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Periwinkle Wilt Bacterium: Axenic Culture, Pathogenicity, and Relationships to Other Gram-Negative, Xylem-Inhabiting Bacteria. M. J. Davis, University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research and Education Centers, 3205 S.W. College Avenue, Ft. Lauderdale 33314; B. C. Raju(2), R. H. Brlansky(3), R. F. Lee(4), L. W. Timmer(5), R. C. Norris(6), and R. E. McCoy(7). (2)Yoder Brothers, P. O. Box 68, Alva, FL 33920; (3)(4)(5)700 Experiment Station Road, Lake Alfred, FL 33850; (6)(7)Institute of Food and Agricultural Sciences, Agricultural Research and Education Centers, 3205 S. W. College Avenue, Ft. Lauderdale 33314. Phytopathology 73:1510-1515. Accepted for publication 20 May 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1510.

The Gram-negative, xylem-inhabiting bacterium associated with periwinkle wilt (PW) disease was consistently isolated on the PW, SC, and BC-YE media from PW-diseased periwinkle, but not from healthy periwinkle. Colonies of the bacterium were circular with entire margins, convex, opalescent-white, and reached 0.7- 1.0 mm in diameter after 2- 3 wk at 28 C. The periwinkle bacterium incited typical PW symptoms during July and August in periwinkle inoculated during the previous fall and winter. The periwinkle bacterium and the bacterium that causes Pierce's disease (PD) of grapevine were pathologically distinct. The periwinkle bacterium infected grapevine, but no symptoms developed which could be attributed solely to the infection. The PD bacterium incited slight chlorosis in periwinkle, but did not incite typical PW symptoms. The ultrastructure and morphology of the periwinkle bacterium in culture, inoculated periwinkle, and a sharpshooter vector, Homalodisca coagulata, were similar. The periwinkle bacterium was distinguishable from similar Gram-negative, xylem-inhabiting bacteria associated with PD, phony disease of peach (PDP), and plum leaf scald (PLS), in that it grew readily on the PW, SC, and BC-YE media, but not on PD2 medium. In an enzyme-linked immunosorbent assay (ELISA), the periwinkle bacterium was closely related to the PDP and PLS bacterium.