Invasive Species Compendium

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Datasheet

Panicum repens
(torpedo grass)

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Datasheet

Panicum repens (torpedo grass)

Summary

  • Last modified
  • 27 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Host Plant
  • Preferred Scientific Name
  • Panicum repens
  • Preferred Common Name
  • torpedo grass
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • As a rhizomatous perennial species, P. repens has proved to be a difficult to control invasive plant in some areas where it has been introduced, most notably in Florida, USA. In the USA, it is listed as a prohibited noxious weed in Arizona and a noxi...

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Pictures

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PictureTitleCaptionCopyright
Left, panicles exserted 10-15 cm above foliage, about 10 (5-20) cm long, with 1-3 branches per node, usually quite stiffly erect. Right, rhizomes up to 1 cm thick, nodes at 10-15 cm intervals tend to be swollen, each bearing a viable but often dormant bud.
TitleInflorescence and rhizome
CaptionLeft, panicles exserted 10-15 cm above foliage, about 10 (5-20) cm long, with 1-3 branches per node, usually quite stiffly erect. Right, rhizomes up to 1 cm thick, nodes at 10-15 cm intervals tend to be swollen, each bearing a viable but often dormant bud.
Copyright©Chris Parker/Bristol, UK
Left, panicles exserted 10-15 cm above foliage, about 10 (5-20) cm long, with 1-3 branches per node, usually quite stiffly erect. Right, rhizomes up to 1 cm thick, nodes at 10-15 cm intervals tend to be swollen, each bearing a viable but often dormant bud.
Inflorescence and rhizomeLeft, panicles exserted 10-15 cm above foliage, about 10 (5-20) cm long, with 1-3 branches per node, usually quite stiffly erect. Right, rhizomes up to 1 cm thick, nodes at 10-15 cm intervals tend to be swollen, each bearing a viable but often dormant bud. ©Chris Parker/Bristol, UK
a, Ligule, ventral view; b1-2, spikelet, two views.
TitleWhole plant - line drawing
Captiona, Ligule, ventral view; b1-2, spikelet, two views.
CopyrightSEAMEO-BIOTROP
a, Ligule, ventral view; b1-2, spikelet, two views.
Whole plant - line drawinga, Ligule, ventral view; b1-2, spikelet, two views.SEAMEO-BIOTROP

Identity

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Preferred Scientific Name

  • Panicum repens L. 1762

Preferred Common Name

  • torpedo grass

Other Scientific Names

  • Panicum aquaticum A.Rich. 1851
  • Panicum arenarium Brot. 1804
  • Panicum chromatostigma Pilg. 1902
  • Panicum convolutum Beauv. ex Spreng. 1825
  • Panicum hygrocharis Steud. 1854
  • Panicum ischaemoides Retz. 1786
  • Panicum leiogonum Delile 1812
  • Panicum nyanzense K. Schum., 1897

International Common Names

  • English: creeping panic
  • Spanish: gramma del norte
  • French: panic rampant
  • Portuguese: escalracho

Local Common Names

  • Argentina: paja voladora
  • Bangladesh: baranda
  • Brazil: capim-torpedo
  • Brunei Darussalam: huma; kerunong
  • Cambodia: chhlong
  • Cuba: alpiste de tierra
  • Egypt: beid el-homaar; neseela na'-ame; zommaar; zommeirentaya
  • Germany: Torpedogras
  • India: injipilla; karigaddi
  • Indonesia: jajahean; lampuyangan; rumput jae-jae
  • Indonesia/Java: suket balungan; suket lempuyangan
  • Israel: dohan zohel
  • Italy: panico strisciante
  • Japan: haikibi
  • Malaysia: kerunong padi; metubong; rumput kerbau; telur padi
  • Mexico: zacate carrillo
  • Myanmar: myet-kha
  • Netherlands: victoriagras
  • Pakistan: chimacara; surpurrcharela
  • Philippines: luya-luyahan; maralaya
  • Poland: proso rozlogowe
  • Senegal: bamba subu; ekena; eselek
  • South Africa: kruipgras
  • Sri Lanka: etora
  • Taiwan: pu-shu-tsao
  • Thailand: ya-chan ka; yakhaemman; ya-onoi
  • Turkey: tuylu dari
  • USA/Hawaii: wainaku grass

EPPO code

  • PANHY (Panicum hygrocharis)
  • PANRE (Panicum repens)

Summary of Invasiveness

Top of page As a rhizomatous perennial species, P. repens has proved to be a difficult to control invasive plant in some areas where it has been introduced, most notably in Florida, USA. In the USA, it is listed as a prohibited noxious weed in Arizona and a noxious weed in Alabama, Hawaii and Texas. In Florida it is designated an invasive exotic (FLEPPC, 2004). It is not included on the Australian noxious weed list nor on the Global Invasive Species Database of IUCN. It is considered invasive and a danger in the Pacific region (PIER, 2004).

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Cyperales
  •                         Family: Poaceae
  •                             Genus: Panicum
  •                                 Species: Panicum repens

Notes on Taxonomy and Nomenclature

Top of page P. repens is a name universally recognized, with no synonyms currently used. The only confusions may occur in East Africa, with the closely related P. repentellum, and in the Americas, with P. gouini (see Similarities with Other Pests).

Description

Top of page P. repens is a rhizomatous perennial grass which can form extensive dominant swards with foliage and inflorescences up to 100 cm high, though more commonly to about 50 cm.

Culms have bladeless scales at the base. Leaves are in two ranks, bright green to slightly glaucous, stiff, almost erect, 15-20 cm long, about 1 cm wide, tapering gradually to an acute tip, sparsely hairy on the upper surface, smooth and sometimes with a waxy bloom on the lower. Leaf sheaths have long white hairs along the margin. The ligule is a very short membrane, 0.5 mm long, fringed with long white hairs.

Robust rhizomes, up to 1 cm thick, grow horizontally at depths down to 20 cm or more and up to several metres distance. Nodes at 10-15 cm intervals tend to be swollen and each bears a viable but often dormant bud.

Panicles exserted 10-15 cm above foliage, about 10 (5-20) cm long, with 1-3 branches per node, usually quite stiffly erect. Spikelets 2-flowered pale green/glaucous, sometimes tinged with purple, oblong-ovate, acute or slightly acuminate, 2.5-3 mm long. Lower glume 1-3 nerved, broadly ovate one-fifth to one-third as long as the spikelet, upper glume and lower lemma similar, 7-nerved, as long as the spikelet. Upper lemma shorter, pale and glossy. Anthers three, yellow-orange, stigmas purple, caryopsis (seed) lanceolate, pale, white or straw-coloured.

Plant Type

Top of page Aquatic
Grass / sedge
Herbaceous
Perennial
Vegetatively propagated

Distribution

Top of page P. repens is an Old World species, most widespread in Africa and Asia but now occurring throughout the tropics and sub-tropics between about 35°S and 43°N. Although it has been suggested that further spread northwards in the USA is unlikely owing to its susceptibility to freezing conditions (Wilcut et al., 1988a), it does persist in Masvingo Province of Zimbabwe where temperatures fall below 0°C in some years. In the tropics it may occur up to 2000 m altitude.

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.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

BangladeshPresentIntroduced Not invasive Holm et al., 1979
Brunei DarussalamPresentIntroduced Not invasive Moody, 1989; Waterhouse, 1993
CambodiaPresentIntroduced Not invasive Holm et al., 1979; Waterhouse, 1993
ChinaPresentIntroduced Not invasive Holm et al., 1979
-Hong KongPresentIntroduced Not invasive Holm et al., 1979
IndiaRestricted distribution Not invasive Holm et al., 1977
-Andhra PradeshPresentIntroduced Not invasive Naidu and Lakshmi, 2000
-AssamPresentIntroduced Not invasive Shukla, 1996
-BiharPresentIntroduced Not invasive Shukla, 1996
-KarnatakaPresentIntroduced Not invasive Shukla, 1996
-KeralaPresentIntroduced Not invasive Musthafa and Potty, 2001
-MaharashtraPresentIntroduced Not invasive Suryawanshi et al., 2001
-MeghalayaPresentIntroduced Not invasive Shukla, 1996
-OdishaIntroduced Not invasive Jena et al., 2002
-RajasthanPresentIntroduced Not invasive Sharma and Bhunia, 1999
-Tamil NaduPresentIntroduced Not invasive Shukla, 1996
-TripuraPresentIntroduced Not invasive Shukla, 1996
-UttarakhandPresentIntroduced Not invasive Pandey et al., 2002
IndonesiaPresentIntroduced Not invasive
-Irian JayaPresentIntroduced Not invasive Soerjani et al., 1987
-JavaPresentIntroduced Not invasive Soerjani et al., 1987
-KalimantanPresentIntroduced Not invasive Soerjani et al., 1987
-SulawesiPresentIntroduced Not invasive Soerjani et al., 1987
-SumatraPresentIntroduced Not invasive Soerjani et al., 1987
IraqPresentIntroduced Not invasive Holm et al., 1979
IsraelPresentIntroduced Not invasive Holm et al., 1979
JapanPresentIntroduced Not invasive Holm et al., 1979
Korea, DPRPresentIntroduced Not invasive Holm et al., 1979
Korea, Republic ofPresentIntroduced Not invasive Holm et al., 1979
LaosPresentIntroduced Not invasive Moody, 1989; Waterhouse, 1993
MalaysiaWidespreadIntroduced Not invasive Holm et al., 1979; Waterhouse, 1993
MyanmarPresentIntroduced Not invasive Holm et al., 1979; Waterhouse, 1993
NepalPresentIntroduced Not invasive Moody, 1989
PhilippinesWidespreadIntroduced Not invasive Holm et al., 1979; Waterhouse, 1993
Saudi ArabiaRestricted distributionIntroduced Not invasive Holm et al., 1979
SingaporePresentIntroduced Not invasive Waterhouse, 1993
Sri LankaWidespreadIntroduced Not invasive Holm et al., 1979
TaiwanWidespreadIntroduced Not invasive Holm et al., 1979
ThailandWidespreadIntroduced Not invasive Holm et al., 1979; Waterhouse, 1993
VietnamPresentIntroduced Not invasive Holm et al., 1979; Waterhouse, 1993

Africa

BotswanaPresentNative Not invasive Gibbs et al., 1990
CameroonPresentNative Not invasive Hepper and ed., 1972
Central African RepublicPresentNative Not invasive Holm et al., 1979
Côte d'IvoirePresentNative Not invasive Hepper and ed., 1972
EgyptPresentNative Not invasive Täckholm, 1974
EthiopiaPresentNative Not invasive Fröman and Persson, 1974
GhanaPresentNative Not invasive Hepper and ed., 1972
GuineaWidespreadNative Not invasive Holm et al., 1979
KenyaPresentNative Not invasive Clayton and Renvoize, 1982
LiberiaPresentNative Not invasive Hepper and ed., 1972
MaliPresentNative Not invasive Hepper and ed., 1972
MoroccoPresentNative Not invasive Holm et al., 1979
NamibiaPresentNative Not invasive Gibbs et al., 1990
NigerPresentNative Not invasive Hepper and ed., 1972
NigeriaPresentNative Not invasive Hepper and ed., 1972
SenegalPresentNative Not invasive Hepper and ed., 1972
Sierra LeonePresentNative Not invasive Hepper and ed., 1972
South AfricaPresentNative Not invasive Holm et al., 1979
SudanPresentIntroduced Not invasive Holm et al., 1979
SwazilandPresentNative Not invasive Gibbs et al., 1990
TanzaniaPresentNative Not invasive Clayton and Renvoize, 1982
-ZanzibarPresentNative Not invasive Clayton and Renvoize, 1982
UgandaPresentNative Not invasive Clayton and Renvoize, 1982
ZimbabwePresentNative Not invasive Holm et al., 1979

North America

USAPresentHolm et al., 1977
-AlabamaPresentIntroduced Invasive Hitchcock, 1950
-CaliforniaPresentIntroduced Invasive USDA-NRCS, 2004
-FloridaPresentIntroduced Invasive Hitchcock, 1950
-HawaiiWidespreadIntroduced Invasive Holm et al., 1977
-LouisianaPresentIntroduced Invasive Hitchcock, 1950
-MississippiPresentIntroduced Invasive Hitchcock, 1950
-North CarolinaPresentIntroduced Not invasive USDA-NRCS, 2004
-South CarolinaPresentIntroduced Not invasive USDA-NRCS, 2004
-TexasPresentIntroduced Invasive Hitchcock, 1950

Central America and Caribbean

Costa RicaPresentRetana-Sánchez et al., 2013
CubaPresentIntroduced Not invasive Holm et al., 1979
Dominican RepublicPresentIntroduced Not invasive Holm et al., 1979
Puerto RicoPresentIntroduced Not invasive Holm et al., 1979

South America

ArgentinaPresentIntroduced Not invasive Holm et al., 1979
BoliviaPresentIntroduced Not invasive Holm et al., 1979
BrazilPresentIntroduced Not invasive Lorenzi, 1982
-BahiaPresentIntroduced Not invasive Lorenzi, 1982
-GoiasPresentIntroduced Not invasive Lorenzi, 1982
-Mato Grosso do SulPresentIntroduced Not invasive Lorenzi, 1982
-Minas GeraisPresentIntroduced Not invasive Lorenzi, 1982
-ParanaPresentIntroduced Not invasive Lorenzi, 1982
-Rio de JaneiroPresentIntroduced Not invasive Lorenzi, 1982
-Santa CatarinaPresentIntroduced Not invasive Lorenzi, 1982
-Sao PauloPresentIntroduced Not invasive Lorenzi, 1982
ParaguayPresentIntroduced Not invasive Holm et al., 1979
UruguayPresentIntroduced Not invasive Holm et al., 1979

Europe

AlbaniaPresentIntroduced Not invasive Tutin et al., 1980
CyprusPresentIntroduced Not invasive Meikle, 1977
FrancePresentIntroduced Not invasive Tutin et al., 1980
-CorsicaPresentIntroduced Not invasive Tutin et al., 1980
GreecePresentNative Not invasive Tutin et al., 1980
ItalyPresentNative Not invasive Tutin et al., 1980
PortugalPresentIntroduced Not invasive Tutin et al., 1980
SpainPresentIntroduced Not invasive Tutin et al., 1980
-Balearic IslandsPresentIntroduced Not invasive Tutin et al., 1980
Yugoslavia (former)PresentIntroduced Not invasive Tutin et al., 1980

Oceania

AustraliaPresentIntroduced Not invasive Holm et al., 1979
Northern Mariana IslandsPresentIntroduced Not invasive PIER, 2004
PalauPresentIntroduced Not invasive PIER, 2004

History of Introduction and Spread

Top of page P. repens has become established as an invasive species beyond its natural range through introduction as a fodder species. It is cultivated on wet alluvial sandy soils in Africa, South America, North America and India but is very difficult to eradicate once established. After it was introduced into Pakistan for this purpose it did not persist (Cope, 1982).

Risk of Introduction

Top of page The greatest risk of further spread would be through introduction to a new area for use as a forage or for stabilising eroded soils. A full risk assessment should be carried out prior to any introduction. The species is a prohibited plant in southern USA.

Habitat

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A plant of generally wet places, both coastal and inland, occurring naturally along the edges of rivers, irrigation channels, lakes and brackish shorelines. It does not tolerate long-term submergence (Thayer and Haller, 1990), but may occur as a component of floating islands, in succession to, or as a co-dominant with e.g. Eichhornia crassipes or Cyperus papyrus. Natural habitats are often sandy, but it is able to persist in heavy soils that remain moist due to high rainfall, poor drainage or irrigation. It is most commonly a weed of perennial plantation crops in the humid tropics, but may also occur in moist sub-tropical situations (e.g. southern Europe) and as a weed in annual crops where tillage is not sufficiently deep and drainage is poor.

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial – ManagedCultivated / agricultural land Present, no further details Harmful (pest or invasive)
Managed forests, plantations and orchards Present, no further details Harmful (pest or invasive)
Managed grasslands (grazing systems) Present, no further details Harmful (pest or invasive)
Terrestrial ‑ Natural / Semi-naturalRiverbanks Present, no further details Harmful (pest or invasive)
Wetlands Present, no further details Harmful (pest or invasive)
Littoral
Coastal areas Present, no further details

Host Plants and Other Plants Affected

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Biology and Ecology

Top of page Genetics

Accessions from Egypt and India are diploid with a chromosome number of 2n = 36 (MOBOT, 2004).

Physiology and phenology

P. repens is a serious weed mainly on account of its perennial habit, including its ability to spread and persist by rhizomes in any moist situations where there is inadequate deep tillage. Once a new plant is established, rhizomes develop within a few weeks, growing horizontally for several metres, usually at 5-20 cm depth, but sometimes deeper. Hossain et al. (1996) reported rhizomes mostly in the top 30 cm but some down to 42 cm in a reddish soil in southern Japan. They also recorded that one rhizome node could give rise to over 20,000 new rhizome buds in 365 days. Most axillary buds on the rhizome remain dormant until there is fragmentation by cultivation. Pieces of rhizomes with six nodes are able to regenerate from 8-16 cm depth (Wilcut et al., 1988a). Under suitable conditions, new plants can develop from any single-node segment of rhizome. P. repens is resistant to fire (Weber, 2003).

Reproductive biology

Seeds are usually produced in considerable numbers but may be unimportant as a means of spread in some localities. Flowering and seed production are said to be rare, e.g. in Java, while Chandrasena and Dhammika (1988) show that different clones of the weed in Sri Lanka may differ significantly in flowering behaviour. Seeds are sometimes claimed to be non-viable but Moreira (1976a, 1978) has shown germination levels up to 100%. Dormancy may be high in young seed, but germination can be enhanced by chilling, nitrate and alternating temperatures, e.g. between 20 and 30°C. Populations in Florida, USA, do not produce viable seed (Weber, 2003).

Ecology

The weed can occur in a wide range of soil types and is not sensitive to pH between 4.2 and 6.7 (Wilcut et al., 1988a) or to moderate-to-high salinity (up to 10,000 p.p.m.) (Peng et al., 1977; Peng and Twu, 1979; Nemoto et al., 1987). Although adapted to wet conditions and presumably needing these for active growth, it can, once established, survive moderately prolonged drought conditions, particularly where there is a high water table. Optimum temperatures for growth are 30-35°C and it is killed by persistent frost (Wilcut et al., 1988b). It prefers open sunny conditions but persists in semi-shaded plantation crop situations.

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
620 1500

Air Temperature

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Parameter Lower limit Upper limit
Mean annual temperature (ºC) 19 27
Mean maximum temperature of hottest month (ºC) 25 31
Mean minimum temperature of coldest month (ºC) 16 22

Rainfall

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ParameterLower limitUpper limitDescription
Dry season duration07number of consecutive months with <40 mm rainfall

Rainfall Regime

Top of page Bimodal
Summer
Uniform
Winter

Soil Tolerances

Top of page

Soil drainage

  • impeded
  • seasonally waterlogged

Soil reaction

  • acid

Soil texture

  • heavy
  • light
  • medium

Special soil tolerances

  • saline

Natural enemies

Top of page
Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Parasteneotarsonemus panici Herbivore
Toya tuberculosa Pathogen
Ustilago hypodytes Pathogen

Notes on Natural Enemies

Top of page Lists of natural enemies are given by Moreira (1976b) and by Waterhouse (1994) but there are no reports of serious damage from natural insect enemies or fungi, nor serious consideration of their potential for biological control. Waterhouse (1994) also noted that most of the arthropod enemies are polyphagous pests of crops which might explain the absence of any serious attempt to find biological control agents. Insects do not hold promise but records of fungal pathogens merit investigations. There may be host-specific species or forma speciales which might be introduced into areas where they are not present. There is one report of the white amur (grass carp - Ctenopharyngodon idella) consuming P. repens where it occurs as part of a floating island vegetation (Sutton et al., 1977).

Means of Movement and Dispersal

Top of page Natural dispersal

P. repens spreads by means of rhizomes. Seed is rarely produced.

Agricultural practices

P. repens is planted in grazing land and may invade adjacent areas if not carefully managed. A careful impact assessment should be made before introducing the species as forage to a new area.

Plant Trade

Top of page
Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Bulbs/Tubers/Corms/Rhizomes Pest or symptoms usually visible to the naked eye
True seeds (inc. grain) Pest or symptoms not visible to the naked eye but usually visible under light microscope

Wood Packaging

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Wood Packaging not known to carry the pest in trade/transport
Loose wood packing material
Non-wood
Processed or treated wood
Solid wood packing material with bark
Solid wood packing material without bark

Impact Summary

Top of page
CategoryImpact
Animal/plant collections None
Animal/plant products None
Biodiversity (generally) Negative
Crop production Negative
Environment (generally) Negative
Fisheries / aquaculture Negative
Forestry production None
Human health None
Livestock production None
Native fauna Negative
Native flora Negative
Rare/protected species None
Tourism Negative
Trade/international relations None
Transport/travel Negative

Impact

Top of page P. repens is a troublesome weed in a wide range of perennial crops, being noted by Holm et al. (1977) as a serious or principal weed of sugarcane in Taiwan and Hawaii; pineapple in West Africa; tea in India, Indonesia and Sri Lanka; various orchard crops in Thailand; rubber, coconut and oil palm in Malaysia; also of rice in Indonesia and Sri Lanka. In a number of these situations it is listed as one of the three most serious weeds. There are few estimates of crop losses but Peng and Sze (1974) report that in Taiwan rhizome density can reach 15 t/ha, while a density of 5 t/ha can cause 50% reduction in sugarcane yield. It is also reported to have allelopathic effects (Perera et al., 1989; Chon, 1989).

P. repens may act as an alternative host to rice leafhopper, Ustilago and Pyricularia spp. (Holm et al., 1977).

Impact: Biodiversity

Top of page As P. repens spreads by means of rhizomes, it can form dense pure swards that replace native species (Weber, 2003). In the Lake Okeechobee area of Florida, USA, the grass has spread over thousands of acres of the Lake's western marsh, displacing native plants and the valuable fish and wildlife habitat that they once provided (LOPP, 2004).

Social Impact

Top of page P. repens can build up along irrigation canals and drainage ditches requiring costly control programmes. It also has to be controlled in golf course turf in Florida, USA (Busey, 2003).

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Negatively impacts agriculture
  • Negatively impacts tourism
  • Reduced amenity values
  • Reduced native biodiversity
Impact mechanisms
  • Competition - monopolizing resources
  • Pest and disease transmission
Likelihood of entry/control
  • Difficult/costly to control

Uses

Top of page P. repens has been widely used as a forage species. Its salt tolerance makes it a useful species for reclaiming saline soils (Ghaly, 2002). It is a source of ethno-medicines in India (Kaushal-Kumar, 2002).

Uses List

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Animal feed, fodder, forage

  • Fodder/animal feed
  • Forage

Environmental

  • Erosion control or dune stabilization

Similarities to Other Species/Conditions

Top of page Not readily confused with other commonly occurring perennial grass weeds but in eastern and southern Africa, a closely related species P. repentellum also occurs, in similar wet habitats. The latter is distinguished by a smaller more delicate habit, and nerveless lower glume. In southern USA, Central and South America, a further closely related species, P. gouini(i), occurs. This is also less robust and almost glabrous. It is not certain to what extent either of these species may also occur as weeds.

Prevention and Control

Top of page Cultural

The use of leguminous smothering crops is important and effective in plantation crops in sufficiently humid climatic conditions, e.g. in oil palm or rubber. In Florida wetlands, maintenance of high water levels favours indigenous species and reduces spread of P. repens (David, 1999).

Mechanical

Among traditional weeding methods, hoeing and hand-weeding are ineffective, owing to strong and rapid regrowth from the underground rhizome system. Tillage can be effective but it must be deep enough to disturb as many of the rhizomes as possible, and persistent enough and under the right climatic and soil conditions to result in good desiccation. One or two cultivations under wet conditions may serve only to spread the problem.

Chemical

Older herbicides used for control of P. repens include dalapon and asulam and these may still have applicability in particular situations, e.g. in sugarcane (Peng et al., 1977; Yeh and Wang, 1980) and along irrigation channels (Panchal, 1981). MSMA was reported by Coats (1974) to be inferior to asulam for control of P. repens in turf, but MSMA has been tested with some success in tea (e.g. Soedarsan et al., 1974). Quinclorac has also been shown to be an effective treatment in turf (Busey, 2003). Otherwise the herbicide of choice where crop safety allows, is glyphosate. Split doses a few weeks apart have given better results than a single application (Chandrasena, 1990). At lower doses activity may be decreased in hard water (Ca 5 mM) or in the presence of iron salts (Shilling et al., 1990a) or in mixtures with triazine or urea herbicides, whereas activity may be enhanced by various additives including ammonium sulphate, kaolin and surfactants (Kathiravetpillai and Punyasiri, 1989; Shilling et al., 1990b; Reddy and Singh, 1992). Fluazifop-butyl was not fully effective in Florida citrus (Singh et al., 1985) and Seth and Madin (1984) found glyphosate superior to fluazifop-butyl. However, working with fluazifop-P-butyl, Chandrasena (1989, 1991) was able to improve performance with surfactant and oil additives. In pot experiments Parker (1982) found both fluazifop-butyl and sethoxydim to have activity at least equal to that of glyphosate. These two graminicides should be of value in broad-leaved crops. Imazapyr has given longer-lasting control than glyphosate in irrigation channels (Nir, 1988).

References

Top of page

Busey P, 2003. Reduction of torpedograss (Panicum repens) canopy and rhizomes by quinclorac split applications. Weed Technology, 17(1):190-194; 9 ref.

Chandrasena JPNR, 1989. Fluazifop-butyl activity on perennial torpedograss (Panicum repens L.). Proceedings, 12th Asian-Pacific Weed Science Society Conference Taipei, Taiwan; Asian-Pacific Weed Science Society, No. 1:159-164

Chandrasena JPNR, 1990. Torpedograss (Panicum repens L.) control with lower rates of glyphosate. Tropical Pest Management, 36(4):336-342

Chandrasena JPNR, 1991. Enhancement of fluazifop-P toxicity to torpedograss (Panicum repens L.) by surfactant and oil-additive. BIOTROP Special Publication, No. 40:133-143; [a symposium on aquatic weed management held in Bogor, Indonesia, 15-17 May 1990].

Chandrasena JPNR; Dhammika WHY, 1988. Studies on the biology of Panicum repens L. 1 Comparative morphological development of three selections from different geographical localities in Sri Lanka. Tropical Pest Management, 34(3):291-297

Chon CH, 1989. Allelopathic research of subtropical vegetation in Taiwan. IV. Comparative phytotoxic nature of leachate from four subtropical grasses. Journal of Chemical Ecology, 15(7):2149-2159

Clayton WD; Renvoize SA, 1982. Flora of Tropical East Africa. Graminea (Part 3). Rotterdam, The Netherlands: A.A. Balkema, 448 pp.

Coats GE, 1974. Preliminary evaluation of asulam for torpedograss control in common bermudagrass. Proceedings 27th Annual Meeting Southern Weed Science Society., 149

Cope TA, 1982. Poaceae. In: Nasir E, Ali SI, eds. Flora of Pakistan. Kew, UK: Royal Botanic Gardens.

David PG, 1999. Response of exotics to restored hydroperiod at Dupuis Reserve, Florida. Restoration Ecology, 7(4):407-410.

FLEPPC, 2004. Invasive plant list of Florida Exotic Pest Plant Council. World wide web page at http://www.fleppc.org.

Fröman B; Persson S, 1974. An Illustrated Guide to the Grasses of Ethiopia. Assella, Ehiopia: Chilalo Awraja Development Unit.

Ghaly FM, 2002. Role of natural vegetation in improving salt affected soil in northern Egypt. Soil and Tillage Research, 64, (3-4):173-178.

Gibbs Russell GE; Watson L; Koekemoer M; Smook L; Barker NP; Anderson HM; Dellwitz MJ, 1990. Grasses of Southern Africa. Memoirs of the Botanical Survey of South Africa No 58. Pretoria, South Africa: National Botanic Grdens/ Botanical Research Institute.

Hepper FN, ed. , 1972. Flora of West Tropical Africa, Volume III (Part 2), 2nd edn. London, UK: Crown Agents.

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