Etiology of a New Stemphylium-Incited Leaf Disease of Alfalfa in Australia. J. A. G. Irwin, Department of Botany, University of Queensland, St. Lucia, 4067, Australia. Plant Dis. 68:531-532. Accepted for publication 29 February 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-531.

A recently discovered leaf spot disease of alfalfa caused by a Stemphylium sp. has become widespread in Queensland, Australia. The symptoms and temperature requirements for disease development are similar to those reported in the United States for the leaf spot disease caused by the Californian biotype of Stemphylium botryosum. However, the anamorph of the Australian biotype more closely resembles S. vesicarium than it does S. botryosum but has characteristics that do not fit descriptions for either species. The teleomorph has ascospores that are consistently smaller than those reported for the Californian biotype but are still within the limits of those described for Pleospora herbarum.