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Datasheet

Sporobolus pyramidalis
(giant rat’s tail grass)

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Datasheet

Sporobolus pyramidalis (giant rat’s tail grass)

Summary

  • Last modified
  • 22 November 2019
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Preferred Scientific Name
  • Sporobolus pyramidalis
  • Preferred Common Name
  • giant rat’s tail grass
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • Sporobolus pyramidalis is a highly invasive tussock grass probably native to the African region. It is a grass of very low palatability and regarded in Australia as a very serious and declared weed. It is dispe...

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Pictures

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PictureTitleCaptionCopyright
Sporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia.  May 2006.
TitleHabit
CaptionSporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia. May 2006.
Copyright©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0
Sporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia.  May 2006.
HabitSporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia. May 2006.©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0
Sporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.
TitleHabit
CaptionSporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.
Copyright©Mark Marathon/via wikipedia - CC BY-SA 4.0
Sporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.
HabitSporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.©Mark Marathon/via wikipedia - CC BY-SA 4.0
Sporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.
TitleHabit
CaptionSporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.
Copyright©Mark Marathon/via wikipedia - CC BY-SA 4.0
Sporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.
HabitSporobolus pyramidalis (giant rat’s tail grass); habit. inland from Walvis Bay, Namibia. December 2014.©Mark Marathon/via wikipedia - CC BY-SA 4.0
Sporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia.  May 2006.
TitleHabit
CaptionSporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia. May 2006.
Copyright©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0
Sporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia.  May 2006.
HabitSporobolus pyramidalis (giant rat’s tail grass); habit. 45 km N of Rockhampton, Queensland, Australia. May 2006.©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0
Sporobolus pyramidalis (giant rat’s tail grass); flower spike. Flowerheads are initially long (20-45 cm), narrow, contracted panicles with stiff overlapping branches. Branches diverge at maturity to form a pyramidal open panicle. Australia. July 2006.
TitleFlower spike
CaptionSporobolus pyramidalis (giant rat’s tail grass); flower spike. Flowerheads are initially long (20-45 cm), narrow, contracted panicles with stiff overlapping branches. Branches diverge at maturity to form a pyramidal open panicle. Australia. July 2006.
Copyright©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0
Sporobolus pyramidalis (giant rat’s tail grass); flower spike. Flowerheads are initially long (20-45 cm), narrow, contracted panicles with stiff overlapping branches. Branches diverge at maturity to form a pyramidal open panicle. Australia. July 2006.
Flower spikeSporobolus pyramidalis (giant rat’s tail grass); flower spike. Flowerheads are initially long (20-45 cm), narrow, contracted panicles with stiff overlapping branches. Branches diverge at maturity to form a pyramidal open panicle. Australia. July 2006.©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0
Sporobolus pyramidalis (giant rat’s tail grass); spikelet. Spikelets ca.1.5-2 mm long and single-flowered, with an upper glume 30-50% the length of the spikelet. 45 km N of Rockhampton, Australia.  May 2006.
TitleSpikelet
CaptionSporobolus pyramidalis (giant rat’s tail grass); spikelet. Spikelets ca.1.5-2 mm long and single-flowered, with an upper glume 30-50% the length of the spikelet. 45 km N of Rockhampton, Australia. May 2006.
Copyright©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0
Sporobolus pyramidalis (giant rat’s tail grass); spikelet. Spikelets ca.1.5-2 mm long and single-flowered, with an upper glume 30-50% the length of the spikelet. 45 km N of Rockhampton, Australia.  May 2006.
SpikeletSporobolus pyramidalis (giant rat’s tail grass); spikelet. Spikelets ca.1.5-2 mm long and single-flowered, with an upper glume 30-50% the length of the spikelet. 45 km N of Rockhampton, Australia. May 2006.©Harry Rose (Macleay Grass Man)/via flickr - CC BY 2.0

Identity

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Preferred Scientific Name

  • Sporobolus pyramidalis P. Beauv.

Preferred Common Name

  • giant rat’s tail grass

Other Scientific Names

  • Agrostis extensa Schumach. & Thonn.
  • Sporobolus hypseloteros Chiov.
  • Sporobolus indicus var. pyramidalis (Beauv.) Veldkamp
  • Sporobolus pyramidalis var. jacquemontii (Kunth) Jovet & Guédès
  • Sporobolus rueppellianus Fresen.
  • Vilfa pyramidalis (P.Beauv.) Trin. ex Steud.
  • Vilfa ruppelliana (Fresen.) Steud.

International Common Names

  • English: West Indian dropseed ; West Indies smutgrass; whorled dropseed

Local Common Names

  • Australia: cat's tail dropseed; cat's tailgrass; giant rats-tail grass; Parramatta grass

Summary of Invasiveness

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Sporobolus pyramidalis is a highly invasive tussock grass probably native to the African region. It is a grass of very low palatability and regarded in Australia as a very serious and declared weed. It is dispersed very easily by several mechanisms and once established it can quickly dominate existing pastures. Pastures dominated by this grass become unproductive and land values are adversely affected. Control on extensively grazed properties is problematic such that every effort must be made to prevent its introduction on to clean properties.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Cyperales
  •                         Family: Poaceae
  •                             Genus: Sporobolus
  •                                 Species: Sporobolus pyramidalis

Notes on Taxonomy and Nomenclature

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Sporobolus is a genus of about 160 species endemic to tropical and subtropical regions (Simon and Jacobs, 1999). They present considerable taxonomic difficulties in identification, particularly those in the indicus complex (Pilger, 1956; Baaijens and Veldkamp, 1991) in which S. pyramidalis is placed. In Australia, five invasive,exotic species of the indicus group (S. africanus, S. fertilis, S. jacquemontii, S. natalensis, S. pyramidalis) are known collectively as the weedy sporobolus grasses (Bray and Officer, 2007; Palmer, 2012). The considerable difficulty in identifying these species led to the development of molecular tools to assist (Shrestha et al., 2003; Shrestha et al., 2005; Peterson et al., 2014).

In Australia, a second species is also known as giant rat’s tail grass (or GRT). That species is S. natalensis which is sympatric with S. pyramidalis. The two species are very difficult to distinguish and no doubt there has been some confusion in the applied literature.

The name Sporobolus indicus (L.) R. Br. var. pyramidalis (P. Beauv.) Veldkamp is a recognised synonym of both the very closely related species, S. pyramidalis and S. jacquemontii. The Plant List (2013) regards S. jacquemontii as a synonym of S. pyramidalis.

There are also two true species with very similar specific epithets, S. pyramidalis and the New World species S. pyramidatus (Lam.) C.L.Hitchc. There is every possibility that there is some confusion in the literature regarding these two species.

Description

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An erect, perennial tussock grass usually growing to 2 m in height. Alternately arranged leaves with leaf blades being 6 cm to 18 cm in length, glabrous, acuminate and weakly convoluted. Inflorescence is paniculate, pyramidal, open and exserted. The seed head can range from 25 to 80 cm long and side branches from 3 to 8 cm long (Simon and Jacobs, 1999). It changes shape from a ‘rat’s tail’ when young to an elongated pyramid shape when mature. Detailed line drawings of the various plant parts are given in Palmer (2012).

Plant Type

Top of page Grass / sedge
Perennial
Seed propagated
Vegetatively propagated

Distribution

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S. pyramidalis is of African origin (Simon and Jacobs, 1999) and possibly also native to South America (eMonocot, 2015). It is found throughout much of Africa, particularly sub-equatorial Africa, East Africa, the Nile Valley and West Africa and also Madagascar, Mauritius, and the Arabian Peninsula. In the western hemisphere it is found principally in tropical South America, Central America and the West Indies. It has been introduced to Australia where it is a very serious weed in coastal areas of Queensland and New South Wales, and also to Myanmar. It has also been recorded in Slovakia in Europe. It is listed as naturalized in south Florida (Institute for Regional Conservation, 2018).

The taxonomy and identification issues regarding closely related Sporobolus species, with the smaller narrow-leaved grass S. jacquemontii being sometimes listed as a synonym of S. pyramidalis, means that some distribution records could be of these related species.

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: 10 Jan 2020
Continent/Country/Region Distribution Last Reported Origin First Reported Invasive Reference Notes

Africa

AngolaPresenteMonocot (2015)
BeninPresenteMonocot (2015)
BotswanaPresenteMonocot (2015)
Burkina FasoPresenteMonocot (2015)
BurundiPresenteMonocot (2015)
CameroonPresenteMonocot (2015)
Central African RepublicPresenteMonocot (2015)
ChadPresenteMonocot (2015)
EswatiniPresenteMonocot (2015)
EthiopiaPresenteMonocot (2015)
GabonPresenteMonocot (2015)
GambiaPresenteMonocot (2015)
GhanaPresenteMonocot (2015)
GuineaPresenteMonocot (2015)
Guinea-BissauPresenteMonocot (2015)
KenyaPresenteMonocot (2015)
LiberiaPresenteMonocot (2015)
MadagascarPresentIntroducedNaturalizedMadagascar Catalogue (2018)Naturalized
MalawiPresenteMonocot (2015)
MaliPresenteMonocot (2015)
MauritiusPresenteMonocot (2015)
MozambiquePresenteMonocot (2015)
NamibiaPresenteMonocot (2015)
NigerPresenteMonocot (2015)
NigeriaPresentIntroducedInvasiveKomolafe (1976)
RwandaPresenteMonocot (2015)
SenegalPresenteMonocot (2015)
SeychellesPresenteMonocot (2015)
Sierra LeonePresenteMonocot (2015)
South AfricaPresenteMonocot (2015)
TanzaniaPresenteMonocot (2015)
TogoPresenteMonocot (2015)
UgandaPresenteMonocot (2015)
ZambiaPresenteMonocot (2015)
ZimbabwePresenteMonocot (2015)

Asia

OmanPresenteMonocot (2015)
Saudi ArabiaPresenteMonocot (2015)
YemenPresenteMonocot (2015)

Europe

SlovakiaPresentIntroducedInvasiveMochnacky (2005)

North America

BahamasPresenteMonocot (2015)
BelizePresenteMonocot (2015)
Cayman IslandsPresenteMonocot (2015)
Costa RicaPresenteMonocot (2015)
CubaPresenteMonocot (2015)
Dominican RepublicPresenteMonocot (2015)
El SalvadorPresenteMonocot (2015)
GuatemalaPresenteMonocot (2015)
HaitiPresenteMonocot (2015)
HondurasPresenteMonocot (2015)
JamaicaPresenteMonocot (2015)
MexicoPresenteMonocot (2015)
NicaraguaPresenteMonocot (2015)
PanamaPresenteMonocot (2015)
Puerto RicoPresenteMonocot (2015)
Trinidad and TobagoPresenteMonocot (2015)
United StatesPresenteMonocot (2015)
-AlabamaPresenteMonocot (2015)
-FloridaPresentIntroducedInstitute for Regional Conservation (2018)
-HawaiiPresenteMonocot (2015)

Oceania

AustraliaPresentIntroducedInvasiveSimon and Jacobs (1999)
-New South WalesPresent, WidespreadIntroducedInvasiveSimon and Jacobs (1999)
-Northern TerritoryPresentIntroducedInvasiveSimon and Jacobs (1999)
-QueenslandPresent, WidespreadIntroducedInvasiveSimon and Jacobs (1999)Very serious weed
FijiPresentIntroducedeMonocot (2015)

South America

BoliviaPresenteMonocot (2015)
BrazilPresent, WidespreadeMonocot (2015)
ColombiaPresenteMonocot (2015)
EcuadorPresenteMonocot (2015)
French GuianaPresenteMonocot (2015)
GuyanaPresenteMonocot (2015)
PeruPresenteMonocot (2015)
SurinamePresenteMonocot (2015)
VenezuelaPresenteMonocot (2015)

History of Introduction and Spread

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There is little definitive information on the history of its introduction to Australia or Myanmar and the fact that the taxonomy of the now recognised species was not then clear further obfuscates.

It is not known how S. pyramidalis was introduced into Australia. Most likely it was a contaminant in pasture seed but it has also been suggested that straw stuffing used by camel herders might have been responsible. Whatever the mechanism, there is literature extant suggesting that the plant was first thought to be a potential pasture species and trials for pasture and soil conservation were undertaken (Cook and Dias, 2006). In the course of time, this view changed until its recognition as a very serious weed (Bray and Officer, 2007).

Risk of Introduction

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The risk of introduction of this plant should be considered high because there are several effective dispersal mechanisms for it. International movement would be more likely as a contaminant in pasture seed but could also occur through movement of machinery, fodder, livestock or animal skins. Regionally, as well as these mechanisms, there are also water movements, movements on wild animals, vehicles and even people’s clothing.

Habitat

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S. pyramidalis can establish in a wide range of soils and conditions. It could be expected to prosper in tropical and subtropical regions receiving more than 500 mm annual rainfall. Its distribution in Australia together with the potential distributions predicted using climate modelling software is given in Palmer (2012). It is a weed of pastures, roadsides, disturbed sites, open woodlands, grasslands, parks, footpaths and lawns in sub-tropical, tropical and sometimes also warmer temperate regions (Weeds of Australia, 2018).

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial – ManagedManaged grasslands (grazing systems) Principal habitat Harmful (pest or invasive)
Disturbed areas Secondary/tolerated habitat Natural
Rail / roadsides Principal habitat Natural
Terrestrial ‑ Natural / Semi-naturalNatural grasslands Principal habitat Harmful (pest or invasive)

Biology and Ecology

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Genetics

S. pyramidalis has a chromosome number of 2n=12, 24, 30 or 36 (Spies and Voges, 1988; Simon and Jacobs, 1999).

Physiology and Phenology

The grass is a prolific seeder and is capable of producing up to 85,000 seed per sq m per year. A short-term dormancy (<6 months) occurs for 15-95% of freshly dropped seeds and is related to moisture availability (Vogler and Bahnisch, 2006). Seed viability is about 90% and a significant portion of seeds can remain viable for up to 10 years. Because there is no long-acting dormancy and germination is successful over a wide range of temperatures, large-scale germination and emergence is likely as soon as environmental conditions are favourable (Vogler and Bahnisch, 2006).The mucilaginous pericarp of the grain, a feature common to all Sporobolus spp.(Simon and Jacobs, 1999), is an important adaption for dispersal.

S. pyramidalis can flower throughout the year (Simon and Jacobs, 1999).

S. pyramidalis has a C4 photosynthetic pathway of the phosphoenolpyruvate carboxycarbonate subtype (Wand et al., 2001) Species falling into this subtype are most abundant in tropical and subtropical areas of intermediate rainfall (Wand et al., 2001). The plant does not produce more leaf in response to elevated CO2 but did produce a greater non-leaf shoot biomass (Wand et al., 2001). Presumably the plant will therefore be even less palatable in the future when there will be higher global CO2 levels.

S. pyramidalis is regarded as a desiccation sensitive plant which lacks the ability to recover from a water potential of -540 MPa (Gaff et al., 1997). Other Sporobolus spp. are regarded as more desiccation tolerant (Gaff et al., 1997).

Climate

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ClimateStatusDescriptionRemark
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Preferred < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Preferred < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
Cs - Warm temperate climate with dry summer Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Preferred Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
30 32

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall5001500mm; lower/upper limits

Rainfall Regime

Top of page Summer

Soil Tolerances

Top of page

Soil drainage

  • free

Soil reaction

  • acid
  • alkaline
  • neutral

Soil texture

  • heavy
  • light
  • medium

Special soil tolerances

  • infertile
  • shallow

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Curvularia crustacea Pathogen Seedlings
Curvularia ravenelii Pathogen Seedlings
Parepichloë cinerea Pathogen Seedlings
Phyllachora sylvatica Pathogen Seedlings
Uromyces tenuicutis Pathogen Seedlings
Ustilago sporoboli-indici Pathogen Seedlings to genus

Notes on Natural Enemies

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Surveys of natural enemies have been undertaken in southern Africa. While the plant has a considerable arthropod fauna and some pathogens associated with it, few of these were good prospects for biological control (Palmer et al., 2008). Further attempts to find agents are very likely.

Means of Movement and Dispersal

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There is little definitive information on the dispersal of this plant to new major regions of the globe. Dispersal within a local area is perhaps better understood. In all probability, natural dispersal mechanisms such as water, on wild animals, accidental dispersal by seed contamination, movement of dirty machinery, and even intentional dispersal where the plant has been considered beneficial have all been involved.

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Breeding and propagation Yes Yes
Crop production Yes Yes
Forage Yes Yes
Harvesting fur, wool or hair Yes Yes
Hitchhiker Yes
Seed trade Yes Yes

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Clothing, footwear and possessions Yes
Hides, trophies and feathers Yes Yes
Machinery and equipment Yes Yes
Mulch, straw, baskets and sod Yes Yes
Livestock Yes Yes
Land vehicles Yes Yes
Water Yes Yes
Wind Yes

Economic Impact

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In Australia, S. pyramidalis is becoming an increasingly important weed of the cattle grazing industry. The grass is not only very unpalatable but it becomes so tough that cattle cannot physically break the leaves from the tussock. Animals in paddocks with a high proportion of this grass may face starvation. Because cattle graze other species preferentially and because S. pyramidalis is a prolific seeder, the grass quickly becomes a dominant species in the pasture. Badly infested pastures are associated with reduced carrying capacity and up to 80% loss of production. Cattle and horses can also develop loose teeth when grazing such pastures. The economic costs incurred in managing this species with herbicides are also quite high, and heavily infested areas have reduced land values (Weeds of Australia, 2018).

Environmental Impact

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S. pyramidalis is considered a significant environmental weed in Australia as it invades native grasslands, open woodlands, conservation reserves and wetland areas. When well established it can form monocultures capable of excluding native flora, creating a significant threat to rangeland biodiversity in central and northern Queensland. This also affects native herbivores which find the plant unpalatable. Dense infestations can also increase fire intensity in sensitive environmental areas.

Social Impact

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There are no health concerns related this plant. The major social impact would be the potential severe degradation of productive pasture which may lead to significant drop in land values for affected farms and regions. Reduction in land values is likely to stress landholders and their families.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Is a habitat generalist
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Highly mobile locally
  • Benefits from human association (i.e. it is a human commensal)
  • Fast growing
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
  • Has high genetic variability
Impact outcomes
  • Altered trophic level
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Modification of fire regime
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts agriculture
  • Negatively impacts animal health
  • Negatively impacts livelihoods
  • Reduced native biodiversity
  • Threat to/ loss of native species
  • Damages animal/plant products
  • Negatively impacts trade/international relations
Impact mechanisms
  • Competition - monopolizing resources
  • Herbivory/grazing/browsing
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Uses

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There are few productive uses for this plant. Some landholders manage the problem by preventing the grass from maturing and thereby getting some grazing utility from it. However, without question, all properties would be in better condition had they not been infested with S. pyramidalis.

Detection and Inspection

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There are no easy methods for detecting S. pyramidalis in the field. In areas likely to become infested, land holders must remain vigilant to grasses with the general characteristic of this plant and seek early expert identification of any possible incursion. Similarly, it is very difficult to distinguish its seed from those of other grass species. The recommended approach is to ensure that machinery and vehicles are completely cleaned of all plant matter before being allowed on to clean country.

A laboratory technique has been developed to identify seeds of S. pyramidalis from seeds of other plants (Shrestha et al., 2005). A RAPD-PCR technique was used to develop molecular markers which would identify the plant. The technique has not been employed on a routine screen.

Similarities to Other Species/Conditions

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S. pyramidalis differs from S. natalensis by the upper glumes being about a third the spikelet length and truncate and erose at the apex as opposed to acute in S. natalensis (Simon and Jacobs, 1999). It differs from S. jacquemontii by its more robust habit, by the pyramidal shape of the inflorescence and by its greater height of up to 2 m (Simon and Jacobs, 1999). These two species are regarded as phylogenetically closest to S. pyramidalis but it should be noted that all the species in the indicus group are difficult to distinguish and in all probability there has been taxonomic confusion particularly in historical literature.

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.

Prevention

It is very important to prevent infestation of pastures with S. pyramidalis. The seeds are very easily moved on animals, vehicles, people, and fodder so strict property hygiene is essential. Landholders in areas likely to become infested must be alert to new infestations and eliminate these as quickly as possible. It is also important to maintain existing pastures in a vigorous and dense condition to increase competition for any weed seedlings that establish.

Viable seeds of S. pyramidalis, and other Sporobolus spp., can take several days to pass through a cow’s digestive system (Andrews, 1995) and a withholding period of 7 days has been recommended before stock grazing in infested pastures are introduced into new areas.

Government can assist by declaring the plant noxious and regulating to prevent its movement. In Australia, S. pyramidalis is a declared weed in Queensland and New South Wales.

Eradication

Eradication of this grass would be extremely problematic even at a property level. There are no cases where S. pyramidalis has been eradicated from an area of any appreciable size.

Control

Cultural control and sanitary measures

Sanitary measures are of critical importance in preventing the spread of this grass into clean areas. Cattle coming from infested areas can be kept away from clean pastures until seeds have passed through the digestive system. Strict precautions must be taken to ensure that any seed or fodder brought on to a property is not infested, thoroughly cleaning machinery and vehicles or refusing entry on to clean areas of machinery that has been in infested areas.

Physical/mechanical control

For small and new infestations, plants can be hand chipped, bagged and removed from pasture for burning or similar destruction.

Biological control

Although the Australian grazing industry is desperately keen to have a biological control for this weed, prospects are not good (Palmer, 2012). Grasses are difficult targets for biological control for several reasons. Australia also has some 15 native congeners necessitating a very high degree of host specificity of any prospective agent. One agent, the smut Ustilago sporoboli-indici was fully screened but rejected because of attack on Australian native Sporobolus spp. (Yobo et al., 2009). Investigations were undertaken in Australia to see whether endemic fungal pathogens from the genus Bipolaris might be useful. While S. pyramidalis was highly susceptible to both B. ravenelii and B. crustacean, variation was significant (Hetherington and Irwin, 1999) and bioherbicides have not been developed from this work.

Chemical control

Two herbicides are available for chemical control, glyphosate and flupropanate. These can be used by spot spraying, boom spray or by pressurized wick wiper. The wick wiper option requires three treatments over an 18-month period to be effective, with grazing using increased stocking periods after the first treatment in midsummer (Weeds of Australia, 2018).

There are withholding periods for both dairy and beef cattle when flupropanate is applied to pasture. In a laboratory trial, none of twenty three herbicides screened were particularly effective against mature plants (Vogler, 2010).

IPM

There are integrated weed management options useful in minimizing the detrimental effects of this weed. These options include strict hygiene to prevent initial infestations, early detection of infestation, maintaining competitive pastures of non-Sporobolus species, minimizing overgrazing, grazing strategies to prevent S. pyramidalis maturing and appropriate herbicide application.

Gaps in Knowledge/Research Needs

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Despite considerable advancements in the taxonomy and phylogeny of the Sporobolus genus in the past two decades, there are still issues in identification that could be clarified with further work using the most recent techniques of DNA analyses and relating these studies to morphological characters suitable for field identification. These studies need to be undertaken at the global level. One benefit of definitive identification is that knowledge from various countries can be pooled.

References

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Andrews, T. S., 1995. Dispersal of seeds of giant Sporobolus spp. after ingestion by grazing cattle. Australian Journal of Experimental Agriculture, 35(3), 353-356. doi: 10.1071/EA9950353

Baaijens, G. J., Veldkamp, J. F., 1991. Sporobolus (Gramineae) in Malesia. Blumea, 35(2), 393-458.

Bray S, Officer D, 2007. Weedy sporobolus grasses best practice manual. 3rd edition. Brisbane: State of Queensland, Department of Primary Industries and Fisheries. 38 pp

Cook, G. D., Dias, L., 2006. It was no accident: deliberate plant introductions by Australian government agencies during the 20th century. Australian Journal of Botany, 54(7), 601-625. http://www.publish.csiro.au/?nid/66 doi: 10.1071/BT05157

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Distribution References

eMonocot, 2015. eMonocot - an online resource for monocot plants.,

Institute for Regional Conservation, 2018. The floristic inventory of South Florida., https://regionalconservation.org/ircs/database/plants/PlantPage.asp?TXCODE=Sporpyra1

Komolafe DA, 1976. Weed problems in tree crops in Nigeria. In: PANS, 22 (2) 250-276.

Madagascar Catalogue, 2018. Catalogue of the Vascular Plants of Madagascar., St. Louis, Missour and Antananarivo, USA and Madagascar: Missouri Botanical Garden. http://www.tropicos.org/project/mada

Mochnacky S, 2005. Invasive Communities in East Slovakia. [Proceedings of the 5th International Conference Anthropization and environment of rural settlements Flora and vegetation], [ed. by Mosyakin SL, Shevera MV]. Ukraine: NAS of Ukraine: Kholodny Institute of Botany.

Simon B K, Jacobs S W L, 1999. Revision of the genus Sporobolus (Poaceae, Chloridoideae) in Australia. Australian Systematic Botany. 12 (3), 375-448. DOI:10.1071/SB97048

Organizations

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Australia: Queensland Department of Agriculture and Fisheries, GPO Box 46, Brisbane QLD 4001, https://www.daf.qld.gov.au/

Contributors

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14/12/2015, original text by:

Dr Bill Palmer, Biosecurity Queensland, Australia

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