Cyperus iria (rice flatsedge)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- Biology and Ecology
- Notes on Natural Enemies
- Uses List
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Cyperus iria L. (1753)
Preferred Common Name
- rice flatsedge
Other Scientific Names
- Chlorocyperus iria (L.) Rikli (1895)
International Common Names
- English: grasshopper's cyperus
Local Common Names
- Bangladesh: barachucha
- Brazil: tiririca-do-brejo
- Cambodia: kak kangkep
- India: morphula
- Indonesia: dekeng wangin; djekeng; nyur-nyuran; rumput jekeng kunyit; umbung
- Japan: kogomegeyatsuri
- Korea, DPR: chambang-donsani
- Malaysia: rumput menderong
- Nepal: chow; guchen; mothey; ochumani
- Pakistan: khana
- Philippines: alinang; ballayang; payong-payong; sirau-sirau; sudsud; taga-taga
- Thailand: kok huadaeng; yaa rangkaa khaao
- USA: rice flatsedge
- CYPIR (Cyperus iria)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Cyperales
- Family: Cyperaceae
- Genus: Cyperus
- Species: Cyperus iria
Notes on Taxonomy and NomenclatureTop of page
C. iria was first described by Linnaeus (1753). It originated in the Old World tropics and subtropics and is one of approximately 650 species in the genus Cyperus (Haines and Lye, 1983). Courtoisia, Kyllinga, Mariscus and Pycreus are included in the genus Cyperus (Haines and Lye, 1983) though they are often cited as genera in their own right. Under the classification of Lye (1981), C. iria is in the subgenus Cyperus which contains about 300 species, including the common and important sedge weeds C. rotundus and C. esculentus.
DescriptionTop of page
The inflorescence is simple or compound, usually open, 1-20 cm long and 1-20 cm wide, with groups of spikes which are either sessile or on 0.5-15.0 cm long peduncles (rays). Inflorescence bracts (involucre) are leafy, three to five (occasionally seven), the lower one longer than the inflorescence, 5-30 cm long, 1-6 mm wide. The spikes are sessile or almost so, elongate, and rather dense. Spikelets are erect-spreading, crowded, 6-24-flowered, 2-13 mm long, 1.5-2.0 mm wide, golden to yellowish-green.
Glumes are broad-ovate, 1.0-1.6 mm long, golden-brown. There are two or three stamens. The style is 3-branched. The fruit is a small achene (nutlet), 1.0-1.5 mm long, 0.6-0.7 mm wide, obovate, triangular in cross section, dark-brown to almost black; the surface is almost smooth. These descriptions are based on Haines and Lye (1983) and Holm et al. (1977).
DistributionTop of page
Distribution TableTop of page
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: 25 Feb 2021
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|China||Present||Original citation: Wang, 1990|
|-Guangdong||Present||Original citation: Wang, 1990|
|-Hebei||Present||Original citation: Wang, 1990|
|-Shaanxi||Present||Original citation: Wang, 1990|
|-Xinjiang||Present||Original citation: Wang, 1990|
|-Yunnan||Present||Original citation: Wang, 1990|
|India||Present||Present based on regional distribution.|
|-Andaman and Nicobar Islands||Present|
|-Haryana||Present||Original citation: Malik et al. (1981)|
|-Jammu and Kashmir||Present|
|-Punjab||Present||Original citation: Sidhu et al. (1982)|
|Indonesia||Present||Original citation: Kostermans et al., 1987|
|Cuba||Present||Original citation: Wazniak, 1976|
|Trinidad and Tobago||Present|
|-Louisiana||Present||Original citation: Baker and Shrefler (1983)|
|-Mato Grosso do Sul||Present|
|-Rio de Janeiro||Present|
|Colombia||Present||Original citation: Häfliger et al. (1982)|
|Venezuela||Present||Original citation: Häfliger et al. (1982)|
Risk of IntroductionTop of page
HabitatTop of page
Hosts/Species AffectedTop of page
Host Plants and Other Plants AffectedTop of page
|Oryza sativa (rice)||Poaceae||Main|
Growth StagesTop of page
Biology and EcologyTop of page
Chromosome numbers vary in C. iria (n=56, 64) and intraspecific variation in genotype and phenotype occurs (Bir et al., 1992). Natural hybridization can occur between C. iria and C. microiria (Chozin and Yasuda, 1991) to produce progeny of new-type plants of similar dormancy to the parents, showing clear segregation in spikelet characteristics and floret morphology. C. iria has Kranz-type leaf anatomy and, like C. rotundus, has two layers of bundle sheath cells (Lin et al., 1982). This is indicative of C4 photosynthesis which is generally not a characteristic of weeds growing in wet habitats.
Notes on Natural EnemiesTop of page
ImpactTop of page
C. iria is rated by Holm et al. (1977) as one of the three most important weeds of rice in Sri Lanka, India and the Philippines. It is a principal weed in Indonesia and Japan and a common weed in Fiji, Thailand and the USA. It is principally a weed of rice around the world but Holm et al. (1977) also noted its occurrence in bananas, cassava, groundnuts, maize, pastures, pineapples, sweet potatoes, tea and vegetables. It is difficult to separate the competitive effects of C. iria from those of other components of the weed flora but the weed caused 40% yield reductions in rice (Ampong-Nyarko and DeDatta, 1991).
The costs of controlling C. iria, whether manual, mechanical or chemical, are significant. C. iria is a host for several pests of rice. In Cuba, it is a host of the rice nematodes Pratylenchus zeae and Hirschmanniella spinicaudata (Fernandez and Ortega, 1982). Criconemella onoensis is a rice nematode which uses C. iria as a host in the southern USA. Complete control of the weed is necessary before nematicides (e.g. fensulfothion) can be effective in increasing rice yields (Hollis, 1972).
Arthropod rice pests which use C. iria as a host plant include Scotinophara latiuscula (Barrion and Litsinger, 1987), Nisia atrovenosa (Cruz and Dela-Cruz, 1986), Lissorhoptrus brevirostris (Meneses-Carbonell and Carbonell, 1985), Nymphula depunctalis (Pillai and Nair, 1979), Baliothrips biformis and B. holorphnus (Ananthakrishnan and Kandasamy, 1977).
Pathogens of rice that have been reported on C. iria include Pyricularia oryzae [Magnaporthe grisea] (Singh and Singh, 1988), Rhizoctonia solani (Gokulapalan and Nair, 1983) and Acrocylindrium oryzae [Sarocladium oryzae] (Balakrishnan and Nair, 1981). Also the nematode Pratylenchus zeae (Waterhouse, 1994).
Uses ListTop of page
Detection and InspectionTop of page
Similarities to Other Species/ConditionsTop of page
A very experienced eye is required to distinguish the seeds of C. iria from those of other Cyperus species.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.Cultural Control
The principles of good weed management in rice, such as those advocated by Ampong-Nyarko and DeDatta (1992), are applicable to C. iria in rice and other crops. These include the need to prepare clean seedbeds, prevent seed production, establish a healthy and vigorous crop and avoid contamination of crop seed at harvest. C. iria is susceptible to many of the usual methods of weed control in rice and other crops. These include hand-pulling, manual and mechanical tillage and trampling in puddled fields. Flooding has a major suppressive effect during the early growth stages of C. iria (Civico and Moody, 1979) but established plants are difficult to control in this way and can tolerate 90 cm of floodwater for four days (Singh et al., 1983).
At present there are no biological control agents for C. iria but Phoma cyperi sp. nov., a pathogen of C. iria, may have some potential.
A number of herbicides are approved for use in rice but their use is dictated by the conditions used to grow the crop, e.g. whether the crop is irrigated, rainfed lowland, upland and deepwater. C. iria is susceptible to the herbicides commonly used in rice: bensulfuron, bentazone, bifenox + 2,4-D, butachlor, butralin, 2,4-D, MCPA, molinate, oxadiazon, pendimethalin, piperophos + dimethametryn, pretilachlor + antidote (e.g. fenclorim), propanil, thiobencarb, thiobencarb + 2,4-D. Cinmethylin and fluorodifen were also active against C. iria (Ampong-Nyarko and DeDatta, 1991). Paraquat and glyphosate can both be used as non-selective, post-emergence herbicides against C. iria, for example in land preparation using zero-tillage.
Integrated Weed Management
Integrated weed management is recommended for cost-effective weed control; combinations of treatments such as: planting clean seed into a weed-free seedbed; sowing crop at optimum spacing; good water control; applying appropriate herbicides or cultivations; and harvesting crop grain which is not contaminated by weeds may be combined for an effective integrated control strategy.
ReferencesTop of page
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Chozin MA; Nakagawa K, 1988. Autecological studies on Cyperus iria L. and C. microiria Steud., annual cyperaceous weeds. I. Seed dormancy, germination, and seedling emergence. Weed Research, Japan, 33(1):23-30
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