The most valuable thing in Grandma's vegetable garden - other than Grandma, of course - may not be the okra she's frying this weekend, but its underlying genetic code.

In an age of genetically engineered crops and seed hybrids, scientists are turning to old-fashioned plant varieties that could hold the key to warding off devastating blights to Southern crops.

Loss of genetic diversity in food crops emerged as an issue in the 1960s. Based on concerns that population would outgrow food supply and millions would starve, scientists developed new "super" seeds by crossbreeding plants. These hybrid seeds, which were resistant to most insects and diseases, yielded millions of additional tons of grain a year.

But the miracle seeds weren't perfect. Not only did the hybrids lose their traits of open pollination, but insects and viruses also mutated and foiled the genetic resistance of the new seeds. The pests sent scientists scurrying to find other genes that would help crops withstand the threats. Meanwhile, the old varieties and wild plants were disappearing from many places, replaced by improved - but genetically uniform - crops.

The danger of depending on a single seed variety hit home in 1970 when a new fungus wiped out nearly 50 percent of the Southern corn crop. A virulent new strain of corn leaf blight appeared in South Florida that winter and raced north like a killer flu. The homogenous rows of hybrid corn contained no line of natural resistance, so the fungus destroyed half the crop from Florida to Texas, costing the South a billion dollars in crop losses.

Field crops weren't the only victims. Orchard trees were just as vulnerable. In 1984, a bacterial disease forced Florida nurseries to destroy 18 million citrus trees and seedlings.

When these blights swept through the South, there was no organization or network dedicated to preserving the region's "heirloom" plants that could safeguard genetic diversity. That led Robert Rhoades and Virginia Nazarea to start UGA's Southern Seed Legacy (SSL) project in 1993.

"We started realizing that Southerners had this very strong tradition of saving and passing along seeds," Rhoades said. "But we found no research on it, or no organization for Southerners to exchange their seeds like they have up North and out West."

With the help of their students, the two anthropologists have been collecting heirloom seeds, no longer widely available in stores, from gardeners and farmers across the South. They locate these "seed savers" through surveys, newsletters and market bulletin ads; they even rely on word of mouth.

According to Rhoades, it is estimated that by the middle of the 21st century, 25 percent of all plant species may vanish - victims of deforestation and the shift to overgrazing, water-control projects and urbanization. "Since plant breeders now produce a relative few hybrid varieties, it has become essential to rediscover and protect the old strains," he said.

The researchers are preserving not only the old-timey varieties, but also the gardeners' memories of the plants and their cultivation histories. The study includes family secrets, from the special fertilizer passed down from generations to how late in the season the beans should be planted. Acquiring this type of firsthand knowledge, known as memory banking, is crucial to a successful heirloom plant conservation program. Nazarea first developed memory banking in the Philippines in the early 1990s. (Her 1998 book, Cultural Memory and Biodiversity, examines the results of this program.)

"There's an infusion of the human dimension into technology," Nazarea said. "And that's what we wanted to do here: look at local people's knowledge and harness that information."

Anyone may request seeds from the SSL program, which now boasts more than 350 samples. However, growers must agree to return one-third of the seeds from a successful crop to the SSL program and pass one-third to another gardener or farmer. The remaining third, they keep. They also must keep detailed records of growing methods, general environmental conditions and descriptions of plant performance.

"We didn't want to be a central clearinghouse," Nazarea said. "We wanted to create a network. This way, it spreads like a chain letter."

That's exactly what happened.

"Word of mouth got out, and the next thing we knew," Rhoades said, "we had hundreds of accessions."

Representative of them is the colloquial advice of Georgia seed saver Ernest Keheley, who practices the techniques he learned from his parents more than a half century ago: "You don't fertilize peas when you plant," he advised the SSL program. "They make their own nitrogen down there, and if you fertilize 'em, they'll grow up into a bunch of vines and no pods."

Throughout the South, local plant varieties have become a source of pride enveloped in the culture. For many gardeners, a sense of place and a link to the past are reason enough to save their seeds.

"A lot of the people who save [seeds] in the South are not really the type of people to join a big organization," Rhoades said. "They're very intimate with their environment."

Although experimental trials have just begun, Rhoades said the heirloom varieties seem to have more resistance to drought and insects. Studies also show the old-timey seeds have more to offer. "Even though there's a lower yield, and they're somewhat smaller in size, the overall profitability is actually higher with some of the heirlooms," he said.

The U.S. Department of Agriculture first funded the SSL in 1996 with a three-year grant from SARE - Southern Region Sustainable Agriculture Research and Education - but now the project is self-financed. A $10 annual fee entitles members access to SSL's resource directory and seed bank, and to receive a quarterly newsletter.

Rhoades and Nazarea worked on similar programs in Peru and the Philippines, respectively, before establishing the SSL program. This past summer, with the help of some UGA students, Nazarea set up a memory banking program in Ecuador.

Rhoades said he plans to seek funding for the next phase of the SSL program, which will focus more on the cultural aspect of these seed savers.

"Why do people continue to maintain these seeds? After all these years, why do they keep such an attachment to their seeds? As anthropologists, we are interested in this way through which people hang on to their past and their cultural heritage," Nazarea said.

"It's not very easy to approach people and ask for their story," she said. "The seeds are a great medium for people to connect. You start talking about seeds, and then the stories begin to stumble out."

Access http://www.uga.edu/~ebl/southernheirloom/ for more information.

Catherine Gianaro, who has served as guest editor for the past two issues of Research Reporter, is an award-winning, Chicago-based freelance writer and editor. She also is a former UGA assistant director of research communications.