By Luke Schulte, Beck’s Hybrids
Farmers and the agricultural community have waited patiently since June for a decision regarding the labeled use of approved dicamba-containing herbicide formulations for use within the Roundup Ready 2 Xtend and XtendFlex soybean systems. Fortunately, the wait is over, providing farmers a valuable tool to combat herbicide resistance.
On October 27, 2020, the EPA announced the registration of XtendiMax, Engenia, and Tavium herbicides for use in dicamba-tolerant crops (RR2 Xtend/XtendFlex soybeans and XtendFlex cotton). In 2021, farmers will have access to more technology choices regarding soybean herbicide tolerances than ever before. While the comfort level and familiarity of many herbicide platforms is high, newer technologies such as XtendFlex and Enlist E3 may not be as well understood.
While Enlist herbicides (Enlist One, Enlist Duo) and the approved dicamba-containing herbicides mentioned above are all growth regulators or auxin herbicides, they do not share the same advantages. Enlist One and Enlist Duo contain 2,4-D choline. XtendiMax, Engenia, and Tavium each contain dicamba herbicide. Both 2,4-D choline and dicamba target the same sight of action (SOA) to terminate weeds, however, they do not always produce the same results.
Specific management will be required to maximize the strength of each system.
Key findings and differences:
Spring Burndown: Dicamba herbicides perform more consistently than Enlist or 2,4-D containing herbicides in cool weather or when experiencing significant temperature fluctuations, particularly on marestail. Frequently, spring daily highs compared to daily lows vary 25 to 35 degrees F resulting in reduced efficacy. PFR data showed at 21 days after treatment, Engenia + Roundup PowerMAX had 91% marestail control and Enlist One + Roundup PowerMAX had 73% marestail control.
Soil activity: Dicamba products such as XtendiMax have documented soil activity for up to 14 days. Dicamba complements a pre-emergence residual program to further prevent weed emergence, thus reducing pressure on the POST application.
Enlist E3 System: Greatest efficacy of tough-to-control weeds and glyphosate-resistant weeds will be achieved by tank mixing Enlist One with Liberty rather than glyphosate. This is especially important to waterhemp as well as marestail control. Liberty will also provide more consistency when timely POST treatments are challenged, thus larger weeds. Tank mix Enlist One with Liberty at a 1:1 ratio (32 ounces per acre Enlist One to 32 ounces per acre of Liberty).