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A Bacterial Leaf Spot of Highbush Blueberry Hardwood Cuttings Caused by Pseudomonas andropogonis. Donald Y. Kobayashi,, Assistant Professor, Department of Plant Pathology, Rutgers, The State University of New Jersey, New Brunswick 08903. Allan W. Stretch, Plant Pathologist, USDA-ARS, Blueberry and Cranberry Re-search Center, Chatsworth, NJ. 08019; and Peter V. Oudemans, Assistant Professor, Department of Plant Pathol-ogy, Rutgers, The State University of New Jersey, Blueberry and Cranberry Research Center, Chatsworth 08019. Plant Dis. 79:839-842. Accepted for publication 15 May 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0839.

A leaf spot has been observed for several years on nursery-grown blueberry cuttings through-out southern New Jersey. A bacterium that produced a white-pigmented colony on yeast extract-dextrose-calcium carbonate agar and was nonfluorescent on King's B agar was repeatedly isolated from lesions on diseased leaves collected from various locations. The bacterium was identified as Pseudomonas andropogonis using diagnostic tests, Biolog, and fatty acid analysis. Infiltration of bacterial suspensions at concentrations of 106 and 108 cells per ml into leaves of 3- to 5-year-old potted plants and 1-year-old hardwood cuttings resulted in the appearance of necrotic lesions similar to leaf spot symptoms observed on plants in the field. The bacterium was reisolated from the necrotic lesions produced by these inoculations. Inoculation of blueberry isolates into cranberry leaves also caused pathogenic responses. This is believed to be the first report of a bacterial leaf spot on Vaccinium species.