An Improved Semiselective Medium for Recovery of Xanthomonas campestris pv. phaseoli. R. B. Mabagala, Graduate Student, Department of Botany and Plant Pathology, USDA-ARS, Michigan State University, East Lansing 48824-1312. A. W. Saettler (deceased), Research Plant Pathologist, USDA-ARS, Michigan State University, East Lansing 48824-1312. Plant Dis. 76:443-446. Accepted for publication 18 November 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0443.

An improved solid semiselective medium (M-SSM) for isolation of Xanthomonas campestris pv. phaseoli was developed by the addition of starch, dyes, and agar to a liquid semiselective medium. The solid medium was equal or superior to two other semiselective media for isolation of X. c. phaseoli from diseased bean (Phaseolus vulgaris) tissues. The medium was easy to prepare, and it remained stable in cold storage over a 45-day period. Each of 19 strains of the pathogen grew on the medium; the colonies appeared earlier, and grew larger, than those of nontarget bacteria. Colonies of the pathogen were easily distinguished from other bacteria, and most nontarget bacteria were effectively suppressed.