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| ## purple nutsedge {#purple-nutsedge .Title-Header}                   |
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| *Cyperus rotundus* L.                                                 |
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| Plant Symbol = CYRO                                                   |
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## *Contributed By: USDA, NRCS, National Plant Data Center & Louisiana State University-Plant Biology; partial funding from the US Geological Survey and the US National Biological Information Infrastructure*

# Caution: This plant is considered a noxious weed in several states and considered highly invasive by various sources. Consult the Noxious and Invasive portion of PLANTS for additional information.

# 

# Alternate Names

nutgrass, nutsedge, coco sedge, cocograss, red nut sedge, coquito,
souchet rond.

# Uses

*Ethnobotanic*: Purple nutsedge has been used in traditional medicine
and in landscaping in China. There are reports of its use in India as a
soil binder. It is undesirable as fodder, because it quickly becomes
fibrous with age, but in the absence of more desirable plants, it can
serve that purpose (Holm et al. 1977). Extracts and compounds isolated
from purple nutsedge have medicinal properties such as the reduction of
fever, inflammation, and pain. The literature contains numerous
references to the use of this plant's roots for essential oils and its
seeds for food products. Tuber extracts may reduce nausea and act as a
muscle relaxant (Wills
1987).![](media/image2.jpeg){width="2.1638888888888888in"
height="4.5680555555555555in"}

*Noxiousness*: Purple nutsedge, has been called the "world's worst"
weed. A befitting designation for a species known from more countries
(at least 92) than any other weed that infests at least 52 different
crops worldwide (Holm et al. 1977). It grows in all types of soils and
can survive the highest temperatures known in agriculture. In the United
States, purple nutsedge infests cultivated fields, waste areas,
roadsides, pastures, and natural areas. It is considered a headache for
the southern gardener because of its insidious, rapid growth in
flowerbeds and vegetable gardens. Purple nutsedge produces an extensive
system of underground tubers from which they can regenerate. Nutsedge is
very difficult to control once it is established.

Purple nutsedge greatly impacts agriculture and has an unfavorable
effect on natural ecosystems by displacing native plants or by changing
the availability of food or shelter for native animals. Although
relatively small in stature, purple nutsedge provides formidable
resource competition for much larger crop plants and ornamentals. This
rapid growing plant can quickly form dense colonies due to its ability
to produce an extensive system of rhizomes and tubers. Many studies
document reduced yields in sugar cane, corn, cotton, rice, vegetables,
and numerous other crops. The abundantly produced tubers present an
efficient means of dispersal and reproduction. These features together
with the ineffectiveness of herbicides make this weed nearly
indestructible.

*Impact/Vectors*: Reduction in crop yields is one of the greatest
impacts of this species. In extreme cases purple nutsedge can reduce
sugarcane yields by 75% and sugar yields by 65%. In Australia, in
experimental plots with cultivation, sugarcane yield was reduced by 38%.
In Colombian cornfields, when purple nutsedge was allowed to grow for 10
days, yield was reduced by 10%. If allowed to remain for 30 days, yield
dropped to 30%. Similar dramatic effects of this weed on cotton, corn,
tomatoes, tobacco, mulberries, lemons, and many other crops have been
demonstrated (Holm et al. 1977).

Rochecouste (1956) noted that even in humid regions the production of
purple nutsedge shoots and tubers could severely restrict water
availability to sugarcane. Approximate quantities of fertilizer that may
be mobilized and stored in purple nutsedge equal 815 kilograms of
ammonium sulfate, 320 kilograms of potash, and 200 kilograms of
phosphate per hectare (Holm et al. 1977).

Besides resource competition, evidence suggests that organic substances
released from the decay of dead subterranean tissues may be allelopathic
and reduce crop yields where purple nutsedge infestations are severe.
Purple nutsedge may produce up to 40,000 kilograms of subterranean plant
material per hectare. Under experimental conditions, barley yield was
reduced by 15 to 25% by *Cyperus rotundus* residues in the soil
(Horowitz & Friedman 1971).

Tuber and rhizome production are important factors in this species'
success as a weed. Rhizomes provide the major means by which the plants
may colonize an area. Tubers offer a mechanism for asexual reproduction,
and they are the major dispersal unit that can survive extreme
conditions. Tubers make the plant difficult to control, because only
translocated herbicides are potentially effective on this species.

Rhizomes and tubers form extensive networks in the soil. While most
tubers are found growing in the upper 15 to 20 cm of soil, a few
penetrate to a depth of 40 cm. The root system in heavy clay may extend
more than a meter deep (Andrews 1940; Smith and Fick 1937). Under
favorable conditions, a single tuber could produce 99 tubers in 90 days
(Rao 1968). Experimental plantings of tubers set on 0.9 meter centers
resulted in their nearly five-fold increase by the end of the growing
season (Hauser 1962).

Tubers resist all but high temperature extremes, but seem more sensitive
to lower temperatures. Germination failed in tubers held for 12 hours at
50^0^ C. However, greater than 80% germination occurred after exposure
to 40^0^ C. Tubers exposed to temperatures of -5 ^0^C or lower did not
survive more than two hours (Ueki 1969).

Tubers and basal bulbs serve as vegetative propagules. They are carried
on farm tillage implements and may be spread by erosion and running
water. Severe storms may bring tubers to the surface and transport them
to new areas. Such propagules may also be transported long distances
with nursery stock. Even though purple nutsedge flowers abundantly, it
rarely produces viable seeds. Seeds, although of little reproductive
significance in the southern United States, are disseminated by wind or
water, transported in mud, or carried onto fields by flooding streams or
with irrigation water (Wills 1987; Holm et al. 1977).

# Status

Please consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status, such as, state noxious
status, and wetland indicator values.

# Description

*General*: Purple nutsedge is a colonial, herbaceous, perennial with
fibrous roots that typically grows from 7-40 cm tall and reproduces
extensively by rhizomes and tubers. The rhizomes are initially white and
fleshy with scaly leaves and then become fibrous, wiry, and very dark
brown with age. Rhizomes may grow in any direction in the soil. Those
growing upward and reaching the soil surface become enlarged forming a
structure 2-25 mm in diameter variously called a "basal bulb, a tuberous
bulb, or a corm" that produces shoots, roots, and other rhizomes.
Rhizomes that grow downward or horizontally form individual tubers or
chains of tubers. Individual tubers are dark reddish-brown when mature,
about 12 mm thick, and vary from 10-35 mm long.

![](media/image3.jpeg){width="2.6993055555555556in"
height="1.7993055555555555in"}

The dark green, shiny, three-ranked leaf blades arise from or near the
base of the plant. They are narrow and grass-like ranging in size from
5-12 mm wide to 50 cm long and have a prominent channel in cross
section. The leaf sheaths are tubular and membranous and attach to
compact nodes at or near the base of the plant.

The upright culms or stems are 10-50 cm tall, smooth, triangular in
cross section, and support a much-branched inflorescence. Two to four
leaf-like bracts subtend the inflorescence which is umbel-like
consisting of 3-9 unequal length branches (sometimes referred to as
rays) bearing spikes of 3-10 spikelets. Spikelets are flattened and
linear ranging in length from 10-30 mm long, and generally dark reddish
purple or reddish brown in color. Each of the 20 or so flowers (florets)
in a spikelet are each subtended by a keeled scale (glumes) 2-5 mm long
that have a green midvein and a membranous margin. The flowers are
bisexual each with three stamens and a pistil bearing three stigmas.
Fruit, although rarely produced, consists of a three-angled achene
(nutlet).![](media/image4.jpeg){width="2.8in"
height="1.8666666666666667in"}

Purple nutsedge possesses the C~4~ photosynthetic apparatus, which is an
adaptation to assimilating CO~2~ at higher temperatures and higher light
intensities compared to C~3~ pathway plants. C~4~ plants typically
exhibit their best growth rates at temperatures characteristic of
tropical and subtropical regions. The leaf anatomy for purple nutsedge
is of the Krantz-type. Sheaths of cells that form around the vascular
bundles serve to compartmentalize the photosynthetic events. Greater
anatomical and physiological details for purple nut sedge are given by
Wills (1987).

*Cyperus esculentus,* yellow nut sedge, is another problematic weedy
species that reproduces by tubers. It is more widespread and also grows
in more temperate parts of the United States. Purple nutsedge is readily
distinguished from yellow nut sedge and other sedges by its purplish
brown spikelets and scaly or wiry rhizomes that often bear chains of
tubers.

*Distribution*: Purple nutsedge is reportedly native to India, but it
has been introduced around the World (Holm et al. 1977). The plant is a
serious pest in the Southeast ranging from Virginia to central Texas. It
also has become established in parts of Arizona and California and has
the potential to invade other Pacific states. (Southern Weed Science
Society 1995; FICMNEW 1997). This species occasionally occurs in more
temperate regions. For example, its presence in Stearns County,
Minnesota was documented by a specimen in the University Herbarium
collected by J. E. Campbell, July, 1896 (MIN: accession number *81217*),
but purple nutsedge has not persisted there and other cold locales. The
northern limit of nutsedge in Japan is in a region where the average
minimum atmospheric temperature is -5^0^C, the temperature below which
tubers will not germinate (Ueki, 1969). Temperature appears to limit the
species to more tropical and warm temperate regions. For current
distribution, please consult the Plant Profile page for this species on
the PLANTS Web site.

# Control

For control measures that are pertinent to your area, please contact
your local agricultural extension specialist or your city/county weed
control specialist.

*Mechanical*: Moisture loss is detrimental to tubers. Tuber death ensued
after moisture content dropped to 15% or less. Tubers left at the
surface of dry soil exposed to full sun desicated beyond recovery after
4 days. Under simulated field conditions, tubers at 5 and 10 cm depths
in dry soil that were protected from rain but exposed to sunlight were
killed after 8 and 12 days at those respective depths (Holm et al.,
1977).

Purple nutsedge tubers can be destroyed with repeated summer tillage
because of their susceptibility to drying. Infested fields plowed or
disked at three-week intervals for the entire growing season reduced
tuber number by 80%. At four-week tillage intervals, tuber numbers
actually increased. Summer dry fallowing is most effective in light,
sandy soils but less so in wetter, heavier soils. Springtooth harrows
are an excellent implement for this method. Such tillage methods are
often impractical, because the land cannot be used for one or more
growing seasons. An exception would be where October to June cropping is
feasible (Holm et al. 1977).

Where tillage is possible, it can give crops a competitive advantage.
The use of precision equipment to cultivate as closely as possible, and
hand or mechanical thinning can help to reduce nutsedge competition.
Nutsedge is susceptible to shading, which reduces vegetative growth and
tuber production.

*Chemical*: Purple nutsedge has proved difficult to control with
herbicides. To be effective, the herbicide must be translocated
throughout the rhizome and tuber network of the plant. Always follow the
manufacture's recommendations for application and observe all
precautions when using herbicides. Also, observe applicable local,
state, and federal regulations. A few case histories of herbicide
control are cited to indicate progress being made in controlling purple
nutsedge.

Field experiments over a 10 year period were conducted at the USDA,
Southern Weed Science Lab, Stoneville, Mississippi, to determine the
effects of tillage and herbicide inputs on purple nutsedge control in
cotton. Four tillage cotton production systems (conventional, two levels
of reduced-tillage and no-tillage) were evaluated with two herbicide
(glyphosate) input levels each. For the most part, seed cotton yields
were equivalent for the conventional and reduced tillage production
systems regardless of the herbicide input level. Seed cotton yields were
less in no-till systems 6 of 10 years regardless of herbicide input
levels. It was discovered that the timing of glyphosate application, as
a preplant foliar treatment, was extremely important. Purple nutsedge
control decreased (i.e., nutsedge populations increased) with glyphosate
applications 2 to 4 weeks prior to cotton planting. When glyphosate
applications were made at planting in the no-tillage plots, higher
levels of purple nutsedge control were realized. Based on predicted
costs of herbicide and tillage operations, no-tillage cotton production
systems saved monetary inputs and increased net profits 8 of 10 years.
Effective and efficient purple nutsedge control in cotton can be
obtained in reduced-tillage production systems, but additional research
is needed to develop more effective systems of purple nutsedge control
in no-tillage cotton production system (Bryson 1996).

In cotton and corn, alachlor (no longer permitted in cotton in
California due to its damaging effects on the crop plants) is effective
against yellow nutsedge, but is less effective on purple nutsedge. DSMA
and MSMA provide control of purple nutsedge when applied to cotton as
directed-sprays after the cotton plants have two or more leaves. If
these herbicides accidentally get on the growing point of cotton plants,
they will retard the plant\'s growth. Because nutsedge is sensitive to
competition by shade, early chemical control will allow later shading
from the cotton canopy to provide additional control. Smart sprayers
that detect and spray only infested areas can save on herbicide costs
and introduce less pesticide into the environment (Vargas et al. 1997).

Preplant treatment with the soil fumigant, metam-sodium, may provide
control if applied during summer fallow i.e., allowing the soil to
remain undisturbed for approximately 90 days. (Vargas et al.1997).

In four recent studies, a combination of the pesticides Telone® C-17 and
Tillam® suppresses weeds including purple nutsedge, nematodes, and
certain diseases and achieved yields similar to those obtained by
fumigation with methyl bromide for Florida tomatoes intended for fresh
markets).

Nutsedge is very difficult to control once it is established in turf.
Therefore, plant in seedbeds that are free of nutsedge where possible.
Small localized infestations of nutsedge may be controlled with metham
or repeated applications of glyphosate. Maintaining a closed,
competitive turf and avoiding overly wet soil will help control purple
nutsedge. Reportedly, Manage® Turf Herbicide does an excellent job on
yellow and purple nutsedge in lawns.

*Biological*: Efforts at biological control have explored the usefulness
of the moth genus *Bactra* and searches have been made for potentially
effective fungi, viruses, and nematodes. *Bactra,* a natural insect
enemy of sedges in the genera *Cyperus, Kyllingia*, and *Scirpus*, has
been considered well-suited for biological control of sedge species
(Frick & Chandler 1978). Species of *Bactra* are found in many warmer
regions of the world where purple nutsedge is a problem. Their larva
feed mainly on sedges. They do not cause appreciable damage to their
host plants because of delayed seasonal buildup. Numbers of larvae
remain low until early August whereas, large numbers are needed in late
May and early June to control nutsedge (Frick & Chandler 1978).

Over a six year period, studies were made on the effectiveness of
introducing large numbers of adults and larvae early in the growing
season to enable insect establishment on nutsedge prior to the time of
wide use of insecticides in crops (Frick & Chandler 1978). The studies
were conducted on cotton at the USDA, Southern Weed Science Laboratory.

Early-season augmentation of *Bactra* populations is a feasible method
for controlling purple nutsedge. Large-scale releases would have to use
adults because of the difficulties and time consuming nature of
releasing larvae. Releases should continue over a six week period
beginning after crop planting. Because of the rapid growth rate of
nutsedge, five to ten larvae per shoot are needed. The number of moths
to release per unit area would be estimated on the basis of a 50:50 sex
ratio and an average of 180 eggs per female (Frick and Chandler 1978).

*Cyperus rotundus* is susceptible to rice grassy stunt tenuivirus, rice
tungro bacilliform badnavirus, and rice tungro spherical waikavirus
(Brunt et al. 1996). Purple nutsedge is an alternate host for the fungi
*Fusarium* and *Puccinia canaliculata*. It is also infected by the
nematodes *Meloidogyne*, *Rotlylenchus,* and *Tylenchus*. Leaf scorch of
purple nutsedge is caused by *Ascochyta cyperiphthora* (Pomella &
Barreto 1997). However, none of these agents causes sufficient
destruction to provide sufficient control of this weedy plant (Holm et
al. 1977).

# Illustrations and Photographs

Gleason, H. A. 1952. *Illustrated flora of the northeastern United
States and adjacent Canada*. Lancaster Press, Inc., Lancaster,
Pennsylvania. (line drawing, vol 1, p. 254.).

Holm, L. G., D. L. Plucknett, J. V. Pancho, & J. P. Herberger 1977. *The
world\'s worst weeds, distribution and biology*. East-West Center,
University Press of Hawaii, Honolulu. 609 pp. (excellent line drawings
of vegetative and reproductive parts).

Radford, A. E., H. E. Ahles, & C. R. Bell 1968. *Manual of the vascular
flora of the Carolinas*. University of North Carolina Press, Chapel
Hill, North Carolina. (small line drawing, p 175).

Texas A&M University 1999. *Vascular plant image gallery*.
Bioinformatics Working Group.
\<http://www.csdl.tamu.edu/FLORA/gallery/gallery_query.htm\>. College
Station, Texas.

# References

AboElKheir, A. M., Y. F. ElBanna, & M. A. Khafagy 1992. *Morphological
and anatomical injuries of glyphosate and surfactants to purple nutsedge
(Cyperus rotundus L.)*. Journal of Agricultural Sciences 17:3542-3554.

AbuIrmaileh, B. & L. Jordan 1982. *Effect of roundup formulation and
components on* *purple nutsedge* (*Cyperus rotundus*). Dirasat
9:105-119.

AbuIrmaileh, B. E. & L. S. Jordan 1978. *Some aspects of glyphosate
action in purple nutsedge* (*Cyperus rotundus*). Weed Science
26:700-703.

Aharonov, B., M. Marmelstein, & Z. Feller 1979. *Flordon controls
Cyperus rotundus in cotton without damage to the crop*. Hassadeh
59:1780-1781.

AlAli, F. A., S. R. A. Shamsi, & S. M. Hussain 1978. *Sprouting and
growth of purple nutsedge, Cyperus rotundus, in relation to pH
hydrogen-ion concentration and aeration*. Physiol. Plant 44:373-376.

Alam, S. M. & A. R. Azmi. 1991. *Effect of purple nutsedge (Cyperus
rotundus) leaf extract on germination and seedlings growth of wheat (cv.
Pavon)*. Pakistan Journal of Weed Science Research 4:59-61.

Almeida, F-S-de \"Tiririca\", 1972. *Cyperus rotundus and Cyperus
esculentus control (contribution to its study)*. Agron-Mocambicana,
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Anderson, W. P. & G. Hoxworth 1987. *Yellow nutsedge control in onions
with metolachlor*. Research Progress Report. Western Society of Weed
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Anderson, W. P.& M.P. Dunford 1970. *Control of purple nutsedge with
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competition of weed on Virginia tobacco \"Speight G.28\" variety*.
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Anonymous 1975. *Biological weapon against purple nutsedge (Cyperus
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p.

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purple nutsedge control in cotton*. TEKTRAN. USDA, Agricultural Research
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\<http://www.nal.usda.gov/ttic/tektran/tektran.html\>.

Burgis, D. S. 1969. *Phytotoxicity to purple nutsedge (Cyperus rotundus
L.) and soil persistence of some hormone type herbicides*. Florida State
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(chlorimuron) and harmony (thiameturon)*. Journal of Environmental
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biotypes, and seed production*. 39^th^ Proceedings of the California
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weeds, Cynodon dactylon (L.) Pers., Sorghum halepense (L.) Pers. and
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Horowitz, M. 1972b. *Growth, tuber formation and spread of Cyperus
rotundus L. from single tubers*. Weed Research 12(4):348-363.

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Weed Research 11:88-93.

Pomella, A. W. V. & R. W. Barreto 1997. *Leaf scorch of purple nutsedge
(Cyperus rotundus) caused by Ascochyta cyperiphthora sp. nov*. 65:
459-468.

Plowman, T. C., A. Leuchtmann, C. Blaney, & K. Clay 1990. *Significance
of the fungus Balansia cyperi infecting medicinal species of Cyperus
(Cyperaceae) from Amazonia*. Economic Botany 44:452-462.

Rao, J. 1968. *Studies on the development of tubers in nutgrass and
their starch content at different soil depths*. Madras Agriculture
Journal 55(1):19-23.

Richburg, J. S., J. W. Wilcut, & E. F. Eastin 1993. *Weed control and
peanut (Arachis hypogaea) response to nicosulfuron and bentazon alone
and in mixture*. Weed Science 41:615-620.

Rincon, D. J. & G.F. Warren 1978. *Effect of five thiocarbamate
herbicides on purple nutsedge (Cyperus rotundus).* Weed Science
26(2):127-131.

Rochecouste, E. 1956. *Observations on nutgrass (Cyperus rotundus) and
its control by chemical methods in Mauritius*. Pages 1-11. IN:
*Procedings of the Ninth Congress of the International Society of Sugar
Cane Technologists*.

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# Prepared By

## *Lowell Urbatsch*

Department of Plant Biology, Louisiana State University, Baton Rouge,
Louisiana

# Species Coordinator

## *Mark Skinner*

USDA, NRCS, National Plant Data Center, Baton Rouge, Louisiana

Edited 19sep00 jsp;10feb03 ahv; 05jun06 jsp

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

*The U.S. Department of Agriculture (USDA) prohibits discrimination in
all its programs and activities on the basis of race, color, national
origin, sex, religion, age, disability, political beliefs, sexual
orientation, and marital or family status. (Not all prohibited bases
apply to all programs.) Persons with disabilities who require
alternative means for communication of program information (Braille,
large print, audiotape, etc.) should contact USDA\'s [TARGET
Center](http://www.usda.gov/oo/target.htm) at 202-720-2600 (voice and
TDD).*

*To file a complaint of discrimination write USDA, Director, Office of
Civil Rights, Room 326-W, Whitten Building, 14th and Independence
Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964 (voice or
TDD). USDA is an equal opportunity provider and employer.*

*Read about [Civil Rights at the Natural Resources Convervation
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