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Evaluation of Indirect Immunofluorescence and Ice Nucleation Activity as Rapid Tests for Identifying Foliar Diseases of Tomato Transplants Incited by Fluorescent Pseudomonads. J. B. Jones, Postdoctorial Associate, Department of Plant Pathology, University of Georgia, Athens 30602. R. D. Gitaitis, Assistant Professor, Coastal Plain Experiment Station, Tifton, GA 31793, and S. M. McCarter, Professor, Department of Plant Pathology, University of Georgia, Athens 30602. Plant Dis. 67:684-687. Accepted for publication 2 December 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-684.

Indirect immunofluorescence (IIF) and ice nucleation activity (INA) were evaluated for detection and identification of two bacterial foliar pathogens of tomato transplants. When 127 lesions from 11 transplant fields and two research plots were triturated in water and tested by IIF with two antisera prepared against Pseudomonas syringae pv. tomato (PST), 74% reacted positively with one antiserum. Similar results were obtained when the IIF procedure was used on 117 pure cultures isolated from the lesions. Only 24% of the 117 cultures, however, were PST, whereas most of the remainder were P. syringae pv. syringae (PSS). The antisera (one was cross-absorbed with Xanthomonas campestris pv. vesicatoria [XCV]) reacted negatively with pure cultures of four strains of XCV and with lesions from artificially inoculated plants. All lesions that yielded PST tested negatively for INA, whereas 76% of those with PSS tested positively. All pure cultures of PST from field plants tested negatively, whereas 95% of PSS cultures were positive. These results suggest that IIF and INA, when used in combination, are useful diagnostic tools for distinguishing PSS from PST on tomato transplants and will assist in certification efforts.