August 2022 - 8

ARKANSAS FRUIT BREEDER'S PROGENY
GROWN THROUGHOUT WORLD
University program transitions to new leadership
University of Arkansas fruit breeder John Clark's blackberry varieties are grown on nearly every continent. He plans to retire from the fruit breeding program he's headed for
the last four decades. Photos: University of Arkansas
By Doug Ohlemeier
Assistant Editor
As University of Arkansas (UA) fruit
breeder John Clark prepares to leave
the program he's helmed since 1997, his
accomplishments are seen in the varieties
growing throughout the world.
Over nearly 60 years, the UA System
Division of Agriculture's breeding program
has released more than 60 varieties of
blackberries, blueberries, grapes, peaches
and nectarines. Clark is the resident
director of the university's Fruit Research
Station at Clarksville, which is renowned
for blackberry and grape cultivars.
Arkansas genetics birthed new industries
and are grown on nearly every continent.
At 65, Clark, a guitar picking
distinguished professor, has spent his
career designing better blackberries. In
December, Clark, who has been with the
university's horticulture department since
earning his Ph.D. in the early 1980s, plans
to retire from leading the world's largest
blackberry breeding program.
The program's scientists developed the
parent of the Cotton Candy table grape
variety. With Arkansas-bred flavors
combined with California grapes, the
variety is grown throughout the world.
Other varieties, including Candy Hearts,
Candy Dreams and Bebop, possess
Arkansas parents for flavor, Clark said.
Because there isn't a large blackberry
growing industry in Arkansas, variety
royalties and breeding agreements help
fund the program.
Blackberry gold
In 2002, Jerry and Keith Mixon, who
used to own SunnyRidge Farm, a Winter
8 | FruitGrowersNews.com
Haven, Florida, grower and shipper of
blueberries and strawberries, invited
Clark to visit their operation and help
them grow blackberries.
The Mixons planted 200 acres of UA's
new Ouachita variety in southern Georgia.
While the variety was bred in a region
that receives more than 1,000 chill hours
during the winter, growers found the
broadly adapted variety can produce well
in Georgia and Florida with 450 hours.
As more companies planted the fruit,
Ouachita became the backbone of the
southern blackberry industry. Other
regions grew the fruit, including east Texas,
but the Georgia plantings were the first
major effort which created the southern
blackberry shipping market.
Breeding program goals include peaches
without fuzz, blackberries without thorns
and seedless winegrapes and muscadines.
Dwarf blackberry plants are also in
development.
While UA's peaches are considered
among the program's best offerings,
because of various factors and a difficult
deal, growers haven't expressed much
interest in growing them, Clark said.
The UA program breeds for texture
differentiation.
" We have some really firm material here
that nobody grows, " he said, " but, it has a
place. It's a matter of the peach industry
being tough. "
Grape developments
Because of costs and the inability of
growers to compete with California
due to weather challenges, UA stopped
breeding table grapes and winegrapes.
The program was successful in creating
local market table grapes. Winegrape
breeding was a small effort.
Margaret Worthington selects muscadine grapes for advancing toward release as
varieties. Worthington is set to succeed John Clark in heading UA's fruit breeding.
A major initiative is crossing muscadine
grapes. Margaret Worthington, who will
succeed Clark as assistant professor of fruit
breeding and genetics in leading breeding,
is expected to release a series of seedless
muscadines that could eventually change
the industry, Clark said.
In 2013, UA released Prime-Ark
Freedom as a local market and home
garden blackberry variety. When found
to possess unexpected low chilling hour
requirements, it proved to be a valuable
fruit in the Deep South for floricane
cropping and grows well in central Florida,
Clark said.
Prime-Ark 45 was introduced as the
first shipping quality primocane fruiting
blackberry, capable of producing two
crops a year (under the right conditions)
and extending blackberry harvesting
into the fall.
" The primocane fruiting trait that we
have been working on for a number of
years will change how blackberries are
grown throughout the world, " Clark said.
Other prominent varieties include
Shawnee, Navaho and Ponca blackberries,
Ozarkblue blueberries, the Cardinal
strawberry, Reliance and Jupiter table
grapes, and Dazzle, Enchantment and
Indulgence winegrapes.
Clark attributes UA's success to
remaining interactive and committed to
the goals of developing new varieties.
" You have to have someone who is an
inspired individual who is disciplined and
wants to go out and work with growers to
lead breeding, " he said.
Guitar pickin' breeder
In his last year of breeding, Clark is
addressing growers throughout the U.S.

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August 2022

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