Rapid and specific detection ofPseudomonas syringaepv.phaseolicolaby immunological methods

An enzyme‐linked immunosorbent assay (ELISA) has been developed for the specific detection of Pseudomonas syringae pv. phaseolicola, the agent of haloblight disease of beans. Using as an immunogen a preparation of a surface polysaccharide known to be characteristic of the organism because of involvement in the mechanism of pathogenicity, antisera have been raised which show no cross‐reaction with other pathovers of P. syringae tested, and which recognized all strains of pv. phaseolicola tested. This degree of specificity has not previously been reported. The assay limit of detection is 2 × 10 4 cells ml −1. A positive result was obtained when artifically inoculated bean flour was analysed by ELISA. The antiserum was also used for detection of the organism by fluorescence microscopy. The method is considerably faster than alternative methodology.