Rust on Asian Rubus - Gerwasia rubi

Species of blackberry or Rubus are attacked by a number of species of rust fungi many of which occur only in South America or Asia and thus are potentially invasive on North American species of Rubus. Gerwasia rubi is widespread in Asia and has been reported once in the western hemisphere (Mexico). Gerwasia rubi is unlike G. imperialis in that G. rubi commonly produces uredinia and telia. The orange yellowish uredinia of G. rubi develop on the upper surface of leaves as solitary or a few aggregated, small, yellow or purple, rounded spots. This fungus is similar to Gerwasia Rosae in the shape of the teliospores but the latter occurs only on Rosa spp.

Gerwasia rubi Racib. 1909

Spermogonia intraepidermal.

Aecia like uredinia.

Uredinia epiphyllous (on upper surface of leaf), solitary or a few aggregated on small yellow or purple spots, small, rounded, 0.1-0.3 mm diam, covered by epidermis, orange yellow, reddish brown or yellowish brown; urediniospores globose, ovate or ovate-ellipsoid, sparsely echinulate, hyaline or pale yellowish, 22-35 × 16-26 µm, wall 2-3 µm thick.

Telia hypophyllous (on lower side of leaf), white, developing in minute, rounded, yellow lesions; teliospores formed on cells emerging though stomata, globose, short-pedicellate, 20-30 × 18-22 µm, walls smooth, thin, hyaline.

See Hirastuka et al. (1992) and Ito (1950) for a more detailed description.

Hosts: Known on various species of Rubus including Rubus adenotrichos Schltdl., R. alcaefolius Poir., R. amphidasys Focke, R. amplifolius P.J.Müll., R. angulosus Gremli, R. buergeri Miq., R. cochinchinensis Tratt., R. formosensis Kuntze, R. hypopitys Focke, R. laciniatostipulatus Hayata ex Koidzumi, R. multibracteatus H. Lév. & Vaniot, R. palmatus Thunb., R. pinnatisepalus Hemsl., R. reflexus Ker Gawl., R. reflexus var. lanceolobus F.P. Metcalf, R. setchuenensis Bureau & Franch., R. shimadai Hayata, R. swinhoei Hance

Geographic distribution: Widespread in Asia, reported from China (Fujian, Tai, 1979, Guangxi, Teng, 1996, Guizhou, Tai, 1979, Hainan, Teng, 1996, Hong Kong, Berkeley & Curtis, 1859, Hunan, Tai, 1979, Sichuan, Tai, 1979, Teng, 1996), Indonesia (Jorstad, 1959, Java, Raciborski, 1909); Japan (Honshu, Kyushu, Shikoku, Hiratsuka et al., 1992); Nepal (Zhuang & Wei, 1999), Thailand (Gjaerum, 1995) and Vietnam (Kaneko et al. 2007). A recent report from Mexico (Gallego & Cummins, 1981) is questionable.

The hosts of Gerwasia rubi are primarily native Asian species of Rubus but exotic germplasm for breeding imported into North American may be infected with this rust.

References:

Arthur, J.C., and Cummins, G.B. 1936. Philippine rusts in the Clemens collection 1923-1926, II. Philipp. J. Sci. 61: 463-488.

Berkeley, M.J., and Curtis, M.A. 1859. Characters of new fungi, collected in the North Pacific exploring expedition by Charles Wright. . Proc. Amer. Acad. Arts. 4: 111-130.

Dietel, V.P. 1912. Ueber die Verwandtschaftsbeziehungen der Rost ilzgattungen Kuehneola and Phragmidium. . Ann. Mycol. 10: 205-213.

Gallegos, M.L., and Cummins, G.B. 1981. Uredinales (royas) de Mexico, Vol. 2. Instituto Nacional de Investigaciones Agricoles, Culiacan, Sinaloa, Mexico, 492 pages.

Gjaerum, H.B. 1995. Rust fungi from various countries. Lidia 3: 145-170.

Hiratsuka, N. 1939. Miscellaneous notes on the east-Asiatic Uredinales with special reference to the Japanese species (VI.). J. Jap. Bot. 15: 621-627.

Ito, S. 1950. Mycological Flora of Japan. Vol. II. Basidiomycetes. No. 3. Uredinales -- Pucciniaceae. Uredinales Imperfecti. Yokendo Ltd., Tokyo, 435 pages.

Jorstad, I. 1959. Notes on some Asiatic Uredinales. Nytt Mag. Bot. 7: 129-144.

Kaneko, S., Pham, T. Q., and Hiratsuka, Y. 2007. Notes on some rust fungi in Vietnam. Mycoscience 48: 263-265.

Raciborski, M. 1909. Ueber einige javanische Uredineae. Bull. Int. Acad. Sci. Cracovie, Cl. Sci. Math. 1909: 266-280.

Tai, F.L. 1947. Uredinales of Western China. Farlowia 3 : 95-139.

Zhuang, J.-Y. 1983. [A provisional list of Uredinales of Fujian Province, China.]. Acta Mycol. Sin. 2: 146-158.

Zhuang, J.-Y., and Wei, S.-X. 1999. Fungal flora of tropical Guangxi, China: a preliminary checklist of rust fungi. Mycotaxon 72: 377-388.

Nomenclature

Specimens in BPI

Additional distribution data

Suggested citation: Yun, H.Y. Systematic Mycology and Microbiology Laboratory, ARS, USDA. . Invasive Fungi. Rust on Asian Rubus - Gerwasia rubi. Retrieved November 21, 2009, from http://nt.ars-grin.gov/sbmlweb/fungi/index.cfm .