The Environmental Protection Agency is proposing to restrict and monitor atrazine use to address impacts on aquatic plants, including by prohibiting applications in saturated fields and, for growers of sorghum, sweet corn and field corn, limiting annual application rates to 2 pounds.
The agency also plans to set the acceptable level of atrazine in watersheds – called the concentration equivalent level of concern, or CE-LOC – at 3.4 parts per billion, well below the previously proposed 15 ppb.
Grower groups and atrazine manufacturer Syngenta said the herbicide is essential to no-till or reduced tillage systems, with Syngenta warning that farmers of nearly 24 million acres of corn, sorghum and sugarcane "potentially" could have to start using tillage practices if the new CE-LOC is adopted.
The agency’s re-evaluation, prompted by a court challenge in the U.S. Court of Appeals for the 9th Circuit, “concluded that [the increase to 15 ppb] was not adequately supported by science,” but was instead a “policy decision” by the previous administration.
The agency also would prohibit all aerial applications and any applications “during rain or when a storm event, likely to produce runoff from the treated area, is forecasted to occur within 48 hours following application,” EPA’s Office of Pesticide Programs said.
Lastly, EPA would require sorghum, field corn and sweet corn growers in watersheds with atrazine levels above 3.4 ppb (about 18% of all watersheds in the U.S.) to choose from a “picklist” of practices, partially including cover crops, contour buffer strips, terrace farming or field borders, depending on the crop. (Sweet corn has five picklist practices, and sorghum and field corn each have twelve.)
EPA is also “proposing options through a picklist format to allow higher rates in Southern field corn production,” and is proposing an annual limit of 8 pounds/year for sugarcane production in Florida, and 4 pounds/year in Louisiana and Texas (with no picklist requirements).
Watersheds “with predicted atrazine concentrations” above 9.8 ppb “would have the highest level of required picklist mitigations to select,” EPA said.
The National Corn Growers Association blasted the proposed changes to EPA’s September 2020 interim registration decision.
“The new labeling requirements will impose arduous new restrictions and mitigation measures on the herbicide, limiting how much of the product farmers use,” NCGA said.
NCGA President Chris Edgington said the group remains committed to working with EPA as the decision moves forward. The agency is taking comments for 60 days.
The National Sorghum Producers also expressed alarm, saying the “ultra-low 3.4 ppb CE-LOC proposed in 2016 [is] a severely restricted level not supported by credible scientific evidence that would have a devastating impact on farmers.” But it added that it was "encouraged the EPA has committed to an ‘external peer review’ and are hopeful the EPA will use a Scientific Advisory Panel to use the best quality research to get the CE-LOC right."
Atrazine manufacturer and registrant Syngenta issued a statement saying it is "carefully reviewing EPA’s voluminous docket, but as we’ve said all along, atrazine is a vital tool for farmers across the nation, and it is especially important to farmers who implement conservation tillage, or no-till farming, which plays a significant role in carbon sequestration."
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"Farmers are committed to carbon-smart farming," the company said. "However, if the CE-LOC of 3.4 ppb is adopted and as such farmers are unable to effectively use atrazine, approximately 23,748,852 average corn, sorghum and sugarcane acres will potentially need to return to tillage practices, thus adversely impacting carbon savings across these acres."
Nathan Donley, environmental health science direct at the Center for Biological Diversity, said he was pleased the agency lowered the CE-LOC, whose previous increase to 15 ppb CBD had strongly criticized.
“Going back to the 3.4 CE-LOC is a great move,” he said. “But I do have some concerns that this label is getting incredibly complex.”
EPA has proposed requiring differing levels of mitigation depending on the predicted concentrations of atrazine in watersheds and the amount of product applied.
“The picklist components are extremely vague,” Donley said, mentioning vegetated buffer strips as an example.
“That can mean anything from an actual managed buffer strip to just grass, basically.”
“I just don't see the compliance really being there just because of the complexity and the vagueness of some of these requirements,” he said.
The solution, he said, is to ban atrazine. “The science leaves no doubt that any amount of atrazine in the water is too much,” Donley said.
EPA acknowledged some concerns about the proposed revisions.
“Reducing the rate of atrazine used is likely to complicate herbicide resistance management by potentially increasing selection pressure for atrazine-resistant weeds and making atrazine less effective as a tool to control weeds that are resistant to other herbicides,” it said in its "proposed revisions" document.
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This story has been updated to include comments from Syngenta.
