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Archontophoenix alexandrae, a New Host of Pseudomonas solanacearum in Australia. E. Akiew, Plant Pathology Branch, DPI, P.O. Box 1054, Mareeba 4880, Queensland, Australia. F. Hams, Kamerunga Research Station, Redlynch 4872, Queensland, Australia. Plant Dis. 74:615. Accepted for publication 8 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0615A.

Recently, Alexandra palm trees (Archontophoenix alexandrae H. Wendl. & Drude) in a commercial palm nursery in Cairns, Queensland, began dying prematurely. Diseased trees failed to produce seeds and had wilted, desiccated leaves and vascular tissues with brown to black discoloration. Copious milky white droplets of bacterial exudate formed on freshly cut vascular tissues a few hours after cutting. A steady stream of whitish bacterial ooze emanated from pieces of discolored vascular tissues that were suspended in water. A gramnegative, rod-shaped bacterium (0.5 X 1.5 µm) isolated from border lesions in the trunks of infected trees was found to be pathogenic to l-yr-old Alexandra palm seedlings. The bacterial isolates were identified as Pseudomonas solanacearum (Smith) Smith based on the scheme presented by N. J. Palleroni in Bergey's Manual of Systematic Bacteriology (1984). The isolates were classified as biovar III on the basis of their ability to utilize three hexose alcohols (mannitol, sorbitol, and dulcitol) and to produce acid from three disaccharides (cellobiose, maltose, and lactose) (1). The bacterium caused symptoms typical of bacterial wilt in Nicotiana tabacum L., Capsicum annuum L., Solanum tuberosum L. S. melongena L., Arachis hypogaea L., and Lycopersicon esculentum Mill. This is the first report of a member of the Palmae as a host for P. solanacearum in Australia and elsewhere.

Reference: (1) A. C. Hayward. J. Appl. Bacteriol. 27:276, 1964.