Monitoring the spread of Xanthomonas campestris pv dieffenbachiae introduced from symptomless Anthurium cuttings into production fields

In field crops the origin and movement of bacterial inoculum is difficult to determine due to inadequate means of distinguishing strains of bacteria, In this study the introduction, establishment, and spread of Xanthomonas campestris pv. dieffenbachiae (McCulloch and Pirone) Dye into anthurium fields were examined by monitoring the distribution of serologically distinct strains recovered from propagation benches and production fields. One thousand Anthurium andraeanum Lind. plants were indexed for X. c. pv. dieffenbachiae and 962 mere later introduced into a production field, Strains recovered from the propagative stock were serotyped using a panel of 10 monoclonal antibodies and serotypes were compared to serotypes of strains already prevalent in the production field, Four distinct serotypes were identified which were not characteristic of strains already prevalent in the production field, Two biotypes of X. c. pv, dieffenbachia were also identified, based on their ability to hydrolyze starch, Sensitivity to 500 ppm streptomycin sulfate also was used to characterize strains associated with introduced propagative stock, Of 248 strains isolated from field plants, 39% were streptomycin resistant, whereas none of the strains isolated from introduced cuttings at the initial indexing were resistant. Over a 3-year period, strains with serotypes associated with the propagation material became established in the field, but spread to other cultivars was limited, This paper demonstrates the utility of serological methods for epidemiological studies.