A New Foliar Blight of Impatiens Caused by Pseudomonas syringae. D. A. Cooksey, Associate Professor, Department of Plant Pathology, University of California, Riverside 92521. S. T. Koike, Farm Advisor, University of California Cooperative Extension, 118 Wilgart Way, Salinas 93901. Plant Dis. 74:180-182. Accepted for publication 2 October 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0180.

Large water-soaked and necrotic lesions were observed on leaves of Impatiens cultivar New Guinea Hybrid in a commercial greenhouse in Santa Barbara County, California. An oxidase-negative, fluorescent bacterium was consistently isolated from diseased tissues and identified as Pseudomonas syringae. Rapid water-soaking and necrotic symptoms resulted after New Guinea Hybrid and I. wallerana were inoculated with this bacterium. Hypersensitivity developed within 24 hr after inoculation of tobacco, tomato, common bean, and mung bean. No reactions occurred after inoculation of Begonia × semperflorens-cultorum, Dieffenbachia maculata, or Calendula officinalis. The bacterium was resistant to 1.6 mM CuSO₄.