Kurt Vollmer, Weed Management Specialist | kvollmer@umd.edu
University of Maryland Extension
Many may be preparing to apply certain postemergence herbicides to soybeans in the next couple of weeks. Those planning to spray Liberty (glufosinate) or Enlist One (2,4-D), should be aware that time is running out to spray these herbicides this season. The crop cutoff stage to apply Liberty in soybeans is “R1” and Enlist or Enlist Duo is “through R1.”
In addition, many may want to apply one of these products as a rescue treatment to control large weeds. At this time of year, it is likely that these weeds are beyond the label recommended growth stage. Some may have previously applied glufosinate and want to follow up with 2,4-D or vice versa. However, research has shown that tank mixing these products will provide better control of larger weeds compared to individual products alone. Both of these products can be applied over the top of E3 soybeans. Consider using the maximum-labeled rate for each herbicide. Liberty can be applied at maximum rate of 43 fl oz/A per application (87 fl oz/year) and Enlist One can be applied at a maximum rate of 2 pt/A (6 pt/year). Be sure to include 1.5 to 3 lbs of ammonium sulfate, apply at a spray volume of 15 gal/A, and follow all label instructions concerning drift.
Group 14 products such as Cobra (lactofen) can still be applied later to control smaller weeds, but control is likely to decrease, especially if weeds are taller than the soybean canopy. For more information see Control of Large Palmer Amaranth and Common Ragweed in Soybean or Corn (FS-1192) and Evaluating Late Season Burndown Options for Palmer Amaranth.
