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Datasheet

Cyperus rotundus (purple nutsedge)

Summary

  • Last modified
  • 22 November 2017
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Host Plant
  • Preferred Scientific Name
  • Cyperus rotundus
  • Preferred Common Name
  • purple nutsedge
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • C. rotundus has been considered as one of the world’s worst weeds. It has been reported in more than 90 countries where it grows as a weed infesting at least 52 different crops worldwide (

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Pictures

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PictureTitleCaptionCopyright
A highly variable perennial sedge: flowering stems erect, up to 60 cm tall; inflorescence a terminal, open umbel subtended by several leafy bracts.
TitleGrowth habit
CaptionA highly variable perennial sedge: flowering stems erect, up to 60 cm tall; inflorescence a terminal, open umbel subtended by several leafy bracts.
CopyrightDennis S. Hill
A highly variable perennial sedge: flowering stems erect, up to 60 cm tall; inflorescence a terminal, open umbel subtended by several leafy bracts.
Growth habitA highly variable perennial sedge: flowering stems erect, up to 60 cm tall; inflorescence a terminal, open umbel subtended by several leafy bracts.Dennis S. Hill
Roots fibrous; tubers dark brown to black, irregularly shaped, 1-2 cm long when fully grown. Each tuber has an apical bud and several lateral buds.
TitleWhole plants
CaptionRoots fibrous; tubers dark brown to black, irregularly shaped, 1-2 cm long when fully grown. Each tuber has an apical bud and several lateral buds.
Copyright©S.D. Sawant
Roots fibrous; tubers dark brown to black, irregularly shaped, 1-2 cm long when fully grown. Each tuber has an apical bud and several lateral buds.
Whole plantsRoots fibrous; tubers dark brown to black, irregularly shaped, 1-2 cm long when fully grown. Each tuber has an apical bud and several lateral buds.©S.D. Sawant
Several unequal rays, 2-6 cm long, support 3-8 reddish-brown to purplish-brown, flattened spikelets, 1-2 cm long and 2 mm wide, each with up to 30 glumes.
TitleInflorescence
CaptionSeveral unequal rays, 2-6 cm long, support 3-8 reddish-brown to purplish-brown, flattened spikelets, 1-2 cm long and 2 mm wide, each with up to 30 glumes.
Copyright©S.D. Sawant
Several unequal rays, 2-6 cm long, support 3-8 reddish-brown to purplish-brown, flattened spikelets, 1-2 cm long and 2 mm wide, each with up to 30 glumes.
InflorescenceSeveral unequal rays, 2-6 cm long, support 3-8 reddish-brown to purplish-brown, flattened spikelets, 1-2 cm long and 2 mm wide, each with up to 30 glumes.©S.D. Sawant
a, Spikelet; b, flower; c, nut.
TitleWhole plant - line drawing
Captiona, Spikelet; b, flower; c, nut.
CopyrightSEAMEO-BIOTROP
a, Spikelet; b, flower; c, nut.
Whole plant - line drawinga, Spikelet; b, flower; c, nut.SEAMEO-BIOTROP
Nutgrass spreading in the field: branched chains of rhizomes and tubers become an extensive underground network.
TitleGrowth habit
CaptionNutgrass spreading in the field: branched chains of rhizomes and tubers become an extensive underground network.
CopyrightBill Parsons
Nutgrass spreading in the field: branched chains of rhizomes and tubers become an extensive underground network.
Growth habitNutgrass spreading in the field: branched chains of rhizomes and tubers become an extensive underground network.Bill Parsons
C. rotundus growing between vines: much of its economic importance is due to its capacity to remove nutrients from the soil and store them in its tubers, making them unavailable to crops.
TitleWeed competition
CaptionC. rotundus growing between vines: much of its economic importance is due to its capacity to remove nutrients from the soil and store them in its tubers, making them unavailable to crops.
CopyrightBill Parsons
C. rotundus growing between vines: much of its economic importance is due to its capacity to remove nutrients from the soil and store them in its tubers, making them unavailable to crops.
Weed competitionC. rotundus growing between vines: much of its economic importance is due to its capacity to remove nutrients from the soil and store them in its tubers, making them unavailable to crops.Bill Parsons
C. rotundus habit of flowering plant with young plantlets.

Reproduced from the series 'Plant Resources of South-East Asia', Vols 1-20 (1989-2000), by kind permission of the PROSEA Foundation, Bogor, Indonesia.
TitleWhole plant - line drawing
CaptionC. rotundus habit of flowering plant with young plantlets. Reproduced from the series 'Plant Resources of South-East Asia', Vols 1-20 (1989-2000), by kind permission of the PROSEA Foundation, Bogor, Indonesia.
CopyrightPROSEA Foundation
C. rotundus habit of flowering plant with young plantlets.

Reproduced from the series 'Plant Resources of South-East Asia', Vols 1-20 (1989-2000), by kind permission of the PROSEA Foundation, Bogor, Indonesia.
Whole plant - line drawingC. rotundus habit of flowering plant with young plantlets. Reproduced from the series 'Plant Resources of South-East Asia', Vols 1-20 (1989-2000), by kind permission of the PROSEA Foundation, Bogor, Indonesia. PROSEA Foundation

Identity

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Preferred Scientific Name

  • Cyperus rotundus L.

Preferred Common Name

  • purple nutsedge

Other Scientific Names

  • Chlorocyperus rotundus (L.) Palla
  • Chorocyperus salaamensis Palla
  • Cyperus agresti Willd. ex Spreng. & Link
  • Cyperus arabicus Ehrenb. ex Boeck.
  • Cyperus bicolor Vahl
  • Cyperus bifax C.B.Clarke
  • Cyperus bulbosotoloniferus Mig.
  • Cyperus comosus Sm.
  • Cyperus disruptus C.B.Clarke
  • Cyperus herbicavus Melliss
  • Cyperus hexastachyos Rottb.
  • Cyperus hildra Poir.
  • Cyperus hydra Michx.
  • Cyperus laevissimus Steud.
  • Cyperus leptostachyus Griff.
  • Cyperus merkeri C.B.Clarke
  • Cyperus micreilema Steud.
  • Cyperus nubicus C.B.Clarke
  • Cyperus ochreoides Steud.
  • Cyperus oliganthus Gand.
  • Cyperus olivaris O.Targ.Tozz.
  • Cyperus platystachys Cherm.
  • Cyperus procerulus Nees
  • Cyperus pseudovariegatus Boeck.
  • Cyperus purpureovariegatus Boeck.
  • Cyperus radicosus Sm.
  • Cyperus rudioi Boeckeler
  • Cyperus taylorii C.B.Clarke
  • Cyperus tetrastachyos Desf.
  • Cyperus tuberosus Rottb.
  • Cyperus weinlandii Kuk.
  • Cyperus yoshinagae Ohwi
  • Pycreus rotundus (L.) Hayek
  • Schoenus tuberosus Burm.f.

International Common Names

  • English: coco grass; java grass; nut sedge; nutgrass; purple nut-grass; purple nut-sedge; red grass; red nut sedge; water grass
  • Spanish: castanuela; cebolleta; chufa; chufila; cipero; contra yerba; corocilla; cortadera; jonquillo; juncea; lengua de gallina; negrillo; paraquita; pasto bolita; totorilla
  • French: souchet an forme d'olive
  • Chinese: xiang fu zi
  • Portuguese: alho-bravo; capim-alho; capim-dandá; junca de conta; tiririca; tiririca-vermelha

Local Common Names

  • Bangladesh: motha
  • Brazil: alho; alho-bravo; capim-alho; capim-dandá; junca; junca-aromática; tiririca; tiririca-comum; tiririca-vermelha; tres-quinas
  • Cambodia: smao kravanh chrouk
  • Chile: almendra de tierra; chufa; coquillo
  • Colombia: cortadera
  • Cuba: ajo cimarron; basarillo; caramana; cebolleta; cebolleta de la provincia; cebollin; coquito; corojillo; corojito; juncia redonda; macaguita; yerba del rinon
  • Dominican Republic: afio; caramaná; coquillo; junquillo de sabana; ronquillo; saqui-saco
  • Egypt: seid
  • Fiji: soronakabani; vucesa
  • Germany: Apotheker-Cypergras; Asiatisches-Cypergras; Runde-Cypergras; Runde-Zyperwurzel
  • Greece: kupere
  • India: deela; gantola; korai; nagar motha
  • Indonesia: teki
  • Iraq: oyarslan
  • Italy: cipero orientale; cipero rotondo; stancia rotonda
  • Jamaica: nut-grass
  • Japan: hamasuge
  • Kenya: moikut
  • Malaysia: rumput haliya hitan
  • Mexico: cebollin; pimientillo
  • Myanmar: monhnyin-bin
  • Pakistan: notha
  • Peru: coco; coquillo; coquito
  • Philippines: balisanga; boto-botonis; mala-apulid; mutha; sur-sur
  • Puerto Rico: coqui; coquillo
  • Samoa: mumuta
  • South Africa: rooiuintjie; uintjie
  • Sri Lanka: kalanthi
  • Suriname: adroe
  • Taiwan: hsiang-fu-tzu
  • Thailand: haew moo; ya-haeo-mu
  • Tonga: pakopako
  • Turkey: topalak

EPPO code

  • CYPRO (Cyperus rotundus)

Summary of Invasiveness

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C. rotundus has been considered as one of the world’s worst weeds. It has been reported in more than 90 countries where it grows as a weed infesting at least 52 different crops worldwide (Holm et al. 1977). It grows in all types of soils and can also survive high temperatures. C. rotundus can be found in a wide variety of habitats including cultivated fields, waste areas, roadsides, pastures, riverbanks, sandbanks, irrigation channels, river and stream shores and natural areas.  It is considered a headache for gardeners and farmers because of its insidious and rapid growth and its herbicide tolerance. C. rotundus produces an extensive system of underground tubers from which they can regenerate and consequently is very difficult to control once it is established (USDA-NRCS, 2014). 

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Cyperales
  •                         Family: Cyperaceae
  •                             Genus: Cyperus
  •                                 Species: Cyperus rotundus

Notes on Taxonomy and Nomenclature

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Cyperus rotundus is the universally accepted name. Several subspecies are described though they are rarely recognized in literature on the weed. Haines and Lye (1983) describe four subspecies from East Africa, rotundus, merkeri, taylorii and tuberosus, but this is not accepted by all authors. Hutchinson et al. (1972), for example, recognize C. tuberosus Rottb. as a species, not as a subspecies of C. rotundus. Variations in C. rotundus have led to descriptions of ecotypes, such as those from India based on glume colour (Ranade and Burns, 1925), morphotypes (Wills, 1998) and chemotypes, such as those from Japan and China based on sesquiterpenes in tubers (Komai and Ueki, 1981).

Description

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C. rotundus is a highly variable perennial sedge. Flowering stems are erect, up to 60 cm tall, 3-sided, smooth with swollen bases (basal bulbs). The leaves have a distinct midrib, are linear, usually shorter than the flowering stem, up to 7 mm wide and emerge from a sheath around the shoot base. The inflorescence is a terminal, open umbel subtended by several leafy bracts. Several unequal rays, 2-6 cm long, support 3-8 reddish-brown to purplish-brown, flattened spikelets, 1-2 cm long and 2 mm wide, each with up to 30 glumes, 3.5-4 mm long. Roots are fibrous. Rhizomes are wiry, dark and persistent, connecting a network of daughter shoots and tubers. The tubers are dark brown to black, irregularly shaped and 1-2 cm long when fully grown. Each tuber has an apical bud and several lateral buds. The fruit (often, but erroneously, known as the seed) is a 3-angled achene, 1.5 mm long, dark brown or black.

Plant Type

Top of page Annual
Grass / sedge
Perennial
Seed propagated
Vegetatively propagated

Distribution

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C. rotundus is thought by some authorities to have originated in India but others believe that the origins are more widespread, including northern and eastern Australia (Parsons and Cuthbertson, 1992). At present, the most widely accepted distribution range considers this species as native to the tropical and subtropical Old World, principally Africa and Eurasia (Govaerts, 2014; USDA-ARS, 2014). Holm et al. (1977) have recorded its occurrence in 92 countries but its presence can be assumed in all countries of the tropics and subtropics.

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

AfghanistanPresentNativeHolm et al., 1979; Govaerts, 2014
BahrainPresentNativeGovaerts, 2014
BangladeshPresentNativeHolm et al., 1979; Govaerts, 2014
BhutanPresentNativeParker, 1992; Govaerts, 2014
Brunei DarussalamPresent Invasive Moody, 1989; Waterhouse, 1993Listed as both native and introduced
CambodiaPresent Invasive Holm et al., 1979; Waterhouse, 1993Listed as both native and introduced
Chagos ArchipelagoPresentIntroduced Invasive Whistler, 1996
China
-AnhuiPresentNativeFlora of China Editorial Committee, 2014Weed
-ChongqingPresentNativeFlora of China Editorial Committee, 2014Weed
-FujianPresentNativeFlora of China Editorial Committee, 2014Weed
-GansuPresentNativeFlora of China Editorial Committee, 2014Weed
-GuangdongPresentNativeZhirong, 1990; Flora of China Editorial Committee, 2014Weed
-GuangxiPresentNativeFlora of China Editorial Committee, 2014Weed
-GuizhouPresentNativeFlora of China Editorial Committee, 2014Weed
-HainanPresentNativeFlora of China Editorial Committee, 2014Weed
-HebeiPresentNativeZhirong, 1990; Flora of China Editorial Committee, 2014Weed
-HenanPresentNativeFlora of China Editorial Committee, 2014Weed
-HubeiPresentNativeFlora of China Editorial Committee, 2014Weed
-HunanPresentNativeFlora of China Editorial Committee, 2014Weed
-JiangsuPresentNativeGuang, 1996; Flora of China Editorial Committee, 2014Weed
-JiangxiPresentNativeFlora of China Editorial Committee, 2014Weed
-LiaoningPresentNativeFlora of China Editorial Committee, 2014Weed
-ShaanxiPresentNativeZhirong, 1990; Flora of China Editorial Committee, 2014Weed
-ShandongPresentNativeFlora of China Editorial Committee, 2014Weed
-ShanxiPresentNativeFlora of China Editorial Committee, 2014Weed
-SichuanPresentNativeFlora of China Editorial Committee, 2014Weed
-TibetPresentNativeFlora of China Editorial Committee, 2014Weed
-YunnanPresentNativeZhirong, 1990; Flora of China Editorial Committee, 2014Weed
-ZhejiangPresentNativeFlora of China Editorial Committee, 2014Weed
Christmas Island (Indian Ocean)PresentIntroduced Invasive Swarbrick, 1997
Cocos IslandsPresentNativeGovaerts, 2014
IndiaPresentHolm et al., 1979
-Andaman and Nicobar IslandsPresentNativeGovaerts, 2014
-Arunachal PradeshPresentNativeGovaerts, 2014
-AssamPresentNativeGovaerts, 2014
-Jammu and KashmirPresentIntroduced Invasive Khuroo et al., 2007Listed as invasive in Kashmir
-SikkimPresentNativeGovaerts, 2014
IndonesiaPresentHolm et al., 1979; Waterhouse, 1993
-JavaPresentNativeGovaerts, 2014
-KalimantanPresentNativeGovaerts, 2014
-MoluccasPresentNativeGovaerts, 2014
-Nusa TenggaraPresentNativeGovaerts, 2014
-SulawesiPresentNativeGovaerts, 2014
-SumatraPresentNativeGovaerts, 2014
IranPresentNativeHolm et al., 1979; Govaerts, 2014
IraqPresentNativeHolm et al., 1979; Govaerts, 2014
IsraelPresentNativeHolm et al., 1979; Govaerts, 2014
JapanPresentNativeGovaerts, 2014
-HonshuPresentNumata et al., 1975
-KyushuPresentNumata et al., 1975
-Ryukyu ArchipelagoPresentNumata et al., 1975
-ShikokuPresentNumata et al., 1975
JordanPresentHolm et al., 1979
KazakhstanPresentNativeGovaerts, 2014
Korea, DPRPresentNativeHolm et al., 1979; Govaerts, 2014
Korea, Republic ofPresentNativeHolm et al., 1979; Govaerts, 2014
KyrgyzstanPresentNativeGovaerts, 2014
LaosPresentMoody, 1989; Waterhouse, 1993
LebanonPresentNativeHolm et al., 1979; Govaerts, 2014
MalaysiaPresentHolm et al., 1979; Waterhouse, 1993
-Peninsular MalaysiaPresentNativeGovaerts, 2014
-SabahPresentNativeGovaerts, 2014
-SarawakPresentNativeHolm et al., 1979; Govaerts, 2014
MaldivesPresentIntroducedGovaerts, 2014
MyanmarPresentMoody, 1989; Waterhouse, 1993; Govaerts, 2014
NepalPresentNativeMoody, 1989; Govaerts, 2014
OmanPresentNativeGovaerts, 2014
PakistanPresentNativeHolm et al., 1979; Govaerts, 2014
PhilippinesPresentHolm et al., 1979; Waterhouse, 1993
Saudi ArabiaPresentChaudhary and Akram, 1987; Govaerts, 2014
SingaporePresentIntroduced Invasive Waterhouse, 1993
Sri LankaPresentNativeHolm et al., 1979; Govaerts, 2014
TaiwanPresentNativeHolm et al., 1979; Govaerts, 2014
ThailandPresent Invasive Holm et al., 1979; Waterhouse, 1993Listed as both native and introduced
TurkeyPresentNativeHolm et al., 1979; Govaerts, 2014
TurkmenistanPresentNativeGovaerts, 2014
UzbekistanPresentNativeGovaerts, 2014
VietnamPresent Invasive Holm et al., 1979; Waterhouse, 1993Listed as both native and introduced
YemenPresentChaudhary and Revri, 1983; Govaerts, 2014

Africa

AldabraPresentNativeGovaerts, 2014
AlgeriaPresentNativeGovaerts, 2014
AngolaPresentHolm et al., 1979; Govaerts, 2014
BeninPresentNativeGovaerts, 2014
BotswanaPresentNativeGovaerts, 2014
Burkina FasoPresentHutchinson et al., 1972; Govaerts, 2014
BurundiPresentNativeGovaerts, 2014
CameroonPresentHolm et al., 1979; Govaerts, 2014
Cape VerdePresentNativeGovaerts, 2014
Central African RepublicPresentNativeGovaerts, 2014
ChadPresentHolm et al., 1979; Govaerts, 2014
ComorosPresentNativeUSDA-ARS, 2014
CongoPresentHolm et al., 1979; Govaerts, 2014
Congo Democratic RepublicPresentNativeGovaerts, 2014
Côte d'IvoirePresentHolm et al., 1979; Govaerts, 2014
DjiboutiPresentNativeGovaerts, 2014
EgyptPresentHolm et al., 1979; Govaerts, 2014
Equatorial GuineaPresentNativeGovaerts, 2014
EritreaPresentNativeGovaerts, 2014
EthiopiaPresentHolm et al., 1979; Govaerts, 2014
GabonPresentHolm et al., 1979; Govaerts, 2014
GambiaPresentNativeGovaerts, 2014
GhanaPresentHolm et al., 1979; Govaerts, 2014
GuineaPresentHolm et al., 1979; Govaerts, 2014
Guinea-BissauPresentNativeGovaerts, 2014
KenyaPresentHolm et al., 1979; Govaerts, 2014
LibyaPresentNativeGovaerts, 2014
MadagascarPresentHolm et al., 1979; Govaerts, 2014
MalawiPresentNativeGovaerts, 2014
MaliPresentHolm et al., 1979; Govaerts, 2014
MauritaniaPresentHolm et al., 1979; Govaerts, 2014
MauritiusPresentHolm et al., 1979; Govaerts, 2014
MoroccoPresentNativeHolm et al., 1979; Govaerts, 2014
MozambiquePresentHolm et al., 1979; Govaerts, 2014
NigerPresentHolm et al., 1979; Govaerts, 2014
NigeriaPresentHolm et al., 1979; Govaerts, 2014
RéunionPresentNativeGovaerts, 2014
Rodriguez IslandPresentNativeGovaerts, 2014
RwandaPresentNativeGovaerts, 2014
Saint HelenaPresentNativeGovaerts, 2014
SenegalPresentHolm et al., 1979; Govaerts, 2014
SeychellesPresentRobertson, 1989; Govaerts, 2014
Sierra LeonePresentHutchinson et al., 1972; Govaerts, 2014
SomaliaPresentNativeGovaerts, 2014
South AfricaPresentHolm et al., 1979; Govaerts, 2014
Spain
-Canary IslandsPresentGovaerts, 2014
SudanPresentHolm et al., 1979; Govaerts, 2014
SwazilandPresentHolm et al., 1979; Govaerts, 2014
TanzaniaPresentHolm et al., 1979; Govaerts, 2014
TogoPresentNativeGovaerts, 2014
TunisiaPresentHolm et al., 1979; Govaerts, 2014
UgandaPresentHolm et al., 1979; Govaerts, 2014
Western SaharaPresentNativeGovaerts, 2014
ZambiaPresentHolm et al., 1979; Govaerts, 2014
ZimbabwePresentHolm et al., 1979; Rambakudzibga, 1999; Govaerts, 2014

North America

BermudaPresentHolm et al., 1979
MexicoPresentIntroduced Invasive Holm et al., 1979; Vibrans, 2009Weed
USA
-AlabamaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-ArizonaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-ArkansasPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-CaliforniaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-DelawarePresentIntroducedUSDA-NRCS, 2014
-District of ColumbiaPresentIntroducedUSDA-NRCS, 2014
-FloridaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-GeorgiaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-HawaiiPresentIntroduced Invasive Wagner et al., 1999
-KentuckyPresentIntroducedUSDA-NRCS, 2014
-LouisianaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-MarylandPresentIntroducedUSDA-NRCS, 2014
-MinnesotaPresentIntroducedUSDA-NRCS, 2014
-MississippiPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-MissouriPresentIntroducedUSDA-NRCS, 2014
-New JerseyPresentIntroducedUSDA-NRCS, 2014
-New YorkPresentIntroducedUSDA-NRCS, 2014
-North CarolinaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-OklahomaPresentIntroducedUSDA-NRCS, 2014
-OregonPresentIntroduced Invasive USDA-NRCS, 2014Quarantine weed
-PennsylvaniaPresentIntroducedUSDA-NRCS, 2014
-South CarolinaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-TennesseePresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-TexasPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014
-VirginiaPresentLorenzi and Jeffery, 1987; USDA-NRCS, 2014

Central America and Caribbean

AnguillaPresentIntroducedGovaerts, 2014Naturalised
ArubaPresentIntroducedGovaerts, 2014Naturalised
BahamasPresentIntroducedGovaerts, 2014Naturalised
BarbadosPresentIntroducedGovaerts, 2014Naturalised
BelizePresentIntroducedGovaerts, 2014Naturalised
British Virgin IslandsPresentIntroduced Invasive Acevedo-Rodriguez and Strong, 2012
Cayman IslandsPresentIntroducedGovaerts, 2014Naturalised
Costa RicaPresentHolm et al., 1979; Gómez-Laurito, 2003
CubaPresentHolm et al., 1979; Govaerts, 2014
CuraçaoPresentIntroducedAcevedo-Rodriguez and Strong, 2012
DominicaPresentIntroducedGovaerts, 2014Naturalised
Dominican RepublicPresentHolm et al., 1979; Acevedo-Rodriguez and Strong, 2012
El SalvadorPresentIntroducedGovaerts, 2014Naturalised
GuadeloupePresentIntroducedGovaerts, 2014Naturalised
GuatemalaPresentHolm et al., 1979; Govaerts, 2014
HaitiPresentIntroducedAcevedo-Rodriguez and Strong, 2012
HondurasPresentHolm et al., 1979; Govaerts, 2014
JamaicaPresentHolm et al., 1979; Govaerts, 2014
MartiniquePresentIntroducedGovaerts, 2014Naturalised
Netherlands AntillesPresentIntroducedGovaerts, 2014Naturalised
NicaraguaPresentHolm et al., 1979; Govaerts, 2014
PanamaPresentHolm et al., 1979; Govaerts, 2014
Puerto RicoPresentHolm et al., 1979; Acevedo-Rodriguez and Strong, 2012
Saint LuciaPresentIntroducedGovaerts, 2014Naturalised, very common
Trinidad and TobagoPresentHolm et al., 1979; Govaerts, 2014
United States Virgin IslandsPresentIntroduced Invasive Acevedo-Rodriguez and Strong, 2012

South America

ArgentinaPresentHolm et al., 1979; Govaerts, 2014
BoliviaPresentHolm et al., 1979; Govaerts, 2014
Brazil
-AcrePresentLorenzi, 1982
-AlagoasPresentLorenzi, 1982
-AmazonasPresentLorenzi, 1982
-BahiaPresentLorenzi, 1982
-CearaPresentLorenzi, 1982
-Espirito SantoPresentLorenzi, 1982; I3N-Brasil, 2014
-Fernando de NoronhaPresentLorenzi, 1982
-GoiasPresentLorenzi, 1982
-MaranhaoPresentLorenzi, 1982
-Mato GrossoPresentLorenzi, 1982
-Mato Grosso do SulPresentLorenzi, 1982
-Minas GeraisPresentLorenzi, 1982; I3N-Brasil, 2014
-ParaPresentLorenzi, 1982
-ParaibaPresentLorenzi, 1982; I3N-Brasil, 2014
-ParanaPresentLorenzi, 1982; I3N-Brasil, 2014
-PernambucoPresentLorenzi, 1982
-PiauiPresentLorenzi, 1982
-Rio de JaneiroPresentLorenzi, 1982
-Rio Grande do NortePresentLorenzi, 1982
-Rio Grande do SulPresentLorenzi, 1982
-RondoniaPresentLorenzi, 1982
-Santa CatarinaPresentLorenzi, 1982
-Sao PauloPresentLorenzi, 1982
-SergipePresentLorenzi, 1982
ChilePresentHolm et al., 1977; Holm et al., 1979
ColombiaPresentHolm et al., 1977; Holm et al., 1979
EcuadorPresentIntroducedGovaerts, 2014
-Galapagos IslandsPresentIntroduced Invasive Govaerts, 2014
French GuianaPresentIntroducedGovaerts, 2014Naturalised
GuyanaPresentIntroducedGovaerts, 2014Naturalised
ParaguayPresentHolm et al., 1977; Holm et al., 1979
PeruPresentHolm et al., 1979; Govaerts, 2014
SurinamePresentHolm et al., 1979; Govaerts, 2014
UruguayPresentHolm et al., 1977; Holm et al., 1979
VenezuelaPresentHolm et al., 1979; Govaerts, 2014

Europe

AlbaniaPresentde Filippes, 1980; Govaerts, 2014
AustriaPresentIntroducedDAISIE, 2014
BelgiumPresentIntroducedDAISIE, 2014
BulgariaPresentde Filippes, 1980; Govaerts, 2014
CyprusPresentNativeGovaerts, 2014
Czech RepublicPresentIntroducedDAISIE, 2014
FrancePresentHolm et al., 1979; Govaerts, 2014
-CorsicaPresentde Filippes, 1980; Govaerts, 2014
GreecePresentHolm et al., 1979; Govaerts, 2014
-CretePresentde Filippes, 1980
ItalyPresentHolm et al., 1979
-SardiniaPresentde Filippes, 1980
-SicilyPresentde Filippes, 1980
PortugalPresentHolm et al., 1979; Govaerts, 2014
-AzoresPresentde Filippes, 1980; DAISIE, 2014
-MadeiraPresentGovaerts, 2014
RomaniaPresentGovaerts, 2014
Russian FederationPresentNativeGovaerts, 2014
SpainPresentHolm et al., 1979; DAISIE, 2014
-Balearic IslandsPresentde Filippes, 1980; Govaerts, 2014
SwitzerlandPresentde Filippes, 1980; DAISIE, 2014
Yugoslavia (former)PresentHolm et al., 1979; Govaerts, 2014

Oceania

American SamoaPresentIntroduced Invasive Space and Flynn, 2000
AustraliaPresentde Filippes, 1980
-Australian Northern TerritoryPresentParsons and Cuthbertson, 1992; USDA-ARS, 2014
-New South WalesPresentParsons and Cuthbertson, 1992; USDA-ARS, 2014
-QueenslandPresentParsons and Cuthbertson, 1992; USDA-ARS, 2014
-South AustraliaPresentParsons and Cuthbertson, 1992; USDA-ARS, 2014
-VictoriaPresentParsons and Cuthbertson, 1992
-Western AustraliaPresentParsons and Cuthbertson, 1992; Govaerts, 2014
Cook IslandsPresentIntroduced Invasive Space and Flynn, 2002
FijiPresentHolm et al., 1979; Smith, 1979
French PolynesiaPresentIntroduced Invasive Florence et al., 2013
GuamPresentIntroduced Invasive Stone, 1970
KiribatiPresentIntroduced Invasive Space et al., 2004
Marshall IslandsPresentIntroduced Invasive Fosberg et al., 1987
Micronesia, Federated states ofPresentIntroduced Invasive Herrera et al., 2010
NauruPresentIntroduced Invasive Fosberg et al., 1987
New CaledoniaPresentIntroduced Invasive MacKee, 1994; Govaerts, 2014
New ZealandPresentHolm et al., 1979; Govaerts, 2014
NiuePresentIntroduced Invasive Whistler, 1988
Norfolk IslandPresentIntroduced Invasive Orchard, 1994
Northern Mariana IslandsPresentGovaerts, 2014
PalauPresentIntroduced Invasive Space et al., 2003
Papua New GuineaPresentHenty and Pritchard, 1975; Govaerts, 2014
SamoaPresentSauerborn and Sauerborn, 1984; Space and Flynn, 2002
Solomon IslandsPresent Invasive Shine et al., 2003
TongaPresentWhistler, 1983; Space and Flynn, 2001
US Minor Outlying IslandsPresentIntroduced Invasive Wagner et al., 1999
VanuatuPresentIntroduced Invasive Shine et al., 2003
Wake IslandPresentIntroduced Invasive Fosberg et al., 1987
Wallis and Futuna IslandsPresentIntroduced Invasive Meyer, 2007

History of Introduction and Spread

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C. rotundus is thought to have originated in Southeastern Asia and from there it was spread to the rest of the world during the last 2000 years. It has been used by ancient people in Africa (i.e., Nile Valley), China, and eastern Mediterranean as food, perfume, and medicine for centuries. For example, this species first appeared in a Chinese medicine book around 500 AD (Negbi, 1992). The most likely method of introduction of this species into new habitat could be related to human activities. Seeds, tubers, and rhizomes may have been introduced as a contaminant in soil, mud, agricultural machinery, fodder, pastures, and crop seeds (Holm et al., 1977). In the United States, it is considered that it was unintentionally introduced during the 1800s (USDA-NRCS, 2014). Since the 1880s, this species appears in collections made on islands in the West Indies (US National Herbarium).

Risk of Introduction

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The risk of introduction of C. rotundus is very high. This species is highly mobile and highly adaptable to different environments. It also benefits from human-related activities. Consequently it is considered one of the “world’s worst weeds” with the potential to negatively impact agriculture and natural ecosystems by displacing native plants or by changing the availability of food or shelter for native animals. This rapidly growing plant can quickly form dense colonies due to its ability to produce an extensive system of rhizomes and tubers. Thus, its likelihood of invading new habitats remains high.

Habitat

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C. rotundus is widespread in the tropics and subtropics, growing in almost every soil type, altitude, humidity, soil moisture and pH, but not in soils with a high salt content (Holm et al., 1977). Its range at increasing latitudes and altitudes is limited by cold temperatures. It occurs in cultivated fields, fallow land, neglected areas, road and rail sides, banks of irrigation canals and streams, edges of woods and sand dunes. Generally, it does not tolerate shade.

Habitat List

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CategoryHabitatPresenceStatus
Freshwater
Irrigation channels Present, no further details Harmful (pest or invasive)
Irrigation channels Present, no further details Natural
Rivers / streams Present, no further details Harmful (pest or invasive)
Rivers / streams Present, no further details Natural
Littoral
Coastal areas Present, no further details Harmful (pest or invasive)
Coastal areas Present, no further details Natural
Terrestrial-managed
Cultivated / agricultural land Present, no further details Harmful (pest or invasive)
Cultivated / agricultural land Present, no further details Natural
Disturbed areas Present, no further details Harmful (pest or invasive)
Disturbed areas Present, no further details Natural
Managed forests, plantations and orchards Present, no further details Harmful (pest or invasive)
Managed forests, plantations and orchards Present, no further details Natural
Managed grasslands (grazing systems) Present, no further details Harmful (pest or invasive)
Managed grasslands (grazing systems) Present, no further details Natural
Rail / roadsides Present, no further details Harmful (pest or invasive)
Rail / roadsides Present, no further details Natural
Urban / peri-urban areas Present, no further details Harmful (pest or invasive)
Urban / peri-urban areas Present, no further details Natural
Terrestrial-natural/semi-natural
Natural grasslands Present, no further details Harmful (pest or invasive)
Natural grasslands Present, no further details Natural
Riverbanks Present, no further details Harmful (pest or invasive)
Riverbanks Present, no further details Natural
Wetlands Present, no further details Harmful (pest or invasive)
Wetlands Present, no further details Natural

Hosts/Species Affected

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Holm et al. (1977) state that C. rotundus has been reported as a weed of 52 crops including vegetables and ornamentals. Some examples are cited in the list of hosts but, in reality, this weed can occur in virtually all crops grown within its range.

Host Plants and Other Plants Affected

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Plant nameFamilyContext
Agave sisalana (sisal hemp)AgavaceaeOther
Allium cepa (onion)LiliaceaeOther
Arachis hypogaea (groundnut)FabaceaeMain
Camellia sinensis (tea)TheaceaeOther
Capsicum (peppers)SolanaceaeOther
Capsicum annuum (bell pepper)SolanaceaeOther
CitrusRutaceaeMain
Cocos nucifera (coconut)ArecaceaeOther
Coffea (coffee)RubiaceaeMain
Corchorus olitorius (jute)TiliaceaeMain
Glycine max (soyabean)FabaceaeOther
Gossypium (cotton)MalvaceaeMain
Oryza sativa (rice)PoaceaeMain
Saccharum officinarum (sugarcane)PoaceaeMain
Solanum lycopersicum (tomato)SolanaceaeOther
Sorghum bicolor (sorghum)PoaceaeOther
Syzygium aromaticum (clove)MyrtaceaeOther
Triticum (wheat)PoaceaeOther
Triticum aestivum (wheat)PoaceaeOther
Zea mays (maize)PoaceaeMain

Biology and Ecology

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Descriptions of the biology and ecology of C. rotundus can be found in Ranade and Burns (1925), Holm et al. (1977), Mercado (1979), Jha and Sen (1985) and Parsons and Cuthbertson (1992).

The typical life cycle of C. rotundus starts with growth of the apical bud of a tuber. As the tuber shoot extends, it swells to form a basal bulb (sometimes called a corm), usually near the soil surface, from which an aerial shoot and roots are produced. Up to three, or slightly more, rhizomes grow out of the basal bulb and produce tubers or new basal bulbs and daughter shoots. Rhizomes from the daughter shoots produce tubers from which new rhizomes and tubers develop. Eventually, branched chains of rhizomes and tubers become an extensive, underground network. Meanwhile, the new shoots grow and produce flowers within 3-8 weeks of emergence if stimulated by short photoperiods of 6-8 hours. Most seeds of C. rotundus are not viable; germination seldom averages more than 1-5 % (Holm et al., 1977) though this may be significant when seed production can exceed 100 million/ha in a single year.

Tuber dormancy is high on undisturbed sites and may last for at least 7 years (Parsons and Cuthbertson, 1992). Fragmentation of the rhizome/tuber network by cultivation breaks the dormancy imposed by a growing tuber on others in the same chain. Hence, cultivation stimulates the growth of C. rotundus. Large populations of shoots and tubers can develop from a single tuber; as many as 600 plants have been produced in a single year. Horowitz (1972) has reported that 2-3 million tubers per hectare per week can be produced during active growing periods, yielding 30-40 million tubers/ha. Forty tonnes of underground organs have been produced on 1 hectare in a year, giving C. rotundus a phenomenal capacity for vegetative reproduction. Most tubers are found in the upper 15 cm of soil but they can grow down to 30 cm or more in favourable conditions. Neeser et al. (1997) found that a tuber population has a half-life of 16 months and a predicted longevity (99% mortality) of 42 months.

C. rotundus has C4 metabolism which supposedly makes it increasingly competitive when temperatures and light intensity rise (Black et al., 1969). It has low tolerance of shade, a property that can be exploited in controlling this weed by crops with dense canopies (Rambakudzibga, 1999). Temperature has a marked effect on the germination of tubers. Sprouting has been reported at temperatures of 13-43°C but the range varies with biotype. Desiccation kills tubers but the duration and temperature of the drying period affects this process. The critical moisture level for tuber germination seems to be in the region of 11.5-15% (Jha and Sen, 1985).

Dispersal of C. rotundus occurs when tubers are moved by tillage equipment or other farm machinery. Flood waters may also carry the tubers. Contaminated soil in nursery stock is an avoidable but common method of dispersal. Under natural conditions, a population of C. rotundus extends its boundary by a few metres in a year. Spread by seed is generally regarded as being unimportant.

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Ascochyta cypericola Pathogen
Athesapeuta cyperi Herbivore Stems
Bactra minima Herbivore Stems
Bactra phaeopsis Herbivore
Bactra venosana Herbivore
Bactra verutana Herbivore
Balansia cyperi Pathogen
Belonolaimus longicaudatus Parasite
Cercospora caricis Pathogen
Chaetococcus australis Herbivore
Cintractia limitata Pathogen
Cochliobolus tuberculatus Pathogen
Dactylaria higginsii Pathogen
Duosporium cyperi Pathogen
Fusarium oxysporum Pathogen Uttar Pradesh
Phytophthora cyperi Pathogen
Puccinia canaliculata Pathogen
Puccinia conclusa Pathogen
Puccinia philippinensis Pathogen
Sipha maydis Herbivore

Notes on Natural Enemies

Top of page See section on Biological Control.

Means of Movement and Dispersal

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Natural Dispersal (non-biotic)

Tubers of C. rotundus can be moved by water from the banks of drainage and irrigation channels or by the flooding of fields.

Seedborne Spread

Spread of C. rotundus by seed is generally considered to be unimportant.

Agricultural Practices

Dispersal of C. rotundus occurs when tubers are moved by tillage equipment or other farm machinery. Tubers and, indeed, living shoots can be dispersed in soil attached to transplanted material, such as trees taken from a nursery.

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Soil, sand and gravelSoil attached to the roots of transplanted material, e.g. tree nursery stock Yes

Plant Trade

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Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Growing medium accompanying plants roots Yes Pest or symptoms usually visible to the naked eye

Economic Impact

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In their survey of the world's weeds, Holm et al. (1977) deduced that C. rotundus was the worst, based on its occurrence in 52 crops in 92 countries and its capacity to cause substantial yield losses. In a later publication (Holm et al., 1979) it was listed as a 'serious' or 'principal' weed in no less than 70 countries, substantially more than any other species. Losses are caused largely as a result of competition for nutrients (for example, Rochecouste, 1956; Bhardwaj and Verma, 1968) and the competitive effects can, to some degree, be counteracted by adding extra fertilizer, especially nitrogen (Horowitz, 1973a, b). In other cases, however, additional nitrogen may exaggerate the losses, for example, in upland rice (Okafor and de Datta, 1976), radish (Santos et al., 1998) and pepper (Morales-Payan et al., 1998). It is presumed that in these cases the extra vigour of the weed in a relatively low growing crop causes competition for light. Competition for water can also be important, as shown in Phaseolus bean, when yields were reduced by 80% in a dry season but by only 50% in a wet season (William, 1973). Additionally there is evidence for an allelopathic effect that cannot be reversed even under optimal conditions of nutrient, light and moisture. In this respect, Horowitz (1973a, b) showed that C. rotundus, together with Sorghum halepense had more serious allelopathic effects than Cynodon dactylon on orange, cotton and mustard. Valliappan (1989) and Warner and Fox (1977) showed probable allelopathic effects on rice and banana respectively, while Meissner et al. (1979, 1982) demonstrated almost certain allelopathy against barley, cucumber, tomato and strawberry. Keeley (1987) provides a comprehensive review of the literature on these topics up to 1987.

The levels of loss caused by C. rotundus are not often satisfactorily separated from those caused by other weeds but by varying techniques, estimates have been obtained which occasionally show little or no loss, as in cassava, where populations up to 60 shoots/square m had no effect on root yields (Villamayor, 1983). Sierra and Mercado (1975) also showed no loss in transplanted tomato. More often very substantial losses have been recorded when the weed is allowed to compete for much or all of the growing season. Mangoesoekarjo (1977) compared a range of annual crops for their susceptibility to competition from C. rotundus and ranked them in the order upland rice (most susceptible), groundnut, maize and sorghum. In a similar study, Kondap et al. (1982) showed losses of 6% in maize, 12% in sorghum, 16% in cowpea, 22% in mung bean, 32% in groundnut and 58% in soyabean. Other studies emphasise the susceptibility of upland rice, losses recorded being 51% (de Datta, 1979), 41% (Okafor and de Datta, 1974) and over 40% (Sierra and Mercado, 1975). Particularly severe losses have also been recorded in squash, with over 90% yield reduction from a heavy population of nearly 900 shoots per square m (Ponchio et al., 1984) and in radish, with 100% yield loss from 125 shoots per square m at 100 kg N/ha or from only 75 per square m at 200 kg N/ha (Santos et al., 1998). In pepper, the loss was as high as 73% from 300 shoots per square m at 210 kg N/ha (Morales-Payan et al., 1998), though losses were much lower at lower densities of weed and at lower N levels (Morales-Payan et al., 1997). Other severe examples include 60% loss in onion (Tewari and Shukla, 1991). Cotton may be seriously affected (Sierra and Mercado, 1975). Cruz et al. (1969) recorded 30% loss in this crop and Saeed et al. (1977) a 14% yield loss from a population of about 600 shoots per square m. In the USA, Whitwell and Everest (1984) reviewed the results of a widespread survey in southern USA and concluded that C. rotundus was among the top 10 most troublesome weeds, infesting 460,000 ha of cotton across 15 states, but yield losses after normal weed control practices were probably modest. Losses in potato have been recorded as 25% (Tewari and Shukla, 1991), and in another study as only 3% (Tewari and Singh, 1991). In maize, results have likewise been varied with losses of only 14% (Tewari and Singh, 1991), while a study in Ghana showed that where C. rotundus was well controlled by prior glyphosate treatment, yields were almost doubled, corresponding to a 46% yield loss where it had not been controlled in spite of hand-weeding in the crop (Darkwa et al., 1999). In Brazil, studies in a range of irrigated vegetable crops showed losses from C. rotundus of 35% in cabbage, 39-50% in carrot, 41% in Phaseolus bean, 43% in cucumber, 62% in okra and 89% in garlic (William and Warren, 1975).

Perennial crops can also be seriously affected and in the study by Mangoesoekarjo (1977), cocoa was most susceptible followed by oil palm and rubber. Turner (1985) and Cerrizuela (1965) recorded 83% and 75% reductions in sugarcane yield respectively and Arevalo et al. (1974) also concluded that competition from C. rotundus for more than 30 days must be avoided if yields of sugarcane were not to be seriously affected. He recorded losses of approximately 15, 30 and 45% from infestations allowed to compete for 30, 45 and 90 days, respectively. Perez recorded 20% losses in pineapple (Perez, 1977). Nedunzhiyan (1995) notes that yields of taro can be 'drastically reduced' by C. rotundus. Holm et al. (1977) also refer to reductions in mulberry in Japan, citrus in Israel and coffee in Kenya.

Apart from direct effects on yield, Mangoesoekarjo (1977) notes how the rhizomes and tubers of C. rotundus can interfere with the harvest of groundnuts. Furthermore, Holm et al. (1977) quote estimates of the very substantial quantities of plant nutrients (and water) not only absorbed during the growing season, but locked away in the rhizome and tuber system for prolonged periods. In economic terms it can be conjectured that infestations of C. rotundus significantly raise the cost of manual weeding operations owing to the difficulty of removing the rhizomes and tubers, though quantification of these extra costs has not been seen.
 

Risk and Impact Factors

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Uses

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Parsons and Cuthbertson (1992) claim that C. rotundus is an important medicine in India and China and note its use by pharmaceutical companies to produce diuretics, anthelminthics and treatments for coughs, bronchial asthma and fever. It makes a poor fodder but has value in binding together soil. However, its negative attributes as a weed far outweigh its usefulness.

Uses List

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Animal feed, fodder, forage

  • Fodder/animal feed
  • Forage

Environmental

  • Erosion control or dune stabilization

Human food and beverage

  • Vegetable

Materials

  • Essential oils

Medicinal, pharmaceutical

  • Traditional/folklore

Similarities to Other Species/Conditions

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In the vegetative stage, C. rotundus resembles several other sedge weeds but it can be distinguished by its wiry rhizomes (usually three per basal bulb) linking a network of tubers. By contrast, C. esculentus has numerous soft stolons bearing terminal tubers and annual species of Cyperus have no tubers or rhizomes. The purplish-brown inflorescence distinguishes C. rotundus from C. esculentus with its yellow inflorescence.

Prevention and Control

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Introduction

Once established, C. rotundus can be such an intractable problem that preventative strategies should be employed to avoid its introduction and spread. Intensive use of the same weed management protocols, such as paraquat in coffee or triazine herbicides in maize, can promote the establishment of high populations of C. rotundus. Integrated control, such as crop rotations (Rambakudzibga, 1999) should be considered as part of the management strategy. Whatever methods are used, modelling the population dynamics of C. rotundus indicates that at least 95% control would be required to eliminate this weed (Neeser et al., 1998).

Physical/Mechanical Control

Successful cultivation depends on destroying the tubers of C. rotundus by exposing them to desiccation or by exhausting the food reserves. It is most effective on dry soils but it must be sustained to avoid re-establishment of the fragmented and dispersed rhizome/tuber network. This could necessitate cultivating every 2-3 weeks until the crop forms a canopy to suppress further growth of the weed. In practice this consumes much time and energy and could be detrimental to soil structure. Mowing 1-3 times a week reduces shoot and tuber populations on recreational turf grass (Summerlin et al., 2000).

Organic mulch made from crop residues, such as coir dust (Van Mele et al., 1996) provides temporary suppression of C. rotundus. A layer of 1000-gauge polyethylene is an effective barrier to growth that can be used in nurseries and high value field crops. Soil solarization by polyethylene cover sheets can control C. rotundus (Ricci et al., 1999). Higher soil temperatures and more effective control are possible with thermal-infrared-retentive (TIR) films than with a low-density polyethylene (LDPE) clear film (Chase et al., 1999). This treatment can have a negative effect on some soil biota.

Travolis et al. (2009) report that soil solarization seems potentially effective on C. rotundus tuber sprouting, as long as it resulted not only in a soil temperature shift, but also to a high diurnal temperature variation. Moreover, the uniform sprouting of about 95% of the tubers in the soil may allow for more complete control by mechanical, biological or chemical methods.

Chemical Control

Few herbicides kill C. rotundus but several have been used to suppress growth until after crop establishment, including carbamate compounds such as EPTC, butylate, pebulate and vernolate, and the uracils bromacil and terbacil. Amitrole, 2,4-D, dichlobenil, MSMA, norflurazon and a range of other herbicides have all been used against C. rotundus but one of the most effective products is glyphosate (Terry, 1985). Applied post-emergence at the flowering stage, glyphosate is taken up by actively growing shoots and translocated to the tubers. Activity on the shoots is not observed until 2-4 weeks after treatment. Tuber populations can be reduced by 95% with multiple in-crop applications of glyphosate (Charles, 1997) or by single applications at the beginning of four consecutive seasons within 2 years (Darkwa et al., 1999). Glyphosate is inactivated on contact with the soil and has no effect on tubers that are not connected to emerged shoots.

Biological Control

It is questionable whether a cosmopolitan weed like C. rotundus with a huge regenerative capacity would be a good target for biological control but Evans (1991) claims that several fungi are promising candidates for classical biocontrol, including Puccinia conclusa, P. philippinensis and Phytophthora cyperi. Evans (1991) also notes that several pathogens are damaging to C. rotundus and warrant evaluation as possible mycoherbicides. The fungal pathogen, Dactylaria higginsii, has shown promise as a bioherbicide for the control of C. rotundus; three applications of 10 million conidia/ml gave >90% control (Kadir et al., 2000). Shabana et al. (2010) found that D. higginsii was more effective against C. rotundus than against Cyperus esculentus. The use of D. higginsii is reported by Yandoc et al. (2006) to be compatible with the use of some pesticides, although others reduced or inhibited conidial germination or mycelial growth.

The use of fungi for biological control of C. rotundus and C. esculentus is reviewed by Morales-Payan et al. (2005). The paper examines the biological enemies of nutsedges in nature (including vertebrates and arthropods), and the fungi associated with nutsedges and their potential for biological control (Balansia, Curvularia, Ascochyta, Puccinia, Cercospora and Dactylaria). Priyadharsini et al. (2013) suggest that metabolites produced by a Streptomyces strain inhibited sprouting of C. rotundus rhizomes.

Arthropod predators of C. rotundus that have been investigated as biological control agents include Athesapeuta cyperi, Chaetococcus australis, Bactra minima, B. venosana and B. verutana (Julien, 1992). Bactra spp. have been widely tested but natural enemies have restricted their impact.

References

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Arevalo RA; Cerrizuela EA; Soldati AA, 1974. Competition of specific weeds in sugar plantations. 1. Cyperus rotundus. Malezas y su Control, 3(1):59-75

Bhardwaj RBL; Verma RD, 1968. Seasonal development of nutgrass (C. rotundus L.) under Delhi conditions. Indian Journal of Agricultural Science 38:950-957.

Black C; Chen T; Brown R, 1969. Biochemical basis for plant competition. Weed Science 17:338-344.

Cerrizuela E, 1965. Effect of weeds in sugar cane fields (Argentina). Revista Industrial y Agricola de Tucum, 43:1-12.

Charles GW, 1997. Herbicide strategies for reducing nutgrass (Cyperus rotundus L.) density in cotton (Gossypium hirsutum L.). Australian Journal of Experimental Agriculture, 37(2):231-241; 19 ref.

Chase CA; Sinclair TR; Locascio SJ, 1999. Effects of soil temperature and tuber depth on Cyperus spp. control. Weed Science, 47(4):467-472; 14 ref.

Chase CA; Sinclair TR; Shilling DG; Gilreath JP; Locascio SJ, 1998. Light effects on rhizome morphogenesis in nutsedges (Cyperus spp.): implications for control by soil solarization. Weed Science, 46(5):575-580; 20 ref.

Chaudhary SA; Akram M, 1987. Weeds of Saudi Arabia and the Arabian Peninsula. Saudi Arabia: National Herbarium, Regional Agriculture and Water Research Center, Ministry of Agriculture and Water.

Chaudhary SA; Revri R, 1983. Weeds of North Yemen. Eschborn, Germany: Deutsche Gesellschaft fur Technische Zusammenarbeit (GTZ) Gmbh.

Cruz R; Romero C; Cardenas J, 1969. Control of Cyperus rotundus in Sinu Valley (Colombia). In: Proceedings, Seminar de la Sociedad Colombiana de Control de Malezas y Fisiologia Vegetal, Bogota, Colombia, 60-61.

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Evans HC, 1991. Biological control of tropical grassy weeds. Tropical grassy weeds Wallingford, Oxon, UK; CAB International, 52-72

Flora of China Editorial Committee, 2014. Flora of China. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=2

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Gómez-Laurito J, 2003. Cyperaceae. Monographs in Systematic Botany from the Missouri Botanical Garden, 92:458-551. [Manual de Plantas de Costa Rica.]

Govaerts R, 2014. World Checklist of Cyperaceae. London, UK: Royal Botanic Gardens, Kew. http://apps.kew.org/wcsp/

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Haines RW; Lye KA, 1983. The Sedges and Rushes of East Africa. Nairobi, Kenya: East African Natural History Society.

Henty EE; Pritchard GH, 1975. Weeds of New Guinea and their Control. Lp, Papua New Guinea: Department of Forests, Division of Botany, Botany Bulletin No.7.

Herrera K; Lorence DH; Flynn T; Balick MJ, 2010. Checklist of the vascular plants of Pohnpei with local names and uses. Allertonia:146 pp.

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Horowitz M, 1973. Competitive effects of Cynodon dactylon, Sorghum halepense and Cyperus rotundus on cotton and mustard. Experimental Agriculture, 9(3):263-273

Horowitz M, 1973. Competitive effects of three perennial weeds, Cynodon dactylon (L.) Pers., Cyperus rotundus L. and Sorghum halepense (L.) Pers., on young citrus. Journal of Horticultural Science, 48(2):135-147

Horowtz M, 1972. Growth, tuber formation and spread of Cyperus rotundus L. from a single tuber. Weed Research, 12:348-363.

Hutchinson J; Dalziel JM; Hepper FN, 1972. Flora of West Tropical Africa, Vol. III. London, UK: Crown Agents for Oversea Governments and Administrations.

I3N-Brasil, 2014. Base de dados nacional de espécies exóticas invasora (National database of exotic invasive species). Florianópolis - SC, Brazil: I3N Brasil, Instituto Hórus de Desenvolvimento e Conservação Ambiental. http://i3n.institutohorus.org.br

Jha PK; Sen DN, 1985. Biology and ecology of Cyperus rotundus Linn. Jodhpur, India; Geobios International, 168pp.

Julien MH, 1992. Biological Control of Weeds: a World Catalogue of Agents and their Target Weeds. Wallingford, UK: CAB International.

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Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA

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