Chlorpyrifos Post-Mortem

Five Things Farmers Need to Know About EPA's Ban on Chlorpyrifos

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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EPA's decision to pull chlorpyrifos off the market will most affect soybean growers, who primarily use it to control spider mites; but insect control in corn, cotton, wheat, alfalfa and other crops will be affected, too. (DTN photo by Pamela Smith)

ROCKVILLE, Md. (DTN) -- After decades of litigation, EPA announced a plan to pull chlorpyrifos off the market last week.

If you missed the breaking news story, see it here:…. But if you saw it and still have questions -- When does the ban start? What products are affected? Is it final? -- you're in the right place.

Chlorpyrifos is an organophosphate insecticide better known to farmers and pesticide applicators by various brand names such as Lorsban and Vulcan. It was a popular insecticide option for farmers for many years, particularly in the fight against soybean aphids. Its use has waned in the past decade, but it remained an option for growers fighting twospotted spider mites in beans, rootworm in corn, aphids in wheat and cutworms and plant bugs in cotton. It's also used in alfalfa and several fruit and vegetable crops.

On Aug. 18, the Biden EPA announced its intention to publish a new rule that will revoke all residue tolerances for the insecticide, essentially making it illegal to use on food and feed crops. This new EPA rule will take full effect in around six months, meaning farmers can still use chlorpyrifos through this growing season, but next year, it won't be an option.

Here's the upshot on how this EPA decision affects farmers.


One of the most common chlorpyrifos insecticides in use was Lorsban, owned by Corteva Agriscience. The product was already discontinued last year, after Corteva announced it was voluntarily ending its production of this insecticide in February 2020, citing low demand. (see the DTN story here:…).

But, in an odd situation for the agricultural industry, the Trump EPA forged ahead with chlorpyrifos's registration review, committed to keeping it on the market despite the departure of its primary registrant and biggest manufacturer. (see more here:…).

That meant generic insecticides using chlorpyrifos remained legal to use and available.

A recent article from the University of Minnesota (found here:…) lists the major remaining chlorpyrifos insecticide products that will be affected by EPA's Aug. 18 decision:

-- Standalone products: Chlorpyrifos, Govern, Hatchet, Vulcan, Warhawk, Whirlwind and Yuma;

-- Premixes that contain chlorpyrifos: Bolton, Cobalt Advanced, Match-Up, and Stallion.

This new EPA rule does NOT affect non-food-crop uses of chlorpyrifos, such as mosquito and roach control products. EPA has said it will review those uses in the coming year.


Farmers and applicators will be able to finish out the 2021 season with any chlorpyrifos products they have in hand.

Except in emergency situations, the World Trade Organization (WTO) requires regulators such as the EPA to provide a "reasonable interval" between the publication of a new rule and its adoption among industry around the world. The minimum interval allowed is six months, and EPA has opted to use this interval.

First, EPA notifies WTO of this new rule revoking chlorpyrifos's tolerances via publication in the Federal Register. That should happen shortly in the weeks to come. Two alarm clocks start ticking at that point -- a 60-day one and a six-month one. After 60 days are up, the rule is considered in place and effective. After the six-month clock is up, the tolerances are officially revoked and chlorpyrifos is illegal to use.

The six-month deadline will likely land sometime early next spring, in February or March.

There is another step that needs to happen, as well. EPA must formally "modify or cancel" the registrations of chlorpyrifos products labeled for use in food or feed crops "in a timely fashion." It's not clear exactly when EPA will do that, but on its website, the agency promised to "issue a Notice of Intent to Cancel" all registered food uses of chlorpyrifos in the future. (See that here:….)


Although chlorpyrifos use had declined significantly in the past decade, it's still in use on agricultural crops. Based on data from EPA, about 7.2 million pounds are used annually, with soybean and corn usage making up 20% of that. With the advent of additional insecticides to the market, such as pyrethroids and neonicotinoids, it has moved farther back in the toolbox, however, accounting for less than 5% of treated acres in corn and soybeans.

The highest use (1.2 million pounds annually) comes from soybean acres, to treat pests such as the twospotted spider mite. It is also still used to treat cutworms and plant bugs in cotton, aphids in wheat, rootworm in corn and maggots in sugarbeets.

Soybean growers looking for alternatives once chlorpyrifos products are off the market should consult the previously mentioned University of Minnesota article. In it, a chart lists a range of alternative insecticides, mainly pyrethroids, for soybean pests previously targeted by chlorpyrifos.

See it here:….

For cotton growers, see this Clemson University article that has a comprehensive list of insecticide options for various cotton pests:….


This decision by EPA is unusual in that it did not originate from the agency's own pesticide registration protocols -- in fact, the agency greenlighted an interim re-registration decision for chlorpyrifos back in December 2020, and was prepared to keep it on the market.

Instead, this action was prompted a ruling by a panel of judges on U.S. Court of Appeals for the Ninth Circuit, which ordered EPA to either ban chlorpyrifos or write new rules that eliminated the risks raised in lawsuits against the agency. (See more here:…).

Faced with this order, and a deadline of Aug. 20, 2021, EPA opted to revoke all food residue tolerances for the insecticide, which effectively bans all agricultural uses of it.

This situation -- a federal regulatory agency pulling a product off the market in response to an order from a federal court -- is an unusual one, but one that is becoming increasingly common recently, noted Brook Duer, staff attorney at Penn State's Center for Agricultural and Shale Law. A similar order was handed down by the Ninth Circuit Court of Appeals back in June 2020, when it ordered EPA to vacate the registrations of three dicamba herbicides -- and the agency complied. (See more here:…).

"I think we're living in somewhat unprecedented times," Duer said of these court-ordered pesticide removals. "Just like with dicamba, we're having exceedingly rare procedural moves happening, ordered by a court. I'm not sure how much of a precedent it sets for EPA's normal procedures, but it was an aggressive action by the court."


The two alarm clocks set in EPA's rule (60 days and six months) do give people or organizations time to intervene legally, Duer noted. It is possible a group or company could file a lawsuit in a federal court, appealing the final rule and, most importantly, asking for a stay. "You would have to have a stay granted, to stop that clock from running," Duer said.

Another appealable action will occur when EPA finally issues notice to cancel chlorpyrifos product registrations, Duer noted. "Those are yet to come, and they could be appealed, too," he said.

Filing an appeal and asking for a stay doesn't guarantee that it would be issued, however.

"To get a stay, you have to prove to a judge that you have a reasonable likelihood of success on the merits of your case," Duer explained.

That could be a long shot, given chlorpyrifos's decades-long history of legal battles over human health concerns, which have culminated in EPA's decision here. But some agricultural groups have released statements condemning the rule, which hint at potential legal strategies.

In its emailed statement to DTN, Corteva stated that as it reviewed the order, "it appears that the rationale used by the Agency is inconsistent with the complete and robust database of more than 4,000 studies and reports that have examined the product in terms of health, safety and the environment."

Likewise, the Agricultural Retailers Association released a statement after the rule was announced, which called the Ninth Circuit's ruling forcing EPA to make this decision a "usurpation" of the agency's control over pesticide use in the country. The group urged EPA to reverse its own decision and "use every legal avenue available [to] reassert its statutory authority to be the regulator of these products."

"The Ninth Circuit Court of Appeals has substituted its judgement for the scientific expertise of the Agency and dictated to EPA a demand to revoke tolerances," the statement read. "Not only is this an unjustified usurpation of the Agency's authority and expertise, but canceling tolerances for a product that remains registered for use creates uncertainty for users."

See EPA's rule, which is still in its prepublication form, here:….

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Emily Unglesbee