Physiologic Specialization of Tranzschelia discolor in Australia. Phillip F. Kable, Principal Research Scientist, Biology Branch, Biological and Chemical Research Institute, Rydalmere, New South Wales, 2116, Australia. Patricia J. Ellison, Plant Pathologist, and Rodney W. Bambach, Former Technical Officer (Scientific), Yanco Agricultural Institute, Yanco, New South Wales, 2703, Australia. Plant Dis. 70:202-204. Accepted for publication 27 August 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-202.

Inoculation of peach with urediniospores of Tranzschelia discolor collected from prune and vice versa demonstrated that physiologic races of the rust exist on peach and prune in Australia. Urediniospores collected from prune were able to infect peach, but the latent period was extended from 13 days to 22–23 days. A similar extension of latent period was observed when prune was inoculated with urediniospores collected from peach. In two tests, it appeared that infection efficiency was decreased in such cross-inoculations. Inoculation of almond with urediniospores from prune resulted in infections that appeared macroscopically as minute flecks. The rust reproduced in these flecks on microsori, each bearing five to 30 urediniospores. The epidemiological and practical significance of physiologic specialization in this rust is discussed.

Keyword(s): stone fruit rust.