Integrated pest management of alfalfa in California will be “profoundly” impacted by the loss of the pesticide chlorpyrifos next year, research scientists say.

The California Environmental Protection Agency announced Oct. 8 that virtually all use of the pesticide chlorpyrifos will end next year following an agreement between the Department of Pesticide Regulation and pesticide manufacturers.

Sale of chlorpyrifos products in California will end Feb. 6, 2020, and growers will no longer be allowed to possess or use them after Dec. 31.

Democratic Gov. Gavin Newsom lauded the agreement as “a big win for children, workers and public health.”

The department was moving toward a ban and had declared the pesticide a toxic air contaminant. Usage dropped more than 50%, from 2 million pounds in 2005 to just over 900,000 pounds in 2017, CalEPA said. It is used to control pests in alfalfa, almonds, citrus, cotton, grapes and walnuts.

“This is a major issue for alfalfa since it is one of the most popular wide-spectrum insecticides for management of key alfalfa pests,” University of California-Davis forage expert Daniel Putnam and entomologists Rachel Freeman Long and Ian Grettenberger wrote in a UC-Davis Cooperative Extension newsletter, the Oct. 11.

They cited the alfalfa weevil, which chews on foliage and an aphid complex that suck juices from the plant.

While use of chlorpyrifos has declined, it was still used on 153,000 acres of alfalfa in California in 2017 and the few alternative pesticides are not as effective, the scientists wrote.

UC-Davis is working to find non-pesticide ways to manage weevil and aphid.

The 153,000 alfalfa acres where chlorpyrifos is used is 27% of California’s alfalfa acreage, said Jon Paul Driver, a Northwest Farm Credit Services hay analyst in Spokane.

“California remains the largest dairy state and largest alfalfa exporting state,” Driver said.

But it is producing less than half the alfalfa it did 10 years ago, he said. Average yield was 6 tons per acre in 2019, the lowest since 1979, he said.

“A change in integrated pest management will further weigh on total production,” Driver said.

Consequently, production may expand outside California, he said.

John Gombos, CEO of The Gombos Co., a large hay exporter in Woodland, Calif., said aphids are a huge problem in Sacramento delta and serious problems could develop there if no substitute is developed.

Gombos said growers he talked with in Dixon, Davis and Tracy are not concerned because they don’t use chlorpyrifos.

Source: Dan Wheat, Capital Press