Today’s strawberries are a something of a modern miracle. As you read this—no matter what time of year or where you live—there are literally millions waiting on grocery store shelves all over the developed world, their plastic clamshells unobtrusive, their shiny red color almost reflective. It’s difficult for most of us to imagine a time when they weren’t a constant.

And yet, like so many of today’s produce darlings, the affordable, year-round strawberry is a relatively recent phenomenon, and the product of an industry that relies heavily on high-tech breeding, cheap labor, and a highly volatile, gaseous form of pesticides called fumigants.

In her new book, Wilted: Pathogens, Chemicals, and the Fragile Future of the Strawberry Industry, Julie Guthman lays out the complex “assemblage” that makes it all possible, with a focus on her home state of California—home to the vast majority of the nation’s strawberries.

Civil Eats recently spoke to Guthman, a professor of social science at the University of California, Santa Cruz and author of the books Agrarian Dreams and Weighing In, about the history of the industry, the phase-out of the popular fumigant methyl bromide, and other impending changes to the crop.

You write that before World War II, 31 states grew strawberries. By 2017, California farmers grew 81 percent of them, and Florida farmers grew most of the rest. Can you talk about what changed in that time?

Strawberries were really a minor crop in the late part of the 19th century. There were people in California who grew them in patches. There was an apple industry in California, and people tried growing strawberries between the rows. There was no market for them, but that changed when the railroad started going from San Francisco to the Pajaro Valley [just north of Monterey]; once they could them ship them to the San Francisco market, the Pajaro Valley became the birthplace of the industry. So, it became a bigger crop but was still really selling for regional markets. It was doing well, but it was a limited season.

The first real turn of events happened in the 1920s and ’30s, when growers started to experience all sorts of blight disease with their crops; they called on the University of California to help identify the diseases and see what they could do. Out of that came the University of California’s breeding program, which was first charged with breeding disease-resistant varietals.

The scientists started experimenting with below-ground fumigation in the late 1950s and they discovered that a combination of chloropicrin, tear gas, and methyl bromide, a flame retardant, was really efficacious in controlling disease as well as weeds and nematodes. That allowed for a huge increase in productivity, and there was a huge expansion in acreage.

That [shift] allowed the breeding program to focus more and more on productive varieties and varieties that were firmer and would last longer so they could ship well. California’s geography also really lends itself to almost year-round strawberry production. In many other places it’s a three-week season, but California growers learned that if you moved your production toward the coast, where you have the natural air conditioning of the Pacific Ocean that often comes with fog in the summer, it made for an eternal spring and the sandy soil drained really well. Those were really ideal conditions for strawberry production, and other places couldn’t compete with that. [The combination of] the support of U.C., this ideal climatic zone, and fumigation are whatallowed it to really expand.

Early on in your research, you learned that strawberry growers don’t plant seeds. Instead, the plants are propagated in nurseries using a pretty complex process, which has essentially created a second companion industry. Can you explain more about how that works?

All those little seeds on the outside of the strawberry? If you planted them, they wouldn’t breed true. In other words, you wouldn’t know what you’d be getting. Almost all [commercial] strawberries derive from a hybrid of a Chilean variety and a Virginian variety. And whenever anybody comes up with the variety that they like, they patent it and then growers pay license fees to obtain a clone.

At first people propagated them on their farms. But a lot of things led to moving the nurseries elsewhere. Initially it was to avoid disease, but land is expensive where they grow the fruit, so why not grow it elsewhere?

The plants propagate better in other climates—in the hot Central Valley or in the far north, depending on when you want them to grow. They’ve found that the strawberry does really well if it’s chilled first. A lot of the nurseries are in the MacDougal Valley, which is in northeast California and it gets really cold there early in the fall; in October they start getting 20-degree nights and so they propagate there and they harvest the runners and the plants and freeze them and then sell them to growers far south in the state and the strawberries get out of those boxes and say, “Hey, it’s spring!” and they start growing really well.

The U.S. began phasing out methyl bromide in 2005 due to its status as an ozone-depleting gas, but you write about how farmers have replaced it with other fumigants that have their own share of unintended consequences.

When [scientists and farmers] were first experimenting with fumigation, they started with chloropicrin; it was kind of expensive to manufacture, so they combined it and methyl bromide, and they found that the two worked really well together. Most of the mix was methyl bromide—I think chloropicrin was only around 2 percent. Methyl bromide is good at shooting through the soil, and chloropicrin has a strong smell, so it was like a warning agent because you can’t detect methyl bromide by smell.

When methyl bromide was taken away, it was not without a big fight, and a lot of delays. And it’s still used in the nurseries to get clean plants, but not elsewhere. So what happened is a lot of growers moved to [straight] chloropicrin, and some are satisfied with it. A lot of growers also started moving toward doing what’s called bed fumigation rather than broadcast fumigation.

With bed fumigation, the rows between the beds aren’t fumigated and growers don’t have to have such large buffer zones. But they started seeing novel pathogens—ones they hadn’t detected before—appear in their fields.

My theory—and I’m not an ecologist, but I’ve talked about it with soil scientists and soil ecologists and plant pathologists—is that these pathogens were probably there all along, but they just didn’t make themselves known at levels that you could detect. And they only become pathogens when they’re damaging to the plant that you’re trying to produce.… There are all these things living in the soil, and they mutate and become beneficial or less beneficial or destructive depending on what else is happening.

You write about the possibility that a complete ban on all fumigants in California could move forward in the coming years. What would that look like?

Brian Leahey, the current head of the California Department of Pesticide Regulation, is a former organic farmer—but it’s not like he’s a radical. He wants to please his clientele. But he, along with some university scientists, growers, and others, put out something called the Nonfumigant Strawberry Production Working Group’s “Action Plan” in 2013. Because what had happened was with the “critical use” exemptions for methyl bromide, the industry had gotten fairly complacent [on alternatives] and wasn’t doing enough research.

That plan vaguely threatened that [fumigants] will be taken away, but, as I understand it, the main goal was to get the research going. Obviously, at the federal level, nothing’s going to happen anytime soon. But California is a different beast, and fumigants are up there as a concern. So, no matter what, there are going to be more restrictions on them, and that’s forcing growers into having to think about what they’re going to do. I asked growers recently: “If it’s taken away, what would you do?” Most said, “I’d probably go to field-based hydroponics.”

You also write that Driscoll’s—with its large staff of breeders and work on alternatives to fumigation—may have a real advantage in the industry if fumigation does go away.

Driscoll’s has been aggressively on the cutting edge since they began. I mean they were the first ones to patent a strawberry variety. They were the first to create their own proprietary breeding mechanism, and they claimed to be some of the first to address labor issues. They have also claimed to have been working on sustainability issues for a while. But it’s important to mention that Driscoll’s doesn’t actually grow strawberries. They license the breed of strawberries they develop to their growers, and they ship shipping materials, and then they buy the berries from growers. But they don’t take the risk of the actual growing.

You say that many growers have been more challenged by the ongoing farm labor shortage than the loss of methyl bromide.

The labor costs do seem to be getting a lot higher. The cost studies I’ve seen seem to demonstrate that between the border restrictions—and this was happening before, although it’s obviously gotten worse—and the fact if people are here a while, they’re going to go toward better work environments, many growers report having problems finding people to take their fields and losing acres and acres of strawberries.

And many growers reported workers showing up to their fields and inspecting the field to decide if they wanted to work there to see if there were enough berries on the vine; or they’d call their friends and ask: “What have you got?” or “What are they paying there?” Growers say they’re competing for laborers. And that may be true, but it’s also true that workers feel pretty vulnerable. I’m sure right now it must be really frightening to be a worker.

Meanwhile, the cost of strawberries—especially conventionally grown berries—has remained quite low for consumers.

Right, because they overproduce. It’s very hard to find data on profits, but I do believe that profitability has decreased, and many growers have gone out of business. And maybe that’s because profits were just low or maybe the business drove them crazy for another reason.

How do you think the industry will be impacted by the moves toward increased mechanization and the fact that more production may leave California for Mexico?

There’s a lot of talk about [strawberry picking robots], and there’s experimentation. Driscoll’s is super proprietary about it, but I did talk to another grower recently who said, “I’ve been experimenting with robotics, and it works pretty well.” But I haven’t seen any in the fields. And some people say it’s at least 10 years off before robots can replace people.

The Mexico question is really interesting because when they first started talking about the methyl bromide phase-out everyone said, “The industry is going to move to Mexico.” There’s no doubt there are a lot of operations in Mexico—Driscoll’s has a lot going on in Mexico—so the real question is whether that’s competing with U.S. production.

In the book you talk about some of the less-toxic ways to disinfect the soil. How far along are those fumigant alternatives?

A lot of growers are hoping for a drop-in replacement [for methyl bromide], another kind of biochemical or something like that, but the two [replacements] that have been of interest are not allowed for use in California. Last time I talked to Brian Leahey about it, he didn’t think they were going to be allowed anytime soon.

Another method that has gotten traction is anaerobic soil disinfestation, which has been developed by researchers at U.C. Santa Cruz. It involves putting a carbon source like rice bran or molasses in the beds, flooding the fields with water, covering them with plastic, and creating the conditions so all the oxygen dissipates, which kills the fungi that cause disease. There are mixed reviews on that. A few years ago, no one had used it on more than a couple of acres, but now some people are doing it on a wider scale. But it’s very water-intensive in a drought-prone state.

Another thing that people are looking at is field-scale hydroponics. Rather than planting in the soil, you use waist-high trays, which are supposedly an advantage to workers. Then you line them with some sort of material and put in a non-fertile substrate like coconut coir or peat moss, so you’re doing away with the soil. At one point the strawberry industry allegedly said they were not interested [in hydroponics] because it would undercut the biggest advantage of California, the sandy soils and coastal weather. Once you go to the full greenhouse operations, then why plant them on that very expensive coast of California? I’ve talked to growers who said they would try it in a pinch, but it’s expensive; it’s a lot of infrastructure.

The other alternative that’s been done for a while is fully integrated systems where you’re rotating strawberries with compost or with plants like brassicas [broccoli, cauliflower, etc.], which have mild fumigation properties. That’s what the more farmers’ market-oriented organic growers do, like Swanton Berry. But most of those folks are not growing enough strawberries for the mass market that currently exists, the one that lets people get strawberries in February for like a dollar a basket.

This interview has been edited for length and clarity.

Top photo includes a CC-licensed strawberry farm image by Glenn Nelson.