By DTN Staff
OMAHA (DTN) -- The U.S. Environmental Protection Agency said in a court motion Tuesday it wants to pull the plug on Dow AgroScience's Enlist Duo herbicide, citing "new information" it received about the potential environmental effects of the herbicide designed to work with genetically-engineered corn and soybean.
In a court document filed with the U.S. Ninth Circuit Court of Appeals Tuesday, EPA stated that because the agency has "new information regarding potential synergistic effects between the two ingredients on non-target plants, EPA seeks a voluntary remand in order to reconsider the Enlist Duo registration in light of the new information." In court documents, the agency said it "cannot be sure, without a full analysis of the new information, that the current registration does not cause unreasonable effects to the environment, which is a requirement of the registration standard under FIFRA (Federal Insecticide, Fungicide, and Rodenticide Act)."
Enlist Duo herbicide, which contains a mix of glyphosate and a new formulation of 2,4-D, received EPA registration in a select number of corn states in fall 2014. The genetically-engineered trait package that gives crops resistance to those two herbicides was approved for corn and soybeans September 2014 and for cotton, July 2015.
In April 2015 the EPA granted final approval of Enlist Duo herbicide for use in nine additional states, bringing the total to 15 states.
Dow had not yet sold the seed and herbicide package commercially. It had been conducting research, seed production and "stewarded" trials for corn and soybean seed in 2015. Dow had said it was holding full commercial release pending Chinese approval of the genetically-engineered traits in grain. Dow had said it did not want producers to run into grain sales issues; China has a recent history of being slow to approve a number of U.S.-approved traits and has refused U.S. corn that contained unapproved traits.
In a statement provided to DTN Wednesday, EPA said Dow made new information available "that suggests (the) two active ingredients could result in greater toxicity to non-target plants. EPA has not yet completed its review of the new information."
Neither EPA nor Dow would specify at press time what the "new information" included. Dow has for months, on its Enlist Duo website (http://www.enlist.com/…) and in sales and marketing materials, heralded "combining the proven control of a new 2,4-D and glyphosate" as one of the key points for growers using the Enlist herbicides and the crops genetically engineered to tolerate both herbicides. Farmers have been using a tank mix of the two products, applied as burndowns and other early season applications, for decades.
According to the motion filed by EPA in court, the agency originally registered the herbicide because it saw "no indication of synergism" with the combination of glyphosate and 2,4-D. So, in approving the new combination product, it reviewed the toxicology and other environmental effects of each herbicide individually. It did not ask for research trial data on the two active ingredients together because, at the time, EPA said "it is reasonable to assume that there are no synergistic interactions for the taxonomic groups that were not tested, including plants."
The court filing this week says that EPA "recently discovered" Dow's claims of "synergistic weed control" in patent filings Dow has made on Enlist Duo. EPA's court filing says it sent a letter to Dow on Oct. 13 saying that the synergistic weed control Dow was claiming could "affect the Agency's assessment of drift reduction measures."
Andrew Kniss, University of Wyoming weed researcher, detailed the meaning of synergistic effects in a blog post Wednesday http://bit.ly/… and noted that Dow's patent http://bit.ly/… indicates synergies exist between the two chemicals.
A Dow spokesman told DTN that the company learned of the court filing Tuesday. He said the company is "considering options" regarding what court actions it may take.
DRIFT CONTROL ISSUE
Drift control has been a critical issue in the Enlist Duo registration, as 2,4-D has a long history of drift issues. The new Enlist herbicide/seed packages would allow the growth-hormone disruption herbicide to be applied much later in the season, when sensitive crops and plants would be growing and much more susceptible to it.
EPA had mandated buffer zones around Enlist crops as part of the original registration in an effort to reduce drift issues.
"EPA is seeking a remand because this new information could lead EPA to a different decision on the restrictions for using Enlist Duo. Specifically, this could result in changes to the width around application areas of no-use buffer zones that EPA imposed to protect unintended plants, including those listed as endangered," the EPA court filing said.
In October 2014, several environmental groups sued EPA in the Ninth Circuit Court of Appeals on the agency's decision to register the Enlist Duo herbicide.
Groups such as the Center for Food Safety and the Environmental Working Group quickly heralded EPA's decision to ask to pull the registration. Several claimed the decision was based on "high toxicity levels," though EPA announcements referred to the need to evaluate spray drift buffer strips and did not discuss toxicity levels.
Enlist Duo had been labeled for use in Arkansas, Kansas, Louisiana, Minnesota, Missouri, Mississippi, Nebraska, Oklahoma, Illinois, Indiana, Iowa, Ohio, South Dakota, Wisconsin and North Dakota. EPA had considered approving the product for use in Tennessee, but decided against it because of concerns it would harm some the endangered plant species Spring Creek bladderpod.
The first six states approved are areas with strong penetration by Dow's Mycogen Seeds and other seed partners. The 10 additional states, particularly the Southern states of Arkansas, Louisiana, Tennessee and Missouri, are key battleground areas for tough glyphosate-resistant weeds such as Palmer amaranth.
Registering in Southern states has been a bit trickier because few crops are as sensitive to 2,4-D drift than non-tolerant cotton. The Enlist cotton trait received regulatory approval July 2015, but Enlist Duo herbicide is still pending for that crop.
The original Enlist Duo registration included a number of use requirements and restrictions that are unusual for an EPA registration. The agency has made it known it is interested in curbing weed resistance to herbicides, and said all new herbicide-tolerant crops, not just this system, will likely carry restrictions to guard against the overuse, and subsequent weed-resistance problems. Similar restrictions for current herbicide-tolerant cropping systems, including glyphosate and glufosinate, are also being discussed.
The registration required 30-foot, in-field, no-spray buffer zones to minimize drift, and does not allow spraying when winds are greater than 15 miles per hour. In addition, EPA required scouting and reporting for potential weed resistance to Enlist Duo, as part of the six-year registration.
Last year, Canada approved the use of Enlist Duo for the same uses that EPA authorized. Other approvals have come from Argentina, Australia, Colombia, Japan, Korea, Mexico, New Zealand, South Africa and Taiwan. In addition, the herbicide mix is approved for use in 26 European Union nations.
EPA has had several recent safety reviews of 2,4-D: in 2005, in 2012 and in 2014.
Neither EPA nor Dow could offer a timeline on when the agency would finalize the current review of any new information. "We expect to complete our review in a timely manner," EPA told DTN in an email.
Dow issued a general response to media, saying the company is "working with EPA to quickly provide further assurances that our product's conditions of registered use will continue to protect the environment, including threatened and endangered plant species." The company said it expects "that these new evaluations will result in a prompt resolution of all outstanding issues."
Timing of that review is critical, Dow and farmers have said during the original Enlist registration process. The combination of the herbicides and traited seeds offers one of the few alternatives to glyphosate-resistant weeds, which are now found in most corn and soybean growing areas. Dow had expected Chinese registration for the grain traits soon, as recent trade visits by U.S. representatives had focused on speeding up Bejing's approval process.
The Enlist issue marks the third regulatory blow to Dow originating in the U.S. Ninth Circuit Court of Appeals in a matter of months.
On Nov. 12, the EPA announced a ban of sulfoxaflor, the active ingredient in Dow's Transform WG insecticide, and the agency has also proposed a ban of chlorpyrifos, the active ingredient in Dow AgroScience's Lorsban insecticide.
The Transform ban was inspired by the Ninth Circuit Court of Appeals' ruling after a lawsuit by the Pollinator Stewardship Council, filed by Earthjustice, questioned whether the EPA had sufficient environmental data to register the chemical. The court ruled that the agency's original registration of sulfoxaflor in 2013 was "based on flawed and limited data" and demanded that agency "obtain further studies and data regarding the effects of sulfoxaflor on bees."
Likewise, the proposed ban on chlorpyrifos stemmed from a Ninth Circuit Court of Appeals' ruling that pressured the EPA to establish food tolerances for the insecticide, an action EPA lacked the data to execute. This time, the lawsuit was filed by Earthjustice on behalf of the Pesticide Action Network and Natural Resources Defense Council.
"This court is known for making rulings that align with activist organizations at the expense of agriculture," former National Sorghum Producer chairman J.B. Stewart said in a press release protesting the Transform ban. "We plan to do our part in pushing back on these nonsensical court decisions that unfortunately are becoming more frequent and to the detriment of farmers and ranchers across the nation," he added.
DTN reporters and editors Todd Neeley, Pam Smith, Chris Clayton and Emily Unglesbee contributed to this story.
© Copyright 2015 DTN/The Progressive Farmer. All rights reserved.