Control of dicamba/glufosinate/glyphosate-resistant volunteer soybean in corn with preemergence and postemergence herbicides

The widespread adoption of multiple-herbicide-resistant corn and soybean often causes the problem of volunteers in corn–soybean rotation, which necessitates alternative herbicides for effective management. The objective of this research was to evaluate PRE and POST herbicides labeled in corn for control of dicamba/glufosinate/glyphosate-resistant volunteer soybean. Field experiments were conducted from 2021 to 2023 near Clay Center, NE. Two separate field experiments were conducted to evaluate 12 PRE and 14 POST herbicides to control volunteer soybean in Enlist® corn. Soybean resistant to dicamba/glufosinate/glyphosate was planted perpendicular to corn rows to mimic volunteer soybean. Among the PRE herbicides tested, acetochlor/clopyralid/flumetsulam (1,190; 1,050/106/34 g ai ha−1) and acetochlor/clopyralid/mesotrione (2,304; 1,961/133/210 g ai or ae ha−1) provided 97% and 99% control of volunteer soybean, respectively, in 2021 and 68% and 89% control, respectively, in 2023 at 42 d after PRE. Among POST herbicides tested, 2,4-D choline (1,064 g ae ha−1), acetochlor/clopyralid/mesotrione (2,304; 1,961/133/210 g ai or ae ha−1), atrazine/bicyclopyrone/mesotrione/S-metolachlor (2,409; 700/42/168/1,499 g ai ha−1), clopyralid/flumetsulam (192; 146/46 g ai ha−1), nicosulfuron + atrazine (34 + 1,120 g ai ha−1), and thiencarbazone-methyl/tembotrione + atrazine (76; 12/63 + 896 g ai ha−1) provided ≥97% volunteer soybean control, ≥94% density reduction, and ≥97% biomass reduction 28 d after POST herbicide application. Corn yield did not differ from the weed-free control in these treatments. The results of this study suggest that PRE and POST herbicides are available for control of dicamba/glufosinate/glyphosate-resistant volunteer soybean in Enlist® corn and that careful selection of an herbicide is required based on the herbicide-resistant soybean planted in the previous year.