Effects of Temperature and Leaf Wetness on Development of Bacterial Spot of Geraniums and Chrysanthemums Incited by Pseudomonas cichorii. J. B. Jones, Assistant Professor of Plant Pathology, IFAS, University of Florida, Agricultural Research and Education Center, Bradenton 34203. B. C. Raju, Chief Plant Pathologist, Yoder Bros., Inc., Alva, FL 33920, and A. W. Engelhard, Professor of Plant Pathology, IFAS, University of Florida, Agricultural Research and Education Center, Bradenton 34203. Plant Dis. 68:248-251. Accepted for publication 9 September 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-248.

Florida Marble and Polaris chrysanthemum stems and leaves and Sprinter Scarlet geranium leaves were inoculated with Pseudomonas cichorii. The number and size of lesions of bacterial spot of chrysanthemum leaves and stems and geranium leaves increased when temperatures were increased from 16 to 28 C but were greatly inhibited at temperatures higher than 28 C. Leaf lesions continued to expand under high-moisture conditions in polyethylene bags but ceased to expand in a low-moisture environment (unbagged). Stem lesions reacted similarly to leaf lesions. However, stem lesions developed on inoculated plants placed in the low-moisture environment, whereas leaf lesions were completely inhibited on inoculated plants placed immediately in the low-moisture environment.