Sporisorium sacchari
(Asian sugarcane smut)

Little published information exists on this plant pathogenic fungus of limited geographic distribution. S. sacchari is one of several Asian species only parasitizing the flowers of Saccharum species, thus causing much less damage to the plants than does the more widespread sugarcane smut that infects buds and reduces the growth of shoots. Although windborne, and probably contaminating seeds, S. sacchari spreads less well with the vegetatively propagated cane plants. Nevertheless, its effects on other possible hosts could pose a threat to native or agricultural plants if it were introduced.

This species is distributed in a wide range of the warmer parts of Asia, from Iran to the Philippines, but is recorded from only parts of India and China (EPPO, 2009). Ciferri (1938) identified it as introduced to Italy, but Vanky (1994) did not indicate that it had become established. One record (Piepenbring, 2002) apparently reports an accidental introduction into Colombia.

The risk of introduction is associated with possible transport of vegetative seed stock or of true seed for use in breeding/hybridization of cultivated species of Saccharum, but is diminished by the fact that the fungus does not infect the vegetative parts, only the flowers. If introduced at planting, the fungus would have to survive in the field until flowering, and then succeed in infecting from the soil or stem.

Some hosts of this fungus may be identified as species in Erianthus, a synonym of Saccharum (Vánky, 2000). No hosts are clearly shared with Sporisorium scitamineum (Vánky, 2000; 2006) except that Saccharum officinarum, the cultivated sugarcane, has been reported as a host in China (Zundel, 1953; Tai, 1979) and the Philippines (Reinking, 1919).

S. sacchari occurs in the individual florets only and is visible as small greyish to dark-brown bodies replacing the ovary and seed. Individual spores mixed with the seed or adhering to stems could only be detected and identified using high magnification light microscopy.

Other smut fungi occurring on Saccharum spp. include:

- Sporisorium erianthi [Sphacelotheca erianthi], which differs in having smaller spores (5-9(-10) µm diameter) and larger sterile cells (12-16 µm diameter).

- Sporisorium macrosporum, which differs in having larger spores (11-15 x 12-18 µm diameter), with larger spines.

- Sporisorium pulverulentum, which differs in having larger spores (8-9 (-12) x 9.5-13.0(-14.0) µm diameter), with a serrulate profile.

- Sporisorium scitamineum [Ustilagoscitaminea], which infects buds and shoots and differs in having the sori produced on the inflorescence stem not in the florets, replacing the panicle with a long thin curved body containing small blackish-brown spores, 5.5-7.5 x 6.5(-10.0) µm. Spore walls vary in profile from smooth to echinulate.

- Sporisorium kusanoi [Ustilago kusanoi], which is only reported on Saccharum bengalense, affects the whole inflorescence in the manner of S. scitamineum, and has small, smooth to finely punctate spores, 3.0-5.5 x 3.5-6.5 µm diameter.

For additional information see Vánky (1994; 2007).

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Cultural Control and Sanitary Measures

Methods for reducing or destroying the inoculum of Sporisorium scitamineum (Lee-Lovick, 1978) could be applied for S. sacchari, but may not be economically feasible.

Host Resistance

Smut caused by S. sacchari is less economically important (Holliday, 1980); therefore the use of resistant varieties, preferred for the control of S. scitamineum (Lee-Lovick, 1978), would be even more preferable for the flower-infecting smut.

Additional information is needed on the biology of survival between crops and the infection of flowers.

06/11/09 Original text by: