In June 2003, uredinial and telial pustules were seen on leaves of accession W6-12755 Allium pskemense B. Fedtsch. originating from Uzbekistan and grown for germplasm increase in Pullman, WA. W6-18947 A. altaicum Pall., originating from Mongolia, displayed similar symptoms in the same garden in June 2000. A. altaicum is a wild onion exploited for food in its native range and is ancestral to A. fistulosum L., bunching onion (2). A. pskemense is a wild perennial sometimes propagated under cultivation (2). Both species have been exploited for research in breeding and systematics of Allium and used to a lesser degree in screening for pest or disease resistance. Clustered, golden orange, amphigenous uredinia were approximately 1 × 0.5 mm and surrounded by stromatic, subepidermal, blackish telia of variable size. Urediniospores (thick-walled, pale orange, echinulate, (25-) 27 to 32 (-34) × (19-) 21 to 25 μm, with as many as 10 scattered, indistinct pores), teliospores (two-celled, smooth, golden brown, 42 to 65 × 18 to 26 μm), and mesospores (27 to 42 × 15 to 21 μm, and approximately 30% as frequent as teliospores) all approximated the description for P. allii Rudolphi (4), but were more strongly congruent with the description of Puccinia blasdalei Diet. & Holw. (1), now considered a synonym (4). Specimens are deposited with WSP, Washington State University, Pullman. P. allii or its synonyms have been recorded from over 30 species of Allium (1,3,4), but to our knowledge, this is the first report of this rust on A. pskemense or A. altaicum.
References: (1) J. C. Arthur. Manual of the Rusts in United States and Canada, Hafner Publishing, N.Y., 1962. (2) J. L. Brewster. Onions and Other Vegetable Alliums. CABI, Wallingford, Oxon, U.K, 1994. (3) D. F. Farr et al. Fungal Databases, Systematic Botany and Mycology Laboratory, On-line publication. ARS, USDA, 2003. (4) G. F. Laundon and J. M. Waterston. Puccinia allii. No. 52 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, U.K., 1965.