Chlorpyrifos’ Ban Reversed: Researchers React

Chlorpyrifos' Ban Reversed: Researchers React

Chlorpyrifos molecule

Last week, EPA declined to ban the pesticide chlorpyrifos, which had been recommended for removal during the Obama administration.

The pesticide has been around for a long time, and is used primarily against soil-borne pests. American Vegetable Grower reached out to several Extension agents to learn their reactions to chlorpyrifos’ dodging the ban.



It’s a Boon for Brassica Growers says Thomas Kumar, Professor and Extension Vegetable Entomology Specialist, Virginia Tech

Chlorpyrifos is among the few organophosphates still registered for use on food crops. Under enactment of the Food Quality Protection Act, many of the more toxic organophosphates have been removed from use on vegetables. These insecticides have largely been replaced by neonicotinoids, pyrethroids, and other insecticide classes.  A few uses of chlorpyrifos on vegetables have remained, particularly where there have not been adequate replacements that have provided similar pest control efficacy.

One example is the control of cabbage maggot on brassica crops. This is a very damaging pest in some regions of the U.S., and chlorpyrifos is the most efficacious insecticide option for control. Thus, the news means that commercial growers of brassica crops in the U.S. will still have this effective insecticide in their pest control arsenal for the time being.


California Regulations Already Cut Deeply into Chlorpyrifos Use,  Says Shimat V. Joseph, IPM Advisor (Entomology) | University of California Cooperative Extension:

In central coast of California, use of chlorpyrifos declined sharply due to regulations enforced by the regional water board. However, growers with large acreage still use it. As Tom indicated, it is primarily used against soil-borne pests such as cabbage maggot, garden symphylans, springtails etc.

Based on my trials, the efficacy of chlorpyrifos against cabbage maggot is questionable. So the growers moved on using other chemistries, as Tom indicated, because of the enforcement of regulation rather than the attempted ban. In the central coast of California, the issue started when toxic levels of chlorpyrifos was detected in surface water threatening the non-targets such as benthic organisms. I still see the value of having chlorpyrifos around as a tool in the tool box.

Please see this article — it discusses some of these points. The paper is primarily targeting pyrethroids, but I have mentioned OP issues too.


Chlorpyrifos is a Much Needed Weapon to Combat Sudden Apple Decline, says Peter J. Jentsch, Hudson Valley Research Laboratory Director, Senior Extension Associate, Entomology, NYSAES Cornell University

I wrote an article last week in support of chlorpyrifos to provide additional detail regarding our need in agricultural production, given the dramatic shift in tree architecture and sudden apple decline (SAD) we are observing in New York State.

In New York, the invasive insect complex, including the brown marmorated stink bug (BMSB) in tree fruit, continues to cause unprecedented injury to crops, requiring significant time to determine best management practices, while older broad spectrum management tools are employed to reduce losses. The use of chlorpyrifos in this case is not necessarily essential, but is one of only a handful of tool capable of reducing BMSB in emergency situations. Although newer, reduced risk technologies and products are available for use in tree fruit production, they are not without concerns.

This was recently evidenced in the reduced risk organophosphates (OP) replacement neonicotinoid insecticide class, targeted for honeybee reduction concerns. Insecticide resistance management, by design, requires rotation of multiple classes of insecticides. The OP class has only a few tools available for use in tree fruit after Food Quality Protection Act (FQPA) reductions of this class. The loss of Lorsban would reduce the resistance management potential in many New York cropping systems. In New York, Lorsban is constrained for foliar applications during the pre-bloom period for black stem borer (BSB), yet dogwood borer (DWB) management using trunk applications can be used post bloom in a single seasonal application. These two insects contribute to SAD in New York. Employing a single trunk application against the BSB would significantly reduce the risk to pollinators and the predatory insect complex, while reducing the potential for introduction to ground water and residue on fruit, yet would optimizing the efficacy in timing to reduce significant losses to the tree fruit industry by boring pests.


California Citrus Mutual Issues a Celebratory Statement

California Citrus Mutual says it was “very pleased” when the EPA declined to ban chlorpyrifos.

“We believe that sound science should prevail in the regulation of crop protection tools,” says CCM President Joel Nelsen.

Nelsen and members of California Citrus Mutual’s Executive Committee met with EPA several times last year to lobby for chlorpyrifos’ use in citrus production, where the pesticide helpls suppress the Asian citrus psyllid, that spreads the deadly huanglongbing (HLB) or citrus greening disease.