ARS Scientists May Solve Dry Rot

Published online: Jun 13, 2002
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ARS scientists in Peoria, IL, are testing soil-dwelling bacteria as a biological alternative to using chemical fungicide as a dry rot control agent in potatoes.

Patricia Slininger and David Schisler and colleagues state that TBZ is losing its effectiveness against Fusarium sambucinum and that the bacterial control agents, already under two United States patents, may hold an answer.

The pair started studying bacteria’s biocontrol potential in 1994, when a third researcher—Ann Desjardens—reported TBZ resistance in 90 percent of dry rot strains she isolated from potato fields.

At the ARS/ National Center for Agricultural Utilization Research, Slininger and Schisler studied different physical and nutritional conditions for mass-producing the bacteria in liquid culture and keeping them viable during cold storage.

Tests show that spraying tubers with the bacteria can diminish dry rot by more than 59 percent. The six strains being tested are harmless to humans, but form a living bandage around potato wound sites that stymies dry rot infections.

They explained that the bacteria secrete natural antibiotics that suppress the fungus. One such antibiotic, indoleacetic acid, may also help retard sprouting on stored potatoes.