Effects of Host Nutrition, Leaf Age, and Preinoculation Light Levels on Severity of Leaf Spot of Dwarf Schefflera Caused by Pseudomonas cichorii. A. R. Chase, Associate Professor of Plant Pathology, IFAS, University of Florida, Agricultural Research and Education Center, Apopka 32703. J. B. Jones, Assistant Professor of Plant Pathology, IFAS, University of Florida, Gulf Coast Research and Education Center, Bradenton 33508. Plant Dis. 70:561-563. Accepted for publication 4 November 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-561.

The roles of preinoculation light level, nutrition, and age of tissue in susceptibility of Schefflera arboricola to bacterial leaf spot caused by Pseudomonas cichorii were tested. Lesion numbers and size were reduced significantly as fertilizer levels were increased up to 12 g/ 10-cm pot (about 6× recommended rate). Lesion number and size decreased as leaf age increased from the top to the bottom of the plant. These fertilizer levels did not affect plant height, color, number of leaves, or fresh weight of tops. Light intensities (125–800 μmol m^-2 s^-1) for plant production before inoculation did not affect the number of lesions that formed.