Agronomy Talk

2020 and 2021 Enlist E3® Post-Emergence

Herbicide and Weed Management Briefs

Published on Friday, November 5, 2021

 

Enlist E3® soybeans allow the opportunity to utilize 2,4-D choline, Liberty and glyphosate in-season. With so many options, what is the best tank mix? Liberty is very effective on glyphosate-resistant (GR) weeds such as waterhemp. However, Liberty will be very weak on grasses and Enlist One will have no grass activity. With today herbicide systems with multiple traits we should target our problematic weeds. For instance, the problematic weed in this plot is GR waterhemp. Therefore, we should utlize Enlist One + Liberty to provide two effective SOA’s on this GR waterhemp population. We know we will sacrifice grass control but glyphosate or clethodim can be utilized in a later application to control any grass escapes.

 

 

For the past two years, Beck’s PFR has conducted studies to determine the best tank mix option for the Enlist system. These studies were POST-emergence only to ensure enough vegetation was present at the time of the application. An effective pre-emerge herbicide with 2 or 3 “effective” SOA’s would have reduced the number of weeds present at the POST-emergence timing. The reduced weed pressure would have resulted in greater POST-emergence control.

 

Just like with any herbicide system, the Power is in the Pre. Two-year data shows a 7% increase in waterhemp control when Enlist One was tank mixed with Liberty instead of glyphosate. However, we seen a 35% reduction in fall panicum control when Enlist One was tank mixed with Liberty instead of glyphosate. Clethodim will provide effective control of grasses and volunteer corn. However, Enlist One can cause antagonism with clethodim reducing clethodim grass control.

 

The addition of clethodim to Enlist One + Liberty resulted in less than 75% control of fall panicum. Though Enlist One can cause antagonism with clethodim, Beck’s PFR studies have shown the antagonism can be reduced when the clethodim rate is increased to 8 to 12 oz. (2 lbs. ai/gal). However, if grasses or the volunteer corn becomes to large consider a separate application. Because of Enlist One + Liberty waterhemp effectiveness we should not separate the two when targeting problematic weeds such as GR waterhemp. Though clethodim does not have any broadleaf activity we did see a 3% increase in waterhemp control. Why? This can be explained by the addition of crop oil to Enlist One + Liberty + clethodim. Adding crop oil will help clethodim penetrate the leaf and can be essential for volunteer corn control. The crop oil also helped Enlist One and Liberty enter the plant and resulted in a 3% increase in waterhemp control. However, the addition of crop oil increased crop response. The addition of glyphosate to Enlist One + Liberty did result in broad spectrum weed control. We see less broadleaf control compared to Enlist One + Liberty and less grass control compared to Enlist One + glyphosate. The more we put in the tank the more chances antagonism can occur. Though we still had greater broad spectrum control we did lose some efficacy. This antagonism can increase in heavy weed pressure scenarios as well as if the grasses become too large. If the weeds become too large consider separate applications. For instance, if waterhemp is your problematic weed utilize Enlist One + Liberty and follow with glyphosate or clethodim to control grasses. If the weeds are small as well as lower densities, Enlist One + Liberty + glyphosate can provide control of waterhemp as well as grasses.

 

 

CONCLUSION:

Two-year data shows Enlist One + Liberty provided 92% control of waterhemp. In 2020 and 2021, the addition of clethodim to Enlist One + Liberty resulted in 73% control of fall panicum. Enlist One + Liberty + glyphosate resulted in broader spectrum weed control. However, greater waterhemp control was achieved withs Enlist One + Liberty and greater fall panicum control with Enlist One + glyphosate. If GR waterhemp is your problematic weed, utilize Enlist One + Liberty and apply a grass herbicide such as clethodim or glyphosate in a separate application if weeds become too thick or large.

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Author: Jim Schwartz

Categories: Agronomy, Agronomy Talk

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