The impact of the chlorpyrifos will have impact on a broad range of crops

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Chlorpyrifos Cancelation Impact

Bob Herzfeld, Product Manager
Bob Herzfeld, Product Manager

Chlorpyrifos is a broad-spectrum pesticide used on many crops that have been on the market for decades. Recently, the EPA decided to cancel the use of chlorpyrifos on food crops, impacting a broad range of crops.

Although the chlorpyrifos label does not recommend using adjuvants to increase effectiveness, the strong warning for the potential of drift would make the addition of a drift control agent sensible. Nowadays, newer chemistries, and a stronger focus on preventing resistance, make recommendations for adjuvants to increase pesticide effectiveness more common.

Chlorpyrifos History

Chlorpyrifos first hit the market in 1965, developed by Dow Chemical, now Corteva Agriscience™.  Chlorpyrifos has been a mainstay for insect control on numerous crops for over 50 years. It was marketed under the trade name Lorsban® for crops and Dursban® for home use, mainly for termite control.

Chlorpyrifos has proven to be very effective for controlling many problem insects and more effective than pyrethroids. 

As the prominent product for a couple of decades, chlorpyrifos had its peak usage in the 1990s.  With the current sales of Lorsban at only 20% of peak production, Corteva stopped manufacturing chlorpyrifos in 2020.  Dursban lost registration and was discontinued for home insect control in 2000. However, as it has been off-patent for some time, numerous generic producers fill a diminishing market. 

Estimated Agricultural use for chlorpyrifos in 2017 and the impact the cancelation has
Image credit: Pesticide National Synthesis Project

Chlorpyrifos controls a broad spectrum of insects across numerous different crops. During the peak usage, chlorpyrifos was extensively used in corn and soybeans. However, with the advent of GMOs, developers were able to create a gene transformation of natural insect control. This stack of genetics in corn has greatly reduced the need for insecticides and chlorpyrifos in particular.  But for some minor crops, such as peanuts, chlorpyrifos is the only effective tool to control pests. 

Table with target pest for the use of chlorpyrifosvarious crops
Table credit:

What is the Problem with Chlorpyrifos?

In a statement from the EPA, chlorpyrifos is applied on numerous crops, including soybeans, fruit and nut trees, broccoli, and cauliflower. Studies have linked it to potential brain damage in children and fetuses that could lead to reduced IQ, memory loss, and attention deficit disorders.

“The ban will safeguard farmworkers, their families, communities, and the food supply,” said Allison Johnson, an attorney with the NRDC[1]. “EPA is finally following its own findings on this poisonous pesticide.”

“The European Union, Canada, and some states including California, Hawaii, New York, Maryland, and Oregon have restricted application of chlorpyrifos on foods. Those limits — and development of replacement pest controls — have led to a decline in farmers’ use of chlorpyrifos,” EPA said.

The table below shows some of the insecticides that can replace chlorpyrifos.

Alternative chlorpyrifos products registered for use in field crops in Iowa
Alternative chlorpyrifos products registered for use in field crops in Iowa. Table credit: Iowa State Extension; Integrated Crop Management

Recently, Corteva developed other, more environmentally friendly insecticides to replace chlorpyrifos. These chemistries are sulfoxaflor (Transform®) or afidopyropen (Sefina™), two new active ingredients. 

Ag Industry’s Response to the EPA Ruling

The following statements and information are from Bloomberg Law News.
Chris Novak, president and CEO of CropLife America, said, “The EPA’s regulatory strategy has created a “tremendous amount of uncertainty” in the food supply. It’s also raised a host of questions, such as who’s liable if a legally treated crop is later tested and contains a tiny amount of chlorpyrifos after the EPA’s ban is in effect.”
Peter Valsakis of the American Peanut Council said, “EPA’s rule is a de facto ban on using chlorpyrifos and that takes one of the most valuable tools they have out of their toolbox.”
On concerns of uncertainty, Kevin Scott, President of the American Soybean Association, wrote, “A critical study of children that the EPA used to reach its chlorpyrifos decision was conducted by the Columbia Center for Children’s Environmental Health. Yet the agency’s rule states it “has been unable to confirm the findings” of that study or get the data enabling it to conduct its own statistical analyses to evaluate the center’s findings.”

A field with peanuts that is impacted by the chlorpyrifos cancellation
A field with peanuts that might be more difficult to keep pest free without chlorpyrifos. Image by Jing - Pixabay

To Summarize

With the support from environmental and opposition groups, the EPA has identified “possible” human negative effects of chlorpyrifos, particularly in children and fetuses.  Also, worker protection organizations have advocated for the ban due to worker exposure and possible adverse effects.

Corteva, with the continuing decline in use, a plethora of generic suppliers, and EPA registration challenges, decided to exit the market.  But while doing so, Corteva developed two new, more environmentally safe chemistries to replace chlorpyrifos. This should be a signal to the industry; it is time to change course on chemistries.

Ag Pesticide Manufacturers and Industry organizations are worried about environmental and opposition groups being able to influence government agencies and regulators without complete data.  The research sited could not identify at what concentration pesticide levels would be a concern.  They are also concerned about the loss of “another tool in the toolbox,” in particular if it is the only control for certain insects and combating resistance issues by rotating chemistries. 

Chlorpyrifos is not totally banned, just on food crops. There remain labels available for non-food use.  Ag pesticide manufacturers will be working on good or better alternatives. There are many other choices of insecticides on the market to fill the gap. It appears the EPA also needs to use more complete data in making decisions. 

Chlorpyrifos label does not recommend the addition of adjuvants to improve performance.  The exception being a drift control, where there is a strong warning and procedures are suggested to reduce drift. This is also the case for replacement insecticides. Some of the replacement insecticides do recommend the addition of an adjuvant to improve performance as well as drift.  It may open up adjuvant opportunities that chlorpyrifos did not recommend.

[1] The Natural Resources Defense Council is a United States-based 501 non-profit international environmental advocacy group, with its headquarters in New York City and offices in Washington D.C., San Francisco, Los Angeles, New Delhi, Chicago, Bozeman, and Beijing. Wikipedia
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