From space, all farmland looks pretty much the same. Slightly irregular rectangles and rhomboids ranging from greenish-brown to brownish-green stretch across every valley, crisscrossed by dirt roads, and—if you look closely enough at the satellite images—raked into mechanically perfect rows as if by a giant, single minded Zen gardener.
Whether it’s a field of artichokes or zucchinis, the strategy is basically the same: wipe the slate clean of all living things, level the land, add fertilizer, plant one crop, water, keep the pests at bay, harvest, and hope the market doesn’t turn on you.
And yet the nearly ubiquitous sight of a conventionally farmed monoculture is fairly new, and the agricultural paradigm that spawned it is causing some severe growing pains.
Of the total habitable land area of the planet, one half is agricultural; about 39% of that is given to grazing and animal feed, and 11% to crop production, according to the UN Food and Agriculture Organization.
The growth of agriculture has been fueled by the adoption of simple chemical and mechanical solutions to complex problems, generating new, interlocking threats to the soil, water, air, and the web of living things that knits them all together.
“I think you can find stories in all sorts of agricultural systems, animal and plant, about a simple solution that’s now causing problems,” says Julie Guthman, professor of social sciences at UCSC who studies the intersection of food systems, politics and economy.
Consider the story of strawberry production as a kind of case study, as Guthman does in her new book Wilted: Pathogens, Chemicals and the Fragile Future of the Strawberry Industry, exploring the coevolution of the crop, the pests and the pesticides, and the fallout from recent regulations.
“Various conditions that were once really advantageous for the strawberry industry, that enabled it to become extremely productive, have now morphed into threats, and the threats interlock with each other because they’ve built on each other,” Guthman says.
Strawberries are in many respects a unique crop, but their story does function as a larger cautionary tale about the use of simple chemical solutions.
Once considered a delicacy–rare, inconsistent and fleetingly seasonal–strawberry production has grown by leaps and bounds to become one of California’s biggest cash crops, grossing $3.4 billion in 2018. Systematic breeding and the use of fumigants to effectively sterilize the soil have prolonged the growing season, homogenized the end product, and increased the average yield of an acre of strawberries in California from 6 tons in the 1950s to 50 tons today.
There is a long history of strawberry production in Santa Cruz County, where they are by far the number one cash crop. In 2018, strawberries brought in nearly half of the total gross agricultural sales in the county, with over 2,500 planted acres producing 18% of all strawberries grown in the state, bringing in more than $220 million.
But growing strawberries is not without its challenges, from the high costs of land, labor and inputs, to climate change, water pollution and the politics of immigration. They are also very susceptible to certain diseases, and half a century of heavy pesticide usage, particularly of the fumigant methyl bromide, has made strawberries one of the more controversial crops.
And now that methyl bromide and other pesticides are more heavily regulated, a new cast of pathogens is entering from the wings, threatening crops and compounding the many other problems with growing strawberries.
Birth of a Berry
To understand the plight of the strawberry, we need to dive deep into their origin story.
Strawberries are members of the rose family, with more than 20 species around the world in the genus Fragaria. Most have small berries, less productive and less palatable than modern cultivars, but prized by early cultures.
The beach strawberry, Fragaria chiloensis, grows on the Pacific shores of North America, South America and Hawaii. In coastal California in the springtime, members of the Ohlone, Miwuk, Pomo and other first nations often camped out on the beaches for the short berry season, and even held strawberry festivals. Native Americans used fire to cultivate strawberries and other food staples, understanding that they produced more fruit the year after a disturbance.
The Mapuche and Huilliche peoples of what is now Chile likely grew F. chiloensis for hundreds of years before Spanish conquistadors arrived, developing a cultivar with walnut-sized berries that caught the eye of a French spy in 1714, who brought living samples back to King Louis XIV.
In the eighteenth century, European colonists were quite taken with the scarlet berries of F. virginiana, a hardy North American species, and sent samples home to enterprising horticulturalists. Breeders in England and France crossed these with native European strawberries before finally attempting a hybrid with the Chilean beach strawberry, and the modern strawberry, F. x ananassa, was born.
Plant breeding in the 1800s was like the wild west. Hypotheses and methodologies proliferated with no systematic framework. Experimentation was often practical, organic, and competitive, leading to breakthroughs that went unnoticed and unrecorded.
Strawberries lend themselves particularly well to this type of experimentation: they constantly produce runners, tiny clones which are easy to transport and transplant, they have a very versatile genome that allows for many different hybrids, and they bear fruit their first year, so each generation is fairly brief.
As a result, innumerable thousands of cultivars were developed, bought, sold, stolen, grown, eaten and forgotten in the first few centuries.
The early mavens of the strawberry industry saw the potential in the sandy soil, warm days and cool nights of the Monterey Bay, and began developing new varieties that they hoped would capture berry lovers’ hearts everywhere.
The strawberry that launched the Driscoll’s empire, the Banner, was planted in Watsonville in 1904. Its fruit was consistently big, candy-apple red and delicious, and it became an instant hit–so much so that after a decade of success, farmers up and down the coast began stealing runners so they could grow the Banner themselves. Pretty soon everyone had it, and there was nothing the proto-Driscoll’s could do about it.
Just in time, the Plant Patent Act of 1930 tamed the wild west of plant breeding by granting the same intellectual property rights to breeders as inventors, giving legal ownership and protection for the novel varieties they created, and incentivizing a more systematic approach to breeding.
When the Banner started coming down with “the yellows,” a viral infection spread by aphids, pathologists at UC Berkeley began looking for disease-resistant strains to cross into the line, establishing a breeding program that developed, tested and released new cultivars to farmers throughout California, with the goals of growing bigger, better and more berries, for longer, in a wider range of conditions.
In the first half of the 1900s, the actual skilled labor of farming strawberries in California was largely the domain of Japanese immigrants, so much so that when the U.S. detained them in internment camps during World War II, the strawberry industry effectively collapsed.
At the same time, UC Berkeley signaled that it was ending its breeding program. Ned Driscoll read the writing on the wall and pulled off a major coup, hiring the two heads of the program and poaching their library of genetic material–thousands of seedlings representing years of research. With these resources at their disposal back in Watsonville, Driscoll’s secured its legacy as a berry magnate.
The UC program didn’t end up folding, but moved to the campus at Davis, where it has continued to shape the evolution of the strawberry ever since.
Growing strawberries is not easy, for many interconnected reasons.
Strawberries fruit best in their first year, so growers nearly always rip out the old crop and plant new seedlings every year. This means high upfront costs to till the field, reform beds, assemble irrigation, lay down plastic for mulch and insulation, and purchase and plant seedlings.
They’re also very labor-intensive because of the drawn-out harvest: Pickers are paid by the tray and must hustle along the rows while bent double. After World War II, Mexican and Latin American immigrants came to dominate agricultural labor in California, and for decades the strawberry industry profited from a surplus of labor, much of it migratory and undocumented.
Then there’s the soil microbiome. If improperly managed, strawberries can suffer from pathogens like Verticillium wilt, which dries plants to a crisp and can persist for years in untreated soil. If farmers grow the same crop in the same fields year after year, an outbreak becomes more and more likely.
Many farmers rotate different crops through each field for a few years until the diseases die out, but because strawberries are so lucrative, growers found other, more convenient solutions that allowed them to grow every year.
In the 1960s, farmers began fumigating with methyl bromide, chloropicrin, and a host of other chemicals, basically sterilizing the soil underneath sheets of plastic before planting in their fervor to control the pathogens.
Without the threat of disease, yields went up and everyone started making real money. But for those working, living and going to school near the fields, the fumigation regime was concerning.
Methyl bromide is highly toxic, with health impacts from inhalation ranging from lung damage to neurological effects to impaired childhood development, but so far it is not classified as a carcinogen by the EPA due to insufficient data.
Chloropicrin was used in large quantities as a tear gas in World War I and went on to become one of the most common pesticides applied to strawberry fields. In 2016, more than 1.5 million pounds of pesticides were sprayed on crops in Santa Cruz County, according to the California Department of Pesticide Regulation, and nearly half was on strawberry fields.
Pesticide manufacturers are responsible for conducting their own safety studies, and always insist that their products are harmless if used correctly, but allegations and anecdotes of pesticide poisonings are persistent.
The trouble is a lack of data on agricultural workers, particularly undocumented immigrants. Besides the language barrier, these workers are often missed on censuses and surveys, and they shy away from hospitals and law enforcement, meaning that studies of the real health impacts of pesticide exposure are not particularly robust.
Methyl bromide was banned internationally as an ozone-layer-depleting substance in 1991, and scheduled to be phased out in California by 2005, but the industry fought for critical-use exemption from the law, claiming that to farm strawberries without fumigation would bankrupt them. The pesticide was finally regulated in 2017.
Tale of two pathogens
So now that methyl bromide is finally being strictly regulated, is the industry suffering?
At first glance, no. 2018 saw the highest productivity ever recorded, with gross product up 4.5% from 2017. But when you look closer at the numbers, there’s more to the story.
The record supply brought prices way down, leaving farmers scrambling to break even. According to the county’s Agricultural Commissioner Juan Hidalgo in the annual crop report, 2018 “proved to be one of the most challenging years for our growers due to historically low prices that persisted throughout the growing season.”
On top of that, labor shortages (or perceived shortages) in recent years have left millions in berries to rot unpicked, spurred by decades of dwindling immigration, the aggressive stance of the current administration, an insufficient guest worker program, and the opportunity for better wages in the construction and service industries.
“One of the things that’s really weird is that amidst all this complaining about labor shortages and fumigation and restrictions and all this, growers also continue to see low prices because there is hyper-productivity in the strawberry industry,” Guthman says.
This is also in spite of the total acreage planted in strawberries steadily shrinking each year, mainly due to the high cost of renting prime coastal ag land, which is being snapped up for development.
“There are a lot of land uses bearing on the coast that make good strawberry land extremely scarce and expensive, including real estate development, because a lot of suburbanites like the same natural air conditioning as strawberries do,” Guthman says.
According to the California Strawberry Commission’s (CSC) 2018 California Strawberry Acreage Survey, over the previous three years, planted acreage declined by 13% while yields increased by 6%, with organic acreage maintaining a proportional share at 12.6%.
And just when you thought that growing strawberries was complicated enough, two new adversaries enter from the wings.
Two pathogens previously unobserved in strawberries have started showing up as fumigants have become more restricted.
Macrophomina phaseolina, aka charcoal rot, is a fungal pathogen that infects hundreds of crop species, causing the plant to rot and collapse. It was first detected in strawberries in Ventura and Orange Counties in 2005, associated with fields that had discontinued fumigating with methyl bromide and chloropicrin.
Fusarium wilt, another fungus, was discovered to be enervating and drying out strawberries the next year in Ventura County. Both diseases hit harder when plants are stressed by weather extremes, drought and poor soil conditions, adding another level of anxiety that they might get worse with the changing climate.
Guthman says the industry blames the rise of these two pathogens on the changing fumigation regime.
“I speculate that either these pathogens were there all along and they didn’t make themselves known because they were suppressed, or because the conditions under which the industry has been treating strawberries have created pathogenic environments,” she says.
Or maybe, because strawberries have been bred for decades in (and for) fumigated soils, perhaps they have lost some resistance to these diseases that they might once have had.
“They bred from hybrids of the hybrids of the hybrids,” Guthman says, “and so a lot of the more ancient qualities that might have been useful for disease resistance are very hard to find in the genome.”
In any case, the new pathogens have spread, and the industry is scrambling to adapt. Many fumigants are still in use, including chloropicrin, but without methyl bromide they are less effective and still subject to strict regulation, particularly from the California EPA.
So strawberry growers and researchers are frantically looking for alternatives–and the news isn’t all bad. Carolyn O’Donnell, communications director of the CSC, says that they are researching non-chemical means of disinfestation, such as steaming the soil before planting, as well as a production system using plastic-lined troughs in the soil containing a sterilized growing substrate, but so far these have proven to be cost-prohibitive.
A technique called anaerobic soil disinfestation (ASD) is much more promising. Joji Muramoto is a researcher at UCSC who has been studying organic strawberry production for over 20 years, and has been key in developing ASD as a way to create more favorable conditions for strawberries in the soil microbiome.
By flooding fields with water and a source of carbon like rice bran, grape pomace or molasses, Muramoto says he has seen promising results for controlling strawberry wilt and rot, decreasing synthetic fertilizer use and increasing organic yields.
He also says that new field DNA tests will make the identification of pathogens quick and easy, so farmers can figure out what they’re up against, and research into beneficial soil microbes could yield good results for organic growers.
Muramoto was recently appointed the first Organic Specialist for the UC Cooperative Extension, and says he plans to network with organic researchers across the state and provide resources for organic growers.
“The main challenge for organic growers,” Muramoto says, “although we now have more tools than before, growers have to integrate all available tools to better control soilborne pathogens.”
In 2020, new technologies are also being brought to bear on the strawberry industry. O’Donnell says the CSC is researching the effectiveness of tractor-sized vacuums to suck up lygus bugs, a common strawberry pest, and that automation is a priority.
But so far attempts to replace human labor have been unsuccessful due to the delicate nature of strawberries: robot pickers are still not sensitive enough to identify the perfect ripeness and to pick berries without damaging them.
Looking ahead to the next generation of agricultural specialists, Cabrillo College introduced a new multidisciplinary associate’s degree in Ag Tech last year, intended to prepare students for jobs in the rapidly growing sector with a combination of courses in horticulture, GIS, engineering and computer science.
Peter Shaw, the chair of the Cabrillo Horticulture department, says that fields and greenhouses are becoming increasingly sophisticated and automated, with remote sensors collecting data about environmental factors like water, temperature or the amount of nitrogen in the soil.
“The technology just seems to be exploding,” Shaw says. “It’s about maximizing yield while minimizing the amount of energy, water and fertilizers that you’re pushing through the crop, and that tends to go down the drain.”
And finally, strawberry breeders are reprioritizing and reinventing themselves.
The UC Davis Public Strawberry Breeding Program holds patents on over 30 cultivars, representing 60% of the strawberries consumed worldwide. But the program was rocked to its core over the last decade when its two head researchers, Douglas Shaw and Kirk Larson, left to pursue their work in the private sector.
They joined California Berry Cultivars, a proprietary company based in Watsonville, much in the same way as Berkeley’s strawberry breeders left for Driscoll’s 60 years earlier, bringing along the precious new cultivars they had been working on. But this time, a series of lawsuits and counter-suits followed, trying to prevent Shaw from absconding with his own work. He still works for CBC, but his prior cultivars are in legal limbo.
The new head of the Davis program, Steve Knapp, is taking it in a new direction, sequencing and studying the strawberry genome and incorporating genomic techniques in breeding new cultivars. Last summer the program released five new cultivars with an emphasis on disease resistance, minimizing inputs and maximizing yield and quality.
Guthman says that none of these solutions is surefire, but maybe some combination will keep the strawberry industry alive.
“The book suggests a fragile future, but it’s really hard to predict what that future will look like,” she says.