Texas Cotton: Best Management Practices for Auxin-Tolerant Crop Tech

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In recent news, new auxin herbicides have received Section 3 approval for use in XtendFlex (dicamba-tolerant) and Enlist (2,4-D tolerant) cotton. Currently, two dicamba herbicides (XtendiMax with VaporGrip Technology and Engenia) and one 2,4-D containing herbicide (Enlist Duo with Colex-D Technology). 

At the time of this writing, XtendiMax with VaporGrip Technology and Engenia have received approval for use in Texas. It is anticipated that Enlist Duo with Colex-D Technology will receive state approval in the near future.

The ability to use these herbicides will certainly provide additional options for managing troublesome glyphosate-resistant Palmer amaranth and common waterhemp, but will also present some challenges with regard to off-target movement of these herbicides.

As you may be aware, there was significant misuse of dicamba in portions of the Midsouth in 2016, resulting in widespread damage to non-tolerant soybeans. These problems were due in large part to improper (and illegal) applications of dicamba formulations not labelled for use in these crops.

To avoid these issues in Texas, it will be critical to only use the approved herbicides (XtendiMax with VaporGrip Technology and Engenia for XtendFlex cotton, and Enlist Duo with Colex-D Technology for Enlist cotton), and to diligently follow the label application requirements.

What follows in Table 1 are important application requirements for these herbicides. Please note that these are application requirements, not recommendations, and it is expected that applicators fully read and follow them as outlined on the product label.

Know Your Surroundings

With the many different herbicide tolerant traits on the market in 2017 and labeled herbicides, the potential for off-target movement and self-inflicted damage is much increased.

The Flag-the-Technology concept (publication and mobile app) has been developed to address this issue. The publication can be found here, while the mobile app can be downloaded from iTunes and Google Play. The Hit-the-Target crop registry will soon be available as well, which will help producers identify the proximity to susceptible and sensitive crops.

Sprayer Cleanout

Herbicide Resistance Info


Due to extreme sensitivity of many crops to these herbicides, thorough sprayer system cleanout procedures will be necessary after the use of these auxin herbicides before moving to other crops. The labels of all three of these herbicides will outline an extensive sprayer cleanout protocol. Be sure to read and follow these cleanout procedures fully if the sprayer will be used for non-tolerant crops.

For more information on weed management in cotton, visit here.

Table 1. Application requirements as outlined on product labels

 
XtendiMax with VaporGrip Technology
Engenia Enlist Duo with Colex-D Technology
Active ingredient(s) dicamba 2.9 lb/gal dicamba 5 lb/gal 2,4-D 1.6 lb/gal
+ glyphosate 1.7 lb/gal
For use in: XtendFlex cotton XtendFlex cotton Enlist cotton
Use rates Preplant, preemergence:
22 – 44 fl oz/A
Postemergence:
22 fl oz/A
12.8 fl oz/A 3.5 – 4.75 pt/A
Maximum annual use rate 88 fl oz/A/year 51.2 fl oz/A/year 14.25 pt/A/year
Application window Preplant through 7 days prior to harvest Preplant through 7 days prior to harvest Preplant through mid-bloom stage
Aerial applications allowed? NO NO NO
Tank-mixtures with other pesticides or adjuvants? Only if approved by EPA1 Only if approved by EPA1 Only if approved by EPA1
Ammonium salts allowed? (AMS, UAN) NO NO AMS and approved AMS substitutes allowed.  Do not substitute water with nitrogen solutions as carrier
Approved spray nozzle(s) TeeJet TTI 11004,
See product website for additional nozzles
TeeJet TTI 11004,
See product website for additional nozzles
Several approved nozzles on product label, see product website for additional nozzles
Maximum operating pressure 63 psi Do not exceed nozzle manufacturer’s recommended pressure Varies depending on nozzle, read label
Total spray volume 10 GPA minimum 10 GPA minimum 10-15 GPA
Spray boom height Minimum of 20 inches, maximum of 24 inches above crop or pest canopy Minimum of 20 inches, maximum of 24 inches above crop or pest canopy Apply at minimum height based upon nozzle manufacturer’s directions
Minimum wind speed 3 mph 3 mph 3mph4
Maximum wind speed 10 mph as set by TDA 10 mph as set by TDA 10 mph as set by TDA
Non-treated buffer area/zone Downwind only
110 ft (22 fl oz/A), or
220 ft (44 fl oz/A) to sensitive areas
Downwind only, 110 ft to sensitive areas Downwind only, 30 ft to sensitive areas
Do not apply product if wind is blowing toward: Adjacent commercially sensitive crops, including tomatoes and other fruiting vegetables, cucurbits, and grapes. Neighboring specialty crops, tomatoes, fruiting vegetables, cucurbits, peas, potato, tobacco, flowers, fruit trees, grapes, ornamentals, including greenhouse and shade house grown broadleaf plants Adjacent commercially grown tomatoes and other fruiting vegetables, cucurbits, grapes, and non-Enlist cotton
Target weed size Less than 4 inches tall Less than 4 inches tall Apply 3.5 to 4.75 pt/A to weeds less than 6 inches tall. For weeds larger than 6 inches, apply 4.75 pt/A. Glyphosate resistant Palmer amaranth may require application at smaller growth stages.

1For approved tank mix partners for Xtendimax, visit: www.xtendimaxapplicationrequirements.com
2For approved tank mix partners for Engenia, visit: www.engeniatankmix.com
3For approved tank mix partners for Enlist Duo, visit: www.enlisttankmix.com
4Not specified on product label, however a minimum of 3 mph wind speed is recommended by AgriLife Extension specialists.