Brown rust of sugarcane - Puccinia melanocephala

The two major rust fungi on sugarcane are brown rust caused by Puccinia melanocephala and orange rust caused by P. kuehnii. Brown rust is relatively common, found everywhere sugarcane is grown, whereas orange rust has only recently been found in the Western Hemisphere (Chavarria et al. 2009).

Puccinia melanocephala Syd. & P. Syd 1907

Spermogonia and aecia unknown.

Uredinia primarily hypophyllous (on lower surface of leaves), cinnamon-brown, linear up to 4 mm, urediniospores obovoid or ellipsoidal, 25-39 × 17-28 µm, cinnamon to dark-brown, echinulate, germ pores 4-5, equatorial, wall 0.8-2.3 µm; paraphyses hyaline to golden, capitate or spathulate, 32-98 µm × 12-25 µm, wall 1-2.8 µm thick, 4-15 µm at apex.

Telia hypophyllous, exposed, black to dark-brown, teliospores 34-56 × 16-24 µm, mostly clavate, walls 2-3.5 µm thick at sides, 2.5-8 µm at apex, upper cell dark brown, lower cell paler, pedicels brown, thin-walled, usually not collapsing, 4-17 µm long; telial paraphyses long, capitate.

Host range: Sugarcane and its relatives in the Poaceae including Bambusa vulgaris, Bambusa spp., Eulalia fastigiata, Miscanthus floridulus, M. sacchariflorus, M. sinensis, Miscanthus spp., Phyllostachys aurea, P. bambusoides, P. glauca, P. nigra var. henonis, Saccharum narenga, S. officinarum (sugarcane), S. rufipilum, S. ravennae, Sinarundinaria spp., Sorghum spp.

Geographic distribution: Widespread, occurring wherever sugarcane is grown.

See Hiratsuka (1992) and Virtudazo et al. (2001) for a more detailed description.

Brown rust is distinct from orange rust in producing abundant, capitate paraphyses. Walls of the paraphyses are thicker at the apex. The urediniospores of brown rust are generally smaller than orange rust, although the size ranges overlap. Urediniospore walls of brown rust are uniformly thick, whereas those of orange rust are thicker at the apex. Brown rust teliospores are pigmented, the upper cell is dark brown and the lower cell is paler. Teliospore walls of brown rust are thicker than those of orange rust and are also thicker at the apex. Telial pedicels are long and dark brown, unlike orange rust having teliospores that are sessile or have hyaline pedicels. Telial paraphyses of brown rust are long and capitate. Like orange rust, spermogonia and aecia are unknown.

Here is a link to a chart comparing Puccinia melanocephala with Puccinia kuehnii

References:

Chavarria, E., Subiros, F., Vega, J., Ralda, G., Glynn, N.C., Comstock, J.C., and Castlebury, L.A. 2009. First report of orange rust of sugarcane caused by Puccinia kuehnii in Costa Rica and Nicaragua. Pl. Dis. 93: 425.

Virtudazo, E.V., Nojima, H., and Kakishima, M. 2001. Taxonomy of Puccinia species causing rust diseases on sugarcane. Mycoscience 42: 167-175.

Nomenclature

Specimens in BPI

Additional distribution data

Suggested citation: Dixon, L. Systematic Mycology and Microbiology Laboratory, ARS, USDA. . Invasive Fungi. Brown rust of sugarcane - Puccinia melanocephala. Retrieved November 21, 2009, from http://nt.ars-grin.gov/sbmlweb/fungi/index.cfm .