Review of herbicide label requirements: Dicamba
This article is the first in a series reviewing unique or updated label requirements for key herbicides.
Certain dicamba products (Engenia, Fexapan, and Xtendimax) were approved for post-emergence control of weeds in Xtend Soybean in 2017. The labels for these products include some additional requirements intended to reduce the potential for non-target injury caused by herbicide drift.
Figure 1. Soybean plots at the Ashland Bottoms Research site in Manhattan, KS. Photo was taken moments before sunset in July 2019, outside the application window for dicamba treatments. Temperature inversions commonly occur near dawn and dusk. Photo taken by Tyler Meyers, agronomy graduate student, K-State Research and Extension.
Key requirements for dicamba application on current labels include:
- Annual training for all applicators (online modules available on websites listed below)
- Only approved nozzles and tank mix partners (lists can be found on websites listed below)
- Keep spray solution pH greater than 5 – no AMS
- Ground speed less than 15 mph
- Boom less than 24 inches above target weeds
- Wind speed 3 to 10 mph
- Soybean growth stage of emergence through first bloom (R1) or 45 days after planting, whichever comes first. In cotton, the application window is emergence through mid-bloom or 60 days after planting.
- Make applications between 1 hour after sunrise and 2 hours before sunset (see Figure 1)
- No temperature inversion (current inversion conditions in Kansas can be found at https://mesonet.k-state.edu/agriculture/inversion/)
- Application buffers of 110 feet downwind between the field and sensitive areas. An additional 57-foot buffer is required on all other sides in counties where ‘endangered terrestrial dicot plant species’ may be found. Affected areas are identified at https://www.epa.gov/endangered-species/bulletins-live-two-view-bulletins. Based on information available at this site, Anderson County is the only Kansas county affected by this requirement. Applicators can also call 1-844-447-3813 to verify this requirement.
- Sprayer cleanout before and after application
- Creating records within 72 hours of application and maintaining records for two years (information required for records can be found on the websites listed below).
These requirements apply to Engenia, FeXapan, and Xtendimax, as well as to Tavium, which is a combination of dicamba and S-metolachlor (Dual). All of these labels expire on December 20, 2020.
Annual training modules and other resources can be found at:
Stay tuned for the next installment in this series…Paraquat.
Sarah Lancaster, Weed Science Specialist