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AU TESTS SAVE SATSUMA TREES, BUT 1996 CROP LOST TO COLD
FAIRHOPE-- For those anticipating the sweet taste of Alabama-grown
satsuma oranges this fall, the news is bad--real bad. For those anticipating
Alabama's "heavenly tangerine" in the future, the news is
real good.
Cold weather last winter knocked out virtually all the satsuma crop
along Alabama's gulf coast. Once a thriving business, consecutive freezes
back in the 1930's ended the State's citrus industry. However, mild
winters throughout the 1990's continued homeowner production, and the
increase of population and subsequent markets in southern Baldwin County
brought a small revitalization of commercial satsuma production.
Researchers at the Gulf Coast Substation in Fairhope planted a satsuma
test orchard in 1990. They equipped the test orchard with several systems
in an effort to protect the trees from freezing.
"We didn't expect to save the entire satsuma tree when temperatures
dropped into the teens, but we hoped that some of our treatments would
at least protect a portion of the tree thus eliminating having to start
all over again by replanting. Some of the treatments used were the old
standard freeze protection of banking the trees with about 18 inches
of soil. In addition, micro-sprinklers were used in various combinations
to apply a constant fine mist of water, thus creating an insulation
of ice and hopefully protecting the tree," noted Alabama Agricultural
Experiment Station researcher Ronnie McDaniel, who is associate superintendent
of the Gulf Coast research station.
Mother Nature put the Auburn University researchers to work early and
often in the winter of 1995-96. On January 7, when the air temperature
dropped to 31 degrees, water was turned on and the Senniger irrigation
mist system worked like a charm--quickly coating the satsuma trees with
ice. Ice insulates the trees at 32 degrees, which satsumas can tolerate.
Some of the trees in the test orchard have two misters, one about 2.5
feet from the ground and second mister about 5.5 feet from the ground.
Other trees have only one mister about 5.5 feet from the ground. In
addition to the banked trees, there are other trees which have no protection.
On February 3, the misters were turned on again, when the temperature
dropped to 32 degrees. The low of 15 degrees and high of 30 degrees
on February 4, could be low enough to kill satsuma trees and certainly
would defoliate unprotected trees. "We were surprised that the
satsuma coated with ice kept their leaves, and we were hopeful that
we could make a crop after that freeze," McDaniel said.
But again on February 16, the Senniger system was turned on and temperatures
dropped to 23 degrees on February 17. "After surviving the February
4 freeze, we wanted to try everything we could to save the foliage that
we had worked so hard to save during the earlier freezes. And, we did,"
McDaniel pointed out.
However, Mother Nature wasn't quite done with satsuma. In early March,
after several days of mild weather, Another freeze was experienced with
four nights of below freezing temperatures - ranging from 27 degrees
to 32 degrees during the period of March 8 thru 11.
The Senniger system was turned off during the day and on at night for
90 consecutive hours. The prolonged freeze killed any hope of making
a satsuma crop in the test orchard in 1996, but demonstrated clearly
that growers can save trees.
"The level of freezes we had the past winter defoliated the satsuma
trees, and hence killed any chance of a normal crop. The unprotected
and banked trees did not fruit while some of the iced trees set a few
fruit," McDaniel said.
Back when satsuma production was a major agricultural industry in Alabama,
they had several winters back-to-back with temperatures from 6-12 degrees
and growers couldn't afford to replant and wait for the trees to get
into production. The citrus industry in Alabama didn't die from lack
of interest in satsuma, or lack of markets, because growers used to
ship train loads of the fruit to Chicago, New York, Boston and other
metropolitan areas up north. The industry died because growers couldn't
provide the fruit every year and consumers began looking for sources
of fruit."
Though satsuma trees survived freezing temperatures, the heavy coating
of ice took a heavy toll. "It seems like the most damage from limb
breakage came on trees that had only one mister up high on the tree.
We seemed to prune out less dead wood on the trees with both an upper
and lower mister," McDaniel noted.
Saving satsuma trees with ice also is not cheap. Researchers at the
Gulf Coast Station applied about 5,500 gallons of water per acre per
hour. Future studies may indicate some more efficient timing of application,
but the cost of water and labor will still be high.
For producers and consumers alike, the cost of saving satsuma trees
may be money well spent. For those who have tasted the sweet, nearly
seedless, soft-skinned satsuma, it is easy to understand why the earliest
of Alabama's Gulf Coast referred to it as the Heavenly tangerine.
-30-
Roy Roberson
July 11, 1996
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