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Association of Serratia marcescens with Crown Rot of Alfalfa in Pennsylvania. F. L. Lukezic, Professor, Department of Plant Pathology, Pennsylvania State University, University Park 16802; D. C. Hildebrand(2), M. N. Schroth(3), and P. A. Shinde(4). (2)(3)Assistant plant pathologist and professor, respectively, Department of Plant Pathology, University of California, Berkeley 94720; (4)Former graduate student, Department of Plant Pathology, Pennsylvania State University, University Park 16802, Present address: 450 Shanwar Peth, Satara Cty, Dist Satara, Maharashtra, India. Phytopathology 72:714-718. Accepted for publication 15 October 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-714.

Comparative investigations of the physiological and biochemical properties of strains of a bacterium isolated from alfalfa and designated Erwinia amylovora var. alfalfae and a test isolate of Serratia marcescens showed that they differ by production of pigments with different solubility properties and absorption spectra. Otherwise, the results of the biochemical tests for the two strains were similar. The guanine-plus-cytosine content of the DNA from the alfalfa strains ranged from 56.6 to 57.9 moles percent (thermal denaturation) compared to 56.6 for the isolate of S. marcescens. These data indicate that the Gram-negative, pink-pigment-producing bacterium associated with crown rot of alfalfa is a strain of S. marcescens.