Common weeds in rice fields are grouped into three categories Grasses, Sedges and Broad leaved weeds Grasses Grasses are the monocots with two ranked leaves, that are usually long, narrow and upright with parallel venation's. Resemble rice crop the stems are more or less round in shape, possess nodes, internodes are generally hollow with scattered vascular bundles. Leaves have ligule and auricle at the junction of lamina and leaf sheath. Some of the grassy weeds are as follows, Echinochloa colonum Echinochloa crussgalli Setaria glauca Digitaria longifolia Dactyloctenium aegyptiacum Cynodon dactylon Saccharum munja Eleusine indica Eragrostis interupta Paspalum scrobiculatum Leersia hexandra Eragrostis aspera

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Sedges Sedges are very similar to grasses but have three ranked leaves. The stems are usually triangular and they won't possess nodes and internodes. Several species have modified rhizomes which are used for food storage and propagation. Some of the sedges are given below Cyperus rotundus Fimbristylis milliaceae Cyperus iria Cyperus difformis Scirpus erectus Cyperus haspan Biological Control of Weeds Certain insects and microbes feed on weeds and contributing to the weed control. Some of the examples where the weeds are controlled through biological method are furnished below. Weed Species Natural Enemies Cyperus rotundus Athesapenta cyperi (Rhizome and stem  boring weevil), Bactra minima (Tertric stem borer), Bactra venesoma. Salvinia molesta (Water fern) Grasshoppers (Paulinia acuminata) Hydrilla, Chara (Water fern) White amur, Tilapia (Fishes).

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Broad Leaved Weeds Broad leaved weeds are usually dicots with tap root system. The stem has branches and leaves with a net venation. Some of the broad leaved weeds are Eclipta alba Commelina benghalensis Sphenoclea zeylanica Monochoria vaginalis Ludwigia parviflora Aegetarum conyzoides Eichornia crassipes Salvinia molesta Alternanthera sessilis Ammanea baccifera Details of Weeds in Rice Common name Botanical Name Family Plant Description Habitat Method of propa-gation Suitable herbi-cides No of seeds Goat weed Agera- tum cony- zoides Compo- sitae An erect branched annual Garden lands and wet lands By seeds like achenes 2,4-D --- --- Astera-canta Longi- folia Acantha-ceae A tall herb with dense clusters of narrow leaves and long woody spines Rice field & Margins of tanks By seeds 2,4-D & 2,4,5-T ---   Centella asiatica Umbelli- feraceae A prost-rate herb Rice fields along bunds of irri-gation chan-nels By bits of fruits 2,4-D --- Cara-velle seed Cleome gynandra Cappa- ridaceae Annual Rice fallows & cultiv-ated lands seeds 2,4-D 8000 Tropical spider wort Com-melina bengha-lensis Comma-linaceae A Fleshy, branched perennial herb Culti-vated fields & waste lands seeds 2,4-D --- Field bind weed Convo-lvulus arvensis Convol-vulaceae An obnoxious weed with a deep root system Culti-vated fields & waste places By seeds & Under ground stems --- 200 to 400 more   Crota-laria quin-quefolia Legumi-naceae An errect annual herb Rice fields in coastal areas By seeds --- 2500   Cyanotis axillaris Comme-linaceae A succulent annual herb In rice fields and moist situ-ations By seeds and bits of stem 2,4-D --- Ber-muda grass or Dub grass Cynodon dactylon Grami-naeceae A perenneal hardy and much branched herb Culti-vated fields ,waste lands By grains & under ground stems Dala-pon TCA, Amitrol --- Bulb grass Cyperus bulbosus Cype-raceae An errect herb growing in small clumps Culti-vated and waste places By bulbs & Nuts Chloro-picrin, Methyl bromide ---   Cyperus difformis Cype-raceae An errect, tuffed, glabrous annual Rice fields By seeds --- ---   Cyperus iria Cype-raceae An erect glabrous annual Rice fields, Marshy places and in ponds & ditches during mon- soon By seeds --- --- Nut grass Cyperus rotundus Cype-raceae An erect, glabrous perennial herb Culti-vated lands & waste fields By seed like Nuts and under-ground stems Chloro-picrin, methyl bromide 3000 / aerial shoot

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