07/11/1996

AU Tests Save Satsuma Trees, but 1996 Crop Lost to Cold

FAIRHOPE, Ala. - 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.

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News from:

Office of Ag Communications & Marketing

Auburn University College of Agriculture
Alabama Agricultural Experiment Station
3 Comer Hall, Auburn University
Auburn, AL 36849
334-844-4877 (PHONE) 334-844-5892 (FAX)

Contact Jamie Creamer, 334-844-2783 or jcreamer@auburn.edu
by Roy Roberson

July 11, 1996