Weed Management in rice

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I.     Effect of weeds on rice
II.   Types of weeds found in rice
III.  Critical period of crop weed competition
IV.   Methods of weed control

 I. Effect of weeds on rice

1. Reduce the yield and quality of rice by competing for nutrients, water and sunlight

          Upland direct seeded rice          :  35-45% reduction in yield
          Direct seeded on puddle land     :  20-25% reduction in yield
          Transplanted rice                     :  10-15% reduction in yield 

2. Weeds intensify the pest and disease problem by serving as alternate host
3. Reduce the efficiency of harvesting
4. Reduce the land value
5. Problems of water contamination

 

II. Types of weeds

A. Low land rice

1. Annual grasses

Echinocloa crusgalli  ssp. Hispidula (Barn yard grass)
Kannada Name: Kadu dabbe hullu
Family: Poacea
Description:

• Tufted annual grass.
• Height - 30- 60 cm with thick, coarse, mostly erect smooth and branching at the base.
• Sessile leaf blades attached to a smooth sheath which encircles the stem in the absence of ligule. The leaf blade is 10-30 cm long and 5-20 mm wide. Midrib is prominent.
• Stem is stout. Culms branches at the base and produce tillers.
• Inflorescence is 10-20 cm long with slender spike like. Panicle green or purplish in colour. Spikelets are densely crowded in 2-4 rows on each side of the stem. Seeds are light orange yellow in colour.
• Adventitious root system.
• Widely distributed throughout the warm tropics.
• Propagation - seeds.

Echinocloa colonum L. Link ( Jungle rice)
Kannada Name: Oodalu, kadu haraka hullu
Family: Poacea
Description:

• Slender annual
• Height - 60-90 cm. Stem is creeping below and erect above, with rooting at lower nodes. Leaf blade 7.5 to 15 cm long; often blotched with purple or almost black cross bands. Ligule is absent.
• Inflorescence is a panicle branching racemes rather distant.
• Widely distributed throughout the warm tropics.
• Propagation - seeds

 

Annual broad leaf weeds (dicotyledons)

Monochoria vaginalis ( Monochoria)
Kannada Name: Tamaara
Family: Pontederiaceae
Description:

• Root stock short and sub erect
• Leaves linear or narrowly ovate with cordate base 5 to 15 cm long
• Pedicel long; flowers in recemes, usually blue spotted with red;petaloid; perianth;1-6 stamens inserted at the base of perianth; ovary superior, tricarpellary 3 celled with many ovules in each cell; fruit a capsule.
• Propagation - seed and root stock.
• Thrives well in moist places

 

Ludwigia parviflora L. Roxb
Family: Onagraceae
Description:

• Annual herb
• Height - up to 60 cm
• Leaves linear or lanceolate; simple, alternate
• Flowers small, axillary, solitary, yellow; calyx tube narrow with 4-6 lobes; corolla 5 lobed; stamens 8-10; ovary inferior,4-5 carpels, 4-5 celled, ovules many in, vertical rows; fruit a capsule smaller, 4 sided, about 2 cm long with persistent calyx at the tip; seeds small, pink
• Propagation - seeds.

 

Marselia quadrifolia L. ( Marsilea)
Family: Marsileaceae (Pteridophyta)
Description:

• Amphibious herb with procumbent rhizomes and variable leaves
• Sporocarps produced only on exposure to air not during emergence
• Petiole adjusting its length to the depth of water; occurs in paddy field and floats on running water.
• Propagation- rhizomes

 

Annual sedges

Cyperus  difformis L.
Kannada Name: Kari sanna jambu hullu
Family: Cyperaceae
Description:

• Slender weak plant.
• Stem tufted, 12.5 to37.5 cm long
• Leaves flaccid, as long as the stem; bracts 2-3, 5 to 20 cm long
• Spikelets many, densly grouped into congested globose heads; glumes obovate, apex rounded; nut subequally trigonous, yellow or pale brown.

 

Cyperus   iria L. (Umbrella sedge)
Kannada Name:  Dabbe jambu hullu
Family: Cyperaceae
Description:

• Widely distributed species in paddy fields
• Stems 15 to 50 cm high, trigonous
• Leaves up to 42.5 cm long; bracts 3-5 to 25 cm long; spike consists of 5-15 spikelets; spikelets linear, oblong, yellow or pale brown; glumes plicate; nuts trigonous, oboviod, black.

 

Fimbristylis milacea L. Vahl.
Family: Cyperaceae
Description:

• Stems weak;12.5 to 45 cm high;
• Leaves narrow, acuminate; bracts 2-3;
• Spikelets subglobose; glumes broadly ovate, brown or medium brown;
• Nuts three angled, yellowish brown
  

 

Perennial grass

Panicum  repense L.
Kannada Name: shunti hullu
Family: Poaceae
Description:

• Creeping perennial
• Leaves - 15-25 cm long and 1.5 cm wide or less, linear, flat or folded, with a round base.
• Panicles are 6-18 cm long, somewhat loose and open and erect.
• Spikelets are two flowered pale green or pale yellow.
• Persistent weed
• Propagates - vegetatively through rhizomes. Rhizomes are knotty and swollen and send out erect culms from nodes.

 

Paspalum  conjugatum Berg ( Hilo grass)
Kannada Name:
Family: Poaceae
Description:

• Creeping solaniferous perennial grass
• Culms are 20-40 cm long, erect with smooth nodes.
• Leaves are 5-20 cm long 5-15 mm wide, lanceolate, smooth, flat and hairy with rough or stiffy hair margins.
• The spikes are paired at the apex of culm, widely spreading straight or arched. The spikelets are flattened pale green the margin fringed with long white silky hairs. Root is fibrous and shallow. Nodes strike roots when comes in contact with soil.
• Propagation - runners and seeds. It also spreads quickly through stolons.
• It is prominent in humid tropics and is a serious weed in India.

 

Perennial sedges

Scirpus  maritimus L. ( Bull rush)
Family: Cyperaceae
Description:

• Rhizomatous plant. Rhizomes with tubers
• Stems rigid, erect 30-120 cm high; leaves often as long as stem; bracts 3-5, up to 10 cm long; spikelets 2 to many in umbels; clustered, glumes broadly ovate, brown or golden brown; nut acute, smooth, dark, olive-brown, shining.
• Propagation -rhizomes.

 

B. Upland rice

Annual grasses (Graminae family)

Echinochloa colonum L. Link ( Jungle rice)
Kannada Name: Oodalu, kadu haraka hullu
Family: Poacea
Description:

• Slender annual
• Height - 60-90 cm. Stem is creeping below and erect above, with rooting at lower nodes. Leaf blade 7.5 to 15 cm long; often blotched with purple or almost black cross bands. Ligule is absent.
• Inflorescence is a panicle branching racemes rather distant.
• Widely distributed throughout the warm tropics.
• Propagation - seeds

 

Digitaria  sanguinalis L. scop (Large crab grass)
Family: Poacea
Description:

• Annual grass
• Culms are stout, smooth and 30-90 cm long when prostrate.
• Plant strikes roots when nodes touch the soil
• Leaves 5-15 cm long, 5-10 mm wide and somewhat hairy;
• Spike is 5-15 cm long, with 3-13 finger like segments in whorls at the top of the stem. Spikelets are 3 mm long paired along one side of the rachis. Though it is annual it exhibits perennial growth. It flowers between July and September.
• Propagation - seeds
• Thrives both in tropical and temperate climates, moist as well as dry and hot weather conditions

 

Eleucine  indica L. Gaertn (Goose grass)
Kannada Name: Hechhuli hullu
Family: Poacea
Description:

• Coarse tufted annual grass
• Height of 30-45 cm with laterally flattened shoots.
• Leaf blades are flat.
• The inflorescence consists of 4-8 narrow finger like spikes, 4-15 cm long, arising from the top of the stem to form a spreading umbel. The spikelets are sessile on one side of the rachis, 3-5 mm long and densely crowded in two rows along the lower side of the spike. Each spikelet consists of 5 florets which are without bristles.
• The roots are fibrous, deep and spreading.
• It flowers between June and September. 
• Propagation - seeds and old roots
• Distributed throughout India

Dactyloctenium  aegyptium L. Beauv. (Crowfoot grass)

Kannada Name: Kadu ragi hullu, Konana tale hullu
Family: Poacea
 
Description:

• Height - 10-62.5cm
• Leaves flat, 5-20cm long, glabrous;
• Inflorescence of 2-5 spikes in terminal umbel, dark olive-grey, digitately radiating; the rachis projecting in a point beyond the spikelets.

 

Annual broad leaf weeds (dicotyledons)

Amaranthus  spinosus L. Spiny amaranth
Kannada name: Mullu kire soppu
Family: Amaranthaceae
Description:

• Erect spinous herb
• Stem reddish; it has pair of straight spines of 1 cm long at the base of petioles. Leaves long petioled, ovate or oblong, leaf axils with spines;
• Flowers in dense or lax axillary panicles, bracteate, bracts setaceous, bristle tipped, unisexual; perianth 5 lobed, acuminate in the male flowers; obtuse in the female flowers stamens 5; ovary compressed; styles short, filiform; utricle with a thickened top.
• Propagation - seeds.
• Distributed in warm areas

 

Ageratum   conyzoides L. Goat weed

Kannada Name: Ooraala gida, Muguti gida
Family: Asteracae
Description:

• Winter annual
• Erect, softly hairy and 50-90 cm tall annual herb;
• Leaves opposite soft stalked, ovate, 2-10 cm long, 0.5 to 3 cm wide with a pointed tip and the margin regularly serrated with blunt teeth.
• Stem is erect, hairy, cylindrical and nodes enlarged.
• Inflorescence is terminal often axillary and made of several branches each bearing a number of flower heads arranged in a showy flat topped cluster. Flowers light blue, purple or violet. Flower head contains 50-70 tubular flowers which are surrounded by 2 or 3 rows of narrow, pointed bracts.
• Fruit is achene black and ribbed with pappus of fine sift hairs on the upper end.
• Propagation - seeds.
• Distributed in tropical and subtropical countries

 

Celosia argentia L. ( Cox comb)

Kannada Name: Anne soppu, Anne huvu
Family: Amaranthaceae
Description:

• Erect glabrous tall herb with 1-1.5 m tall;
• Leaves alternate, simple and unbranched.
• Inflorescence is pinkish white and the plants can be recognized from a distance in the field.
• Two distinct forms of Celosia argentia with lanceolate acute leaves and the other with ovate obtuse leaves.
• Stamens 5 united blow a cup, anthers 2 celled. Ovary 1 celled ovoid: style filiform.
• Shallow root system.
• Propagation -seeds which germinates with the onset of rains.

 

Commelina  benghalensis L. Day flower

Kannada Name:Kanne soppu, Kannaalu
Family: Commelinaceae
Description:

• Broad leaf herbaceous weed
• Widely distributed in the tropics.
• Succulent or fleshy creeping and rooting below
• Lower nodes some times develop naked under ground shoots which bear small white flowers ripening into seeds under ground.
• Leaves are alternate, simple parallel veined and ovate with entire margin contracted at the base into a narrow stalk like portion and a sheath enclosing the stem. The broken pieces of stem can strike roots and grow as a separate plant. Flowers blue, under ground flowers white; sepals 3, petals 3, two long clawed; stamens 3, perfect, 2-3 imperfect; capsule membranous, shining, dorsal valve striolate.
• Seeds closely pitted.
• It s well adapted to moist swampy conditions making rapid growth and thick infestation can smother low growing crops.
• Propagation - broken pieces of stem.

 

Eclipta alba

Family: Asteraceae
Description:

• Diffusely branched annual herb.
• Leaves opposite, sessile, linear or oblong lanceolate narrowed at both ends;
• Heads small, axillary or terminal peduncles slender; Outer flowers female, fertile or sterile; corolla linear, ligulate, white or yellow; inner bisexual flowers tubular, fertile; style arms short, flattened; pappus minute, toothed.
• Propagation - seeds.
  

 

Portulaca  oleracia L.Common purslane

Kannada Name: Dodda gone soppu
Family: Portulacacaeae
Description:

• Prostrate succulent herb.
• It produces by seeds and stem fragments.
• Stem is succulent, fleshy, freely branched, normally forming mats when infesting intensively. Branches often reddish or purplish.
• Leaves thick, fleshy, spirally arranged or opposite. They are sessile with smooth margins and broad-rounded tips, 0.5 to 2.0 cm wide.
• The flowers are yellow, sessile and found solitary in the leaf axils or as clusters at the terminal end; ovary half inferior; Ovules numerous, capsules circumcises, crustaceous.
• Distributed throughout the tropical and subtropical areas.
• It thrives well in moist and irrigated areas.
• The stem fragments can reestablish and survive as individual plants.

 

Trianthema  portulacastrum L ( Horse purslane)

Kannada Name: Pasale soppu
Family: Aizoaceae
Description:

• Prostrate, profusely branching, glabrous annual herb
• Leaves opposite, petioled. Petiole sheathing at the base, obovate, in unequal pairs; Flowers solitary, sessile, sheathed by the base of the petiole; calyx 5 lobed, lobes obtuse, green above and pink inside. Ovary superior, 1-2 celled free style1, subulate.

 

Annual sedges

Cyperus iria L.  umbrella sedge

Kannada Name:  Dabbe jambu hullu
Family: Cyperaceae
Description:

• Widely distributed species in paddy fields
• Stems 15 to 50 cm high, trigonous
• Leaves up to 42.5 cm long; bracts 3-5 to 25 cm long; spike consists of 5-15 spikelets; spikelets linear, oblong, yellow or pale brown; glumes plicate; nuts trigonous, oboviod, black.

 

4. Perennial grasss

Imperata  cylindrica L. Beauv. ( Cogon grass)

Kannada Name: Niru hatti hullu, Sanna darbe hullu
Family: Poaceae
Description:

• One of the worlds worst weed and has extensive and deep penetrating system of rhizomes.
• Height of 60-120 cm.
• Leaves are linear, upright, with rough sharp edges and a long tapering point.
• The panicle is 20-30 cm long, 0.5 to 2 cm wide, and silky with silvery white dense, fluffy, wooly hairs amidst which are concealed the spikelets with purple stigma and yellow anthers. The spikelets are lanceolate to oblong. It is a prolific seed producer.
• A crop of one hectare of Imperata may produce 4.5 million shoots, more than 10 tonnes of leaf material and 6 tonnes of rhizomes.
• The root system is fibrous.
• It flowers between May and September.
• Propagation- seeds and rhizomes

 

Cynodon  dactylon L. (Bermuda grass)

Kannada Name: Garike hullu, Kadu garike
Family: poacea
Description:

• One of the worlds worst weed
• Perennial grass with long runners which strike roots at the nodes and extensive under ground rhizomes.
• The leaves are 3-20 cm length. Membranous ligule is absent.
• The flowering stems may be 15-50 cm long.
• The inflorescence consists of 4-5 slender purplish spikes of 10 cm long. The spikelets are light green or purplish, sessile, laterally compressed alternatively 2- seriate, imbricate and 1-flowered.
• Propagation - vegetatively more than by seeds.

 

5. Perennial sedges

Cyperus   rotandus L. (Purple nut sedge)

Kannada Name: Konnari gedde, Tunge hullu
Family: Cyperaceae
Description:

• One of the worlds worst weed.
• Height -15-60 cm.
• The plant is swollen and thickened at the base. It has triangular smooth scape, 10 to 60 cm in height, arising from the centre of a basal cluster of narrow grass like leaves of 30-50 cm long and 8 mm wide.
• The leaves are smooth shiny, dark green and grooved on the upper surface.
• The slender underground runners grow out from the base of the stem and form series of black, irregular shaped or nearly round tubers which are 2 cm in length. Tubers sprout to produce new plants while still attached to parent plant.
• The inflorescence arises from stem apex. It consists of a number of slender branches which carries a cluster of spikelets at the end which are brown to dark brown in colour. Each spikelet consists of 10-30 small crowded florets which ripen to form black triangular nuts.
• The rhizomes give rise to underground tubers which proliferates intensively. Tubers are concentrated in the surface 10 cm soil and store food and are effective means of propagation. New tubers are produced within 3 weeks after sprouting of individual tuber. Tubers have nodes, internodes and scale leaves.
• The plant is sensitive to shade.

 

III. Crop-weed competition - Depends on

1. Type of rice culture

• up land- severe competition
• Low land- Less competition
• Deep water- Less competition

2. Method of crop establishment

• Transplanting- Less to moderate
• Direct seeding- Severe competition

3. Variety

• Tall - Less competition
• Semi dwarf- More competition
• Low tillering- More weed competition
• High tillering- Less competition

4. Cultural practices

• Land preparation
• Puddled - Less competition
• un puddled- More competition

Critical period of crop weed competition:

• The period from sowing up to which the crop has to be maintained in a weed free environment for remunerative crop production 

How long we should keep the rice field free of weeds?

• Transplanted rice:  30-45 days after transplanting
• Direct seeded rice: 15-45 days after seeding

 

IV. Methods of weed control

I. Preventive methods

• They check weed introduction and spread of weed seeds.
• Easy and economical
• Preventive measures include use of weed free seeds; weed free seed bed, clean tools and machinery, clean irrigation canals.

II. Complementary practices

1. Land preparation:

           Puddling before transplanting incorporates weeds and gives rice seedlings a head start over weeds.

2. Using weed free crop seed and seedlings

3. Planting methods:

• Straight-row planting: Easy to weed by hand or by mechanical tool
• Random planting    :  Difficult to weed and to pass mechanical tool 
• Transplanting: Weed competition is less
• Direct seeding: Weed competition is severe

4. Variety:

• Tall growing traditional varieties: Compete more with weeds
• Modern semi dwarf varieties      : weed problem is more

5. Plant spacing and density

• Closer spacing: Minimize weed competition
• Higher density: Minimize weed competition

6. Fertilizer application:

• Apply fertilizer after weeding

7. Water management

• Continues submergence: Minimize weed growth
• Alternate wetting and drying: More weed growth

 

Direct methods of weed control

A. Transplanted rice

      1. Hand weeding:

• Pulling by hand or using tools like hoe, spade or sickle
• Take up one or two hand weeding between 20-42 days after transplanting

Advantages:

Most common, easy and effective. Can be taken up even where random planting is done

Disadvantage:

       Costly, Laborious

 Plates 25:  Hand weeding in paddy field (left) and weeded paddy field (right)

       2. Mechanical weeding:

• Rotary weeder: Pushed by hand or powered between straight rows

Advantages:

                Saves labour

Disadvantage:

                Require row transplanting or seeding

      3. Chemical weeding

   Herbicides: Chemicals that is capable of killing some plants (weeds) without  

                        significantly affecting the other plants (crops).

 Herbicide activity: An herbicide is said to be active or to posses activity if it hinders, inhibits or prevents the germination and growth processes of the plant. It is active on sensitive plants and inactive on tolerant plants. Herbicide activity is determined by degree of tolerance of the plant to herbicides.

 

Herbicide selectivity: Refers to phenomenon where in a chemical kills the target plant species in a mixed plant population without harming or only slightly affecting the other plants. Herbicide selectivity is the single most factors that lead to success of chemical weed control in crops.

 Advantages of herbicide:

1. Pre emergent herbicides provide early season weed control. This is beneficial as weed competition is more severe during early stages than later stages.

2. Herbicides can be applied to weed control in crop rows where cultivation is not possible.

3. Very effective than other methods.

4. Systemic herbicides can control many perennial weed and brush species which cannot be efficiently controlled by other methods.

5. They reduce the need for pre planting tillage

 

Classification of herbicides

I. Based on time of application:

Pre planting: Herbicides are applied before the crop is planted. Herbicide with greater toxicity on emerging crop seedlings are usually before crop is planted.

Pre emergence: Herbicides are applied before a crop or weeds have emerged.

Post emergence: Herbicides are applied after the emergence of weed or crop

 

II. Based on mode of activity:

Systemic or translocated herbicide:

            Herbicides that are translocated throughout the plant system and brings the activity at a place distant from the point of application

Contact herbicide:

 Herbicide that kills the plant part that comes in contact with it. Little movement from point of application

 

III. Based on selectivity:

      1. Selective herbicide: Kills only the target plant species (weeds)  

         in a mixed plant population ( crop plants and weeds).

     2. Non selective herbicides: kills all the plants that come in contact  

        with the herbicide.

 

IV: Based on Placement:

      1. Soil applied: When applied to soil

      2. Foliage applied: When applied on the foliage of weeds

 

V: Based on chemical group

1. Aliphatics:

2. Amides and acetamides

    eg. Alachlor and Butachlor

3. Arsenicals

4. Benzoics and phenyle acetates

5. Bipyridiliums

6. Carbamates & Carbanilates

7. Dinitroanilines

    e.g. Oryzalin, Pendimethalin, Trifluralin

8. Diphenyle ethers

    e.g. Nitrofen, Oxyfluorfen

9. Nitriles

10. Phenols

11. Phenoxyacids

    e.g 2,4-D

12. Pyridazinones

13. Thiocarbamates

     e.g. Benthiocarb

14. Triazines

15. Triazoles

16. Uracils

17. Ureas

18. Unclassified

        e.g. Glyphosate

 

A. Herbicides for Transplanted rice

Herbicides	Trade Name	Dose(kg/ha)		Time of application (Days after transplanting)
		a.i	Commercial product
Pre-emergent
2,4-D Ethyl ester	Weedex 5%G	0.75	15	5-7
Butachlor	Machete 50EC	1.25	2.5	5-7
Butachlor	Machete 5%G	1.5	30	5-7
Thiobencarb	Saturn	4		5
Pretilachlor	Eraze-x50 EC	0.5	1.00	5-7
Oxadiazon 25 EC	Ronstar	0.5-1.0		3-5
Oxadiargyl	Oxadiargyl 80%WP	0.1	0.125	3-5
Anilofos	Anilogaurd 30EC	0.45	1.50	5-7
Quinclorac50%WP	Facet	0.186	0.375	3-5
Bensulfuron methyl 60%DF	Londax	0.1	0.166	5
Pendimethalin	Stomp 30EC	0.9-1.0	3.0-3.5	3-5
Pyrazosulfuron ethyl		0.02-0.03		3
Post emergent
2,4-D Sodium salt 80%EC	Fernoxone	2.0	2.5	21-28
Propanil 35  EC	Stam	2.5	7.5	1-2 leaf stage
Triazolopyramidine sulfonamide		0.015-0.025		15

 

Herbicide combinations:

                  Herbicide combinations or mixtures are chemicals containing two or more herbicides for effective and economical weed control.

 

 

Advantages of herbicide combinations:

1. A mixture will control wide variety of weeds commonly present in the fields.

2. Synergistic or additive effect due to combinations may increase the weed control  

   efficiency

<!--[if !supportLists]-->3.      <!--[endif]-->Scope for reducing the application rate of herbicides.

 

 Herbicide combinations for transplanted rice

 1. Pre emergent Anilogaurd plus  (Anilofos 24% +2,4-D 32%) @ 0.85kg 

       a.i/ha 5-7 DAT  (1.50 kg/ha commercial product)

 2. Pre emergent Bensulfuron methyl 0.6%G+ Pretilachlor 6.0% G @  

         75+750g   a.i/ha (12.5 kg/ha commercial product)

 3. Pre emergent Butachlor 1.5 + 2,4-D 0.5 kg/ha

 4. Pre emergent Thiobencarb 1.5 + 2,4-D 0.5 kg/ha

 

Integrated weed Management (IWM):

                  Creative application of agronomic, mechanical biological and chemical methods usually referred to as integrated weed management.

 

  Integrated weed Management (IWM) in transplanted rice:

1.Puddling , Pre.em application of Butachlor 50EC @2.5kg/ha 5-7 days after transplanting + one hand weeding 30-40 days after transplanting

                              or

2. Puddling, Pre.em application of Butachlor 50EC @2.5kg/ha 5-7 days after transplanting + post emergent application of 2, 4-D EE @1.0 kg/ha at two to three leaf stage of weeds.

                              or

3. Puddling, Pre.em application of Oxadiargyl @0.075 kg/ha 5-7 days after

 transplanting + continuous submergence of water.

 

B. Wet seeded rice on puddled land

           1. Hand weeding:

• Pulling by hand or using tools like hoe, spade or sickle
• Take up one or two hand weeding between 20-42 days after sowing

 

  2. Chemical

Herbicide	Trade Name	Dose(kg/ha)		Time of application (Days after sowing )
		a.i	commercial
Pre-emergent
Anilofos	Anilogaurd 30EC	0.45	1.5	7
Pyrazo-sulfuron ethyl		0.025		10
Pretilachlor + safener	Eraze-x	0.75	1.5	7
Halosulfuron methyl		0.015		3
Bensulfuron methyl	Londax 60%DF	0.1	0.166	5

 

  Integrated weed Management (IWM) in wet seeded rice:

1. Pre.em application of Anilofos @ 0.4 kg/ha + 2 hand weedings at 30 and    60 DAS

1. Pre.em application of Pretilachlor  @ 0.5 kg/ha + 2 hand weedings at 30 and  60 DAS

 

C. Upland dry seeded rice

           1. Hand weeding:

               Pulling by hand or using tools like hoe, spade or sickle

              Take up one or two hand weeding between 20-42 days after sowing

          2. Mechanical weeding:

              Repeated inter cultivation by passing hoe or small blade harrow 2-3 times

              between 20-45 days after sowing

 

   3. Chemical

Herbicide	Trade Name	Dose (kg/ha)		Time of application (DAS)
		a.i	commercial
Pre-plant
Molinate	Ordram	2-3		Before sowing
Trifluralin	Treflan	1.0-1.5		Before sowing
Pre-emergent
Alachlor	Lassso 50EC	0.5-1.0	1-2	3-5
Butachlor		1.25	2.5	5
Thiobencarb		1.5	3.0	5-7
Anilofos		0.4	1.5	5-7
Oxadiargyl	Topstar	0.1	0.125	3-5
Bensulfuron methyl	Londax 60%DF	0.1	0.166	5
Pendimethalin	Stomp 30EC	1.0	3.0	5
Post emergent
Propanil 35 EC	Stam	2.5	7.5	4 weeks after sowing
Ethoxy sulfuron		0.018		21
Triclopyr		0.5

 

Herbicide combinations for dry sown rice

 

  1. Pre emergent Butachlor 1.5 + 2, 4-D 0.5 kg/ha

 2. Pre emergent Thiobencarb 1.5 + 2, 4-D 0.5 kg/ha

 

  Integrated weed Management (IWM) in dry sown rice:

1. Pre.em application of Butachlor 1.5+ 2,4-D 0.5kg/ha 5-7 days after 

    sowing + one hand weeding 30 DAS  

2. Pre.em application of Thiobencarb 1.5+ 2,4-D 0.5kg/ha 5-7 days after 

    sowing + one hand weeding 30 DAS                                                           

3...Pre.em application of Anilofos 0.4+ 2,4-D 0.5kg/ha 5-7 days after 

    sowing + one hand weeding 30 DAS                                                           

 

      D. Deep water rice

           1. Hand weeding:

<!--[if !supportLists]-->o       <!--[endif]-->Pulling by hand or using tools like hoe, spade or sickle

<!--[if !supportLists]-->o       <!--[endif]-->Take up one or two hand weeding between 20-42 days after sowing

          2. Mechanical weeding:

              Repeated inter cultivation by passing hoe or small blade harrow 2 times between 20-42 days after sowing

         3. Chemical

Herbicide	Trade Name	Dose(kg/ha)		Time of application (DAS)
		a.i	commercial
Post-emergent
2,4-D		0.75		4-6 weeks after establishment
MCPA		0.75