Yellow nutsedge

Images above: Upper left: Sprouting yellow nutsedge tuber with roots and a new shoot (Randall Prostak, University of Massachusetts). Upper right: Yellow nutsedge tillers (Antonio DiTommaso, Cornell University). Bottom: Yellow nutsedge inflorescence in fruit (Scott Morris, Cornell University).

Identification

Other common names:  chufa, rush-nut, yellow nut-grass, northern nutgrass, coco, coco-sedge, nut sedge, edible galingale

Family:  sedge family, Cyperaceae

Habit:  Grass-like perennial, spreading by rhizomes and tubers.

Description:  Seedlings have very similar above ground characteristics to the more commonly occurring, vegetative shoots.  Newly emerging vegetative shoots have three glossy, light green, grass-like leaves.  Leaves are flat or slightly V shaped and set around a very short stem in threes such that the shoot base is triangle shaped.  Foliage of the mature plant is similar to the young plant with leaves 8-36” (20-91 cm) long by 0.2-0.4” (0.5-1 cm) wide.  Leaves are long, tapered, and sharply pointed with a prominent midrib and parallel veins that sometimes give the leaves a ridged appearance.  Leaves lack ligules and auricles and have a closed, overlapping sheath that forms a triangular, three-edged, unbranched, stem-like structure at the base.  The inflorescence develops at the end of a 0.5-3 ft (15-91 cm) long triangular, spongy or corky centered, yellow-green stem that is usually no longer than the leaves.  Several long, lance-shaped, green, roughly horizontal, leaf-like bracts are located just below the inflorescence; they are of equal or lesser length than the inflorescence.  The inflorescence consists of multiple stalked, yellowish, bottlebrush-shaped clusters of spikelets.  Flowers are arranged into groups of three-sided, 0.1” long, oval shaped, yellow-brown spikelets.  The fruit contains one light brown seed.  Seeds often fail to germinate, instead extensive underground networks of rhizomes and tubers perpetuate yellow nutsedge.  Scaly white rhizomes, reaching up to 6.5 ft (2 m) in all directions, give rise to new tubers at their tips.  The tubers are white and scaly when young.  Mature tubers are hard, round, nutlike, brown to black in color, 0.13-0.75” (0.3-1.8 cm) in diameter, and can number up to 7,000 produced in one year; they eventually shed their scales, enlarge into bulbs, and give rise to vegetative shoots and roots.

Similar species:  Purple nutsedge (Cyperus rotundus L.) has dark green foliage and purple inflorescences.  Purple nutsedge foliage tends to be shorter than yellow nutsedge foliage, with tips blunt compared to acutely elongated tips with yellow nutsedge.  Tubers are produced along the length of the rhizome, not just at the tips.  

Management

Although some yellow nutsedge tubers may form as deeply as 18” (46 cm), the vast majority of tubers are found in the top 6” (15 cm) of soil (Stoller 1981).  Consequently, this species is sensitive to tillage in late spring and early summer after the tubers have sprouted but before daughter plants or new tubers have formed.  Although the tubers can make new sprouts from dormant buds, these will be weaker and more easily controlled by cultivation (Stoller et al. 1972).  Thus, crop rotations that include late spring/early summer tillage help control yellow nutsedge populations.  By the same principle, in early-planted row crops, deep cultivation once or twice beginning in early June will substantially reduce a yellow nutsedge population and in a competitive crop may provide sufficient control for the remainder of the season (Stoller 1981).  Tillage after summer harvested crops will help disrupt tuber formation, which occurs primarily in late summer and fall.

The tubers will die if you can dry them out completely. You can do this most effectively by repeatedly turning the soil during dry weather.  Solarization can be an effective control measure in climates where soil can be heated in excess of 113 °F (45 °C) (Wang et al. 2008).  However, soil temperatures may not always achieve these levels for sufficient duration throughout the soil profile from which tubers emerge (Webster 2003).  An integrated approach where fallow tillage precedes solarization can achieve more reliable results (Johnson et al. 2007).

Since the plants are short, a dense planting or other measures that increase the competitiveness of the crop are particularly effective for suppressing yellow nutsedge (Keeley and Thullen 1978).  Similarly, since tubers are short-lived in soil, rotations that include good weed control in highly competitive crops for 2-3 years will substantially reduce yellow nutsedge populations.  Although potatoes are relatively competitive, avoid planting them in infested fields, because nutsedge rhizomes can penetrate potato tubers and make them unmarketable (Felix and Boydston 2010).  Good fertility is more likely to increase the vigor of the crop than the growth of yellow nutsedge.

The large food storage in the tubers allows yellow nutsedge to penetrate even very thick layers (e.g. 6” or 15 cm) of organic mulch materials.  Allelopathic substances from sweet potato, wild radish, and rye, however, reduce yellow nutsedge density and vigor (Eckerman 2001, Harrison and Peterson 1991, Norsworthy and Meehan 2005).  Suppression of yellow nutsedge by rye is most effective if the rye root system is present as well as the straw (Eckerman 2001).  Soil amendment with wheat bran partially reduced tuber sprouting and reproduction (Shrestha et al. 2018). 

The sharp points of the newly emerged shoots easily pierce thin opaque horticultural plastic film, but not clear plastic film, where light induces leaf expansion and blunts the sharpness of the emerging shoot (Chase et al. 1998).  Thicker plastic mulch whether opaque or clear can suppress yellow nutsedge (Chase et al. 1998), as can heavier materials such as landscape fabric (Daugovish and Mochizuki 2010).  Tuber production and patch expansion also are suppressed by plastic film (Webster 2005a,b).

One of the most effective methods for managing yellow nutsedge is to graze swine on the field occasionally.  Their eradication of tubers will be quicker and more complete if the soil is tilled first.  A novel approach using a peanut digger in conjunction with a collection cart has successfully removed substantial numbers of tubers from fields in the southeastern U.S.A. (Johnson et al. 2015).

Ecology

Origin and distribution:  Yellow nutsedge is native to North and South America, southern Europe, and Africa (Mulligan and Junkins 1976).  Native populations in North America occur in wetlands, and weedy races in the U.S.A. may be introduced.  The species occurs widely in the U.S.A. and southern Canada, with the exception of the Intermountain West and prairie provinces (USDA Plants).

Seed and tuber weight:  Seeds: 0.19 mg (Stevens 1932), 0.15 to 0.20 mg (Bell et al. 1962), 0.13 to 0.31 mg (Thullen and Keeley 1979).  Mean tuber weight varies substantially between locations: Minnesota – 70 mg, Illinois – 150 mg, Tennessee and Maryland – 700 mg (Stoller 1981); Illinois – 75 mg (Stoller and Wax 1973); Georgia – 160 mg (Webster 2005a).   

Dormancy and germination:  The tubers are dormant when produced and usually sprout the following spring.  Water-soluble chemicals in the skin of the tubers apparently enforce dormancy because washing breaks dormancy.  Water percolating through the soil probably acts similarly (Stoller 1981).  Tuber dormancy, however, is also broken by one month of cold treatment (38-50 °F (3-10 °C) (Bell et al. 1962, Stoller 1981).  Thus, tubers usually do not sprout until they have overwintered.  Temperatures above 54 °F (12 °C) are required to initiate tuber sprouting (Stoller and Wax 1973). 

Cold treatment also reduces the dormancy of seeds (Bell et al. 1962).  Some seeds will germinate in the dark provided the temperature is greater than 75 ° F (24 ° C), but germination in light is greater than in dark (Bell et al. 1962, Thullen and Keeley 1979).  In light at 95 °F (35 °C), nearly all seeds will germinate (Bell et al. 1962).  Nitrate has minimal effect on seed germination (Bell et al. 1962).  Germination increases with increasing seed mass (Bell et al. 1962, Thullen and Keeley 1979).

Tuber and seed longevity:  Tubers can persist in the soil for 3 years, but few survive more than two winters in most field situations (Bell et al. 1962, Stoller 1981, Tumbleson and Kommedahl 1961).   Half-life was 4.4 to 5.8 months (Stoller and Wax 1973).

Most seeds near the soil surface germinate or die within 3 years but deeply buried seeds last longer (Lapham and Drennan 1990).  Germination of seeds stored in cold moist conditions was less than for seeds stored in cold dry conditions (Bell et al. 1962).

Season of emergence:  Dormant tubers sprout in mid-spring and form a non-dormant basal bulb near the soil surface from which the shoot emerges from late spring to early summer (Stoller 1981).  Later emerging shoots arise primarily from upturned rhizomes (Jansen 1971, Stoller et al. 1972).  These thicken to form additional basal bulbs and above-ground shoots.  Such shoots will continue to form throughout the growing season. 

Seed germination is in the spring, but seedlings are extremely rare.

Emergence depth:  Percentage emergence is greatest when tubers are in the top 4 to 8” (10 to 20 cm) of soil (Bell et al. 1962, Stoller and Wax 1973), but emergence from up to 32” (81 cm) has been recorded. 

Seedlings emerge best from seeds very near the soil surface.  A few seedlings can emerge from up to 1” (2.5 cm), but none from 1.5” (3.8 cm) (Bell et al. 1962).  Successful emergence and establishment requires long periods of wet soil, so seedling establishment in agricultural fields is rare (Lapham & Drennan 1990). 

Photosynthetic pathway:  C4 (Elmore and Paul 1983)

Sensitivity to frost:  The foliage is sensitive to frost (Bell et al. 1962).  Only the tubers overwinter, and even these survive poorly at soil temperatures below 20 °F (-7 °C) (Stoller and Wax 1973).  Tubers at shallow depths of 1 to 2” (2.5 to 5.1 cm) are most susceptible to winterkilling (Stoller and Wax 1973).

Drought tolerance:  Yellow nutsedge can tolerate a few weeks of drought, but growth and tuber production are enhanced by soil moisture conditions optimum for crops (Bell et al. 1962, Ransom et al. 2009).

Mycorrhiza:  Yellow nutsedge is readily colonized by mycorrhizae (Norsworthy and Meehan 2005).

Response to fertility:  This species is relatively unresponsive to soil fertility (Bell et al. 1962, Ransom et al. 2009).  However, soil amendments with a low C:N ratio (= 10) and high soil N content increased above-ground growth and decreased below-ground growth and tuber production compared to amendments with a high C:N ratio (= 40) and low soil N content (Shrestha et al. 2018).

Soil physical requirements:  Yellow nutsedge tolerates a wide range of soil texture and drainage conditions, including sustained flooding (Stoller 1981), but it does poorly on sandy soils (Tumbleson and Kommedahl 1961) unless the field is irrigated regularly.

Response to shade:  This species tolerates shade poorly, but can still produce some tubers at low light levels (Bell et al. 1962, Jordan-Molero and Stoller 1978, Keeley and Thullen 1978, Stoller 1981).

Sensitivity to disturbance:  Yellow nutsedge plants are most sensitive to disturbance after several leaves have formed.  At this point, the original tuber and the newly formed basal bulbs are both low on stored carbohydrates and any new shoots that sprout will be weak.  After that, tubers may be spread around the field by tillage and cultivation implements.

Time from emergence to reproduction:  Most reproduction occurs by formation of tubers, and these can begin forming within 3 weeks of shoot emergence from the previous tuber.  Typically, however, long days promote basal bulb formation and vegetative growth, while tuber formation occurs as daylength shortens in the fall (Jansen 1971, Stoller 1981).  Tuber formation of plants that emerged in spring begins in late summer at a day-length of 14 hours, but is delayed by a month or more if emergence did not occur until summer (Jordan-Molero and Stoller 1978).

Flowering occurs from July to September when day-length is 12-14 hours (Jansen 1971).  Time from emergence to flowering in Wisconsin was 8 weeks (Doll 2002).  Plants grown in the field from seed sown in late May flowered in late August and September (13-16 weeks) (Bell et al. 1962).  Viable seeds are produced beginning 2 to 3 weeks after flowers open (Bell et al. 1962, Thullen and Keeley 1979).          

Pollination:  Yellow nutsedge is wind pollinated and is self-sterile. 

Reproduction:  Most reproduction is vegetative (Stoller 1981) and occurs via both production of tubers and production of new shoots from rhizomes.  By the end of the season more than one-third of the total plant dry weight is composed of tubers (Stoller 1981).  A single tuber planted in Minnesota and allowed to grow without competition or management produced 6,900 tubers by the fall and 1,900 daughter plants the following spring in a 34 square ft (3.2 square m) patch (Tumbleson and Kommedahl 1961).  A single tuber in eastern Oregon produced 20,000 tubers (Ransom et al. 2009). 

No seeds are produced by about 90% of populations because they are composed of a single clone.  One seed producing population averaged 1,500 viable seeds per inflorescence.  Only 1 to 17 % of flowers contain seeds (Thullen and Keeley 1979).

Dispersal:  Since seedlings are very rare, dispersal is primarily by transport of the tubers.  The low genetic diversity among yellow nutsedge populations is consistent with asexual dispersal by tubers (Horak et al 1987).  In natural conditions transport is by water.  Populations probably occasionally establish in low lying fields when flood waters wash in tubers.  Most populations in agricultural fields probably establish from tubers brought in on tillage and cultivating machinery.  Sources of new populations include root balls of nursery stock and topsoil that is spread after construction (Follak et al. 2015).  If uprooted nutsedge plants are composted at low temperatures, the resulting compost can potentially spread the weed.

Common natural enemies:  Few natural enemies have been reported for this species, and our observations in central New York indicate negligible damage by natural enemies in the field.

Palatability:  The foliage is unpalatable.  The tubers or “tiger nuts” are highly palatable, and have been a foodstuff in Mediterranean countries for centuries (Sánchez-Zapata et al. 2012).  Tiger nuts have higher oil, protein and starch content than most tuber crops, and a milky beverage product of tiger nuts called "horchata de chufa" is considered a health drink.  The domestic "chufa" is a variety of yellow nutsedge (Stoller 1981).  It is commonly planted to attract wildlife by sportsmen (C. Johnson, personal communication).  Swine are fond of the tubers.

Note:  Yellow nutsedge tubers and tuber extracts are allelopathic to crops (Drost and Doll 1980).

References:

• Bell, R. S., W. H. Lachman, E. M. Rahn, and R. D. Sweet.  1962.  Life history studies as related to weed control in the Northeast. 1. Northern nutgrass.  Bulletin 364, Agricultural Experiment Station, University of Rhode Island: Kingston, RI.
• Chase, C. A., T. R. Sinclair, D. G. Shilling, J. P. Gilreath, and S. J. Locascio.  1998.  Light effects on rhizome morphogenesis in nutsedges (Cyperus spp.): Implications for control by soil solarization.  Weed Science 46:575-580.
• Daugovish, O., and M. J. Mochizuki. 2010.  Barriers prevent emergence of yellow nutsedge (Cyperus esculentus) in annual plasticulture strawberry (Fragaria X ananassa).  Weed Technology 24:478-482.
• Doll, J.  2002.  Knowing when to look for what:  Weed emergence and flowering sequences in Wisconsin.  https://extension.soils.wisc.edu/wp-content/uploads/sites/68/2016/07/Doll-2.pdf
• Drost, D. C., and J. D. Doll.  1980.  The allelopathic effect of yellow nutsedge (Cyperus esculentus) on corn (Zea mays) and soybeans (Glycine max).  Weed Science 28:229-233.
• Eckerman, L.  2001.  Suppression of yellow nutsedge (Cyperus esculentus) using a rye cover crop in reduced tillage corn.  M. S. Thesis, Cornell University.
• Elmore, C. D., and R. N. Paul.  1983.  Composite list of C4 weeds.  Weed Science 31:686-692.
• Felix, J., and R. A. Boydston.  2010.  Evaluation of imazosulfuron for yellow nutsedge (Cyperus esculentus) and broadleaf weed control in potato.  Weed Technology 24:471-477.
• Follak, S., U. Aldrian, D. Moser, and F. Essl.  2015.  Reconstructing the invasion of Cyperus esculentus in Central Europe.  Weed Research 55:289-297.
• Harrison, H. F. Jr., and J. K. Peterson.  1991.  Evidence that sweet potato (Ipomoea batatas) is allelopathic to yellow nutsedge (Cyperus esculentus).  Weed Science 39:308-312.
• Horak, M. J., J. S. Holt, and N. C. Ellstrand.  1987.  Genetic variation in yellow nutsedge (Cyperus esculentus).  Weed Science 35:506-512.
• Jansen, L. L.  1971.  Morphology and photoperiodic responses of yellow nutsedge.  Weed Science 19:210-219.
• Johnson III, W. C., R. F. Davis, and B. G. Mullinix Jr.  2007.  An integrated system of summer solarization and fallow tillage for Cyperus esculentus and nematode management in the southeastern coastal plain.  Crop Protection 26:1660-1666.
• Johnson III, W. C., T. R. Way, and D. G. Beale.  2015.  An undergraduate student project to improve mechanical control of perennial nutsedges with a peanut digger in organic crop production.  Weed Technology 29:861-867.
• Jordan-Molero, J. E., and E. W. Stoller.  1978.  Seasonal development of yellow and purple nutsedges (Cyperus esculentus and C. rotundus) in Illinois.  Weed Science 26:614-618.
• Keeley, P. E., and R. J. Thullen.  1978.  Light requirements of yellow nutsedge (Cyperus esculentus) and light interception by crops.  Weed Science 26:10-16.
• Lapham, J., and D. H. Drennan.  1990.  The fate of yellow nutsedge (Cyperus esculentus) seed and seedlings in soil.  Weed Science 38:125-128.
• Mulligan, G. A. and B. E. Junkins.  1976.  The biology of Canadian weeds. 17. Cyperus esculentus L.  Canadian Journal of Plant Science 56:339-350.
• Norsworthy, J. K., and J. T. Meehan.  2005.  Wild radish-amended soil effects on yellow nutsedge (Cyperus esculentus) interference with tomato and bell pepper.  Weed Science 53:77-83.
• Ransom, C. V., C. A. Rice, and C. C. Shock.  2009.  Yellow nutsedge (Cyperus esculentus) growth and reproduction in response to nitrogen and irrigation.  Weed Science 57:21-25.
• Sánchez-Zapata, E., J. Fernández-López, and J. Pérez-Alvarez.  2012.  Tiger nut (Cyperus esculentus) commercialization: Health aspects, composition, properties, and food applications.  Comprehensive Reviews in Food Science and Food Safety 11:366-377.
• Shrestha, U., E. N. Rosskopf, and D. M. Butler.  2018.  Effect of anaerobic soil disinfestation amendment type and C:N ratio on Cyperus esculentus tuber sprouting, growth and reproduction.  Weed Research 58:379-388.
• Stevens, O. A.  1932.  The number and weight of seeds produced by weeds.  American Journal of Botany 19:784-794.
• Stoller, E. W.  1981.  Yellow Nutsedge: A Menace in the Corn Belt.  U.S. Department of Agriculture Technical Bulletin No. 1642.  16 p.
• Stoller, E. W., D. P. Nema, and V. M. Bhan.  1972.  Yellow nutsedge tuber germination and seedling development.  Weed Science 20:93-97.
• Stoller, E. W., and L. M. Wax.  1973.  Yellow nutsedge shoot emergence and tuber longevity.  Weed Science 21:76-81.
• Thullen, R. J., and P. E. Keeley.  1979.  Seed production and germination in Cyperus esculentus and C. rotundus.  Weed Science 27:502-505.
• Tumbleson, M. E., and T. Kommedahl.  1961.  Reproductive potential of Cyperus esculentus tubers.  Weeds 9:646-653.
• USDA Plants.  USDA, Natural Resources Conservation Service.  Plants Database. http://plants.usda.gov/
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• Webster, T. M.  2003.  High temperatures and duration of exposure reduce nutsedge (Cyperus spp.) tuber viability.  Weed Science 51:1010-1015.
• Webster, T. M.  2005a.  Mulch type affects growth and tuber production of yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus).  Weed Science 53:834-838.
• Webster, T. M.  2005b.  Patch expansion of purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) with and without polyethylene mulch.  Weed Science 53:839-845.