Can steam replace chemical fumigants? Watsonville berry growers will put it to the test

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Five berry growers in Watsonville will test out an alternative soil fumigant in their fields as part of a three-month pilot program led by the county’s agricultural commission. 

The pilot program plans to explore an alternative non-chemical soil fumigation by injecting steam at a high temperature to reduce soil-borne pests, weed seeds and plant pathogens, such as fungi and bacteria, according to Santa Cruz County Agricultural Commissioner David Sanford. 

Sanford told Lookout that the $175,000 pilot program is funded by the California Department of Pesticide Regulation. He added that this alternative farming method has been around for years and continues to be researched. 

“The engineering is really tricky,” he said. “It’s challenging to get to know the machines that are functional and working. This is still very much a work in progress and very research oriented still.” 

The current equipment for this farming method is at a small scale and there’s work being done on technology to accommodate commercial farming, Sanford said. As part of the county’s pilot program, Sanford said they’ll be working with people beginning to build the equipment — large steam rigs that use propane tanks to heat up the water — at a commercial level. 

Historically, this technique has been used in Europe and sometimes for nurseries and soil sterilization, according to Sanford. “But taking it to field level is a bigger endeavor,” he said. 

The participating growers primarily own strawberry fields, with the exception of one raspberry field, with small acreages and focusing on the areas where there’s a high mix of agricultural and urban areas. Sanford added that a few of the growers participating are also located within a quarter mile of school sites.

Groups such as Campaign for Organic Regenerative Agriculture (CORA) and Safe Ag Safe Schools have long advocated for safer farming practices, and pushed for Driscoll’s — the region’s largest berry grower — to convert all of its fields near schools and residential areas to organic ones. 

The groups have also demanded local and state authorities implement larger buffer zones between sensitive areas, such as schools and homes, and agricultural fields. 

Sanford said the pilot program is a “positive development,” as the county is exploring an alternative farming technique that does not use chemical fumigants, like more traditional methods do. 

Kathleen Kilpatrick, a member of Safe Ag Safe Schools, said in a news release last week that the grassroots organization is supportive of the exploration of non-chemical alternatives on fields near schools, and hopes that pilot programs like this one will “provide tools for pesticide reduction and expansion of organic buffers.” 

The county is also partnering with UC Santa Cruz researcher Jenny Broome, who has experience examining alternative farming practices, to spearhead the research aspect of the program, said Sanford. He added that Broome is interested in looking at crop performance data and exploring how viable this method is in controlling soil-borne pests. 

Sanford said his department is aiming to start the pilot program next month and that a bulk of the data collection will happen within that first month. 

Additionally, the agricultural commission will be hosting a pair of outreach meetings to inform community members about the pilot program, and once there is data, to reflect on what’s worked. The first meeting is scheduled for Aug. 18 at 5:30 p.m. in the Greg Caput Community Room at the South County Government Center at 500 Westridge Dr. in Watsonville. 

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