Effects of Fertilizer Rate on Severity of Alternaria Leaf Spot of Three Plants in the Araliaceae. A. R. Chase, Associate Professor of Plant Pathology, University of Florida, IFAS, Agricultural Research and Education Center, 2807 Binion Road, Apopka 32703. R. T. Poole, Professor of Ornamental Horticulture, University of Florida, IFAS, Agricultural Research and Education Center, 2807 Binion Road, Apopka 32703. Plant Dis. 70:1144-1145. Accepted for publication 2 May 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-1144.

Alternaria leaf spot of Brassaia actinophylla (schefflera), Dizygotheca elegantissima (false aralia), and Schefflera arboricola (dwarf schefflera) is caused by Alternaria panax. Mean numbers of lesions per plant of schefflera and dwarf schefflera decreased linearly as preinoculation fertilizer was increased to about six times the recommended rate. Growth of schefflera or dwarf schefflera was not affected over this fertilizer range, but height and quality of false aralia decreased significantly. The mean percentage of false aralia foliage infected with A. panax was unaffected by fertilizer treatment.