Alternaria Leaf Spots of Brassaia actinophylla, Dizygotheca elegantissima, and Tupidanthus calyptratus. J. Y. Uchida, Research Associate, Department of Plant Pathology, University of Hawaii, Honolulu 96822. M. Aragaki, Plant Pathologist, Department of Plant Pathology, University of Hawaii, Honolulu 96822; and M. A. Yoshimura, Associate Professor, Department of Biological Science, California Polytechnic State University, San Luis Obispo 93407. Plant Dis. 68:447-449. Accepted for publication 27 January 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-447.

A severe leaf spot on Brassaia actinophylla, Dizygotheca elegantissima, and Tupidanthus calyptratus was shown to be caused by Alternaria panax. No evidence for host specialization was seen in cross-inoculations. Conidia from Brassaia leaf tissue were considerably larger than those formed on agar medium. Between 16 and 28 C, the longest conidia were produced at 20 C, whereas the widest were formed at 28 C. To a limited extent and for a limited time, conidia continued to grow on either substrate, developing into grotesque shapes suggestive of hyperplasia.

Keyword(s): Alternaria actinophylla, A. araliae, A. raphani, Araliaceae, conidial morphology, Schefflera actinophylla, S. arboricola.