IX.—Uromyces punctatus Schroet. in Britain

Abstract

SynopsisOn the European continent, Uromyces punctatus is heterœcious and occurs on 35 species and 1 variety of Astragalus, 6 species of Oxytropis and 1 species of Onobrychis. There are 3 æcidial hosts recorded, the major one being Euphorbia cyparissias. At St Andrews, the uredo stage of the rust is confined to A. danicus and only uredospores and teleutospores have been found. Experiments conducted showed that the local population of the rust was capable of infecting 9 species of Astragalus and 1 species of Medicago, out of 27 species of Astragalus, 5 species of Medicago and 28 species of other legumes inoculated. No host specialization within the local population was evident. Attempts to germinate the teleutospores, using a variety of methods, failed, with the exception of a single spore. The major æcidial host, when inoculated with teleutospores, failed to show any signs of æcidial infection over a period of four years. Possible factors affecting the shortening of the life cycle of the rust are discussed.