When you think of a strawberry, you envision a piece of fruit and wonder whether it will be sweet and juicy. When a farmer thinks of a strawberry, he sees a plant and has a completely different set of concerns. He wonders whether it will be resistant to all the many pests and diseases that afflict the species. He wonders whether it will have the vigor to grow strong in what might be challenging climatic or soil situations. Will it be a heavy bearer?
He wonders about the fruit, too. Will it appear at the times it makes him the most money—early and late in the season? Will it appear consistently, rather than in fits and starts, so he can keep a steady crew employed? Will it look good? (Supermarket shoppers buy with their eyes, not their palates.) Will it be firm enough to survive the days of shipping it takes to get to market? How will it taste? It has to taste good enough, certainly; that goes without saying. But if the rest of those criteria aren’t met, all the flavor in the world won’t mean a thing.
Plants that can do all those things do not just happen. Almost every fruit or vegetable that we eat is the result of centuries—even millennia—of careful breeding and selection. At its most primitive level, this happens almost accidentally. Because genetics is constantly evolving, seeds from even the same plant can grow into new plants that are slightly or even markedly different from each other—just like kids from the same set of parents. So farmers have always selected the seeds of their best plants every season and then stored them to start the next crop. In this way, the traits of the plant are slightly altered each generation. Eventually, this can result in fruits and vegetables that are almost wholly different from their ancestors. (The original corn plant produced ears only slightly bigger than those of wild grass.)
When practiced by family farmers working small plots of land, this kind of selection also can result in plants that are ideally suited for very specific growing areas. Botanists call these varieties “land races.” For example, in the Veneto region of Italy, there are dozens—if not hundreds—of subtly different types of radicchio di Treviso, many adapted to a specific family’s farm (or, since there can be differences in soil and climate within a single holding, even specific parts of a specific family’s farm).
Sometimes these changes are neither slight nor gradual. New plants, radically different from their parents, can happen spontaneously. These genetic mutations, called “sports” by the trade, have played a much more important role in the development of modern agriculture than you might think. The Hass avocado was discovered this way in the 1920s, hanging from a tree of a different variety and then propagated. The original still stands in Whittier, California. The same happened with the Red Delicious apple. The story goes that an Iowa farmer gave the tree a try only after he failed in repeated efforts to kill it. And so, too, the Washington navel orange—the longtime industry standard. The original was a sport found in Bahia, Brazil, in the 1860s. In fact, the larger family of oranges may well have come about in a somewhat similar fashion, as there is no such thing as a true wild orange. (Botanists believe that they probably stem from crosses between giant pummelos and tiny mandarins.)
There was nothing accidental about the development of the modern strawberry. It required not only centuries of selective plant breeding but ocean navigation as well. The strawberry you buy in the supermarket today draws its heritage from very different plants found on entirely different continents. It developed spontaneously in France by a cross between plants from Chile and North America. The last great leap in strawberry quality came in the late 1970s as the result of a happy accident. While walking in the Wasatch Range of Utah, legendary plant breeder Royce Bringhurst came across a wild strawberry fruiting at a time and place it shouldn’t have been. He took it back to his lab and began using it in some of his crosses. The result was a strawberry that could grow in warmer weather and during longer days than was previously possible. These so-called day-neutral berries revolutionized the industry, allowing the eleven-month-a-year harvest we enjoy today. Although the genetics now seem to be more complicated than Bringhurst had originally thought, about 40 percent of the commercial strawberries in the country spring from these varieties.
The journey hardly stopped there, of course. The quest for a better berry continues today—and in much the same way it always has. On twenty acres of University of California-owned farmland tucked against the Irvine Hills in Orange County, strawberry breeder Kirk Larson is tending more than 25,000 plants. Somewhere among them, he hopes, the next great variety is waiting to be discovered. Larson doesn’t know when it will turn up—it may be this year, or it may be five or six years from now. He does know that it will have to be something pretty special, as he and his predecessors have set the strawberry bar high.
In fact, it’s not going overboard to say that in the past twenty years or so, plant breeders have revolutionized the strawberry. What once was a tender icon of spring has become a year-round supermarket staple. This has certainly been good for business: in 2003 strawberries became a $1 billion crop for California. The state now produces more than 85 percent of all the strawberries grown in this country and more than 20 percent of all the strawberries grown in the world.
But every revolution has its casualties, and in this one it was the sweet, melting, incredibly fragrant berry of generations past. You might have thought that berry was remarkable, but for the people whose livelihoods depend on supplying strawberries to the entire country, other characteristics are every bit as important. The history of strawberry breeding is littered with delicious berries that are no longer grown. The most recent example is the Chandler, which ruled the strawberry industry for almost a decade in the 1980s and 1990s until it was done in by its fragility. “The fruit looked great and tasted good, but if you shipped it to New York, when the buyer opened the box, the fruit was all leaking out the bottom—that’s an automatic rejection,” Larson says. “You’ve paid all that money to grow the fruit, pack it and ship it, and it’s a total loss. That only has to happen a couple of times before you get real tired of it.”
That may sound hard-nosed, but it is the philosophy that since World War II has transformed what was once a highly seasonal niche product into one of the marvels of modern industrial agriculture. Since 1950 California strawberry growers have increased their production more than twentyfold, from 81 million to 1.67 billion pounds. At the root of this transformation have been the University of California’s strawberry breeders: Larson, working out of the South Coast Research and Extension Center in Irvine, and his partner Doug Shaw, who operates out of Davis in the north. UC varieties account for almost two thirds of all the berries grown in the state.
In addition to the University of California, there are two other private strawberry breeding programs in the state, managed by shippers Driscoll’s and Well-Pict. These proprietary varieties make up about one third of the California harvest. Overseas, the UC breeders’ impact is even greater. Roughly 90 percent of the strawberries grown in Spain, the second-largest producer, come from the University of California, and those varieties are similarly influential in strawberry fields from Mexico to Morocco.
That’s the kind of success other plant breeders would love to have. To achieve it, they are taking plants to places they might not ordinarily go in nature. One of the biggest pushes in fruit breeding is trying to find seedless varieties. Obviously, left to their own devices, seedless fruits would not last long. But they are incredibly convenient to eat (witness the almost total domination of seedless grape varieties today and what that has done for grape sales). Seedless fruits do occur in nature, but only under very specific conditions and, of course, only for one generation. In some plants, the development of fruit occurs separately from pollination. Some fruits don’t produce seeds because of a genetic imbalance. Bananas, for example, have an uneven number of chromosomes, making the production of seeds rare. (It does happen, though, and you’ll sometimes see a little train of tiny black specks going up the center of the fruit.) Other good examples of this are navel oranges and Satsuma mandarins, which also almost never have seeds. Other fruits will not produce seeds when they are pollinated only by plants of the same variety. Plant Clementine mandarins and Minneola tangelos in orchards that are isolated from other citrus, and they’ll be nearly seedless; plant them close enough to other citrus, and they can be quite seedy. Oddly enough, seedless grapes are a different matter, because they are not truly seedless. Instead, these grape varieties produce seeds that never mature beyond the size of a speck. Technically, they have seeds, but you’d never notice.
So how do seedless plants survive? Mainly with the help of farmers, who propagate them by cutting branches and grafting them onto other plants, or by encouraging the cuttings to develop roots of their own. (In nature this can occur when a plant produces side shoots, which will continue to live after the infertile shoot dies off.)
Seedless mandarins—more commonly known as tangerines—are the primary focus of citrus breeders today. Mandarins are terrifically convenient to eat because they peel so easily. On the other hand, they usually are loaded with seeds (Satsumas and Clementines being the main exceptions). In addition, peak mandarin season is right around Christmas, with a few varieties extending into February. The breeder who can successfully combine easy peeling, seedlessness and an extended market season will have found the holy grail of citrus: a fruit that can be eaten as conveniently as a candy bar.
That breeder might be Mikeal Roose and his crew at the University of California at Riverside. In 2002 Roose introduced three new seedless mandarin varieties, with the California-centric names Shasta Gold, Tahoe Gold and Yosemite Gold. They are all seedless and easy to peel, but beyond that they have marked differences. Shasta has rich, intense mandarin flavor, matures very late and will hang on the tree well into May. Tahoe is earlier but has the same rich flavor. Yosemite falls somewhere in the middle as far as harvest and has an almost candied, Kool-Aid flavor. So far, growers have been slow to pick up on them. The mandarin industry in California is just beginning to catch fire, and it’s far more expensive to graft over an orchard of perennial citrus trees than it is to replant strawberries, at best a biennial.
And, to tell the truth, there haven’t been a great many new citrus additions in the past one hundred years or so, and those few haven’t fared awfully well. Probably the last great citrus fruit rollout was the Oroblanco, a cross between a pummelo and a white grapefruit. It is a spectacular fruit when well grown, sweet but with the pummelo’s characteristic bitterness to balance. Introduced in 1980 to much fanfare, it was picked up by growers pretty quickly.
But the Oroblanco has an unfortunate quirk: its peel is often quite thick and sometimes keeps a greenish cast well past the time the fruit is ready to eat. This discouraged shoppers, and gradually the fruit fell from favor. There’s a twist to the story, though: Israeli farmers picked it up, renamed it the Sweetie and marketed it in Japan as a green fruit. The Japanese loved it, too, and now, twenty-five years after its introduction, Oroblanco plantings are again on the upswing in the United States.
When you walk through Riverside’s research orchards—a pair of tracts totaling twenty-two acres in the foothills next to the university—both the promise and the perils of citrus marketing are evident. Established in 1912, they now contain more than nine hundred types of citrus. Not only are new trees tried out, but the orchards also contain a substantial collection of historical varieties—many of which are no longer grown—and types of citrus that are popular in other countries but have not been introduced here.
Among the latter is an Australian finger lime—a greenish black, long, thin fruit that is filled with lime-colored and lime-scented beads that pop in your mouth like so much citrusy caviar. There’s also something called a “dawn fruit”—a cross between a blood orange and another pummelo-grapefruit combination similar to the Oroblanco. It is absolutely gorgeous, with deep purple flesh and a compelling raspberry-tinged flavor. As good as it is, it will quite likely end up going nowhere, as the costs of introducing a totally new product into the market are staggering.
That’s the main reason so few fruits and vegetables are labeled by specific variety in the market. It’s much easier to sell a “peach” than it is to introduce shoppers to the half-dozen new types that appear every year. This is one more area in which farmers’ markets are changing things, though. More and more, varietally labeled produce—everything from Chioggia beets to Pixie mandarins—is gaining cachet and selling for premium prices.
The promise of varietal marketing is the last thing on Larson’s mind as he prowls his trial fields examining his brood. His fruit will be sold simply as a strawberry, which is a blessing in some ways but totally ignores all the work that went into developing it. To understand how remarkable these plants are, you have to understand the strawberry itself. If ever there was a fruit that seemed designed to frustrate industrial agriculture, this is it.
From the tips of its berries to the ends of its roots, the strawberry is the essence of vulnerability. Unlike most fruits, strawberries wear their seeds on the outside of their flesh rather than the inside, and there is neither skin nor rind to protect the sweet flesh from the predations of climate and pest. This fragility is only amplified after the fruit has been picked, as the teeniest nick or cut can become an open doorway for the fungi that lead to rapid decay. If anything, the roots are even more exposed than the fruit. They are made of extremely simple tissues and lack any corky bark or covering that would protect them from soilborne pests. As a result, an established field of strawberries is little more than a well-advertised, all-you-can-eat buffet for almost any bug around.
Because of all this, strawberries are extremely expensive to produce. A recent study by the California Strawberry Commission, a growers’ organization, predicted costs of more than $30,000 an acre to grow the fruit, harvest it and ship it. Farmers are left scrambling for any advantage to make their investment pay off.
That’s where Larson and Shaw come in. Their job is to find the one plant in a million—almost literally—that can give farmers an edge. It might be a berry that ships better, or one that produces higher-quality fruit. (Even with the newest best varieties, farmers discard up to 20 percent of their fruit as too small, poorly colored or misshapen.) Or it might be a plant that produces exceptionally well either early or late in the season, when the prices are highest. The same flat of strawberries that sells for $6 in July may well go for $30 in January or February. But whatever special traits it has, it will also have to have good flavor, because without flavor the market won’t be interested in it.
The search for this perfect plant begins not with any kind of high-tech genetic manipulation but with old-fashioned birds-and-bees pollination. Larson selects a pollen-bearing male flower from a plant with desirable traits and rubs it around the center of a female flower from another selected plant. When that fruit ripens, the seeds will be collected and planted. (Technically, these “achenes” are actually tiny dried fruits themselves, each one containing a seed.) Each plant will be a fraternal twin of the others from the same berry, sharing many traits, though also being slightly different. The plants that seem most promising will be selected and planted outdoors the next year.
In the field, the new plants are numbered and grouped according to their parentage. If you look closely enough, you can see the resemblances and also the differences. This plant may have large, perfectly formed fruit, while its sister right next to it bears strawberries that are of a similar size but more frequently misshapen.
Most of what Roose does in his citrus breeding program is traditional genetics as well, although he is experimenting with exposing cut branches of trees to low levels of radiation to induce mutations that might result in favorable new characteristics rather than simply waiting for them to happen. This is about as adventurous as most fruit and vegetable breeding gets. Although there has been widespread public concern about genetically modified organisms (GMOs), they are largely restricted to commodity crops such as field corn, cotton, canola and soybeans.
The major exception was the vaunted Flavr Savr tomato, one of the first GMO products. Introduced with great fanfare in 1994, it was supposed to be able to sit on shelves forever without going soft. Unfortunately, once shoppers found that it tasted like cardboard, sitting on shelves was about all it did. Combined with the fact that the plant proved uneconomical to grow in the areas where it was planted, the experiment was a bust, and the Flavr Savr was quietly dropped in 1998.
In most cases, this kind of genetic modification is done to make plants resistant to pesticides and herbicides, so they can be sprayed with a certain company’s chemicals without suffering any damage. This practice may be a boon to growers, but only to growers who buy both the seeds and the chemicals from the same company. No ill effects to the consumer have been demonstrated, but the lack of evidence is hardly reassuring, since the Food and Drug Administration has decided that testing is not required in most cases. Furthermore, the industry is fighting tooth and nail against labeling GMO products, which would give consumers a choice as to whether they want to buy them. Ironically, probably the most GMO-intensive food you can find today is tofu, as about 70 percent of American-grown soybeans are genetically modified.
The work of traditional plant breeding is unimaginably tedious. Larson walks his strawberry fields nearly every day for the twenty-eight weeks that make up the typical Southern California season. He uses a handheld Allegro CX computer loaded with a spreadsheet to score each plant on a variety of criteria. He counts the fruit and grades it for size, shape, color and, to a certain extent, flavor. He grades the plant’s “architecture”—how the leaves and fruit are presented—and several other factors. “I’m looking for the drop-dead gorgeous strawberry poster child,” he says.
At least in the early going, he doesn’t pay as much attention to taste. He tastes the berries from time to time, but flavor is too subjective and complex. “There are so many aspects to strawberry flavor,” he says. “It’s not just sweetness. There has to be the right blend of sweetness and acidity, and then there are all the aromatics that make up flavor as well.” Of course, there are more mundane reasons for not tasting every berry. “I do love strawberries, but I’d have to be eating thousands a day to make it meaningful,” he says. “I try to take a bite whenever I can from plants I like, at least until I start feeling bloated.” Flavor will become much more important at the end of the plant’s selection trials.
At the end of the year, Larson runs the spreadsheet and analyzes each plant for productivity and value. Of the 13,000 or so plants in the initial selection, he picks the best to go on to the next year, based on the criteria of shape, size, color, firmness, architecture, disease resistance, rain tolerance and flavor. This time he cuts runners from the strawberry and plants them. (Seeds vary genetically, whereas propagating from plant division ensures identical clones.) The process will repeat with further winnowing each year until one plant has proved its worth to become a variety. This season, in addition to the new trials, 487 strains from last year’s first selection made the cut. There are also 160 from the year before that, and a few from even earlier. One plant survived more than five years, but Larson says this year will be its last. “I had pretty high hopes for that one to become a variety, but it just doesn’t look like it’s going to make it,” he says. It had great yields, early production and excellent shelf life, but the flavor just wasn’t consistent.
Even after a variety has been selected, it still has to be tried out in test plots maintained by farmers at various locations throughout the state. All told, it takes at least six years to find a plant that is worthy of becoming a named variety. It frequently takes even longer. The Chandler berry, which was introduced in 1983, took seven years for Larson and Shaw’s predecessors, Victor Voth and Royce Bringhurst, to develop. And it took Voth a decade to select the Chandler’s successor, the Camarosa.
Still, that’s a dead sprint when compared to developing new citrus. A fruit tree takes three to five years to reach productive maturity (and eight or nine to hit its peak), not a single season like a strawberry plant. Once a tree with potential has been selected, it goes to an experimental station in the San Joaquin Valley to be tried out there and at other locations as well, since the citrus industry is dispersed through several areas with different climates and soil types. That takes another three to five years. Then it’s released to commercial orchards, where it is tried out again. By the time you add it all up, developing a new citrus takes an average of about thirty years.
It is rare that any breeder sees a citrus tree through from beginning to end. Rather, breeders operate like stonecutters on medieval cathedrals, inheriting works in progress from the previous generation and passing on their own projects to the next. The Gold series of mandarins that Roose introduced in 2002 was begun in 1973 by his predecessors, James Cameron and Robert Soost. They in turn introduced varieties such as the tiny, seedless Pixie mandarin, which had been originally developed in the 1920s by Howard Frost, who along with Walter Swingle practically invented modern citrus breeding. The profession can make for some testy relationships. Larson says he never really understood why Voth was so prickly until a friend explained the difficulty of passing along plants you have developed and nurtured: “Hey, it’s like he was married for fifty years, and all of a sudden he wakes up and you’re sleeping with his wife.”
Once a variety is chosen and endorsed by the growers, it can spread quickly. A single citrus tree can provide thousands of buds for grafting onto other trees. Within four years of their introduction, there were more than 55,000 Yosemite Gold, Shasta Gold and Tahoe Gold trees planted in California orchards.
As you might expect, progress is even faster with a plant like strawberries, which are usually replanted every year. Within just a couple of years of its introduction in 1993, the Camarosa accounted for all but a tiny fraction of the strawberry acreage in Southern California and a huge chunk in the northern part of the state as well. Now the Camarosa is well on the wane, down to less than 20 percent of the state’s harvest. Its successor, the Ventana, was first planted commercially in 2002 and within three years accounted for almost 15 percent of the harvest.
Each succeeding variety offers improvements on the previous one but also has flaws of its own. “No variety is perfect; there are always trade-offs,” Larson says. “There are one hundred criteria we have to assess, and there is no perfect variety that has all of them—and there probably never will be.
“In the twenty years since the Chandler was introduced, we’ve pretty much doubled the yield and probably tripled the shelf life of strawberries. We’ve added at least another month to the season, if not six weeks. If this were a new biotech start-up, everyone would be all over us. But because it’s strawberries and we’re just sticking pollen from one plant onto another, something that’s been done for thousands of years, nobody thinks much about it. Growers are impatient. Everybody always wants something new. We just released the Ventana a couple of years ago, and already people are asking me when I’ll have a replacement for it. I’m telling you, it’s not easy to do, at least partly because we’ve set the bar so high. If you wanted to replace the Chandler right now, I’ve got hundreds of plants that would be better. Replacing the Camarosa or the Ventana is not so easy.”
The Chandler berry had great flavor when everything went well, but it was too soft to ship. The Camarosa, which is exceptionally firm and ships very well, has much larger fruit, is a heavy bearer and is much easier to harvest, but the flavor isn’t quite as good as the Chandler’s. The Ventana bears a lot of fruit early; the fruit tends to have better shape, texture and color than the Camarosa; and it is at least equal to the Camarosa in flavor.
Along with the successes have been varieties that didn’t work out quite as well as the breeders had hoped. The Gaviota, for example, which was introduced in 1997 and is doing well in the farmers’ market niche, has excellent flavor but does not bear heavily, and the fruit doesn’t last. The Diamante, also introduced in 1997, has good flavor but is firm and lacks internal color, which limits its use in processing. Growers will probably begin to replace it when the new Albion variety is ready for the big time. “That’s going to knock people’s socks off with flavor,” Larson says.
That remains to be seen. But you can be pretty sure that however it tastes, this brave new berry will be big, pretty, easy to pick and prolific; will bear over a long period; and will be firm enough to ship from here to the moon without suffering a bruise.