It’s not very often that we discuss pesticide label requirements at the end of the growing season, but recently the Environmental Protection Agency (EPA) has developed a work plan, which includes its “Herbicide Strategy,” in an effort to ensure pesticide registrations comply with the Endangered Species Act. The Herbicide Mitigation Strategy is one of the first phases of the EPA’s work plan to achieve compliance with the Endangered Species Act (ESA) and will set the tone for subsequent changes in the coming years. Moving forward, the herbicide strategy will be applied to all new herbicide active ingredient registrations and be considered during the herbicide registration review process.  

Liberty ULTRA Shows New Framework

Among these changes, the EPA recently announced a final decision to approve Liberty ULTRA (glufosinate-P), making it the first herbicide labeled for agronomic crops to adopt the principles indicated in the Herbicide Strategy, which includes implementing practices for reducing drift and runoff of the product. Liberty Ultra isn’t a new herbicide completely, but rather a new iteration of Liberty herbicide developed by BASF Agricultural Solutions. Liberty 280 SL contains the active ingredient glufosinate whereas Liberty ULTRA contains glufosinate-P., which is a resolved isomer of the original glufosinate active ingredient in Liberty 280 SL. With this new formulation, Liberty ULTRA can be applied at lower use rates than Liberty 280 SL while maintaining weed control performance. Because glufosinate-P is considered a new active ingredient, Liberty ULTRA had to undergo the EPA registration process under the new ESA framework, which includes language to comply with the herbicide strategy. Eventually, Liberty ULTRA will take the place of Liberty 280 SL herbicide on the market and in practice, essentially phasing out Liberty 280 SL altogether according to BASF.

Please note that the product discussed in this article is not the cause for the recent EPA changes, it’s the first product approved under the new ESA framework. While the language on the label will vary among products, the updated language on the Liberty Ultra herbicide label provides a sample of what should be expected on all labels moving forward.  

Minimizing Spray Drift, Runoff, and Erosion

To meet compliance, herbicides that may affect endangered or threatened species or their critical habitat will include instructions for application to minimize spray drift AND require runoff mitigation points (Figure 1 and Figure 2). The goal of the mandatory spray drift mitigations is to minimize the off-target movement of the herbicide during application. Practices to reduce spray drift include altering the characteristics of the spray, changing application techniques to reduce drift, guidance on weather conditions during time of application, and providing a buffer area between the spray zone and environmentally sensitive areas. Mandatory practices to minimize spray drift and guidance on approved spray drift buffers will be included on the label.

In addition to drift reduction, agricultural fields will also be required to meet criteria to reduce the movement of herbicides via runoff or erosion. Herbicides can persist in the soil and during certain environmental conditions can be moved off target and impact unintended areas. To reduce this risk, a certain number of mitigation points are needed to ensure the field characteristics and practices are in favor of reducing the risk of herbicide movement through runoff and erosion. The total number of points required will vary for each herbicide product. Points are accumulated by current field practices and characteristics, and additional points are received by implementing practices described in the EPA’s Mitigation Menu. Both inherent field characteristics, like soil type and slope, and current field practices, like application rate and tillage practices, are included in the mitigation menu for points.

Outlined below are some common field practices considered as in-field runoff and erosion mitigation measures and their associated mitigation points (Table 1). Additionally, the EPA has developed a runoff and erosion point calculator that can help determine the number of points earned from current field conditions/practices, which includes a ‘credit’ for certain counties that have relatively less runoff and erosion vulnerability. Current mitigation points for counties in Wisconsin are shown below (Figure 3).  

So, how would you know if and how much mitigation is required? Applications will need to be planned in advance to determine whether fields are subject to runoff and erosion mitigation. This information can be found on the product label and/or bulletins for the product in the Bulletins Live, Two! system. In addition to the label and bulletins, the EPA outlines a 6-step process to determine which runoff and erosion mitigation measures to consider and implement before utilizing a pesticide product each year. These steps can be found on the Mitigation Menu.  

Outlined below are the key changes to the label and mitigation practice resources. 

You can find more information on the EPA’s Herbicide Mitigation Strategy, at www.regulations.gov. Additionally, the full product label can be found here. The Liberty ULTRA label has been approved by the Department of Agriculture, Trade, and Consumer Protection (DATCP) for use in Wisconsin.

For more pesticide application information, visit the UW Pesticide Applicator Training Program website.

References

Anonymous (2024). Liberty Ultra Herbicide Product Label. EPA Registration no. 7969-500. Research Triangle Park, NC: BASF Corporation.

Updated: Nov. 26, 2024

Collaborators: Daniel H. Smith, Jed Colquhoun, Rodrigo Werle, Nick Roysdon (BASF), and Otto Oemig (WI-DATCP)