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Interim profile, incomplete information Taxonomic name: Cyperus rotundus L. Synonyms: Chlorocyperus rotundus (L.) Palla, Cyperus purpuro-variegatus Boeckeler, Cyperus stoloniferum pallidus Boeckeler, Cyperus tetrastachyos Desf., Cyperus tuberosus Roxb Common names: almendra de tierra (Spanish), balisanga (Ilocano), boto-botonis, castanuela (Spanish), cebollín (Spanish), chaguan humatag (Chamorro), chufa (Spanish), coco (Spanish), cocograss (English), coquillo (Spanish), coquillo purpura (Spanish), coquito (Spanish), cortadera (Spanish), hamasuge (Japanese), herbe à oignons (French), ivako (Fijian), juncia real (Spanish), kili‘o‘opu (Hawaiian), mala-apulid (Pampangan), malanga (Fijian), matie'oniani (Maori-Cook Islands), mau‘u mokae (Hawaiian), mauku'oniani (Maori-Cook Islands), mot ha (Fijian), mumuta (Samoan), nut grass (English), nut sedge (English), nutgrass (English), oniani (Maori-Cook Islands), oniani lau (Maori-Cook Islands), oniani rau (Maori-Cook Islands), oniani tita (Maori-Cook Islands), pakopako (Tagalog), pakopako (Tongan), purple nut sedge, purple nutsedge (English), red nut sedge (English), soranakambani (Fijian), soro ni kabani (Fijian), soronakambani (Fijian), souchet à tubercules (French), souchet d'Asie (French), souchet en forme d'olive (French), souchet rond (French), suo cao (Chinese), sur-sur (Pampangan), te mumute, tuteoneon (Marshallese), vucesa (Fijian), vuthesa (Fijian), xiang fu zi (Chinese) Organism type: sedge Cyperus rotundus may present a problem as a weed of cultivated crops and gardens. It has been reported as a weed in many areas where it has been introduced including New Zealand, Australia and the United States. Description Cyperus rotundus is described as a perennial herb with long rhizomes; sometimes tuberous; culms up to 60 cm tall; leaves 2 to 6 mm wide; spikes ovate, on rays to 6 cm long; spikelets linear, 1 to 2 cm long, 12 to 30-flowered, the rachilla winged; scales purplish, carinate, obtuse; achene sub-obovoid, trigonal, 1.5 mm long, black, minutely papillate (Stone 1970, in PIER 1999). Occurs in: agricultural areas, coastland, natural forests, riparian zones, water courses Habitat description Cyperus rotundus is found in cultivated fields, on roadsides, in neglected areas, at the edges of forests and on the banks of irrigation canals and streams. It is not shade tolerant. Dormant tubers remain viable in shade and during dry periods and emerge as soon as conditions are more favourable. The species is found in all soil types and climates and from sea level to high altitudes. In cool or waterlogged soils it grows slower, flowers little and produces few tubers (Holm et al. 1977, in PIER 1999). It is described as "a cosmopolitan weedy sedge, growing in farmlands, grasslands, and sandy or gravelly shores, riverbanks and waste places" (Wiggins & Porter 1971, in PIER 1999). It is a major weed of cultivated crops and gardens but only a minor weed elsewhere (Swarbrick 1997, in PIER 1999). General impacts Cyperus rotundus is reported mostly as a pest of agriculture land and lawns. It may also be invasive in disturbed habitats. It is listed on the New Zealand noxious weed list and sales of this species are banned in New Zealand. It is also a pest on Christmas Island, Australia (Swarbrick 1997, in PIER 1999). In a risk assessment prepared for Australia C. rotundus scored a total of 13 (reject). It is highly suited to the Australian climates and has a history of repeated introductions outside of its native range. It is an agricultural weed and a known host of pathogens and pests (PIER 2001). Uses Cyperus rotundus is used for medicinal purposes, to make essential oils and may be consumed as a vegetable (USDA-ARS 2001). Geographical range Native range: Native to Eurasia (PIER 1999). Known introduced range: Introduction pathways to new locations Road vehicles (long distance): Cyperus rotundus propagules are likely to be dispersed unintentionally especially in regards to plants growing in areas with much vehicle movement (PIER 2001). Local dispersal methods Water currents: Seeds of Cyperus rotundus are distributed by wind, sheet erosion, floods and irrigated water (Holm et al. 1977, in PIER 1999). Management information Physical: Cyperus rotundus is suppressed under closed canopies. It may be controlled by plastic mulch or competitive crops. Hand-weeding, chipping and cultivation is effective in dry soils. Grazing by poultry and pigs may provide control (Swarbrick 1997, in PIER 1999). Pigs were seen as part of a cultural control system. For example at least as early as 1968 pigs were suggested as a form of control by John L. Hammerton, who was working in Panama. The use of chickens and geese to control nutgrass has also been promoted in Palau and the United States (PestNet 2009). Chemical: C. rotundus is susceptible to fumigants (including methyl bromide, DD and chloropicrin), residual herbicides (including bromacil, EPTC, hexazinone, terbacil, pebulate and vernolat) and translocated herbicides (including glyphosate, amitrole, DSMA, MSMA and 2,4-D); control is often disappointing (Swarbrick 1997, in PIER 1999). CSIRO reported that, in cotton, glyphosate (Roundup) is applied early in the season (Sept/Oct) with shielded hand sprayers so as to avoid drift. Next, nutgrass from the plant line is weeded by hand after rain (not a popular method). Once the cotton has grown, glyphosate is applied regularly with a large shielded sprayer behind a tractor. Problems arise when the weather turns wet and glyphosate cannot be applied in time and nutgrass outcompetes the cotton (Nov/Dec). There is now a field management plan, including chemicals like Sempra (halosulfuron-methyl) and Zoliar (norflurazon) (PestNet 2009). Field studies conducted between 1993 and 1995 were designed to evaluate the use of MON-12051 (a sulfonylurea compound) to control nutsedge in turfgrass environements. MON-12051 outperformed both bentazon and imazaquin in controlling yellow and purple nutsedges without damaging desired turf species. Six weeks post-treatment purple nutsedge control averaged 96% (in comparison control with imazaqiun resulted in only 42%). Reproduction Cyperus rotundus produces viable seed and also reproduces by vegetative fragmentation (PIER 2001). C. rotundus produces tubers and rhizomes and seeds occasionally; seeds are distributed by wind, sheet erosion, floods and irrigated water (Holm et al. 1977, in PIER 1999). Compiled by: IUCN SSC Invasive Species Specialist Group (ISSG) with support from the EU-funded South Atlantic Invasive Species project, coordinated by the Royal Society for the Protection of Birds (RSPB) To contribute information, please contact Shyama Pagad. Last Modified: Monday, 27 April 2009