Strawberry science took a big leap forward in Germany, starting in 1949, when Rudolf and Annelise Bauer treated young seedlings with colchicine, an alkaloid compound in meadow saffron, to increase the number of chromosomes in hybrids of alpine and common strawberries, producing new, genetically stable varieties. Over the years, some breeders have taken advantage of this method to create new hybrids, including a cultivar introduced last year in Japan that has large but soft pale pink fruit with a pronounced peach aroma. Such attempts have often run into dead ends, however, because the hybrids are not only soft but cannot be further crossed with high-performing modern varieties.
To be sure, there's still one place where the original musk strawberry survives in farm plantings, although on a very small scale: Tortona, between Genoa and Milan, where the Profumata di Tortona strawberry has been grown since the late 17th century. Cultivation peaked in the 1930s, and lingered into the 1960s, when the last field succumbed to urban development. Until a few years ago only a few very small plots existed in old-timers' gardens, but recently the municipal authorities, together with Slow Food, an organization devoted to preserving traditional foodways, started a program that has increased Profumata plantings to more than an acre, on nine farms. These pure musk berries are a luxurious delicacy, but they’re expensive to pick and very perishable—a prohibitive combination for commerce. In the United States, most growers would sooner raise wombats than fragile strawberries, no matter how highly flavored.
Swartz says he came to love strawberries as a child in the Buffalo, New York, gardens of his Polish-born grandparents. He majored in horticulture at Cornell, and after finishing his doctoral research in 1979 on apple dormancy, he started teaching at the University of Maryland and helped test experimental strawberry varieties with U.S. Department of Agriculture researchers Donald Scott, Gene Galletta and Arlen Draper—giants in the breeding of small fruits.
Swartz conducted trials for the 1981 release of Tristar, a small but highly flavored strawberry now revered by Northeastern foodies; it incorporates genes for extended fruiting from a wild berry of the Virginian species collected in Utah. But he chose to go his own way and concentrate on raspberries. Working with other breeders, and often using genes from exotic raspberry species, he has introduced eight raspberry varieties, of which several, such as Caroline and Josephine, proved quite successful.
Swartz, who is married to his college sweetheart, Claudia—she and their 23-year-old daughter, Lauren, have had raspberry varieties named after them—has been described by colleagues as a "workaholic," a "visionary" and a "lone wolf." For many years he participated in professional horticultural organizations, attending meetings and editing journals, but in 1996 he gave all that up to focus on fruit breeding. "I can't put up with a lot of academics," he says. To pursue opportunities as he saw fit, Swartz in 1995 formed a private company, Five Aces Breeding—so named, he says, because "we're trying to do the impossible."
Swartz is working on so many ventures that if he were younger, he says, he would be accused of having Attention Deficit Disorder. He's helping develop raspberries that lack anthocyanins and other phytochemicals, for medical researchers to use in clinical studies assessing the effectiveness of those compounds in fighting cancer. He's an owner of Ruby Mountain Nursery, which produces commercial strawberry plants in Colorado's San Luis Valley, possibly the highest—at an elevation of 7,600 feet—fruit-related business in the United States. He's got a long-term project to cross both raspberries and blackberries with cloudberry, a super-aromatic arctic relative of the raspberry. And he recently provided plants for a NASA contractor developing systems for growing strawberries on voyages to Mars.
His musk hybrid project relies on breakthroughs made by other scientists. In 1998, two Canadian researchers, J. Alan Sullivan and Bob Bors, allowed him to license their new strawberry hybrids, bred using colchicine, from a diverse range of wild species, including alpine and musk strawberries. (Sullivan and Bors, after years of experimentation, had created partially fertile musk hybrids with the requisite extra chromosomes.) Swartz's breeding strategies can be idiosyncratic. Like an athlete training at high altitude to boost his stamina, he deliberately chooses difficult growing environments (such as sultry Miami) for his test plots, so that successful varieties will be more likely to excel in more temperate commercial growing districts. His main challenge with the musk hybrids is to increase their size and firmness, so they can be picked and marketed economically. It's a trade-off. Strawberry plants produce limited amounts of photosynthates, which they use for high yield, firmness or sweetness. "You move one up, the others are going to move down," says Swartz, "and it's very rare that you can have all three qualities."
Walking the rows at his Miami test plot, Swartz shows me a puny, malformed fruit, which lacks seeds on one side. "That's what 99 percent of them used to look like a few generations ago," he says. "For years I'd be eating sterile, miserable things, nubbins with two or three seeds." The hormones produced by fertile seeds, he explained, are needed for proper development of the strawberry, which is actually a swollen receptacle, the end of the flower stalk. Still, he would grind up even the most unpromising fruits, take the few good seeds and grow them as parents for future generations.
Could he show me a large-fruited strawberry with full musk flavor? Through seven years of crossing the original Canadian hybrids with cultivated varieties, the musk genes have become increasingly diluted, and it has been hard to retain the sought-after aroma. Typically, only one in 1,000 seedlings offers it, and I've heard that he's nervous we might not find any that do.
But after an hour or so, he picks a medium-sized, conical berry and bites into it. "That's moschata!" From the same plant I choose a dead-ripe fruit. It has an almost mind-bogglingly powerful, primeval aroma. Swartz ties an orange ribbon around the plant, to mark it for use in future crosses, and beams like an alchemist who has found the philosopher's stone.