Sporisorium sacchari (Asian sugarcane smut)

Pictures

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Picture

Title

Caption

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Smut bodies

Smut bodies in florets. Original x20.

USDA-ARS/Systematic Mycology & Microbiology Laboratory

Spore balls

Spore balls. Original x400. Note scale bar.

USDA-ARS/Systematic Mycology & Microbiology Laboratory

Teliospores

Teliospores. Original x400. Note scale bar.

USDA-ARS/Systematic Mycology & Microbiology Laboratory

Teliospores

Teliospores. Original x1000. Note scale bar.

USDA-ARS/Systematic Mycology & Microbiology Laboratory

Identity

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Preferred Scientific Name

Sporisorium sacchari (Rabenh.) K. Vánky 1985

Preferred Common Name

Asian sugarcane smut

Other Scientific Names

Sphacelotheca sacchari (Rabenh.) Cif. 1945
Sphacelotheca sacchari Y. Ling & T.L. Chen 1945
Ustilago sacchari Rabenh. 1870
Ustilago sacchari-ciliaris Brefeld 1895

International Common Names

English: smut of Saccharum

Summary of Invasiveness

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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.

Taxonomic Tree

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Domain: Eukaryota
Kingdom: Fungi
Phylum: Basidiomycota
Subphylum: Ustilaginomycotina
Class: Ustilaginomycetes
Subclass: Ustilaginomycetidae
Order: Ustilaginales
Family: Ustilaginaceae
Genus: Sporisorium
Species: Sporisorium sacchari

Notes on Taxonomy and Nomenclature

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Vánky (1985; 1987) transferred this species to the genus Sporisorium because of its grass host, agreeing with Langdon and Fullerton (1978) that species of Sphacelotheca are restricted to smuts on dicotyledonous plants in the Polygonaceae. Later molecular taxonomic work on the smuts showed that Sphacelotheca belongs in the Microbotryales and that this order is more closely related to the rusts (Pucciniomycetes) than the smuts (Ustilaginomycetes) (Vánky, 2006). Sporisorium is closely related to Ustilago, the type genus of Ustilaginaceae (Piepenbring et al., 2002; Stoll et al., 2003). Among these “true” smuts, morphological characters of the sorus, previously used in taxonomy, are not phylogenetically informative, appearing to be influenced by the host (Stoll et al., 2005), such that additional close examination is required to distinguish genera and species.

The name Sphacelotheca sacchari Y. Ling & T.L. Chen 1945 is a later homonym of the combination made by Ciferri earlier the same year (Vánky, 2007). Ling and Chen did not designate a type, and the type for Rabenhorst’s Ustilago sacchari was destroyed by fire, so that comparisons cannot be made, but Vánky (2000; 2007) agreed with Ling (1953) that the Chinese species is probably a synonym.

Description

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Sori in swollen ovaries, ovoid to short cylindrical, 3-5 mm long, partly hidden by parts of floret; spore masses covered by a pale-brown membrane (peridium) rupturing irregularly, usually at apex, exposing blackish-brown, semi-agglutinated to powdery masses surrounding a short, tapering columella of plant and fungus tissue. Spores initially aggregated in very loose spore balls, 25-30 µm diameter, separating later, globose, subglobose, or ovoid to slightly irregular, 7-10 x 7-11(-12) µm, yellowish-brown; wall approximately 1 µm thick, finely and densely echinulate, spore profile appearing smooth or near smooth. Spore germination produces 3-septate basidia bearing fusiform basidiospores. See Mundkur (1942) and Vánky (2007).

Distribution

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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.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Last updated: 23 Apr 2020

Continent/Country/Region	Distribution	Origin	Reference	Notes
Asia
Bangladesh	Present		CABI (Undated); EPPO (2020)	As Bengal; Original citation: Mundkur and Thirumalachar (1952)
China	Present	Native	Ling (1953); Tai (1979); Guo (2002); EPPO (2020); CABI (Undated)
-Fujian	Present		Ling (1953); CABI (Undated)
-Guangxi	Present		Ling (1953)
-Hainan	Present		Guo (2002); CABI (Undated)
-Jiangsu	Present		Ling (1953)
-Sichuan	Present		Ling (1953); EPPO (2020)
-Yunnan	Present		Guo (2002)
-Zhejiang	Present		CABI (Undated)	Original citation: Teng (1996)
India	Present		CABI (Undated); EPPO (2020)	Original citation: Mundkur and Thirumalachar (1952)
-Bihar	Present		CABI (Undated); EPPO (2020)	Original citation: Mundkur and Thirumalachar (1952)
-Punjab	Present		CABI (Undated); EPPO (2020)	Original citation: Mundkur and Thirumalachar (1952)
-Uttar Pradesh	Present		CABI (Undated); EPPO (2020)	Original citation: Mundkur and Thirumalachar (1952)
Iran	Present		Mundkur (1942); Vánky (1985); EPPO (2020)
Malaysia	Present		CABI (Undated a); EPPO (2020)	Present based on regional distribution.
-Peninsular Malaysia	Present		Zundel (1953); EPPO (2020); CABI (Undated)
Pakistan	Present		Ahmad et al. (1997); EPPO (2020)
Philippines	Present		Reinking (1919); EPPO (2020)
Thailand	Present		Shivas et al. (2007)
Europe
Italy	Absent, Intercepted only		Ciferri (1938); EPPO (2020)
South America
Colombia	Absent, Intercepted only		Piepenbring (2002)

Risk of Introduction

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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.

Habitat List

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Category	Sub-Category	Habitat	Presence	Status
Terrestrial
	Terrestrial – Managed	Cultivated / agricultural land	Present, no further details	Harmful (pest or invasive)
	Terrestrial ‑ Natural / Semi-natural	Natural grasslands	Present, no further details	Natural

Hosts/Species Affected

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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).

Host Plants and Other Plants Affected

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Plant name	Family	Context
Saccharum	Poaceae	Wild host
Saccharum arundinaceum (pin reedgrass)	Poaceae	Wild host
Saccharum bengalense	Poaceae	Wild host
Saccharum narenga	Poaceae	Wild host
Saccharum officinarum (sugarcane)	Poaceae	Main
Saccharum ravennae (ravenna grass)	Poaceae	Wild host
Saccharum spontaneum (wild sugarcane)	Poaceae	Wild host

Growth Stages

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Symptoms

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The fungus replaces the ovary and seed in the individual florets with small bodies containing the compacted to powdery, dark, spore balls. Dissemination of the spores leaves the erect, pale, tapering columella in the centre of the floret.

List of Symptoms/Signs

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Sign	Life Stages	Type
Inflorescence / black fungal spores
Seeds / galls

Means of Movement and Dispersal

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Natural Dispersal

Natural dispersal of the smut spores from infected plants is primarily driven by wind (Lee-Lovick, 1978).

Accidental Introduction

Accidental introduction could occur if spores are present on vegetative planting stock, true seed imported for breeding purposes, or on stems of Saccharum sp. that are marketed or used in construction.

Pathway Vectors

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Vector	Notes	Long Distance	Local	References
Wind	spores		Yes	Lee-Lovick, 1978

Economic Impact

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Holliday (1980) indicated that the smuts on sugarcane other than Sporisorium scitamineum are economically unimportant. Due to the fact that the flowers are infected, rather than the buds, S. sacchari has much less effect on the growth of the stems, which are the harvested plant parts.

Risk and Impact Factors

Top of page Invasiveness

Proved invasive outside its native range
Has a broad native range
Has high reproductive potential
Reproduces asexually

Impact outcomes

Host damage
Negatively impacts agriculture

Impact mechanisms

Pathogenic

Likelihood of entry/control

Difficult to identify/detect as a commodity contaminant
Difficult to identify/detect in the field

Detection and Inspection

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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.

Similarities to Other Species/Conditions

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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).

Prevention and Control

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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.