Simple ‘Soil Steaming’ Found as Effective Replacement for Chemicals in Organic Strawberry Farming.
California researchers are testing steam as a substitute for chemical fumigants in strawberry fields, and an organic grower reported nearly double the yield on steam-treated plots, according to an Associated Press report.
Researchers in California are adapting steam technology to kill soil-borne diseases and weeds in strawberry fields, and one organic grower said the results this year were striking. The Associated Press reported the story.
Rod Koda, a longtime strawberry farmer near the Pacific Coast, said plots treated with steam before planting produced nearly twice as many organic strawberries as other plots. Plants in those rows were still bearing fruit well after harvest would typically end. "It's a very noticeable difference," Koda said.
Steam has been used in greenhouses for decades. The current project aims to bring it to open fields as an alternative to chemical fumigants. Jenny Broome, a UC Santa Cruz researcher on the project, said a machine injects steam into the soil before planting, which can kill key soil-borne diseases and weeds and improve crop productivity. Four growers took part in trials last fall. On Koda's farm, the steam-treated plots yielded more berries and had less damage from fusarium wilt, a fungal disease, she said.
Cost and speed remain open challenges. Broome said making steam cost-effective for farmers is difficult, and supporters are working on faster machines that can cover more ground. Rick Tomlinson, president of the California Strawberry Commission, said researchers have worked on steam for more than a decade. He added that the industry is also pursuing other options, including cutting off oxygen in the soil and developing more resistant plants. Broome said steam might also work for lettuce, carrots and other high-yield crops.
The stakes are high for the state's growers. California supplies nine of every 10 strawberries grown in the United States, on 35,000 acres, and the berry was among the state's top 10 commodities in 2025. David Andrews, chief science officer at the Environmental Working Group, welcomed the search for alternatives. He noted that farmworkers and their families have been the ones exposed to fumigants, and said the technology has improved while concerns about the chemicals have grown.
Note: The headline says steam was found to be an effective replacement. The page describes early trials with four growers, with results reported from Koda's farm, and says cost and machine speed are still challenges.
At a Glance
- Four California growers took part in steam trials last fall, according to UC Santa Cruz researcher Jenny Broome.
- Steam-treated plots on Rod Koda's farm produced nearly twice as many organic strawberries this year as other plots, he said.
- California grows nine of every 10 U.S. strawberries, on 35,000 acres.
- Treated plots on Koda's farm also had less damage from fusarium wilt, a fungal disease, Broome said.
Sources
This brief was written by Brightside Report from the reporting linked above. Spot an error? Request a correction.