Scientists, farmers, and regulators across California are working on a plan to significantly reduce the use of toxic fumigants, such as methyl bromide, in the state’s strawberry fields.
Earlier this month, the Department of Pesticide Regulation released a list of goals for the industry to pursue that includes recommendations to expand breeding programs for plants resistant to soil-borne pests and to research and implement safer growing methods.
The changes could revolutionize strawberry growing in California, which produces 88 percent of the country’s delicious red berries.
Most farmers in the state currently use methyl bromide to kill pests and diseases that could harm the state’s $2.3 billion strawberry industry. The fumigant was technically phased out in 2005 as part of an international protocol, but California farmers continue to use the gas under an EPA-approved exemption.
“It’s tightly controlled. It’s practically on a prescription basis,” said Steve Fennimore, a specialist with University of California Cooperative Extension.
The manufacturer, Arysta LifeScience, tried unsuccessfully to replace the fumigant with methyl iodide in 2011; legal action against the product and criticisms over its toxicity caused the company to cancel its registration in the state in 2012.
“I think people expect a fumigant to be less potent than the one it’s replacing. They think if you’re going to replace it, you should make [the alternative] safe,” Department of Pesticide Regulation Director Brian Leahy said, adding that there’s increasing pressure from the public to return to a “more biological base in farming.”
Here are some of the more biological growing methods described in the department’s plan:
• Anaerobic soil disinfestation: Developed in the Netherlands and Japan, this process uses plastic and the sugars from rice bran, molasses, and other foods to purge the soil of oxygen prior to planting. It’s been proven to reduce soil-borne pathogens by 80 to 100 percent.
• Biopesticides and biofumigants: Just like they sound, these pest-killing products are made using naturally derived chemicals, like the one found in mustard seed that “causes the sharp bite in condiment mustard,” UC Cooperative Extension’s Fennimore said, adding that scientists are still trying to better understand it.
• Soilless substrate: This method uses common gardening materials such as bark, peat, and pumice to grow the strawberries in tarp-lined troughs—without methyl bromide. One of the first substrate trials was conducted in Santa Maria in 2008.
• Steam and solarization: According to Fennimore, who’s been working on steam-based projects for six years, a machine mixes steam with the soil to kill soil pathogens. “We’re working on a commercial model,” he said. Solarization—creating a greenhouse environment by covering the strawberry beds with plastic prior to planting—helps kill weeds and diseases.
To help scientists better understand these methods—and therefore get them to the industry faster—the Department of Pesticide Regulation has forged a research partnership with the California Strawberry Commission. The focus of the $500,000, three-year research project announced in March is growing strawberries in peat or soilless substances. The department is also offering a new research grant program, which includes $500,000 worth of grants annually for researching production practices that reduce reliance on fumigants and other high-risk pesticides.
Department director Leahy said farmers have been very receptive to the report and are interested in the new, methyl bromide-free growing methods.
“You just kind of know when society starts telling you to do something,” Leahy said of the phasing out of methyl bromide.
In addition to increasing pressure from the public, growers are facing increasing costs and loss of land available for production due to buffer zone requirements and other restrictions to protect farm workers and people living near fields. And more restrictions on fumigants are expected by the end of the year that will further affect production costs.
Contact Managing Editor Amy Asman at aasman@santamariasun.com.
This article appears in Apr 18-25, 2013.