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
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
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
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
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
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
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
"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
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
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
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."
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
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
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.
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 firstname.lastname@example.org.
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
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
Return to Summer
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 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
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."
Return to Summer
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
"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
"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.
Return to Summer 1997 Index
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