
New Biofungicide Treats Apples and Oranges
Alike By Judy
McBride December 16, 1999Apples and oranges are all the same
to biofungicides. First introduced in the United States four years ago as a
result of Agricultural Research Servicepatents, these nontoxic biological coatings are replacing synthetic chemicals
for controlling rot-causing fungi on apples, pears and citrus after harvest. Now, ARS has signed an agreement with Micro-Flo Company of Memphis, Tenn.,
to finish development of the next generation of biofungicides for fruit packing
houses. Micro-Flo expects to have a product on the market within two years. Unlike the earlier biofungicides, the new coating has a kickback effect. It
stops fungi that already had a toehold on the fruit, according to ARS
Charles Wilson, who also developed one of the earlier products. Micro-Flo
researcher Ahmed El Ghaouth is working with Wilson, who is at ARS
Appalachian Fruit Research
Station in Kearneysville, W.Va. The new coating combines two bioactive substances with the yeast Candida
saitoana. Innocuous to people, the yeast is a formidable competitor against
the fungi that attack fresh fruits. The bioactive substances are chitosan--a
naturally occurring fiber found in some weight-loss products--and a synthetic
sugar used as a glucose substitute. Chitosan acts as a natural fungicide and turns on defensive enzymes in the
fruit itself. It also forms a film on the fruit that holds in carbon dioxide,
thus increasing shelf life. The synthetic sugar, on the other hand, tricks the
fungi into perceiving it as food, but they cant use it. In several years of tests in commercial packing houses in California and
Florida, the new biofungicide proved as effective against rot-causing fungi as
the two leading synthetic fungicides. Under the new agreement, Micro-Flo and
ARS scientists will optimize its formulation and fine tune its application. ARS
is the chief scientific arm of the U.S.
Department of Agriculture. Scientific contact: Charles L. Wilson, ARS Appalachian Fruit Research
Station, 45 Wiltshire Rd., Kearneysville, WV 25430, phone (304) 725-3451, ext.
330; fax (304) 728-2340, [email protected]. Story contacts Charles L Wilson U.S. Department of Agriculture | |