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Enlist E3 Soybean Weed Control Technology

Enlist E3TM Soybean Weed Control Technology

The Enlist Weed Control System combines traits for resistance to 2,4-D, glyphosate, and glufosinate into soybean varieties. Dow AgroSciences previously developed Enlist Duo™ herbicide that contains both glyphosate [Group 9] and 2,4-D [Group 4] to be used in this system. A Sept. 13, 2017 statement from Dow AgroSciences titled “Enlist™ Weed Control System Expands with Addition of Enlist One™ Herbicide” announced the launch of Enlist One™ herbicide, a 2,4-D-only choline product featuring Colex-D® technology. Enlist soybeans will be available pending final import approvals from countries outside the US.

The Enlist Duo and Enlist One labels must be consulted for specific nozzles with corresponding allowed pressures to use, allowed wind speed conditions, required buffers, allowed spray boom height based on nozzle manufacturer’s directions, and other application requirements. Neither product can be aerially applied. There is no more flexibility with weed size when using the above products as there is with any of the other weed control technologies available prior to their availability; i.e., both products must be applied to small weeds for maximum effectiveness.

Both Enlist Duo and Enlist One herbicides may be applied to Enlist soybeans anytime after soybean emergence but no later than the R2 or full flowering stage. Do not apply either product within 30 days of harvest. Both products may be applied as a preplant burndown to fields that will be planted to non-Enlist soybeans. In this case, apply Enlist Duo no less than 30 days prior to planting, and apply Enlist One no less than 15 days [1 pint/acre rate] or 30 days [2 pints/acre rate] prior to planting. Do not apply either product on sandy soils with less than 1% organic matter. Consult each product’s label for other restrictions.

Enlist Duo and Enlist One herbicides are the only 2,4-D -containing herbicide products labeled for application to Enlist crops. Click here for the 2017 Product Use Guide for the Enlist Weed Control System, here for approved/tested tank mix partners with each of the 2,4-D herbicide products, and here for status of current state registrations. Notice that glufosinate [Liberty–Group 10] is not an approved/tested tank mix partner with Enlist Duo, but that both glyphosate and glufosinate herbicides can be mixed with Enlist One. Thus, Enlist One apparently offers greater flexibility for a customized postemergence weed control program that incorporates multiple modes of action.

A complete and thorough review of the potential issues surrounding the use of the auxin herbicides 2,4-D and dicamba on tolerant crops was published in a 2012 article from Purdue University Extension. Especially pay attention to the section “Factors Affecting Off-Site Movement”. Drift and volatility are the two contributing components to off-site movement of these growth-regulating herbicides. The segment on drift, which is the physical movement of spray particles by wind away from the target, provides details about the factors that contribute to drift and how these factors can be managed. The segment on volatility, which is the movement of the gaseous form of the herbicide after its deposition on the intended target, provides details about factors that contribute to volatility, and how this process can be lessened or minimized. Click here for a detailed discussion of these topics.

The Purdue article also discusses the background leading to the development and evolution of genetically engineered [GE] 2,4-D-resistant technology [Dow Agrosciences Enlist Weed Control System] and dicamba-resistant technology [Monsanto’s Roundup Ready Xtend Crop System] in crops, a description of the two technologies, and concerns about, factors affecting, and methods of minimizing off-site movement of the two herbicides when they are used on tolerant crops.

Since the Purdue article was written, dicamba-resistant soybean has been used, and this has resulted in a veritable plethora of off-target deposition issues associated with its use. Thus, restrictions and requirements pertaining to the use of auxin herbicides on auxin-resistant [AR] crops are in flux. At this time, there is ongoing debate surrounding the use of auxin growth-regulating herbicides on AR soybean. The debate does not center on the utility of these herbicides that can be used to combat herbicide-resistant (HR) weeds, but rather on their safe use.

Hopefully, when Enlist soybean is finally available, off-target deposition issues with use of approved 2,4-D herbicide products will not be an issue. Also, when use of either auxin herbicide-resistant system in soybean is fully used, the auxin herbicides allowed for use in these systems must not be relied on alone to manage HR weeds. Using a diversified approach of applying both residual and postemergence herbicides with different modes of action in combination with sound agronomic best management practices will remain the only durable and productive weed management system for soybeans.

The United Soybean Board [USB] has produced a list of BMP’s to use when applying auxin herbicides to auxin-tolerant crops. The article titled “Managing 2,4-D and Dicamba in Enlist and Xtend Soybean” is a component resource of USB’s “Take Action Against Herbicide-Resistant Weeds” program. This four-page article contains all pertinent information that should be considered when using these herbicides. Technical editing was provided by Drs. Bish and Bradley of the Univ. of Missouri and Dr. Bill Johnson of Purdue Univ.

Composed by Larry G. Heatherly, Sept. 2017, larryheatherly@bellsouth.net