All postemergence applications contained glyphosate (1.125 lb acre–1) plus glufosinate (0.402 lb acre–1). Palmer amaranth [Amaranthus palmeri (S.) Watson], broadleaf signalgrass [Urochloa platyphylla (Munro ex C. Wright) Nash], and pitted morningglory (Ipomoea lacunosa L.) control were always greater than 95%. Saflufenacil plus dimethenamid‐P injured corn 8 and 5% more than S‐metolachlor 21 d after pre‐emergence application. Averaged over pre‐emergence herbicide and atrazine rate, thiencarbazone‐methyl plus isoxaflutole injured corn by 21% in 2017. The addition of atrazine did not improve corn yield in 7 of 16 instances. According to this research, the weeds assessed at these densities can be controlled without atrazine by some programs.