Table Grapes’ New Ally: Muscodor albus

Small but mighty, a beneficial microbe called Muscodor albus may help protect fresh grapes from troublesome gray mold. Experiments conducted over the past several years by Agricultural Research Service (ARS) plant pathologist Joseph L. Smilanick and his ARS and industry colleagues have shown that M. albus can combat Botrytis cinerea, the organism that causes gray mold.

Gray mold can ruin the taste and appearance of fresh-market grapes, according to Smilanick.

For organic growers, Botrytis is especially troublesome because these producers can’t use the typical treatment, sulfur dioxide, to quell it. That’s why, if commercialized, M. albus could benefit conventional and organic growers alike.

Smilanick, who is based at the ARS San Joaquin Valley Agricultural Sciences Center near Parlier, Calif., collaborated in Muscodor experiments with microbiologist Monir Mansour and visiting scientist Franka M. Gabler—both at Parlier—and with industry colleagues.

Muscodor acts as a natural fumigant by emitting compounds, harmless to people and animals, that can kill or inhibit the spread of certain other microbes, such as B. cinerea. For example, in experiments with packaged Thompson Seedless grapes, Smilanick and co-investigators found that Muscodor reduced the incidence of Botrytis-infected grapes by up to 85 percent.

A 2009 article in the journal Plant Disease documents their findings.

ARS and the California Table Grape Commission funded the research. ARS is the chief intramural scientific research agency of the U.S. Department of Agriculture (USDA). The Muscodor research contributes to international food security, a USDA priority.