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Research Magazine > ARCHIVE > Summer 97 > Article

The Dawning of the Perfect Peach
by Dan Rahn
(Photos by James Strawser)

Outside the pickup truck, the morning radiated promise. Inside, though, fatigue fairly filled the air, sagging the shoulders of horticulturists Gerard Krewer and Tom Beckman. It was May 1995, and Krewer and Beckman were trekking the long journey down to the Attapulgus Research Farm of the University of Georgia College of Agricultural and Environmental Sciences. There they would meet fellow researcher Wayne Sherman, and the three partners in a unique peach-breeding program would share one of those "eureka!" moments few scientists get to enjoy.

For most Georgians, Attapulgus seems a long way to go. The research farm is nestled in the undulating terrain off U.S. Highway 27, five miles from the Florida line and 12 miles south of Bainbridge, Ga. As a steadfast crow might fly, the 425-acre farm is 75 miles from Tifton, Ga., 140 miles from Byron, Ga., and 150 miles from Gainesville, Fla., the distant points from which the three scientists had come.

Krewer, a UGA horticulturist, is based at the Rural Development Center on the UGA College of Agricultural and Environmental Sciences campus in Tifton. Beckman, a U.S. Department of Agriculture horticulturist, serves at the Southeastern Fruit and Tree Nut Research Laboratory nearly 100 miles farther up I-75 in Byron. Each made weekly trips to Attapulgus during the peach ripening season, evaluating the fruits of their joint venture. And the miles were wearing on them.

I think we were just exhausted," Krewer said. "We were actually talking about disengaging from the program after the seventh or eighth year. Breeding and evaluation programs require huge amounts of time. And they yield few refereed publications. "Publish or perish" is a real concern." Funding was another worry. The program ekes by, surviving largely on the $11,000 peach growers have provided over the past four years. The long labors were piling up, and rewards seemed too small and far away.

Sherman, though, was in a different mood. A pre-eminent peach breeder with the University of Florida Institute of Food and Agricultural Sciences in Gainesville, he arrived early. He was eager to see the results of a particular cross-breeding effort. Before long, Sherman had found exactly what he had expected.

"I was back at the truck when Tom and Gerard got there," he laughed. "I walked through the first several rows with them and let them write their evaluation notes. Then when we got to row seven I said, 'OK, find me a ripe one that's soft.' After a few minutes, Gerard said, 'I've been had.' They had talked all the way over there about releasing the best from the program and shutting it down," Sherman said. "They talked all the way back about how they could keep it going."
On the soft slopes of the Attapulgus research farm, the three scientists were seeing with their own eyes the closest thing yet to perfect peaches. With their hearts, they were seeing a delicious future unfolding for these sweet fruits kissed with all the beauty and flavor nature intended and wrapped in the toughness growers need to get them to market. And the superpeaches hadn't arrived a minute too soon.

Peaches' Problems
A crop sweetly symbolic of Georgia agriculture, peaches' problems were piling up. Waves of horrible weather, the orchard life limits of peach tree diseases, declining prices and unending labor worries plagued the industry. And in the lower coastal plain, growers had far too few reliable varieties requiring a moderate number (400 to 650) of chill hours (the hours below 45 degrees through Feb. 15). All these problems had begun to pare the number of south Georgia orchards and stymie a potential peach belt that could stretch across the lower coastal plain from North Carolina to Texas. With budget cuts closing down research by Louisiana State, University of Florida and USDA at three sites, the Attapulgus program was the only one left that was devoted to breeding moderate-chill varieties.

The variety shortage is critical in the lower coastal plain, which accounts for approximately 10 to 15 percent of the $30 million Georgia crop but has seen nearly half its acreage go out of production since the late '70s. The Attapulgus researchers figure the key to the future of all Southeastern fresh-market peaches is in their very nature. It's something scientists call "melting flesh," which simply means that as the fruit ripens, it softens.

The macabre term stems from an enzyme, polygalacturonase, which makes the fruit of freestone peaches separate easily from their pits. "A peach's cells are held together by pectin - a polymer of galacturonic acid - much the way mortar holds bricks together," said Al Purvis, a UGA horticulturist at the Coastal Plain Experiment Station in Tifton. As a peach ripens, he said, polygalacturonase breaks down pectin into small, water-soluble units. Finding genetic ways to limit the enzyme level is the principle behind Flavr Savr tomatoes, Flame seedless grapes and other prize produce.

"Melting flesh" will hardly hold a horror movie fan's affection, however evil sounding its name. It is nonetheless a nasty aspect when you combine it with the fact that only as peaches ripen do the trees pack them with the sugars, acids and aromas that make people love to eat them. If you pick a peach too early, it doesn't taste like a peach and never will. "The earlier you pick it, the less potential it has," Beckman said.

On the other hand, if you pick a peach when it's ripe and has that wonderful, tangy-sweet taste you love, you'd best eat it right away. "Some varieties clearly soften very fast as they just begin to ripen," Beckman said. "When one of these peaches is fully ripe, you have to hold it with both hands. It's just a fuzzy bag of juice and strings."

For growers, there's no choice. If they're going to ship peaches to your grocer, they have to pick them a little green. They asked plant breeders for varieties that grew firmer peaches. "But we did it all wrong," Sherman said. "We gave them peaches that turned a good yellow ground color 10 days before they were physiologically mature."

Those peaches looked beautiful on the produce counters, and people bought them. But they were plastic peaches. "No taste at all," Sherman said. And over time, people began to buy fewer peaches.
U.S. consumers ate an average of 11.76 pounds of peaches in 1975. After 20 years, the figure dropped to 9.48 pounds. At the same time, overall fruit consumption is up. "Apples and grapes are on the upswing," Beckman said. "Nectarines are holding their own. But peaches are losing ground. And peaches compete not just with other peaches but with all other U.S. and exotic fruits as well. If the Southeastern peach industry doesn't do something soon, we're going to get our butts whipped."

A New Breed
That's what the horticulturists are trying to change at Attapulgus, the isolated UGA research farm known for its first 37 years as the Shade Tobacco Experiment Station. (Nearby farmers grew about 2,000 acres of shade tobacco, used as the wrapper leaves for cigars, until most of the industry moved to South America.) It was renamed the Extension-Research Center in 1974 and later the Attapulgus Research Farm. UGA scientists use the land for research on horticultural and agronomic row crops.

The Attapulgus peach-breeding program started with a 1990 Georgia-Florida-USDA agreement. "We didn't have a single peach-breeding project across the Southeastern moderate chill zone," Krewer said. "We expect the project to serve the lower coastal plain from Charleston, S.C., to southern Louisiana." The biggest peach industry in that area now, though, is in south Georgia.

Sherman and Beckman do the crossbreeding, using pollen from the Florida selections to pollinate the female parents at Byron. Then Beckman takes the seedlings to Attapulgus, where they're planted in what Beckman calls "hedgerows," spaced 3 feet apart. They don't prune the seedlings, except to remove branches that get in the way of equipment. "We get some pretty wild-looking trees out there," Beckman said.

The seedlings usually fruit in the second year after they're transplanted. Krewer and Beckman evaluate the seedling peaches every three or four days, looking for the biggest, firmest, reddest, best-shaped, best-tasting peaches. Promising selections are budded onto proper rootstocks in Byron and planted the following fall into variety blocks at Attapulgus. There the trees are pruned to the open-center shape of a normal peach tree, like an umbrella blown inside out, and maintained as they would be in a commercial orchard.

Sherman was the natural choice to make the crossbreeding decisions. "He's a world leader," Krewer said. "Sherman is five years ahead of the rest of the world. He decided years ago he'd change over to nonmelting-flesh peaches."

"I pushed and pushed," Sherman said, "but I couldn't get anybody to believe me. You just can't convince anybody until he holds one of these peaches in his hand and eats it. People kept cautioning me, 'Go slow on this.'"

Many scientists just don't think shoppers will go for the firm-flesh peaches. "Southeastern peaches are historically tasty and juicy," said Butch Ferree, a UGA extension horticulturist. "They tend to get soft. These peaches they're breeding at Attapulgus are tasty, but I wonder if Southerners are ready for a crunchy peach."

Early on, there were even bigger reasons to be skeptical. For years the only firm-fruit peaches being grown were used exclusively for canning. "But those peaches are rubbery," Krewer said. "They can be like eating a rubber ball. And they develop a really undesirable off flavor when they get overripe."

The Breakthrough
But what other scientists didn't consider was that those traits aren't an essential part of non-melting peaches. They were just things the canners didn't mind. They didn't matter in canned peaches. "These peaches were just sweet," Sherman said. "They didn't even look like peaches. They had no red color (red becomes brown during canning), no acid, no aroma - they were just sweet."

The breakthrough came when Sherman found some nonmelting peaches in Mexico that didn't have the rubbery texture or excessive off flavor when overripe. He became convinced that the answer to the perfect peach lay in the nonmelters everyone else disdained. Sherman began incorporating the Mexican peach genes, along with germplasm from Brazil and other parts of South America from Colombia to Venezuela, into his own low-chill selections in Florida.

But the trait Sherman has been developing isn't exclusive to Latin-American peaches. "The gene has been in the national germplasm since Chinese clingstone, a parent of Elberta," he said. Georgian Samuel Rumph bred Elberta, the nation's first freestone peach, in the 1870s. "Elberta probably carries the nonmelting gene," he said. "It's just that nobody has ever pushed it."

That's not true anymore.

In the spring of 1991, the new partners planted the first crosses, which included some of Sherman's non-melters, at Attapulgus. In '93, one of the 27 seedlings selected for budding was a nonmelting peach. The second two selections came in '95. Three more followed in '96. This year, at least half will be nonmelters.

"It's clearly the way to go," Krewer said. "With the non-melting types, over time, we can make incremental improvements to our existing varieties. But these peaches give us a quantum leap. When Tom and I saw them at Attapulgus in '95, we were astounded."

Beckman agreed. "You have to be out in the orchard and look at what's available and compare," he said. "That's what does it. In '95, we fruited a whole slew of Wayne's selections. They were out there ripening in the same windows. It was easy to see that they're head-and-shoulders better."

Bouncing Peaches
Sherman, ever the cheerleader for his brave new peaches, said his first Florida "perfect" peach release, UF Gold, "looks even better now than when we released it. And you could bounce it down a mountain on a donkey's back and still have two weeks of shelf life."

He isn't kidding.

"They do that in Central and South America," Beckman said.
"They don't have the infrastructure we do. In Brazil, peaches are called on to survive a nine-hour drive in 90-degree heat in a non-refrigerated truck. These peaches don't need or want that kind of abuse. But they can take it."

Beckman knows what he's talking about. He has tested the peaches with a "bounce meter" - a force impact sensor. "This is a non-destructive way to measure the coefficient of restitution, a measure of the elasticity or resilience of the fruit," he said. "We test peaches at a comparable stage of ripeness, then put them in a cooler for five days and take them out again for two more days. (We're modeling the harvest, shipping to market and two days on the produce counter.) Then we can take the same set of measurements. The non-melters lose less than half the resilience the melters do during the storage trials. They often show only a trivial drop between the two measurements."

The new peaches, Krewer said, aren't crisp or crunchy. "They're resilient," he said. "They just have a smooth, firm texture."
Still, they're different. "It's hard to visualize these peaches if you haven't seen and tasted them," Sherman said. "It's a world of difference. Normally you expect new peach varieties to be like getting a new car. You get a new Mustang every year, and there are some improvements each time. But it's still basically the same car. But this is a quantum leap. This is something really new."

The new varieties are so new, in fact, that the two universities and USDA aren't about to release them without patents. And that may keep you salivating for a while before these sweet new wonders hit the market. "We're probably going to release AP93-25, the first nonmelter we selected back in '93," Krewer said. "But we have to control it tightly until it's patented.

Perfect Peaches
The program has nearly enough data on some promising non- melters, Krewer said. If they can release a variety in '99, though, it will be 2001 before it produces a salable amount of peaches. The new trees should be in full fruiting in '02 - five years away. South Georgia growers' need for new varieties may be more urgent than that. So the Attapulgus program is releasing White Robin, a melting-flesh peach in the middle of the moderate-chill range. Other melters may be released, but the program's emphasis has plainly shifted to nonmelters.

For the moment, at least, growers are more interested in the chill hours than long-range prospects. "We need something that blooms after Floridaking and ripens before Junegold," said Andy Southworth, a Blackshear, Ga.-area grower. "We have to have high-color, two-and-a-quarter-inch peaches. If I can get a variety that gives me those qualities in that chill zone, I don't care what kind of flesh it has."

Growers, Beckman said, will have the last word when the nonmelters finally reach them. "There are two ways they can go," he said. "They can let them ripen a heck of a lot more and deliver a better quality product. Or they can still harvest early and just save on handling losses. When you're telling growers to leave peaches on the tree a little longer, they get nervous. They'll tell you, 'I've never had a load rejected for being underripe.'"

But Beckman's choice is clear. Researchers and extension scientists will need to show growers that the potential to produce perfect peaches is pointless if they don't put them in consumers' hands. "We're going to slowly lose our shirts if we don't," he said. "The only real advantage we have is our proximity to the markets. If we don't give consumers better peaches, we'll be left with nothing more than local markets. Something's got to give."

Many of the Attapulgus trio's colleagues still haven't accepted the direction they've taken their work. But they keep at it, confident of the sweet success they're sure will come when others taste the proof in their peaches.

For more information, e-mail Gerard Krewer at gkrewer@uga.cc.uga.edu.

Dan Rahn, a former English teacher and newspaper reporter, is the extension news editor for the UGA College of Agricultural and Environmental Sciences. He has bachelor's and master's degrees in English education from Georgia Southern University.

A UGA photographer for 25 years, James Strawser of James Strawser Photography is an award-winning photographer and a member of the American Society of Media Photographers.


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New Tops, New Bottoms for Peaches
by Dan Rahn

Commercial peach trees come in parts: tops and bottoms. Variety trials at the UGA Attapulgus Research Farm are focused on developing new tops, or scions. That's the part most people know and love, the part that produces the peaches.

The Attapulgus researchers said they hope to put a lot of new tops in south Georgia orchards. And if they do, chances are good they'll graft them onto a brand new bottom, or rootstock, called Guardian.

Guardian promises to greatly ease Georgia growers' losses to something called "peach tree short life," which is one of the worst things that can happen to a peach grower. Short life kills whole trees in their third to seventh year. In the third year, trees are just beginning to produce peaches. So just when growers start to recover some of the expense of establishing and pruning new trees into shape, they start losing them.

"It's a devastating loss," said Tom Beckman, a USDA horticulturist in Byron, Ga., who developed Guardian in a USDA partnership with Clemson University.

"We established the first commercial-scale block of trees on Guardian rootstock in 1989," he said. "And we released it in '93. We really had planned a more orderly process - it normally takes 20 to 25 years to release a new rootstock, and we had only 10 years from the very first trial. We just had a ground swell of demand for it, particularly in South Carolina, where short life is a much more serious problem."

In 1993, the fifth year of evaluations, no Guardian trees had died where the two commercial standard varieties, Lovell and Nemaguard, had already incurred significant losses. Growers, who needed some relief, didn't want to wait through the normal evaluation process.

"Guardian has tremendous potential to help Georgia growers if it shows in large numbers what it has already shown in small numbers," said M.E. "Butch" Ferree, a UGA horticulturist in Fort Valley, Ga. "If it stands the test of time, it will give our growers a lot more freedom as to where they can plant."

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Pick a Peck of Perfect Peaches
by Dan Rahn

Picking peaches is miserable work. "It's exhausting," said Gerard Krewer, a horticulturist in the UGA College of Agricultural and Environmental Sciences.

"With conventional harvesting, a wagon filled with field boxes moves down every second or third row in an orchard. Workers pick in boxes they carry, and when they get a box about half full - 25 or 30 pounds - they dump it into a field box in the wagon.

"When they start picking in the early morning, the grass and trees are wet," he said. "And then the heat gets up and the fuzz floating in the air gets all over you. It's one of the worst jobs you can do."

Krewer is working with University of Florida and USDA colleagues to develop new non-melting peach varieties - which are firm when ripe - at the UGA Attapulgus Research Farm. He takes a special delight in a new Attaplulgus research project on a new semimechanical peach harvester.

He's not kidding, although anybody who knows anything about peaches might think so.

"They're using these in Australia with apricots," Krewer said. The idea is to move pickers down the rows of trees, on a padded platform. The peaches will be hand-picked, but then just dropped onto a padded slope to roll down to a collection point for field-packing into boxes.

"This would be a disaster with traditional varieties," he said. "But we think it can be a great asset with the more resilient, new, non-melting peaches."

The trees for the trials - both non-melters and traditional melting-flesh varieties - already have been planted at Attapulgus. They'll begin fruiting in 1999, so the researchers have until then to build the harvester.

The trials also should provide peaches for further research.

"The plots should give us enough fruit to test various kinds of post-harvest handling and processing of melting- and non-melting-flesh varieties," Krewer said. "We've already begun some limited testing with freezing and canning. We think these new varieties have some processing potential - if not commercially, then at least for home processing. That would give them more value. Right now, no one puts up early-season peaches."

Krewer said the harvesting trials have another benefit: The heavy handling could show growers clearly just how tough the new varieties are. Believing in the new peaches enough to leave them on the trees a little longer will make them sweeter. And that's what all the Attapulgus researchers are after.

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