Agric.Re~,26(4):235-248,2005

INTEGRATED WEED MANAGEMENT IN MAIZE - GROUNDNUTSEQUENTIAL CROPPING SYSTEM - A REVIEW

D. Audl Reddy and Sanjay Kumar TyaglDepartment of Agronomy,

TamU Nadu Agricultural University, Coimbatore - 641003, India

ABSTRACTMaize, groundnut and maize based sequential cropping systems consisted of wide range of

weed flora of the groups viz., grasses,sedges and broad leaved weeds. Excwt Cyperus rotwJdus,Cynodon dactylon, majority of weed species differ widely due to soil type, season and croppingsystem. Both maize and groundnut should be free from weeds up to 60 days after sowing. Due tocrop weed competition, yield loss ranging from 40 to 80 per cent In maize and 80 to 90 per cent Ingroundnut. Research on weed management practices foJlowed In maize realize that Integrated weedmanagement practices offer not only good weed control but also higher net rebms and B:C ratio.Several reseach findings also indicate that atrazll14! or pendirnethaiin application at recommendeddoses In maize did not~ any residues to affect succeeding crops bite chickpea, cowpea, growxInut,Indian mustard, wheat, linseed and lentU.

Study on integrated weedmanagement in maize-groundnut basedcropping system is in its Infancy. Uterature onearlier work pertaining to weeds and weedmanagement practices in maize and groundnutwere collected under some broad headings likeweed spectrum In maize and groundnut, cropweed competition, methods of weed control,residual effect of herbicides in soil andsucceeding crops, and on economics are brieflyreviewed In this treatise.

1. Weed spectrum in maizeLocality: Weed flora varies with the

locality. In Yugoslavia at Belgrade, Amaranthusa/bus, A.retroflexus, So/anum nigrum andTriticum sp. were found dominant in dry landplots while Sorghum ha/epense, Digitariasanguina/is, Triticum sp. in irrigated plots inmaize (Momirovic et aI., 1998). Whereas inPakistan, at Islamabad and Peshawar, Cyperusrotundus, Cynodon dacty/on, Dacty/octeniumaegyptium, Echinoch/oa c%num, Echinoch/oacrusgalli, Trianthema portu/acastrum andPortulaca oleracea were predominant in maizefields (Shad et al., 1993; Khan et aI., 1998).

In India, Cyperus rotundus andTrianthema portulacastrum were the dominantweed species in spring maize at Hisar

(Devender singh et aI., 1998). Whereas atOrissa, Cynodon dactylon, Digitaria setigera,D.ciliaris, Leptoehloa chinensis,Daetyloctenium aegyptium, E1eusine indica,Cyperus rotundus, Cyperus iria, Celosiaargentea , Commelina benghalensis, Sidaacuta, Aschynomene indica andAcanthospermum hispidum were founddominant in rainfed maize (Rout and Stapathy,1996). Commelina benghalensls, ChenpcxJiumalbum, Cyperus rotundus, Cynodon daetylon,Portulaca oleracea, Phyllanthus niruri,Amaranthus viridis, Acalypha indica and Tridaxprocumbens were the prevalent weed speciesin maize at Dharwad (Lamani et aI., 2000).Sharma and Thakur (1998) reported thatDigitaria sanguinalis, E1eusine indica, Setariag/auca, Panicum dichotomiflorum, Cynodondactylon, Sorghum halepense among grassesCyperus spp. among sedges and Commelinabenghalensis, Galinsoga parvif/ora, Ipomoeapestigridis and Euphorbia hirta among broadleaved weeds, were dominant in maize undermid hill conditions of North western Himalayanregions.

Soil types: In clay loam soil,Chenopodium a/bum, C.murale, Anagallisarvensis, Melilotus indica, Euphorbia hirta,

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Convolvulus arvensis, Cynodon dactylon andCyperus rotundus were the predominant andcommon weed flora at Banswara, Rajasthan(Porwal, 1998). In loamy clay soils,Echinochloa colonurn, Brachiaria ramosa,Digitaria sanguinalis, Dactylocteniumaegyptium, Eleusine indica, Setaria glauca,Sorghum halepense and Panicum spp. amonggrasses, Ageratum conyzoides, Galinsogaparvif]ora, CommeIina benghalensis, Underniacilata, Polygonum hydropiper, Euphorbiageniculata and Oxalis latifolia among nongrassy weeds and Cyperus rotundus amongsedges were the major weed flora observed inmaize fields at Uttaranchal (Pandey et al.,2001).

Seasons: During kharif season,Echinochloa c%num, TrianthemaportuJacastrum, Cyperus rotundus and EJeusineindica were the dominant weeds In maize fieldsat Pantnagar of Uttar Pradesh (Govindra Singhand Ram Prasad, 1994). On the other handat Almora of Uttaranchal, dUring kharifseason,Echinochloa colonum, Brachiaria ramosa,Digitaria sanguinalis, Dactylocteniumaegyptium, Eleusine indica, Setaria glauca,Sorghum halepense, and Panicum spp. amonggrasses; Ageratum conyzoides, GalinsogaparvifJora, Commelina benghalensis ,Lindernia cilata, Polygonum hydropiper,Euphorbia geniculata and Oxalis latifoliaamong broad leaved weeds; Cyperus rotundusamong sedges were the dominant weeds inmaize field (Pandey et al., 2001). On the otherhand during winter season Chenopodiumalbum, C.murale, AnagalIis arvensis, Melilotusindica, Euphorbia hirta, Convolvulus arvensisamong broad leaved weeds, Cyperus rotundusamong sedges and Cynodon dactylon amonggrasses were the dominant weed flora in maizeat Banswara in Rajasthan (Porwal, 2000).

During rainy season, Cyperusrotundus, Cynodon dactylon, Digitariasanguinalis, Dactyloctenium a egyptium ,

Parthenium hysterophorus, Commelinabenghalensis, Amaranthus viridis, Digeramuricata, Euphorbia geniculata andTrichodesma indicum were more prevalentweed flora in maize fields at Hyderabad.(Sreenivas and Satyanarayana, 1994). On thecontrary, dUring rabi season in maize field atCoimbatore, weed flora viz., Panicum repens(17.1%), Dactyloctenium aegyptium (9.1%)and Cynodon dactylon (8.4%) , the grasses(34.6%), Cyperus rotundus , the sedge (8.4%),and the annual broad leaved weeds constituted57% of total weed population comprisingTrianthema portulacastrum (19.2%),Parthenium hysterophorus (18.3%), F7avariaaustralasica and Amaranthus viridis (7.4%)(Kandasamy and Chandrasekhar, 1998).

Cropping system: In maize +soybean intercropping system Echinochloacolonum, Commelina benghalensis, Physalisminima, Celosia argentea, Setaria glauca,Cyperusrotundus, Ageratum conyzoideswerefound dominant (Prasad and Rafey, 1995).Similarly, Kumar and Singh (1992) also statedthat Cyperus rotundus, Echinochloa colonum,Brachiaria ramosa and Commelinabenghalensis, Cynodon dactylon, Sorghumhalepense were the weed flora in maize legumeintercropplng system. But in· maize. - mustardcropping system dlcot weeds, primarily,Trianthema portulacastrum dominated themonacot weeds in first year, while In the secondyear monocots dominated the dicot weedsduring rainy season (Saikia and Pandey,2001a).

Weber et al. (1995) reported thatmaize-based cropping systems with a highfrequency of cereal cropping and low frequencyof non-cereal cropping tended to be dominatedby weeds such as CommeIina spp. and KiJIingasquamulata. As soil fertility declined, Vernoniaspp. and EcJipta prostrata became moredominant. Increased frequency of non-cerealcrops in mixed cropping with cereals was

236 AGRICULTURAL REVIEWS

Convolvulus arvensis, Cynoclon dactylon andCyperus rotundus were the predominant andcommon weed flora at Banswara, Rajasthan(Porwal, 1998). In loamy clay soils,Echinochloa colonum, Brachiaria ramosa,Digitaria sanguinalis, Dactylocteniumaegyptium, Eleusine indica, Setaria glauca,Sorghum halepense and Panicum spp. amonggrasses, Ageratum conyzoides, GalinsogaparvifJora, Commelina benghalensis, Underniacilata, Polygonum hydropiper, Euphorbiageniculata and Oxalis latifolia among nongrassy weeds and Cyperus rotundus amongsedges were the major weed flora observed inmaize fields at Uttaranchal (Pandey et aJ.,2001).

Seasons: During kharif season,Echinochloa colonum, Trianthemaportulacastrum, Cyperus rotundus and EJeusineindica were the dominant weeds in maize fieldsat Pantnagar of Uttar Pradesh (Govindra Singhand Ram Prasad, 1994). On the other handat A1mora of Uttaranchal, during kharifseason,Echinochloa colonum, Brachiaria ramosa,Digitaria sanguinalis, Dactylocteniumaegyptium, Beusine indica, Setaria glauca,Sorghum halepense, and Panicum spp. amonggrasses; Ageratum conyzoides, GalinsogaparvifJora, Commelina benghalensis ,Lindernia cilata, Polygonum hydropiper,Euphorbia geniculata and Oxa/ls latifo/laainong broad leaved weeds; Cyperus rotundusamong sedges were the dominant weeds inmaize field (Pandey et aJ., 2001). On the otherhand during winter season Chenopodiumalbum, C.murale, Anagallis arvensis, Melilotusindica, Euphorbia hirta, Convolvulus arvensisamong broad leaved weeds, Cyperus rotundusamong sedges and Cynoclon dactylon amonggrasses were the dominant weed flora in maizeat Banswara in Rajasthan (Porwal, 2000).

During rainy season, Cyperusrotundus, Cynodon da ctylon, Digitariasanguinalis, Dactyloctenium aegyptium ,

Parthenium hysterophorus, Commelinabenghalensis, Amaranthus viridis, Digeramuricata, Euphorbia genicu/ata andTrichoclesma indicum were more prevalentweed flora in maize fields at Hyderabad.(Sreenivas and Satyanarayana, 1994). On thecontrary, during rabi season in maize field atCoimbatore, weed flora viz., Panicum repens(17.1%), Dactyloctenium aegyptium (9.1%)and Cynoclon dactylon (8.4%) , the grasses(34.6%), Cyperus rotundus , the sedge (8.4%),and the annual broad leaved weeds constituted57% of total weed population comprisingTrianthema portulacastrum (19.2%),Parthenium hysterophorus (18.3%), Havariaaustra/aslca and Amaranthus viridis (7.4%)(Kandasamy and Chandrasekhar, 1998).

Cropping system: In maize +soybean intercropping system Echinochloacolonum, Commelina benghalensis, Physalisminima, Celosia argentea, Setaria glauca,Cyperus rotundus, Ageratum conyzoideswerefound dominant (Prasad and Rafey, 1995).Similarly, Kumar and Singh (1992) also statedthat Cyperus rotundus, Echinochloa colonum,Brachiaria ramosa and Comme/lnabengha/ensis, Cynodon dactylon, Sorghumhalepense were the weed flora in maize legumeintercropping system. But in maize. - mustardcropping system dicot weeds, primarily,Trianthema portulacastrum dominated themonocot weeds in first year, while in the secondyear monocots dominated the dicot weedsduring rainy season (Saikia and Pandey,2001a).

Weber et al. (1995) reported thatmaize-based cropping systems with a highfrequency of cereal cropping and low frequencyof non-cereal cropping tended to be dominatedby weeds such as Commelina spp. and Killingasquamulata. As soil fertility declined, Vernoniaspp. and Eelipta prostrata became moredominant. Increased frequency of non-cerealcrops in mixed cropping with cereals was

Vol. 26, No.4, 2005 237

associated with reduced incidence of weedssuch as Leucas martinicensfs, Dldenlandiacorymbosa, Spermacoce verticellata, Ludwigiahyssopifo/ia, Celosia laxa, Ipomoea spp.

Covarelli (1988)obselVed that seedlingand seed densities of Echinochloa crus-galliwere lower in a winter wheat/maize rotationthan in continuous maize. Schreiber (1992)found that Setaria faberi seedling densitytended to be greatest in continuous maize, intermediate in a 2-year maize/soybean/winterwheat rotation.

2. Weed spectrum in groundnutLocality: In India, at Jalagaon,

Maharashtra, Amaranthus viridis, Partheniumhysterophorus, Acalypha indica, Cyperusrotundus, Cynodon dactylon, Panicum repens,Eelipta alba and Trianthema portulacastrumwere predominant in groundnut during rainyseason (Suryawanshi et a/., 2001) whQreas inAndhra Pradesh, at Hyderabad, sixteen weedswere obselVed, out of which seven were C4and nine C3 weeds. Cyperus rotundus,Dactyloctenium aegyptium, Digitariasanguinalis, Cynodon dactylon among C4plants, Dc/mum eanum, Lagasea mollis,Partheniurn hysterophorus among C3 plants,were predominant during crop growth period(Hiremath et al., 1997). At Anantapur, of the55 weed species belonging to 21 families ingroundnut, 14 were monocotyledons and theremaining 41species were dicotyledons, asreported by Rao and Kumar (1996). In TamilNadu, at Vridhachalam, Trianthemaportulacastrum, Dactyloctenium aegyptium,Digitaria sanguinalis, Cyperus rotundus,Cynodon daetylon and Euphorbia hirta werethe dominant weeds in groundnut(Subramanian and Arulmozhi, 1998).

In Brazil, at Paraiba, Cenchrusechinatus, Eragrostis cillaris, Digitariahorizontalis, Acanthospermum hispidum,Amaranthus retrofJexus and Ageratumconizoides were the predominant weed species

in groundnut (De Azevedo et al., 1998).

Soil type: In sandy loam soils,Cyperus rotundus, Cynodon dactylon,Commelina benghalensis, Chloris barbata,Trianthema portulacastrum, Amaranthusviridis, Boerhaavia diffusa, Euphorbia hirta,Cleome viscose, Cleome gynandra(Gynandropsis pentaphylla), Tribulus terrestris,Phyllanthus niruri, Panicum colonum weredominant among the weed flora in groundnutat Bapatla,Andhra Pradesh (Ravi Kumar andRamakrishna Reddy, 1992). Shankaranara~naet a/. (2000) stated that Acanthospermumhispidum, Cyperus rotundus, Panicum sp.,Dig/taria sp., Euphorbia hirta, Amaranthusviridis, Phillanthus niruri, Tridax procumbens,Commelina benghalensiswere the major weedspecies found in red sandy loam soils ofKarnataka.

In alfisols, Sporobolus spp., Cyperusrotundus, Chlofis inflata, Tragus biflorus andDacyloctenium aegyptium among monocotsand Digera muricata, Borreria articularis,Tridax procumbense, Vernonia spp.,Phyllanthus niruri, Cleome isocandra,Euphorbia h/rta and Achyranthus aspera,among dicot weeds, were dominant ingroundnut at Tirupati, Andhra Pradesh(Sumathi et a/., 2000). In sandy soils atRaigarh, Madhya Pradesh, Celosia argentea,Echinochloa crus-galli, E.colonum, Cynodondactylon and Cyperus rotundus werepredominant in groundnut (Patel et a/., 1997).

Seasons: During kharifseason broadleaved weeds such as Digera arvensis andJusticia prostrata which constituted about 30­40 per cent of total weed population, whilethe grass weeds like Echinochloa colonum,Panicum spp. and Dactyloctenium aegyptlumaccounted for nearly 30 per cent of total weedpopulation in groundnut at Palem, AndhraPradesh (Vijay Kumar, 1992). In West Bengal,Echinochloa crus-galli, E.colonum andDactyloctenium aegyptium were the

238 AGRICULTURAL REVIEWS

predominant weeds found in groundnutduringkhari! season (Ghosh, 2000).

Mahalle (l992) reported that dicotweeds mostly dominated in groundnut duringboth kharl!and rabi seasons, however Celosiaargentea was the major weed in khari! andPortulaca spp. in rabi season at Dapoli,Maharashtra. Rafey and Prasad (1995) notedthat Echinochloa colonum, EJeusine indica,Paspalum dilatatum, Setaria glauca, Cyperusiria, Cyperus rotundus, among narrow leavedweeds and Celosia argentea, Ageratumconyzoides, Amaranthus viridis andTrianthema portulacastrum, among broadleaved weeds were preponderant in groundnutduring rainy season at Ranchi of Bihar state.

Cropping system: In groundnut+sesame intercropping system Amaranthusviridis, A.spinosus, Digera muricata, Cynodondactylon and Cyperus rotundus were dominantamong the weed flora (Maliwal and Rathore,1994). Whereas Pandian and Nambl (2002)highlighted that Cyperus rotundus amongsedges, Cynodon dactylon and Echinochloacolonum in grasses, Trianthemaportulacastrum, Boerhaavia diffusa andAmaranthus viridis in broad leaved weeds werethe dominant weeds under groundnut -basedintercropping systems.

Patel etaJ. (1997) stated that CynodondaeMon, Echinochloa crus-galli, E.colonum,Chenopodium album, Melilotus sp.andCyperus rotundus were dominant among theweed flora in rabi-summer seasons ingroundnut grown after rice.

3. Crop weed competitionCritical period of competition

Establishing the critical period ofcompetition is the most essential to .cfevelopeffective and economical weed controlmeasures.

a) Maize: Maize being a wide spacedcrop with slow early growth, allows the weeds

to compete easily compared to other cereals.So, weed control should start at the earlygrowth and crop development stages of maizethan other growth stages (Tereshchuk et aJ.,2000).

Porwal (2000) observed that in therainy season, emergence of maize and weedswere simultaneous and found that the first 20­30 days were the most critical period ofcompetition for the crop. Whereas Nayltaletal. (1989) reported that in maize during rainyseason, critical stage for crop weed competitionis between 20-60 days after sowing (DAS).

In irrigated winter maize, beyond 30days and up to 45 days after sowing wasdetrimental to maize growth and caused yieldloss in command area of Southern Rajasthan(Porwal, 1998) while, Shad et al. (1993)highlighted that In maize, critical period of cropweed competition was found in between 3 and5 weeks after sowing.

b) Groundnut: Unlike other crops,groundnut seems to have poor competitiveability against weeds and hence weed freesituation up to 45 days after sowing was mostcritical (Singh et aJ., 1985). Kalalselvan et aJ.(1991) and Gupta (1998) stated that the first3 to 4 weeks of crop growth period were morecritical for weed control in groundnut. Subbaiahet al. (1995) observed that groundnut washighly sensitive to weed competition up to 60days after sowing with 62 per cent loss in yield.Rao (2000) opined that weed competition iscritical up to 45 days after groundnut sowingand weed free environment during this periodregistered higher pod yield.

4. Nature of crop weed competitionWeeds compete with crops for most

of the resources viz., nutrients, moisture,iightand space and pose a serious problem togrowth of the crop, if not controlled. (Rao,2000).

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27.83 kg K20 ha·1) under weedy check inmaize in calcareous soils of North Bihar.

b) Groundnut: There was inverserelationship between crop and weeds withrespect to nutrient uptake in case of groundnut.Maximum nutrient depletion and weed drYmatter occurred in the unweeded control asreported by Murthy et aI. (1993) and VijayKumar (1992).

Kori et aJ. (1997) ascribed that inunweeded control, uptake of nutrients by thecrop was significantly lower, while uptake byweeds was greatest in groundnut. Devakumarand Giri (1999) opined that weed dry weightand Nand P uptake by weeds generallydecreased with increasing intensity of weeding.Manickam et aI. (2000) observed thatunweeded control plot' registered the lowestN, P and K uptake of 169.4, 3.6 and 52.2 kgha·1 by crop, respectively. Murthy (2000)highlighted that weeds grabbed 58 kg of N, 6kg of P205 and 45 kg of K20 from thegroundnut field, if the weeds are not controlledat the right time.

Competition for lighta) Maize: Elakkad (1984) and

Assemat et aJ. (1995) reported that naturalweed infestation significantly reduced thephotosynthetically active radiation available forthe lower leaves of maize. This shortened thephotosynthetic life of leaves and lead to yieldreduction.

b} Groundnut: Barbour and Bridges(1995) reported that Desmodium tortuosumand Euphorbia heterophylla by over toppinggroundnut canopy caused reduction inphotosynthetically active radiation reaching thegroundnuts by 45 and 39 per cent respectively.Brecke (1996) stated that Euphorbiaheterophylla intercepted more light and causedgreater groundnut yield reduction upto 31percent.

Competition for moisturea) Maize: Stainforth (1957) found that

yellow foxtail grass competed with maizemainly for moisture. Wiese and Vandiver(1970) stated that EchinochIoa crus-galli andDigitaria sanguinalis depleted soil moisturegreatly and resulted in heavy competition withmaize crop. Hosmani (1976) studied thatinfluence of weeds on evapotranspiration lossin maize and found that moisture loss due toweed infestation was more than 66 per centfrom 0-45 cm soil layer compared to weedfree treatment.

Under condition of limited moisture,weeds thrived better than groundnuts,producing dry-matter yields that were higherthan those recorded under adequate rainfallfor most of weeding regimes (Sibuga et aJ.,1989). Royal et aI. (1997) stated that whenmoisture levels were above normal, the impactof common cocklebur (Xanthium strumarium)on groundnut yield was 9 to 24 per cent lessas compared to normal soil moisture.

Competition for nutrientsa) Maize: In general nutrient removal

by weeds was more in unweeded check thanweeded maize plot. Removal of nutrients byweeds showed a great impact on the availabilityof nutrients to the crop than affecting its drymatter accumulation and on an average, weedsremoved 35.3 kg N, 4.9 kgP and 29.2 kg Kper ha in maize (Saikia and Pandey, 1999).Whereas, Sreenivas and Satyanarayana (1996)suggested that uncontrolled weeds removed52.3, 9.6, 38.9 kg N P K ha·1 in maize.

Channabasappa and Nanjappa (1994)found that weeds absorbed fewer nutrientswhere as crops take more nutrients in theintercropping systems than in the monocropsand nutrient uptake by crops decreased withthe delay in weeding. Sinha et aJ. (2000)reported that nutrient depletion by weeds wasminimum under hand weeding while it wasmaximum (23.18 kg N, 4.92 kg PP5 and

240 AGRICULTURAL REVIEWS

Competition for spacea) Maize: Weeds compete for space

and reduce the yield of crop plants(Hidayatullah and Sen, 1942). King (1966)stated that fast growth in terms of height andleaf development of weeds suppressed the cropby competing for space.

Forcella et aJ. (1992) found that thenarrow rows increased 'crop competitionenough to replace inercultivation for controllingweed growth. Harvey et aJ. (1997) stated thatplanting corn in narrow rows might aid weedcontrol. Teasdale (1998) observed thatvelvetleaf survival, growth and seed productionwere reduced as corn density increased.Tollenaar et aJ. (1994) and Murphy et aJ. (1996)reported that higher corn densities reduced theweed biomass compared to their lowerdensities.

b) Groundnut: In addition tocompeting with the crop, weeds in groundnuthinder its pegging, compete for undergroundspace, and make the crop harvest cumbersome(Gupta, 1998).Murthy (2000) stated that at theinitial stages of crop, the growth will be slow,

. the weed competition will be very high, andweeds occupy the space that is not covered bythe crop resulting in yield decline.

5. Effect of crop weed competitionEffect on growth, yield components andyield

a) Maize: Young et aJ. (1984) reportedthat quack grass (Agropyron repens)interference in corn reduced the plant height,leaf area and photosynthetic productivity, leafarea index (I..AI) and leaf area duration (LAD)which were closely correlated with dry matterproduction and yield reduction and provedgood indicators of the onset of severe weedcompetition._Beck (1985) stated that weedsdecreased cob length and grain number percob by 20 and 30 per cent respectively andcob and stalk diameter by 10 and 20 per centrespectively in irrigated maize. Balyan and

Shan (1987) found that in maize, yieldattributes viz., cobs per plant, grains per cob,100-grain weight were significantly less dueto presence of dominant weeds like Trianthemaportu/acastrum and Echinochloa c%num.

Varga et a/. (2000) found thatunweeded check recorded the greatestdecrease (about 40 per cent) of leaf area inmaize. Devender Singh et aJ. (1998) stated thatgrowth attributes like plant height, dry matteraccumulation and LAI and yield attributes likenumber of cobs per plant, grains per cob,weight of grains per cob and 1000 grain weightwere significantly lower in weedy checkcompared to all other weed control treatments.James et a/. (2000) and Shinde et aJ. (2001)observed that maize in the untreated plotproduced less dry matter and less leaf area thanplants in the treated plots.

Maize yield was reduced by 35 percent due to presence of the dominant weedDigitaria abscedens (Okumara et a/., 1986)Similarly, Amador Ramirez (1995) highlightedthat maize grown In the presence of weedsviz., Amaranthus patmeri, Eragrostis diffusa,Bidens odorata, Brassica compestris for theentire life cycle of the crop showed 86 and 90per cent reduction in grain yield for cvH-204andvs-202 respectively at Mexico. Usmanet aJ. (2001) found that uncontrolled weedgrolA1h resulted in 83 per cent reduction inaverage grain yield of maize'.

Tiwari et a/. (1987) reported thatmaize grain yield was reduced by cent per centdue to weed competition under maize+cowpea inter cropping system. Ferrero et aJ.(1996) stated that the depressing influence onthe crop yield was strongly related to the weedcover degree and weight. Pandey et aJ. (2001)reported that compared to weed free condition,the season long crop weed competitionreduced the grain yield by 84.3 per cent inmaize.Santos et a/. (1993) opined that in thesilty clay loam soils, maize grain. yield loss

Vol. 26, No.4, 2005 241

ranged from 40 to 80 per cent due to weeds.

b) Groundnut: Vijay Kumar (1992)found that groundnut growth in the absenceof weeds attained maximum LAI. Rafey andPrasad (1995) stated that there wassignificantly higher number of pods per plantin all the weed control treatments as comparedto weedy control. Mohanthy et aJ. (1997)reported that physiological growth parametersviz., LAI, CGR, RGR, harvest index (HI) anddry matter production and yield attributes likenumber of pods, pod weight were very low inthe control plants than treated plants.

In general, yield loss in groundnut dueto weeds was reported to be 17 to 84 percent (Dharam Singh et aJ., 1992). Sibugaet a/. (1989) found that weed infestationsbeyond the first 6 weeks reduced yields byabout 46 per cent for MGC 81, 47 per centfor MGC 96 and 55 per cent for MM cultivarsof groundnut as compared with weed freeplots. Prusty et aJ. (1990) reported that dUringrainy season weeds caused 80 per centreduction in pod yield of groundnut. Nimje(1992) opined that groundnut sown with theonset of monsoon suffers heavy loss in the yielddue to severe crop weed competition.Gnanamurthy and Balasubramanian (1998)stated that weeds reduce groundnut yield upto 76 per cent under irrigated condition.

6. Methods of weed controlMechanical and cultural method

The mechanical and cultural methodsinclude hand weeding, mechanical weedingand hoeing, soil solarization, soil mulching,earthing up, discing, conservation tillage etc.

a) Maize: The traditional non­chemical method of two hand weedingseffectively minimized the weed competitionand maximized rainfed maize yield (Kandasamyand Chandrasekhar, 1998). Similarly, Saikiaand Pandey (2001 b) reported that handweeding provided better weed control owing

to effective removal of weeds at critical periodsresulting in lower weed dry matter.

To substitute manual weeding, moreefficient and less energy intensive manual andmachine-operated tools/implements havebeen introduced for weed control in rainfedcrops (Tajuddln et a/., 1991). Sharma et aJ.(2000) reported that hoeing at 15 DAScontrolled the growth of all weed species andtheir population at 30 DAS was less than half(23-32 weeds m·2) compared with nointerculture (67-70 weeds m·2) and theyemphasized that earthing up at 30 DASresulted in virtual elimination of weedsthroughout the crop growth period of rainfedmaize.

Pandey et aJ. (2000) reported thatpine needle mulch + earthing up afterremoving the mulch was the most effectiveweed control treatment to control major andtotal weeds in maize. Melander et a/. (1995)found that weeds growing in maize can besatisfactorily controlled using harrowing aloneor in combination with ridging thus controllingweeds both between and with in the crop rows.Stan Kovic et a/. (1998) stated thatconservation tillage systems were effective incontrolling weeds In the absence of herbicidesIn maize.

Real et a/. (1994) suggested thatmechanical hoeing was effective In the Interrow but along the row, spring tine machineswere essential and were oniy partially effectivein maize weed control. In contrast, Durkic andknezevic (1996) reported that mechanicalweed control treatments did not adequatelycontrol weeds, particularly dUring wet seasonsin maize. Tanchik (1996) observed that rootcuttings from perennial weeds were more likelyto re-establish themselves in maize crops afterblade ploughing than after deep ploughing.

Mikkelsen (1997) stated that with acoarse sandy soil and with a sandy loam soil a

242 AGRICULTURAL REVIEWS

combination of two different kinds ofmachinery was necessary to achieve effectiveweed control, both within and between rows.Though cultural and mechanical weed controlpra,ctices were effective in controlling weeds,due to more labour intensity, time consumptionwith higher cost of cultivation during the peakperiods, these practices were not advisable inlarge-scale maize production.

b) Groundnut: Mahalle (1992) andDharkar et al. (2000) reported that during rabiseason, maximum dry pod yield of groundnut(20.82 q ha'!) was recorded in hand weededtreatment due to complete removal of weeds.They also found that early hand weeding wasmore effective than hoeing at later stages.

Itnal et aJ. (1993) observed that handweeding at 30 DAS with intercultivationat 20DAS gave significantly higher pod yield ofgroundnut compared to Intercultivation aloneat 20 and 40 DAS. Lalitha et a/. (2000)reported that soil solarization with 0.05 mmtransparent polyethylene film ffPE) for 45 daysresulted in high weed control efficiency (94per cent) next to two hand weedings (98 percent) in groundnut.

7. Weed management by inter croppingSeveral authors have reported that

more complete crop cover and high plantdensity of inter cropping cause severecompetition with weeds and reduce the weedgrowth (Enyi, 1973; Moody, 1978).

In wide row crops, planting earlymaturing intercrops helps to cover the vacantinter row spaces rapidly and keeps the weedsunder check (De, 1974). The weed suppressingability of inter crops depends on crops selected,genotypes, density and spatial arrangements(Moody and Shetty, 1981).Tiwari et a/. (1987)opined that cowpea as an inter crop in maizewas able to control 23 per cent of total weedsand there by one hand weeding could besaved.Prasad and Rafey (1996) stated that inter

_______________....t_~~,,;.'"·c·

cropping of maize with soybeans, irrespectiveof their row ratios (1: 1 and 1:2) effectivelyreduced the weed density and dry weight ofweeds at 30 and 60 days after sowingcompared with their pure crops.

Semere and Froud Williams (l997)found that intercropping maize with field peassuppressed weeds as compared to sole maize.Maina and Drennan (1997) reported that tworows of Phaseo/us vulgaris (cv. Rose Cow)grown between maize (cv. H 511) rows gavegood weed suppression and improved maizeyields even under unweeded Gheck.

8. Chemical weed controlPre-emergence herbicides

Pre-emergence herbicides provideearly season weed control by suppressing orkilling the weed seedlings at germination phaseitself.

a) Maize: Pre-emergence atrazine orsimazine at 1.0 kg a.i hat! gave 92-100 percent weed control in maize (Eddowes, 1961).Govindra Singh and Ram Prasad (1994)reported that atrazine at 1.0 and 1.5 kg ha'!provided almost complete control ofTrianthema portuJacastrum in fodder maize.Neelam Sharma and Angiras (1997) opinedthat atrazine at 1.5 kg hat! applied either aspre-emergence or as post-emergence, can beused safely to control weeds in maize. ArunaRajagopal et aJ. (1994) reported that the totalweed population and dry weight of weeds weredrastically reduced with an increase In the rateof atrazine (from 0.25 to 1.0 kg ha'!) in maize.Singh et aJ. (1995) reported that atrazine wasuseful when applied on 30 DAS for significantimprovement in the grain yield of maize.Pandey et aJ. (1999) suggested that in maize,atrazine was more effective against Ageratumconyzoides and Comme/ina bengha/ensis thanpendimethalin.

Blanc and Thierry (1996) stated thatatrazine at the reduced dose of 1.0 kg ha'! did

Vol. 26, No.4, 2005 243

not control annual species such as orche(Atriflex sp.) and mercury (Mercurialis annualwhere as it partially controlled the weed speciessuch as fat hen (Chenopodium album) andnightshade (Solanum sp.) in maize. Saini(2000) highlighted that atrazine both at 2.0and 1.5 kg ha'! provided the lowest weed dryweights during rainy season in maize atHimachal Pradesh.

Anil Dixit and Gautam (1994)reported that different doses of atrazine underfield conditions revealed that lower dose ofatrazine (0.25 kg ha'!) had stimulating effecton maize leaf area, chlorophyll content,photosynthesis, N uptake and finally grainyield. Mishra et al. (1996) reported that pre­emergence application of atrazine @ 1.0 kgha·1 was most effective in controlling weedsand produced highest grain yield of maize inBihar. Saikia and Pandey (2001b) suggestedthat grain yield was declined with an increasein atrazine dose from 1.0 kg ha'! to 2.0 kg ha·!.

b) Groundnut: Pendimethalin at 1.5kg ha·1recorded significantly higher yield andwas on par with hand weeding in maize(Padmavathi et al., 1994). Mohanthy et al.(1997) stated that fluchloralin as well aspendimethalin had better effect than handweeding in respect of most of the growthparameters of groundnut by controlling themajor weeds.

Prasad et al. (1992) observed thatfluchloralin was less effective in controllingbroad-leaved weeds than pendimethalin.Hiremath et al. (1997) found that the w~ed

control efficiency (WCE) was more inpendimethalin and oxyfluorfen, which was dueto effective control of both C

3and C

4weeds.

9. Integrated weed management in maizeComplementing with certain

mechanical measures and vice versa canstrengthen the effect of chemical weed controlmeasure. This integrated approach helps in

avoiding the pitfalls and hazards in excessivedependence on chemical methods andensuring little change in ecological balance.Herbicide and manual weeding combinationseems to be most economical weed controlmethod for maize (lPRC, 1976). Kandasamyand Chandrasekhar (1998) reported that pre­emergence application of atrazine at 0.25 kgha- I with a follow-up hand weeding not onlymaintained the yield but also enhancedeconomic advantage through better weedcontrol efficiency.

Vander Schans et al. (1997) reportedthat a combination of mechanical and chemicalcontrol could reduce the likelihood of problozmweeds in maize.

Risk and El Bially (1996) stated thatthe most consistent and the highest weedcontrol efficiency were achieved bysupplementing shallow hoeing with theapplication of either atrazine (0.6 kg/0.42ha)alone or atrazine +metribuzin (0.4 + 0.35 kg!0.42ha). Vander Schans and Vander Weide(1999) stated that the best weed controlpractice is harrowing before weed emergencefollowed by applications of atrazine (0.2 litreha-I ) + pyridate (0.25 litre ha· l ) + rimsulfuron(30 g ha'!) when weeds were 5 cm tall andhoeing before canopy closing of maize.

10. Chemical weed control in maize basedcropping system

Jat and Gaur (2000) reported thathighest NPK uptake in maize + soybeanintercropping system observed in pre­emergence pendimethalin at 1.0 kg ha·!. AvilKumar and Reddy (2000) observed thatapplication of pendimethalin at 1.0 kg ha'!resulted in maize grain yield which was on parwith hand weeding in maize + turmericintercropping system. Prasad (1995) statedthat combination of pigeon pea + maizeintercropping with pendimethalin at 1.0 kgha'! gave the highest pigeon pea equivalentyield with better weed control efficiency.

244 AGRICULTURAL REVIEWS

Pendimethalin at 1.0 kg ha-1 as preemergence and fluchloralin at 1.0 kg ha-1 aspre-plant incorporation proved as good as handweeding in increasing the grain yield of maizeand soybeans in maize + soybeanintercropping system by controlling the weedsmore effectively (Prasad and Rafey, 1996).

Saikia and Pandey (2001) reportedthat in maize- mustard sequential croppingsystem, weed population and weed dry weightwere reduced greatly due to application of pre­emergence atrazine at all doses right from 1.0kg ha·1 to 2.0 kg ha·1 in maize followed byfluchloralin at 0.75 kg ha·1 in mustard.Similarly, in maize-groundnut based sequentialcropping system, maize + cowpea intercrop'(1: 1) with pre-emergerice pendimethalin at 0.5kg ha' l followed by pre-emergencependimethalin at 1.0 kg ha·1 in groundnutrecorded the highest weed control efficiencyand the highest yield of maize as well asgroundnut (Audi Reddy, 2003).

11. Residual effect of herbicides in soil andsucceeding cr&ps

Excessive use of herbicides leaveresidue in soil and cause damage to thesucceeding crops. Continuous use of singleherbicide leads to evolution of herbicideresistant weed species and shift in weed flora(Sinha and Sinha, 1970; Thakur and Sharma,1996). Sandhu et al. (1999) reported thatatrazine (0.25 and 0.5 kg ha·1) applied as pre­emergence to winter maize persisted up to 20and 100 days in plant and soil, respectively.Saikia et al. (2000) reported that atrazinecontent in sandy loam soil at different intervalsshowed initial slow rate of loss of atrazine insoil up to· 20 days and there after fasterdissipation and at maize harvest (90 days) nodetectabll;! residue. They also reported thatatrazine application right from 1.0 kg ha-1 to2.0 kg ha' l in maize did not leave anydetectable residues to succeeding crops ofchickpea and Indian mustard. Saikia and

Pandey (2001a) stated that atrazine wasbiologically active in sandy loam soil up to 90days and its biological activities (impairmentof vital growth processes like photosynthesisand chlorophyll synthesis) were wellpronounced at 2.0 kg ha·1•

Neelam Sharma and Angiras (1997)reported that pre emergence applications ofatrazine as spray at 1.5 kg ha·1, atrazine asbroadcast at 1.5 kg ha' l and simazine(broadcast) 1.5 kg ha-1 persisted up to 47 daysand simazine (spray) at 1.5 kg ha·1 persistedup to 83 days in the silty clay loam soil.KuIashrestha et aJ. (1976) stated that simazine/atrazine appli~tion at 0.5, 1.0 and 2.0 kg ha-1

did-nol leave any residues to affect injure thesucceeding wheat, linseed and lentil. Sandhuand Randhawa (1992) observed that preemergence atrazine (0.625 kg ha·1) to Irrigatedkhari! maize persisted up to 90 days afterapplication in loamy sand soil without affectingthe succeeding crops.

Shukla and Das (2001) reported thatpendimethalin at all concentrations right from1ppm to 70 ppm persisted up to 90 days andinfluenced the microbial activity in the soil.Padmavathi Devi et aJ. (1994) reported thatgermination was affected by pendimethalinbeyond 0.1 ppm in finger millet, 0.5 ppm inItalian millet;pearlmillet and wheat and beyond2-ppm concentration in maize, sunflower andgreen gram. Aruna Rajagopal et al. (1994)stated that the total weed population wasdrastically reduced by the additive effect of theresidual atrazine (0.25 to 1.0 kg ha·1) andpendimethalin (0.75 kg ha-1) in the succeedingsoybean crop in maize-soybean sequentialcropping system. Audi Reddy (2003) observedthat pre-emergence atrazine (0.25 to 0.5 kgha·1) and pre-emergence pendimethalin (0.5kg ha-1) applied to maize did not leave anysignificant amount of residues to adverselyaffect the gern1ination and yield of succeedinggroundnut.

Vol. 26, No.4. 2005 245

12. Effect of weed control treatments oneconomics

a) Maize: Subramanyam et aJ. (2001)highlighted that pre emergence application ofatrazine at 1.0 kg a.i. ha·1 + metoiachlor at1.0 kg a.i. ha·1 with one hand weeding at 40DAS was effective and economic weedmanagement practice for irrigatedmaize.Pandey et al. (2001) observed thatamong all the weed control practices, alachlorfollowed by earthing up recorded the highestnet returns and benefit-cost ratio in maize.

b) Groundnut: Sumathi et al. (2000)reported that hand weeding twice and preemergence spray of pendimethalin at 0.75 kga.i. ha" + hand weeding at 30 DAS gavehigher benefit-cost ratio compared with otherweed control treatments. Suryawanshi et aJ.(2001) stated that in groundnut, the weed freecheck recorded the highest net returns(Rs. 14797) followed by pre emergenceapplication of pendimethalin'@ 1.0 kg ha·1 +inter cultivations at 30 and 45 DAS + onehand weeding at 30 DAS.

CONCLUSIONThe foregoing review has brought out

that weeds belonging to various species ofgrasses, sedges and broad leaved weeds areassociated with maize and groundnut crops.Except Cyperus rotundus and Cynodondactylon, majority of weed species differ widelydue to locality, soil type, season and croppingsystem. Many of the workers suggested thatTrianthema portuJacastrum was a predominantbroad leaved weed flora in maize basedcropping system. Several workers pointed outthat both maize and groundnut are sensitiveto weed competition upto 60 days aftersowing. Weeds are mainly competing fornutrients, moisture, space and light. On anaverage weeds take out 23 to 52 kg of N, 2.5tolO kg of P, 23 t039 kg of K ha·1 in maizeand 58 to 170 kg of N, 3 to 4 kg of P, 37 to52 kg of K ha·1 in groundnut from the soil, if

the weeds are not controlled at the right time.

Weed competition reduces plantheight, leaf area index, dry matter production,cob length, grain number per cob, 100 grainsweight in maize and plant height, number ofbranches, leaf area index, dry matterproduction, number of pods, pod weight ingroundnut. Several authors highlighted thatyield loss ranging from 40 to 80 per cent inmaize and 80 to 90 per cent in groundnut dueto crop weed competition. In this scenario,though cultural and mechanical weed controlpractices are effective in controlling the weeds,due to more labour intensive, time consumingand ineffective during wet seasons, it has beenforced to search other alternatives.

Intercropping with legumes reducesthe weed menace to some extent, thereby onehand weeding can be saved. As regards,chemical weed control, promising chemicalslike atrazine and simazlne are widely used tocontrol weeds in maize sole crop situation.While, pendimethalin has been proved, bymany workers, as effective broad-spectrumherbicide under maize based intercroppingsystems and in groundnut. Atrazine at lowerdose has stimulatory effect and at higher doses,has detrimental effect. In this regard, there isgeneral agreement among scientists in respectof weed control through integrated approach.Several chemical mixtures and chemical controlmethods complemented with mechanicalpractices are well established by differentworkers at different times.

Nowadays there has been globalconcern regarding environmental safety andthe increasing use of agrochemicals such asherbicides and their persistence in agro­ecosystem. In this situation, different researchfindings realizing that atrazine, simazine andpendimethalin persisted up to 90 days in thesoil. Simazine or atrazine application up to 2.0kg ha-1 did not leave any residues to thesucceeding crops like chickpea, cowpea,

246 AGRICULTURAL REVIEWS

groundnut, Indian mustard, wheat, linseed and lentil.

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