The Environmental Protection Agency has dealt farmers in the region a tough blow with an announcement that it will be banning the insecticide chlorpyrifos in food and feed uses.

In a final rule released on Aug. 18, EPA said it was revoking all “tolerances” for chlorpyrifos, which establish an amount of pesticide that is allowed on food. This means EPA is effectively removing it from the market by ruling there is no safe level of residues. The Notice of Intent to Cancel under the Federal Insecticide, Fungicide, and Rodenticide Act will become effective 60 days after it is published in the Federal Register.

South Dakota State University Extension Field Crop Entomologist Adam Varenhorst said the agency took the action based on safety concerns.

“Chlorpyrifos is an organophosphate and any of those classes of pesticides are dangerous and toxic. So, exposure can lead to severe health issues because they don’t degrade in the human system like other pesticides do,” he said.

The residues can also be a concern.

Newsletter signup for email alerts

Producers in the region better know chlorpyrifos as the former product Lorsban, which is an insecticide that targets biting and sucking pests such as aphids and spider mites. Use of Lorsban has already dropped significantly in the past decade, particularly after Corteva Agriscience, its primary registrant, halted production in 2020. The generic version is primarily used in crops in the region like soybeans, corn and wheat.

Varenhorst said EPA’s announcement means most farmers in the region will no longer be using chlorpyrifos on those insects in the future.

Varenhorst said luckily, populations have been low the last several years but ticked higher this year due to the dry conditions over much of the region. So generic versions of chlorpyrifos were used for control in many of those fields.

In the future, farmers will have to look at other options for control of insects in field crops like corn and soybeans.

“We will be able to move to different insecticide classes. So, it won’t be as if we don’t have anything to use anymore," he said. "However, with some of our pests, we are starting to see some resistance to some of those other insecticide products, and so we are going to have to be very careful moving into the future to make sure we don’t run out of product or drive the resistance towards one product very fast.”

He said growers and applicators will have to look at neonicotinoids and pyrethroids to manage those populations.

“For the spider mites it’s a little more difficult because chlorpyrifos does work quite well and some of our other products can actually cause more of an issue,” he said.

EPA says all food uses of chlorpyrifos will be revoked six months from the final rule’s publication in the Federal Register, which will likely happen in the coming weeks. The ban does not affect non-food uses of chlorpyrifos, such as mosquito control, which will be under review later in 2022.

Kevin Deinert farms near Mount Vernon, South Dakota, and said the loss of this product will be a cost to agriculture and his operation, especially years like 2021 where he has had to spray for spider mites due to the drought.

“There are alternative products, but to use those we’re going to be replacing one chemical formula with maybe two other chemicals that we have to use,” he said.

He said that will drive up the cost of application. Varenhorst said alternative products that are used in other crops to control insects like spider mite and aphids are more expensive.

Farmers like Deinert are also concerned about losing such an effective option for insect control especially since some of those pests are showing resistance to other products.

“Chlorpyrifos has been shown to be one of the most effective ways to control spider mites or aphids,” he said.

Deinert also expects yield loss switching to some of the alternatives to chlorpyrifos.

“We’ve seen in some research especially spider mite damage could result in either 40% to 60% loss on those affected acres. So, in a year like this when we’re already running into low yields that’s a substantial amount,” he said.

Chlorpyrifos has a long history of court challenges, with the Ninth Circuit finally giving EPA an ultimatum in April 2021 to either create a new rule that was justified by data that would ensure the safe agricultural use of the insecticide or revoke its food residue tolerances. EPA had a deadline of Aug. 20, 2021, to issue that decision.

Deinert, who is also second vice president of the South Dakota Soybean Association, said the association doesn't believe EPA is using sound science in making the determination and hopes the agency will reconsider.

“EPA has now gone against some of the research-based science that they themselves have conducted and decided that they’re going to get rid of it. We as producers hope that they would follow the science-based facts and they have so diligently done and listen to their own scientists in regard to allowing chlorpyrifos to be able to be used by farmers,” he said.

Meanwhile, environmental and labor groups that have long battled EPA in court over use of this product are declaring victory.