by Josh McGinty – Extension Agronomist – Corpus Christi, TX:
Phone: 361-265-9203, Email: joshua.mcginty@ag.tamu.edu
Gaylon Morgan – State Cotton Specialist – College Station, TX
Peter Dotray – Extension Weed Specialist – Lubbock, TX
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, three dicamba herbicides (XtendiMax™ with VaporGrip™ Technology, FeXapan™, and Engenia™) and one 2,4-D containing herbicide (Enlist Duo™ with Colex-D™ Technology) have received federal approval. At the time of this writing, XtendiMax with VaporGrip Technology, Engenia, and Enlist Duo with Colex-D Technology have received approval for use in Texas. FeXapan herbicide is not currently approved for use in Texas at the time of this writing, but is anticipated to 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, FeXapan, or 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.
All of these new herbicides have product websites where a list of approved tank-mix partners, approved spray nozzles, and other product updates can be found. These website are being updated constantly as new tank-mixes and spray nozzles receive approval, so please consult the appropriate website before using these herbicides to check for new updates.
• XtendiMax with VaporGrip Technology – www.xtendimaxapplicationrequirements.com
• Engenia – www.engeniatankmix.com
• FeXapan – www.fexapanapplicationrequirements.dupont.com
• Enlist Duo – www.enlisttankmix.com
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? | Several herbicides and adjuvants, check product website1 | Several adjuvants allowed, check product website2 | Many adjuvants, check product website3 |
| 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) | Several approved nozzles on product label, see product website for additional nozzles1 | TeeJet TTI 11004 and 11005 See product website for additional nozzles2 |
Several approved nozzles on product label, see product website for additional nozzles3 |
| Maximum operating pressure | Varies depending on nozzle, check product website1 | 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.
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 at http://publications.tamu.edu/WEEDS_HERBICIDES/FlagTheTechnology.pdf , 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
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:http://agrilifecdn.tamu.edu/coastalbend/files/2016/06/ESC-008.pdf