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Feb. 6 is the last day pesticide can appear on shelves; growers seek alternatives

Tim Hearden, Western Farm Press

January 13, 2020

5 Min Read
California Environmental Protection Agency building
The California Environmental Protection Agency building houses agencies including the Department of Pesticide Regulation, which is implementing a statewide ban on chlorpyrifos.Tim Hearden

The training wheels are about to come off for growers test-driving alternatives to chlorpyrifos, which is being phased out by California regulators this year.

Under an agreement between the state and manufacturers, chlorpyrifos will not appear on store shelves after Feb. 6, and farms must use any they have on hand by the end of 2020.

The state Department of Pesticide Regulation has set up a work group to find viable alternatives to chlorpyrifos, which have been elusive in battling such pests as the alfalfa weevil, leaffooted plant bugs and stink bugs.

“Chlorpyrifos historically has been used on a lot of different pests in a lot of different crops,” said David Havilland, a University of California Cooperative Extension entomology advisor and a member of the work group.


“In every single case, there are alternatives to chlorpyrifos,” Havilland told Western Farm Press. “The question is whether or not the use of the alternatives provides adequate control for what’s needed. But we should never say there are no alternatives.”

Growers will have to “take an integrated approach” that takes into account all the available cultural, biological and alternative chemical tools “used as a program to manage pests,” he said.

Chlorpyrifos is a common insecticide used under the trade names Lorsban and Lock-On and in generic formulations to control pests in a variety of crops, including alfalfa, almonds, citrus, cotton, grapes and walnuts. Its use has greatly declined in the past decade as the state’s regulatory vise has tightened its grip.

Related:UC: Chlorpyrifos ban will affect alfalfa production

Last April, chlorpyrifos was formally listed as a “toxic air contaminant,” which California law defines as “an air pollutant which may cause or contribute to an increase in mortality or an increase in serious illness, or which may pose a present or potential hazard to human health.”


In response, the DPR in May announced its intent to ban chlorpyrifos within two years if not sooner. In October, the agency announced an agreement with Dow AgroSciences and other companies with the following terms, according to a news release:

  • All sales of chlorpyrifos products to growers in California will end on Feb. 6.

  • Growers will no longer be allowed to possess or use chlorpyrifos products in California after Dec. 31.

  • Until then, all uses must follow existing regulations, including a ban on aerial spraying, quarter-mile buffer zones and limiting use to crop-pest combinations that lack alternatives.

“This agreement avoids a protracted legal process while providing a clear timeline for California farmers as we look toward developing alternative pest management practices,” said Jared Blumenfeld, California’s secretary for environmental protection.

Related:California moves to ban chlorpyrifos

In the fall, the DPR and the Department of Food and Agriculture set up a cross-sector working group to identify, evaluate and recommend more sustainable pest management options.

The group is hosting the following roundtable-style discussion workshops in the next week:

Fresno CA
Date: Tuesday January 14, 2020
Time: 5:30 pm -7:30 pm
Location: Mosqueda Community Center (Reading and Beyond) - 4670 E. Butler Avenue Fresno, CA 93702

Sacramento, CA
Date: Thursday January 16, 2020
Time: 1:30 pm - 3:30 pm
Location: Joe Serna Jr. CalEPA Headquarters Building, Byron Sher Auditorium - 1001 I Street Sacramento, CA 95814

Oxnard, CA
Date: Tuesday January 21 2020
Time: 5:30 pm - 7:30 pm
Location: South Oxnard Senior Center -200 E. Bard Road Oxnard, CA 93033

For more information about these workshops, please contact Charlotte Fadipe at (916)445-3974 or Steve Lyle at (916) 654-0462.

“In most cases with chlorpyrifos uses, growers have already switched to other products,” Havilland said. “The effort to find replacements has been going on for more than a decade. But there are about 20 pests in the state for which satisfactory levels of control have been difficult to achieve without the use of chlorpyrifos. That’s the focus.”


The chlorpyrifos ban is a major issue for alfalfa, since it is one of the most popular wide-spectrum insecticides for management of key alfalfa pests, UC scientists Rachael Freeman Long, Daniel Putnam and Ian Grettenberger wrote recently.

These include the alfalfa weevil, Hypera postica, which chews on the foliage, and aphids that suck juices from the plant, the researchers wrote. Though its use has declined, chlorpyrifos was still used on 153,000 acres of California alfalfa hay in 2017, according to the DPR’s Pesticide Use Report.

For alfalfa weevil control, growers can use pyrethroids like Warrior, Steward, Malathion and Entrust, but weevil resistance to pyrethroids is beginning to be a problem throughout the state, the scientists wrote.

Tree nut growers, meanwhile, have complained that no other tool but chlorpyrifos will work against leaffooted plant bugs and stink bugs, which feed on and damage developing nuts. And in citrus and grapes, chlorpyrifos has been the go-to tool for controlling sugar-feeding ants, Havilland said.

“That’s a situation where a grower could definitely take a hit from not having the product available,” he said. Ants could go up vines and disrupt biological controls, making the plant more vulnerable to mealybugs and aphids, he said.


The working group convened by the DPR and CDFA will identify and develop safer and more practical and sustainable alternatives to chlorpyrifos, including the use of biological controls and other integrated pest management practices. They will also work with growers who are struggling to make the transition, officials say.

The current state budget sets aside more than $5 million in grant funding for this purpose, including more than $2.1 million to be awarded by the DPR and another $2 million in grants to be given out by the CDFA. The DPR grants will focus on chlorpyrifos alternatives, while the CDFA awards will encourage innovative, biologically integrated farming systems that reduce chemical insecticide inputs, officials said.

CDFA will also contribute about $1.5 million in research to develop alternatives to chlorpyrifos.

The UC’s Integrated Pest Management Program has long advised growers to rotate insecticide classes to prevent insecticide resistance and to only spray when thresholds reach a level that could lead to economic harm.

“There’s 100 alternatives” to chlorpyrifos, with each depending on the crop and the pest, Havilland said. “Every pest and every crop that chlorpyrifos used to be used for has to be dealt with individually.”

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