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Isolation Media for the Pierce’s Disease Bacterium. M. J. Davis, Former graduate research assistant, Department of Plant Pathology and Entomological Sciences, University of California, Berkeley 94720, Present address: Department of Plant Pathology, Cook College, Rutgers University, New Brunswick, NJ 08903; A. H. Purcell(2), and S. V. Thomson(3). (2)(3)Assistant professors, respectively, Department of Plant Pathology and Entomological Sciences, University of California, Berkeley 94720, (3)Present address: Department of Biology, Utah State University, Logan 84322. Phytopathology 70:425-429. Accepted for publication 9 November 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-425.

Media supporting the first isolations of the xylem-limited bacterium causing Pierce’s disease of grapevines and almond leaf scorch contained PPLO broth base, hemin chloride, bovine serum albumin or starch, and agar. Modifications of these media led to the formulation of the PD2 medium containing (in grams per liter): Tryptone (4.0), Soytone or Phytone (2.0), trisodium citrate (1.0), disodium succinate (1.0), hemin chloride (0.01), MgSO₄·7H₂O (1.0), KH₂PO₄ (1.0), K₂HPO₄ (1.5), Bacto-agar (15.0), and bovine serum albumin fraction five (2.0). Bacterial strains from grapevine and almond had a high viability on the PD2 medium as indicated by comparison of total cell counts to counts of colony forming units, and had a generation time averaging 9.2 hr at 29 C in PD2 broth medium. Ninety percent of the isolation attempts from naturally infected grapevines in vineyards in California and Florida were successful, and the strains were all agglutinated by antisera produced against a California Pierce’s disease strain.