Epitea rust of larch-willow - Melampsora larici-epitea
Melampsora laricis-epitea has been divided into an assemblage of races and form species (Pei et al. 2005). In spite of numerous differences relating to life cycles and hosts, some authors combine several species including Melampsora laricis-epitea into the Melampsora epitea complex. The taxonomy of this group is in need of major revision. In light of this confusion, host ranges, distributions, and the identity of species should be treated with caution as many taxa may be involved as potential threats. Unlike powdery larch-willow rust, M. capraeanum having teliospores with a thickened apex, the teliospores of M. larici-epitea lacks any thickening at the apex. Pei & McCracken (2005) present a recent account of these rust fungi.
Melampsora larici-epitea Kleb. 1899
Aecia caomatal, i.e. lacking a peridium, hypophyllous (on lower surface of leaves), scattered, with yellow spots on upper surface, roundish or oblong, 0.5-1.5 mm long, pale orange-yellow; aeciospores roundish or somewhat, polygonal, finely warty, 15-25 × 10-21 µm; walls 1.5-3 µm thick, with no recognizable germ-pores.
Uredinia sori amphigenous, seated on yellow spots, orange-yellow, 0.25-2 mm diam; urediniospores subglobose to oval or anglar, echinulate, orange to pale yellow, 12-25 × 9-19 µm; walls 1.5 - 3.5 thick, without germ-pores; paraphyses capitate, with a thin pedicel, occasionally clavate, thickened up to 10 µm at apex, hyaline, 35-80 × 15-24 µm.
See Wilson & Henderson (1966) for a more detailed description.
Host range: Aecial stage on Larix decidua, L. laricina, L. kaempferi, L. occidentalis and L. sibirica. Uredinial and telial stage on various species of Salix.
Geographic distribution: Widespread in Europe, also reported from China, India, Iran, Japan, Korea, and Taiwan.
Dietrich, W. 2005. [The rust fungi, smut fungi and downy mildews in the Czech part of Krusne hory (Erzgebirge): first supplement]. Czech Mycol. 57: 257-273.
Ershad, D., and Abbasi, M. 1992. Studies in the rust fungi of Iran. Iran. J. Pl. Pathol. 28: 23-26.
Foister, C.E. 1961. The economic plant diseases of Scotland. Techn. Bull. Dept. Agric. Fish. Scotland 1: 1-210.
Hiratsuka, N. 1940. Uredinales collected in Korea IV. Bot. Mag. (Tokyo) 54: 433-437.
Hylander, N., Jorstad, I., and Nannfeldt, J.A. 1953. Enumerato Uredinearum Scandinavicarum. Opera Bot. 1: 1-102.
Liro, J.I. 1908. Uredineae Fennicae Finlands Rostsvampar. Finska Litteratursallskapets, 640 pages.
Pei, M.H., Bayon, C., and Ruiz, C. 2005. Phylogenetic relationships in some Melampsora rusts on Salicaceae assessed using rDNA sequence information. Mycol. Res. 109: 401-409.
Zhuang, J.-Y. 1989. Rust fungi from the desert of northern Xinjiang. Acta Mycol. Sin. 8: 259-269.
Zhuang, W.-Y. 2005. Fungi of northwestern China. Mycotaxon, Ltd., Ithaca, NY, 430 pages.
Suggested citation: Yun, H.Y. Systematic Mycology and Microbiology Laboratory, ARS, USDA. . Invasive Fungi. Epitea rust of larch-willow - Melampsora larici-epitea . Retrieved February 21, 2019, from /sbmlweb/fungi/index.cfm .