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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #127587
Title: AN AVIRULENT GEOTRICHUM CANDIDUM ISOLATE THAT CONTROLS GREEN MOLD OF CITRUS FRUIT, CAUSED BY PENICILLIUM DIGITATUM.

Author
item EAYRE, CYNTHIA
item SKARIA, MANI
item BULL, CAROLEE
item MACKEY, BRUCE

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2002
Publication Date: 1/22/2004
Citation: EAYRE, C., SKARIA, M., BULL, C., MACKEY, B. AN AVIRULENT GEOTRICHUM CANDIDUM ISOLATE THAT CONTROLS GREEN MOLD OF CITRUS FRUIT, CAUSED BY PENICILLIUM DIGITATUM.. PLANT DISEASE. 2004.

Interpretive Summary: Green mold is a post harvest rot of citrus fruit that causes losses to growers, shippers, grocers and consumers. Dusty, green spores are shed in abundance from rotted fruit, causing soilage of intact fruit and shipping cartons. It is caused by Penicillium digitatum, and is problem in all citrus growing areas of the United States. P. digitatum infects through wounds in the peel, and produces a soft rot with a sour odor. Packhouse use of fungicides reduces the occurence of green mold, but does not control fungicide resistant strains. Some fungicides for postharvest use are no longer available. A strain of another citrus pathogen, Geotrichum candidum, was found to have become avirulenet, or to have lost the ability to cause disease. When fruit were treated with the avirulent strain, incidence of green mold was signifigantly lower. A patent has been granted for the avirulent strain. Use of this strain as a biological control of green mold could result in reduced losses to growers and consumers and in reduced use of chemical fungicides.

Technical Abstract: Green mold, caused by Penicillium digitatum, is the most prevalent postharvest disease of citrus in Texas. An avirulent Geotrichum candidum significantly reduced the incidence of green mold on wounded grapefruit and oranges in three trials. Tests were run three times and each test included five replications of 10 fruit. Although disease incidence varied, the reduction in green mold in fruit treated with the avirulent G. candidum was always significant. The avirulent G. candidum was obtained by frequent subculturing on potato dextrose agar of a virulent isolate, originally isolated in our laboratory. The avirulent derivative was found to inhibit growth of P. digitatum on glucose yeast peptone agar, but not on seven other media. A U. S. patent has been issued for this avirulent organism.