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Etiology

Bacterial Blight of Onion, a New Disease Caused by Xanthomonas sp.. A. M. Alvarez, Assistant Plant Pathologist, Department of Plant Pathology, University of Hawaii, Honolulu, HI 96822; I. W. Buddenhagen(2), E. S. Buddenhagen(3), and H. Y. Domen(4). (2)(3)(4)Plant Pathologist, Research Associate, and Graduate Student, respectively, Department of Plant Pathology, University of Hawaii, Honolulu, HI 96822, (2)(3)Present address: International Institute of Tropical Agriculture, Ibadan, Nigeria. Phytopathology 68:1132-1136. Accepted for publication 21 February 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1132.

A new disease of green and bulb onion in Hawaii is caused by a previously undescribed Xanthomonas sp. Tip dieback, leaf lesions, chlorotic streaks, and, eventually, necrosis of the entire leaf results in stunted plants and undersized bulbs at harvest. The pathogen was isolated from leaf lesions and inoculated onto 15 susceptible onion cultivars. Physiological and biochemical tests showed that the pathogen belonged to the X. campestris taxospecies, but that it differed from other Xanthomonas nomenspecies of the group in pathogenicity, serology, and in utilization patterns of 122 carbon sources.