By Sharon Omahen

University of Georgia

With production expected to reach 90 million pounds this year,
Georgia pecan growers have a lot to smile about. They still
frown, however, at the mention of pecan scab.

Each year the state’s growers spend $200 to $300 per acre on
fungal sprays to fight pecan scab. The disease develops and
spreads in wet weather, particularly when the nuts are growing.

Nuts infected with pecan scab develop black spots on the shuck.
Many will be so covered that the entire nut turns black and falls
before it’s fully developed.

Existing cultivars losing resistance

For decades, commercial growers have relied on just two
varieties, Stuart and Desirable, for most of their pecan crop.

“Stuart was selected in the 1880s, and Desirable came along in
the 1930s,” said Patrick Conner, a pecan breeder with the
University of Georgia College of Agricultural and Environmental
Sciences.

Both had good resistance to pecan scab when they were first
selected. Decades later, though, both are now very susceptible to
the disease.

“Over time, the scab fungus adapted and overcame their
resistance,” he said. “Lately, scab has been very difficult to
control on these varieties, even with fungicide sprays.”

Working closely with state’s growers

Conner became the UGA pecan breeder in 1998 after the state’s
pecan commission rallied for the position. From his Tifton, Ga.,
laboratory, he works closely with growers to develop new
varieties.

When growers find what appears to be disease-resistant pecan
seedlings in their orchards, they bring them to Conner.

“When we find one that has good qualities, we put it through
research trials alongside our crosses and see if it has potential
to be a new variety,” he said.

Conner recently got a $6,000 grant from the Georgia Pecan
Commodity Commission. The grant will help fund his search for new
disease-resistant pecan varieties.

“When it comes to commercial nuts, size is a major factor,
because people like larger pecans,” Conner said. “The percent
kernel, or the way the kernel fills out the nut, is also
essential.”

Pecan breeding takes time

Each spring since 1999, Conner has made new pecan crosses. His
first crosses, or potential new varieties, have just begun to
flower. Next year they will produce their first crop of nuts.

Conner says the breeding program works in two phases. First, he
evaluates seedlings for disease resistance and overall nut
quality. This first phase takes five to 10 years.

The selections that pass this phase are then reproduced and
inspected for other qualities, like tree productivity and regular
bearing. This phase of the breeding program takes about 15 years.

“Once we get the program running, we’ll be releasing new
varieties every few years,” he said. “We hope to have our first
new resistant variety from our crosses in 15 to 20 years.”

In the interim, Conner is evaluating selections from Georgia
growers, Auburn University researchers and the U.S. Department of
Agriculture breeding program in Texas.

“There’s a USDA selection we’re testing that looks good,” he
said. “We’re sending it out to selected Georgia growers this
spring to try. It’s so new it’s referred to by a number, 70-6-15.
It appears to have very good quality and disease resistance.”

Growers have to look way down the row to see the help on the
horizon. “In the future, hopefully, growers will be able to plant
new, improved varieties when they replace trees,” Conner said,
“rather than continuing to plant the same variety over and over.”

For the meantime, Georgia growers keep waiting, and Conner keeps
focusing on daily accomplishments.

“It’s (breeding pecan varieties) definitely a long process,” he
said. “But once you get a variety, the benefits will be
long-term.”