VIEW ARTICLE

A Selective Medium for Soil Isolation and Enumeration of Xanthomonas campestris. N. W. Schaad, Assistant Professor, Department of Plant Pathology, University of Georgia College of Agriculture Experiment Stations, Georgia Station, Experiment 30212; William C. White, Laboratory Technician III, Department of Plant Pathology, University of Georgia College of Agriculture Experiment Stations, Georgia Station, Experiment 30212. Phytopathology 64:876-880. Accepted for publication 21 January 1974. DOI: 10.1094/Phyto-64-876.

A new medium, SX agar, based primarily on starch digestion was developed for the isolation of Xanthomonas campestris. Growth of the bacterium on SX agar was comparable to that on standard plating media; plating efficiencies ranged from 13-63 percent for different isolates. For soil isolations, SX agar was superior to standard plating media and the selective medium, D-5. Because many soil microorganisms grew poorly and failed to hydrolyze starch, it was possible to assay several natural soils at dilutions as low as 1:10. The recovery of X. campestris when added to natural soils was over 10%. By using SX agar, it was possible to determine the relative populations of the pathogen in soil samples taken from a naturally infested field. SX agar also appeared useful for the isolation of eight other Xanthomonas spp.