Common name : Nutsedge, nutgrass, purple nutsedge
Common name in Bengali : Mutha, badhail, bedalle, dila motha, nagarmuta
Common name in Hindi : Motha, dila
Common name in Urdu : Mork, deela
Bangla English Hindi Urdu
Diagnostic characters
Biology
Ecology and distribution
Nuisance
Weed control
Botany
Uses/Remark
References
Cyperus rotundus is the world’s worst weed native to India.It grows in small clump up to 100cm high; it as a dark green basal leaves which are shorter than the inflorescence; a three sided inflorescence stem, with a dark thickening at the base.It grows on moist, fertile soils, and has an extensive subterranean system of rhizomes and tubers. The rhizomes can penetrate and pass completely through root crops.The outstanding characteristic of this plant is its prolific production of underground tubers that can remain dormant and carry the plant through the most extreme conditions of heat, drought or flooding.The common name purple nutsedge remind the reddish to purple brown inflorescence.
Purple nutsedge is a perennial plant; it multiplies mainly by its branched network of underground stems, the length of which form tubers. This propagation may be favoured during cultivation as they readily break off from the connecting rhizomes. The subterranean network of rhizomes produces tubers at intervals and those tubers near the surface give rise to aerial shoots. The tubers have an extensive root system that may reach deeply into the soil. Dissemination by seeds is very weak.
Native to India, purple nutsedge has been reported from more countries, regions and localities than any other weed in the world. It is found in all soil types and from sea level to high-mountain altitudes. It grows in wet but well drained soils and also in dry soils or climates. It is sensitive to shading, with markedly reduces tuber production, leaf area index and dry matter production. It prefers sunny or lightly shaded localities in crops.
C. rotundusis reported to be a weed in 52 crops in 92 countries. It is found in cultivated fields, on road-sides, in neglected areas and the edges of woods, and it may cover the bank of irrigation canals and streams. It may be a serious problem in paddy rice in which the soil is puddle. In seasons of low water supply, when padding cannot be done thoroughly or when the water supply fails after the rice has been transplanted, the nutsedge growing in the drying soil may choke the crop. The tubers are moved in mud on the feet of men and animals and by being caught on machinery. They are also brought into new areas when streams flood after storms, and they are distributed in surface irrigation water.
- Cultural
Being sensitive to shading, C. rotundus can be controlled by narrow row spacing and high plant density of crops to provide rapid shading of the soil surface. In traditional rice-growing areas in India C. rotundus is controlled using pigs. Usually, the pigs are fed with vegetable waste and allowed to forage for tubers in wastelands. Because the tubers are succulent and sweet, pigs are fond of them. They can easily remove the tubers even if the soil is hard. Usually, the field is soaked with water and puddle well and then the pigs are introduced. An animal can collect 2-4 kg of tubers in one day and 60-75 animals can remove the tubers from 1 ha in one day.
- Biological
The tortricid Bactra verutana has been evaluated for efficacy as a biological control agent for C. rotundus. Regardless of the stage of the moth upon release, the degree of control depended on the age and condition of the plant. Rates of infestation were high only when a majority of the shoots were 10-21 days old and growing vigorously.
- Chemical
C. rotundus is difficult to eradicate, but control is most effective when herbicide use is integrated with mechanical weeding. The tuber population can be reduced by repeated application of 2_4-D and cultivation. Five 2_4-D applications at 30 days intervals followed by soil disturbance reduced tuber population by 86%. This can only be done successfully in fallows. In rice crops, almost complete control can be achieved using herbicide combinations such as pre-plant application of 2 kg of glyphosate, followed by 2_4-D at 1 kg ha-1 at 20 days after sowing.
Habit
Purple nutsedge is an erect, glabrous perennial herb growing in small clump up to 100cm high. The leaves are erect and arranged in three directions.
Roots, rhizomes & tubers
Roots fibrous, extensively branched, clothed with bent hairs.The plant spread by extensive, horizontal, slender network of rhizomes which are white and fleshy and covered with scale leaves when young, becoming brown, fibrous or “wiry” when old; rhizomes give rise at intervals of 5 to 25cm to underground tubers which continue to proliferate, forming tuber chains that extend to a considerable depth in the soil.Tubers 2-3cm long and 1cm large, white and succulent when young turning fibrous brown or almost back with age, with strong peppery odour when crushed, covered with papery scale leaves; this scales have axillary buds that form new plants.
Stem
Culms erect, triangular in cross section, smooth 20 to 100cm high, usually longer than the basal leaves. These culms correspond of flowering axis. The base of the plant is swollen, referred to as a basal bulb, forming a thickened.
Leaves
Linear, acute, arranged in three directions, 10 to 50cm long, 5-8mm wide arising from very compact nodes in basal clusters in three rows, through the center of which the upright fertile stem arises. Blade glabous, shiny, dark green, double folded section with margin and midvein scabrous.
Inflorescence
Loose umbel, simple or slightly compound, subtended by two or four leaf like bracts 5 to 25cm long, usually as long as the flower-bearing rays. Flowers in linear and flat spikelets grouped at the end of the umbel rays. Spikelets 0.5 to 4cm long and 2mm wide, 10 to 40 flowered alternate distichously, red, reddish brown or purple brown; glumes closely apprised, prominently 3 to 7 nerves, with a short mucro, reddish to deep brown or purplish brown; calyx and corolla absent; stamens three; style three-branched.
Fruit
Achene (nut) ovate or oblong-ovate, 1.5mm long, 0.8mm wide, three angled, surmounted by the stigma, olive-gray to brown or black in colour.
- Le Bourgeois T., Jeuffrault E., Grard P., Carrara A. 2001. AdvenRun V.1.0. Les principales mauvaises herbes de La Réunion. CD-ROM. Cirad, SPV. France.
- Holm L. G., Plucknett D. L., Pancho J. V., Herberger J. P. 1991. The world’s worst weeds. Distribution and Biology. East-West Center by the University Press. Hawaii.
- Galinato M., Moody K., Piggin C. M. 1999. Upland rice weeds of South and Southeast Asia. IRRI. Philippines.
- Radanachaless T., Maxwell J. F. 1994. Weeds of soybean fields in Thailand. Multiple Cropping Center Publications. Thailand.
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