New herbicide management for runoff, erosion & drift

A recent shift toward more restrictive weed control measures along with new, mandatory pesticide application rules has been mandated by the EPA. Wesley Everman, Ph.D., Iowa State Extension weed specialist, began an explanation of the rule changes with a brief history of what brought the EPA to develop a new herbicide strategy. “The Endangered Species Act (ESA) was first passed in the early 1970s,” Everman said. “It requires the government and its agencies to make sure any actions taken by them do not endanger any species, the environment. They consult with the U.S. Fish and Wildlife Service and the National Marine Fishery Service (or ‘services’).” The EPA regulates herbicide use through the Office of Pesticide Programs , through which they label products and ensure herbicides have been thoroughly vetted for toxicity and use patterns. Since herbicides can affect both plants and animals or their habitat, pesticide regulations are considered “actions.” “Several years ago, there was a lawsuit in which several groups sued the EPA and said ‘they aren’t consulting with these services to make sure these pesticides are safe and doing no harm,’” Everman said. “They went to court and the EPA admitted they haven’t been doing that, so the courts annulled all pesticide registrations. The Herbicide Strategy and other strategies are in response to this.” The EPA came up with strategies, including the Herbicide Strategy, and stated that if farmers bring all herbicides and pesticides into compliance through the strategy, the EPA will keep products registered and not annul any. All new product registrations will go through this process. The process involved switching product registrations based on chemical specifics to pesticide groups. Everman noted that there are still some chemical-specific decisions and assessments occurring due to ongoing litigation and reviews that were already in place. In August 2025, the EPA released the Pesticide App for Label Mitigations (PALM), a tool to assist farmers in using EPA’s mitigation menu. PALM helps farmers determine runoff/erosion mitigation and spray drift mitigation to protect endangered species and their habitats. “They’re going to look at every herbicide as it comes through registration and apply that strategy during the registration or reregistration process,” Everman said. “New products will go through this, and anything on the market already and going through reregistration go through the new Herbicide Strategy.” Pesticide labels will change significantly, with more language on runoff/erosion and additional restriction language. They’ll also include practices farmers will be required to implement for spray drift management. The goal is to keep products on the field and result in better drift management stewardship. Runoff and erosion mitigation is based on historical rainfall frequency and intensity data. Spray drift mitigation is based on estimated herbicide impact on natural and non-managed areas. “Label changes are to encourage people to look at the label,” Everman said. “I know some people have never read labels closely. That’s going to change – we’re going to have to look to see the changes. If there’s a complaint or an investigation and [farmers] aren’t following the mitigation strategies, those could be actionable offenses.” Farmers and applicators will be required to check Bulletins Live! Two (BL2), a website with specific restrictions for products based on geography. BL2 includes requirements for application restrictions based on specific herbicides and specific geographies. It lists threatened or endangered species areas that have pesticide use limitations. Farmers will also have to be aware of Pesticide Use Limitation Areas (PULAs). PULAs are areas where, based on the presence of endangered species or their habitat, extra precautions are required. On the BL2 website, farmers and applicators can access a map and select the intended area of use to determine PULA status. “This is separate from erosion/runoff or drift mitigations,” said Everman. “This could be more restrictive, and these guidelines must be followed first. Some products are not allowed in certain PULAs. Spray drift mitigations are herbicide specific. They are on the label and we have to follow those.” Drift management includes the use of buffers, drift reduction agents, boom height and droplet size. The EPA realized that no threatened or endangered species have been eliminated by a pesticide since the EPA was created and started labeling products. The EPA also acknowledged farmers have already been taking steps to mitigate harm. Rather than whole farm management, each field will be handled as a management area. Mitigation measures garner points, which are earned through practices that reduce erosion and runoff. These include nutrient management, tile drains, non-irrigated fields, cover crops, no-till, reduced tillage, strip tillage, grassed waterways and riparian buffers. Many farmers will be able to achieve mitigation points without changing a lot of practices. “Once you have points, unless you change how the field is farmed, accumulated points don’t expire,” Everman said. “The product with the most points is what you have to reach. It isn’t additive.” Doing the search in early spring should cover the growing season, but farmers should check the site again before putting in the next crop. For pastures, there are different mitigations according to factors such as soil type and/or slope and distance to critical habitat. The points that apply to crop fields apply to pastures. “Read the label each time a pesticide is purchased,” said Everman. “Make sure you know what language has changed and what has to be done for mitigation, whether it’s runoff/erosion or drift. Think about the land currently farmed as well as rented land. Have discussions with landowners and make sure there’s a roadmap regarding how fields will be managed.” New herbicides with new labels will come online regularly, so it’s important for farmers to follow news regarding the ESA. Because labels are continually updated, farmers should look for any new statements. Examine conservation practices already in place and check for PULAs in BL2. Those factors determine whether points are needed and potential mitigation strategies. “Prepare for the unpredictable nature and prepare for implementing the Herbicide Strategy through weather events,” said Everman. While there may be some growing pains with the new program, he predicts its success. “Runoff/erosion and drift come from weather. Have good programs, plan ahead and understand the strategy.” Visit epa.gov/pesticides/pesticide-app-label-mitigations for the pesticide app. by Sally Colby