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Direct Fluorescent Antibody Stain Procedure Applied to Insect Transmission of Erwinia carotovora. J. A. Phillips, Graduate research assistant, Department of Plant Pathology, 1630 Linden Drive, University of Wisconsin, Madison 53706, Present address: Department of Bacteriology, University of Wisconsin, Madison 53706; A. Kelman, professor, Department of Plant Pathology, 1630 Linden Drive, University of Wisconsin, Madison 53706. Phytopathology 72:898-901. Accepted for publication 19 January 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-898.

A fluorescent antibody stain (FAS) procedure was used to determine the possible dissemination of Erwinia carotovora subsp. carotovora (Ecc) by insects from a potato cull pile to adjacent potato plants. A serologically distinct strain of Ecc that was introduced into the cull pile was identified by the FAS procedure in isolations from insects (usually Diptera), leaves, and daughter tubers. Levels of Ecc decreased with increasing distance from the cull pile; however, no symptoms of blackleg or soft rot were observed either on the plants or daughter tubers in the field plot area. The FAS procedure was used to demonstrate insect transmission of Ecc from decayed tubers to wounded plants in insect cages. Differentiation of E. carotovora subsp. atroseptica from Ecc was facilitated by use of a solid medium containing tetrazolium chloride and α-methyl glucoside as a carbon source.