A half-mile down Dairy Road, the Watsonville Strawberry Field Station hides in a clandestine guise behind the shade of a eucalyptus windbreak amid miles of agriculture. The field station is positioned to the left of a three-acre experimental strawberry plot, where the dark, sandy loam in each row is topped with crimson strawberries.
As one of the state’s top strawberry research facilities, the field station is supported by the UC Agriculture and Natural Resources Department. It is a haven to agricultural researchers and farm advisors who help to maintain Watsonville’s fresh-market strawberry industry, a market that reached another record-high production last year, with a revenue valued at $756 million.
“Strawberries are a full-blown economic driver for Watsonville,” said farm advisor Mark Bolda, a strawberry and caneberry specialist at the Watsonville Strawberry Field Station. “Acreage is at its largest ever. The industry is sustainable.”
This summer’s peak harvests will stem from the Watsonville-Salinas district’s 14,528 acres, comprising a tri-county strawberry patch spanning from Santa Cruz’s north coast down to the Monterey Peninsula. It is the world’s largest region of strawberry production, accounting for nearly half of California’s total, according to the California Strawberry Commission (CSC), the single state-chartered agency representing the strawberry industry.
Sustaining Economic Efficiency
Post-harvest months are in August and September and many of Watsonville’s 600-plus growers will produce strawberries back-to-back, conventionally, in soil typically treated with the potent soil fumigant mixture of methyl bromide and chloropicrin (MBCP). The treatment reduces the incidence of soil-borne pathogens like Verticillium dahliae, a fungus that leaves the plant wilted and entire fields at risk of quarantine.
“MBCP has been the pesticide standard for years,” said UC Davis plant science professor Douglas Shaw, a principal investigator at the field station.
Shaw presented his latest soil fumigation trials at the field station’s annual Strawberry Pomology Field Day in early May.
In front of three rows in the experimental plot, with a portable amplifier and microphone in hand, stands the veteran strawberry pomologist of 21 years in farmer’s garb and a baseball cap.
A crowd of nearly 100 growers, farm advisors, corporate representatives and agricultural commissioners observe the trials.
The left row is labeled “MBCP,” the right “non-fumigated,” and the middle row is the inner buffer zone, fumigated twice with MBCP.
Shaw mentions that the slope of the field and angle of the sun might create an optical illusion, making it difficult to see a difference in plant size.
“If I had it my way, and if it were economically possible, I wouldn’t fumigate with methyl bromide and chloropicrin,” he says. He pauses as observers kneel down to row height. “I would fumigate with methyl bromide and chloropicrin twice.”
The difference between strawberries in non-fumigated soil and those in MBCP-treated soil was visible at any angle — fumigation works. Shaw calls the result, nearly a 40 percent higher yield, “somewhat of a miracle.”
No more weed problems, no more nematodes that damage the strawberry plant’s sensitive roots — there’s no more anything that was once alive in the soil.
“You don’t need fumigation to grow strawberries,” Shaw says. “You just need fumigation to grow strawberries economically.”
A Safer Alternative?
To agriculturalists, methyl bromide heralds efficiency in disease control, yet it has equally deleterious effects on our atmosphere’s protective ozone layer.
Normalcy among those closest to the multi-million dollar berry industry has upended with the international ban on ozone depleting substances — known as the Montreal Protocol — which intends to phase out methyl bromide by 2015.
In response to the ban, the Environmental Protection Agency (EPA) registered methyl iodide, a highly neurotoxic and carcinogenic soil fumigant, in 2007.
Shaw’s fumigation trials showed that when using methyl iodide and chloropicrin (MC), there was only a 4 percent less yield than MBCP.
“It’s the only real alternative presented in the last three years,” he said.
While it may be statistically considered methyl bromide’s best drop-in replacement, it is also called “one of the most toxic chemicals on earth” by UCLA public health professor John Froines, an eminent toxicologist.
The EPA’s own evaluation reports symptoms of methyl iodide exposure, including “increased cancer incidence, thyroid toxicity, permanent neurological damage, and fetal loss.”
UC Berkeley professor Robert G. Bergman and Cornell University’s Roald Hoffmann, with full support of the national scientific community, addressed the EPA administration in 2007. They said methyl iodide’s high volatility and water solubility made its agricultural use a “guarantee” of emissions and human exposure.
They were “skeptical,” they said, of the risk assessment processes of methyl iodide, and asked the administration to “delay the decision and assemble a blue-ribbon panel of independent (conflict-free) scientists.”
Then-EPA administrator Stephen L. Johnson didn’t respond to Bergman and Hoffmann’s request to re-evaluate methyl iodide.
“You simply cannot separate the political profile from this chemical,” said farm advisor Bolda, who was involved with 1998 in-field residue studies of methyl iodide for the California Department of Pesticide Regulations.
A Turn in Conventional Production
With all the controversy surrounding soil fumigants — more specifically, the recently approved methyl iodide — there is little discussion of whether a strawberry industry without them could even exist.
Farm advisor Bolda maintains that with the loss of methyl bromide, strawberry production will decrease by only 10 to 15 percent. Due to the drop in production, he said, we will see a rise in the price of berries to buffer any loss.
“The doom-and-bloom scenarios that we hear are completely wrong,” he said. “There will still be Watsonville strawberries in New Jersey in the winter.”
As the go-to guy for berry growers in the Central Coast, Bolda sees the advent of blogging and global informatics as an occupational standard, and this could now be utilized for an entire industry: an upgrade, per se.
His blog, Strawberries and Caneberries, reaches a widespread audience. On his Blackberry, he posts recent findings in the field identifying the latest soil-borne pathogens and nasty pests along with their seasonal life cycles and methods of control.
“Look at nuclear weapons — they’re outdated,” Bolda said. “Understanding how the soil works, the pests you are trying to control — that is the smart bomb. It’s a lot less messy.”
His new take on pest management includes use of Geographic Information Systems (GIS) to accurately track soil-borne infestations. Bolda believes the toxic soil fumigants could be used in less amounts, but far more effectively.
“Let’s say in a field there are three places that have pathogens, and you need to fumigate,” he said. “If you have the technology to pinpoint the locations of the pathogen, you can do this without the extraneous effects that fumigants have … Methyl iodide is too blunt a tool, and I think we could do better.”
Bolda advocates for more control with soil fumigants and Shaw believes there is no substitute to MBCP. Meanwhile, others have a different notion of the post-methyl bromide era in agriculture, including Joe Schirmer, owner of Santa Cruz organic farming business Dirty Girl Produce. A leader in the Central Coast region, he sits on the board of directors for the Center for Urban Education on Sustainable Agriculture in San Francisco and is president of the Santa Cruz Community Farmers’ Markets.
“The strawberry industry isn’t sustainable because of the soil fumigants. Fumigant technicians walk around in HazMat suits handling that material, and it’s still considered safe,” Schirmer said. “In reality, methyl bromide and methyl iodide are a big joke and will eventually be phased out.”
Organic production trends are growing in the Watsonville-Salinas district. CSC reports an 8 percent increase in organic acreage since last year, accounting for three-quarters of the state’s organic production. Large-scale commercial growers are going organic, and the number of small-scale growers is rising.
“The answer lies in crop rotation,” Schirmer said, offering his own solution to the pending dilemma. “Growers who produce just strawberries can’t do back-to-back production and not expect diseases. They don’t care what their strawberries taste like, they just care about yield.”
Schirmer’s Dirty Girl has expanded from 3 acres in 1997 to 40 acres just recently, making up four different plots on which the farm owner cultivates. He distributes produce throughout the Bay Area.
Another realm of research that could reduce the reliance on fumigants is developing strawberry varieties, or cultivars, that are more resistant to the same opponents that methyl bromide and methyl iodide try to kill.
Strawberry cultivar development by traditional crossbreeding has become somewhat of an art for Shaw and fellow UC Davis strawberry pomologist Kirk Larson. UC cultivars account for 85 percent of the state’s fruit.
Shaw and Larson conduct much of their breeding research at the field station’s UC Strawberry Breeding and Licensing Program.
Cultivars bred at the field station are produced exclusively in California, with few exceptions. Each is tested for superior characteristics, often with the help of MBCP. Now there is a higher incentive for strawberry growers and CSC to breed cultivars for disease resistance.
“A cultivar that can produce more and earn more because of less disease would translate into a lower rate for crop insurance and a higher guarantee for producers,” said Sandy Sanchez, a specialist and outreach coordinator for Risk Management Association at UC Davis.
Along with the fumigation trials, Shaw and Larson presented some of their latest cultivar studies in early May at the Pomology Field Day.
Ten cardboard cartons sit on the deck overlooking the experimental plot. Larson picks up a dark crimson giant from the carton labeled 6.137-2, bred for very high yields and great appearance — its taste, however, needs more work. 6.137-2 is one of many experimental cultivars yet to be certified by the licensing program.
In his other hand, Larson picked up an Albion berry, what he called a “good-eater” and has a long shelf-life. Its robust and flavorful characteristics make it the most popular of the UC strawberry varieties.
“I hear people saying Albion is one of the best to grow — it has high yields and it just has a wonderful flavor,” said Grant Livingston, a UC Santa Cruz soil science graduate.
A Long Shot that Might Work
“The incentives to protect the crop are very high,” said Carol Shennan, director of the Center for Agroecology and Sustainable Food Systems (CASFS) at UC Santa Cruz. “Soil fumigation is the ultimate silver bullet.”
Both Shennan and CASFS research associate Joji Muramoto have done comprehensive research on large-scale commercial alternatives in strawberry production while keeping agroecological principles in mind.
“If you plant strawberries frequently, it converts to a lower soil fertility and higher populations of lethal-pathogens in the soil,” Muramoto said. “More so than it would be for other vegetables. We demonstrated what growers speculated: that longer rotation is better.”
Muramoto maintains the importance of agroecosystem health on an organic strawberry-vegetable rotation system. He demonstrated that with more years of crop rotation and with the right crops in rotation — lettuce attracts Verticillium fungus and broccoli hinders its growth — the produce will be higher in quality and there will be less of a need for harmful pesticides.
Shennan and Muramoto have also made recent advances toward a “no-chemical approach” that is raising eyebrows.
“The method was originally developed in the Netherlands on small-scale farming systems,” Muramoto said. Known Anaerobic Soil Disinfestation (ASD), the practice has been expanded to large-scale commercial strawberry production in California.
While ASD may seem unconventional to commercial growers, it proves to be highly effective in the eradication of soil-borne disease. ASD is saturated in a concealed raised strawberry bed with water, leaving no oxygen in the soil, purging all microbial activity.
Costs of conventional production are rising and many growers turn to cheaper alternatives.
“Methyl bromide application costs have increased as high as $3,500 per acre,” Muramoto said. “ASD treatment is measured around $2,000 per acre.”
However, gravity works against the chemical-free system in Watsonville’s Strawberry Hills. The region’s steep slopes and sandy sediment matrix are drawbacks, as water must be retained homogeneously in the raised bed for ASD to perform properly.
While research is still underway, Muramoto and Shennan are adopting their system to Watsonville’s geography, and they speculate more advances with tandem efforts of different techniques.
“We don’t think ASD could be the methyl bromide silver bullet as it is,” Muramoto said. “However, maybe it will when use the combination of this with mustard mill.”
Using ASD in combination with Ida Gold mustard mill, a naturally —toxic compound, Muramoto explained, could be highly effective.
Soil fumigation is a deep-rooted convention in strawberry agriculture and the Montreal Protocol intends to change this, but much is still in question.
Legal action against methyl iodide use in agriculture has been the recent focus for pesticide watch groups. In March 2011, Pesticide Action Network North America (PANNA) rallied over 200,000 signatures in a petition to oust the chemical.
On Sept. 29, PANNA and Pesticide Watch, as part of a national campaign, will combine efforts at the regional Central Coast Forum on Methyl Iodide.
The Watsonville Strawberry Field Station is a model microcosm of the region’s rolling strawberry hills lined with miles of crimson. The longstanding pillars of soil fumigation are beginning to crumble under the industry and the state’s top researchers are working to provide more dynamic alternatives — keeping ethics and soil health in mind.
Meanwhile, strawberry growers strive to keep their yields up to make the cut, despite growing costs of conventional production methods.