Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 27, 2000
Publication Date: N/A
Technical Abstract: The primary causal agent of Fusarium dry rot in potato storages is Gibberella pulicaris (Fr.:Fr.) Sacc. (anamorph: Fusarium sambucinum Fuckel), which produces trichothecenes implicated in mycotoxicoses. Yearly crop losses due to dry rot have been estimated at $100-$500 million. Thiabendazole (TBZ) is the only chemical registered for postharvest use on tubers for human consumption, but resistance to TBZ is found in over 80% o G. pulicaris strains. In the U.S., CIPC (1-methylethyl-3- chlorophenylcarbamate) is applied to inhibit sprouting in over 50% of the potato crop, but its use faces increasing restrictions due to health concerns about its persistence in potato tissues. Enterobacter cloacae S11:T:07 (NRRL B-21050) is a promising biological control agent, which significantly reduces both dry rot and sprouting in lab and pilot potato storages. Phenylacetic acid (PAA) and indole-3-acetic acid (IAA) were isolated from S11:T:07 liquid cultures, and their bioactivities were investigated via TLC bioautography of antifungal activity, wounded potato assays of dry rot suppressiveness, and cored potato eye assays of sprout inhibition. For the first time, both IAA and PAA were shown to have antifungal activity against G. pulicaris and to suppress dry rot infection of wounded potatoes. Dosages of IAA, resulting in disease suppression, also resulted in sprout inhibition. These results suggest the potential for designing a novel dual purpose biological control agent to suppress fungal dry rot as well as inhibit sprouting of stored potatoes.