Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/16/1995
Publication Date: N/A
Technical Abstract: Silver scurf has become a major storage disease of potatoes primarily because many strains of Helminthosporium solani have developed resistance to thiabendazole. Soil and tuber samples were collected from 48 sites throughout the United States. Individual samples of live soil were added to sterilized field soil containing potato periderm (5:93:2 w/w/w, respectively) to produce samples that were chemically, physically and nutritionally similar, but microbiologically dissimilar. After incubation, the samples were assayed for biological suppression of H. solani conidiophore production using a whole-tuber/infested soil assay. Conidiophores covered 11 to 75% of the surface area of treated tubers. Over 250 isolates of bacteria, yeasts and actinomycetes were recovered from the 9 most suppressive soil samples. Preliminary results indicate that at least three bacterial isolates suppress silver scurf.