Lime-Sulfur Bath Curbs Citrus Mold, RotBy
California researchers say giving oranges and lemons a warm bath in a
lime-sulfur solution might offer packinghouses an effective and environmentally
friendly way to quell green mold and sour rot. These fungi are among the worst
threats to stored citrus.
Chemically, lime-sulfur is calcium sulfide, widely used as a soil
conditioner. This fact may help enable packinghouses to gain approval to dispose
of fruit "bathwater" on soil or in sewer systems.
In preliminary lab tests, researchers dipped oranges and lemons in a
3-percent solution of lime-sulfur in water heated to about 105 degrees F. The
tactic reduced up to 99 percent of green mold (Penicillium digitatum) and
up to 65 percent of sour rot (Geotrichum citri- aurantii).
Joseph L. Smilanick with the Agricultural
Research Service in Fresno, Calif., led the study.
Today in Parlier, Calif., Smilanick plans to describe the technique to
visitors at a scheduled groundbreaking ceremony for a new, 78,000-square-foot
ARS research center. Within about two years, ARS labs now in Fresno will move
to the Parlier complex, called the ARS San Joaquin Valley Agricultural Sciences
Currently, scientists are scrutinizing the dipped fruits to ensure they
retain their taste and texture. ARS is doing this jointly with
Sunkist Growers, Exeter, Calif.; Best
Sulfur Products, Fresno; and the University of California's Citrus Research and
Extension Center, Lindcove, Calif.
Larger tests are under way, using a commercial-size packing-line at the
Lindcove center. Scientists expect to try the dip with grapefruits and mandarin
oranges, as well. They will also conduct lab tests to determine whether calcium
and sulfate residues are easily removed by rinsing the fruit. A grant from the
California State Department of Pesticide
Regulation helps fund the research.
Use of lime-sulfur as a fungicide dates to the 1800's, but the
ARS-led team is apparently the first to extensively test potential packinghouse
application of the compound to safeguard citrus.
Scientific contact: Joseph L. Smilanick, ARS Horticultural Crops
Research Laboratory, 2021 So. Peach Ave., Fresno, CA 93727, phone (209)
453-3084, fax (209) 453-3088, Jsmilanick@aol.com.