A new report from conservation groups says that the U.S. Environmental Protection Agency should not re-approve the herbicide dicamba for use on genetically modified crops until the agency can prove it doesn’t harm wildlife.

Since 2017, at least five millions acres of non-resistant crops have been harmed by the herbicide moving off of where it is applied, but the damage goes well beyond crops, according to the report. 

The report, Drifting Toward Disaster: How Dicamba Herbicides are Harming Cultivated and Wild Landscapes, found that tens of millions of acres of critical wildlife habitat has been damaged by the herbicide since the crops were introduced, beginning in 2015.

“This is not just happening to crops. It’s happening to wild places and it’s something we really need to pay attention to,” said  Kim Erndt-Pitcher, agriculture programs specialist with Prairie Rivers Network, an Illinois-based conservation nonprofit that authored the report.

Prairie Rivers Network partnered to produce the report with the National Wildlife Federation and Xerces Society, a nonprofit organization that focuses on invertebrate conservation.

Dicamba was introduced in the 1960s and used predominantly on corn fields before planting as well as lawn care. 

But the herbicide was not widely used during the growing season because of its tendency to harm non-target crops through volatility, when it turns from a liquid into a gas in the hours after it is sprayed and then moves around.  

Its use began to spike in 2015, when the agribusiness company, Monsanto, introduced new genetically modified crops that could withstand being sprayed by dicamba. In  2017, Monsanto and BASF introduced new versions of dicamba less likely to move off target. 

Despite these formulations, the damage continued.

Earlier this year, the U.S. Ninth Circuit Court of Appeals banned dicamba for over the top use on cotton and soybeans, after finding that the EPA ignored risks posed by the weed killer to other farmers and the natural environment. The EPA said farmers had until July 31 to spray all existing stocks of dicamba.

Bayer, which bought Monsanto in 2018, BASF and other makers of dicamba have said they will work to get the herbicide re-approved by the EPA in the coming months for the 2021 growing season.

“In terms of registration, BASF submitted Engenia herbicide to the EPA for re-registration. In addition, we have also submitted a registration for a new combination product that includes dicamba and other active ingredients for over-the-top use on soybeans and cotton,” BASF spokeswoman Odessa Patricia Hines said.

Bayer did not respond to a request for comment.

But so far, the companies haven’t proven that the herbicide can stay on-target, said Lekha Knuffman, agriculture program specialist with the National Wildlife Federation. 

The off-target movement matters to wildlife.  When plants are damaged, pollinators and other species that depend on flowering plants have to work much harder for food needs, Knuffman said. 

“There’s a cascading ripple effect,” Knuffman said. She said she is also concerned about the environmental loading, which is when the pesticide builds up after being sprayed year after year, of dicamba.

The Ninth Circuit ruling on the lawsuit, which was brought by conservation groups, didn’t address Endangered Species Act claims brought by the groups. 

Knuffman said the EPA hasn’t properly considered the impact that the drift has, which can result in fewer flowers and vegetation that leads to less food for birds and other wildlife. 

“We feel the assumptions they made under the Endangered Species Act listing did not account to the amount of volatility we’re seeing,” she said. “It needs to be revisited, and it needs to be expanded to take in more species.”

The report was undertaken because many people have been monitoring crop damage, but few have been monitoring ecological damage. 

As a part of its $10 billion Roundup settlement, Bayer has also entered into a $400 million settlement agreement over the allegations that dicamba caused widespread damage to soybean and specialty farmers across the Midwest.

The Drifting Toward Disaster report calls for the EPA to take a number of steps, including: 

  • The EPA not renewing over-the-top registrations until “independent research shows with certainty that dicamba formulations will not cause off-target injury to crops and wild plants, including from vapor drift;” 
  • The EPA should include a full risk assessment for all species “under the Endangered Species Act, migratory birds, native pollinators, and aquatic life that includes direct and indirect effects from exposure to dicamba due to drift, volatilization, and runoff;
  • The USDA should reject petitions for additional genetically modified crops that are resistant to dicamba until research shows the herbicide won’t move off-target; 
  • And increased investment in sustainable weed management beyond herbicide-only control.

In an additional report focusing on Illinois, Prairie Rivers Network published the results of its multi-year monitoring program of trees across the state. 

The report found widespread damage to dozens of species of plants. The damage to some trees was seen more than half a mile from any crop fields, according to the report.

In addition to in-season harm, much of the damage appears in pre-plant applications, which happen in the spring to kill weeds before a crop is planted, according to the report. The damage is consistent with dicamba and another herbicide, 2,4-D.

The report said that the monitoring data, which was collected in response to an increasing number of pesticide misuse complaints, is incomplete and raises more questions than it answers. 

Erndt-Pitcher said the damage is everywhere across the state, from native plants to people’s yards.

“It’s not just hurting crops. It’s hurting the 80 year-old oaks in your grandparents’ yard. It’s hurting the vegetable garden someone spent hours and hours planting and weeding,” Erndt-Pitcher said.

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