Selection and Performance of Bacterial Strains for Biologically Controlling Fusarium Dry Rot of Potatoes Incited by Gibberella pulicaris. D. A. SCHISLER, Research Plant Pathologist, USDA-ARS, National Center for Agricultural Utilization Research, Peoria, IL 61604. P. J. SLININGER, Biochemical Engineer, Fermentation Biochemistry Research, USDA-ARS, National Center for Agricultural Utilization Research, Peoria, IL 61604. Plant Dis. 78:251-255. Accepted for publication 19 November 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1994. DOI: 10.1094/PD-78-0251.

The microbiota from 29 different agricultural soils were individually transferred to separate samples of y irradiation-sterilized field soil enriched with potato periderm. After incubation, the samples (chemically, physically, and nutritionally similar but microbiologically dissimilar) were assayed for biological suppressiveness to Fusarium dry rot using a whole-tuber/infested-soil assay. Over 350 isolates of bacteria, yeasts, and actinomycetes were recovered from tubers and soil associated with the five most suppressive soil samples. In three of four soils assayed, periderm amendment increased suppressiveness over that in the same soil without the amendment. In a whole-tuber assay, 18 bacterial strains consistently suppressed dry rot incited by three different strains of Gibberella pulicaris, including one resistant to thiabendazole. Strains effective in biological control included members of the genera Pseudomonas, Enterobacter, and Pantoea. The time of isolation after initiating the whole-tuber/infested-soil assay and the isolation medium influenced the number of effective strains recovered. The majority of the 18 superior biological control strains were recovered from two of the five suppressive soil samples.