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Wheat ( Triticum aestivum L.) is one of the most important cereal crops globally and a major contributor to food security. However, weed infestation is a serious constraint in wheat production, causing significant yield and economic losses. Weeds compete with crop plants for nutrients, moisture, light, and space, leading to reduced productivity. Yield losses due to weeds in wheat may reach up to 24% or more depending on weed density and environmental conditions . This review focuses on major weed flora, crop–weed competition, critical periods of weed control, and various weed management strategies including cultural, mechanical, chemical, and integrated approaches. Emphasis is placed on sustainable weed management practices to enhance wheat productivity and environmental safety. Weeds are among the most persistent biotic constraints in wheat production, causing yield losses of 20–40% if unmanaged. Conventional reliance on herbicides has led to resistance in major weed species such as Phalaris minor , necessitating integrated approaches. This review synthesizes cultural, mechanical, chemical, and biological methods, emphasizing Integrated Weed Management (IWM) as a sustainable pathway. Challenges such as herbicide resistance, environmental concerns, and climate variability are discussed, with future directions highlighting precision agriculture, climate-smart practices, and ecological sustainability.
Keywords: Wheat; weeds; herbicides; integrated weed management; crop competition; integratedweedmanagement
1.Introduction inthewheatfields.Theinfestationofweedsdepends onthefrequentrainfalli.e.whenrainfallishigherthe Wheatisastaplefoodcropcultivatedacrossdiverse infestationofthespecieswillbemore.Thefarmersdid agro-climaticregions. Weedinfestationisoneofthe notusedtheproperweedmanagementpracticesto majorbioticstresseslimitingwheatyield. Weedsre- controlweedsintheirfields.InearlierstudiesMuham- ducecropproductivitybycompetingforessentialre- mad et al. (2009) also found 34 broad leaf, sedges sourcesandinterferingwithcropgrowth. Thediver- andgrassyweedspeciesinmaizecropthatresultedin sityofweedfloravariesdependingonsoiltype,irri- maizeyieldreduction.Relativeweeddensity(%)The gationpractices,croppingsystems,andclimaticcon- resultsonrelativeweeddensityofaparticularspecies ditions.Theincreasingrelianceonherbicideshasled areshowninTable2.Therelativeweeddensityofdom- toissuessuchasherbicideresistance,environmental inatedspecies(16.8%)wasrecordedforPhalarisminor pollution,andshiftsinweedflora.Therefore,sustain- (G.sokay)followedbyCannabissativa(15.6%).While, able weed management strategies are essential for the lowest relative weed density was calculated for long-termproductivity. Weedsareunwantedplants Chenopodiumalbum(2.4%)inthewheatfields.Thein- whichprovidehardtimetoanyparticularcropinwhich festationofweedsdependsonthefrequentrainfalli.e. it occurs. Its svariety and distribution differs from whenrainfallishighertheinfestationofthespecieswill croptocrop. Suchvegetationisfoundabundantin bemore.Thepeoplesarenotawareaboutintegrated cultivatedfieldsofgreatfinancialandbiologicalsig- managementpracticesthat’swhyweedinfestationin nificance (Jabeen Ahmed, 2009). These unwanted wheatcropismorecriticandneedspropermanage- plantsgrowalongwithagriculturalplantsandcause menttechniques.InearlierstudiesMuhammadetal. gradualandimportantlossincropyieldbecausethey (2009)alsofound34broadleaf,sedgesandgrassyweed can compete with crop plants for want of available speciesinmaizecropthatresultedinmaizeyieldre- nutrients,space,watercontents,sunlightetc(Dang- duction.Weedfrequency(%)Theweedfrequencyof waletal.,2010). Weedoccurrenceisthemajorprob- weedsisthebestwayofindicationfortheprevalence lem in wheat crop which can reduce wheat produc- of weed species in the studied area. The results on tionby25-30%in(Nayyaretal.,1994).Weedutilizes weedfrequency(%)ofaparticularspeciesareshown soil nutrients and competes for space and sunlight inTable2.Onthebasisofthedataprovidedthehighest with crop, thus reduce crop yield and subsequently frequencywascomputedforCannabissativa(88%)fol- marketvalue(PervaizandQuazi,1992).Besidesmea- lowedbyStellariamediaandPhalarisminor(G.sokay) sureableeffectsonyield,weedsalsoaffectthequality (84%respectively);while,thelowest(60%)fequency ofcropduetopresenceoftheirseedsandfragments. wasrecordedforChenopodiumalbum.Theremaining Themagnitudeofcropyieldlossisdeterminedbythe weedsincludedintheTable-2wereofminorphytoso- persistenceofweeds,theirdensity,typeandalsoby ciologicalstatusandrelativelyunimportantasfaras thepracticesusedforcropmanagement. Thechief wheatproductioninthetargetareaisconcerned.The weedsofwheatareWildoat,Avenafatua,Lamb’squar- highestweedfrequencyinwheatfieldsmightbedue ters,Chenopodiumalbum,Canarygrass,Phalarismi- tolackofweedmanagementinthetargetareathat’s nor, Wild medic, (Medicago polymorpha), Blue pim- why,weedsreproducemoreandarefrequentlyoccur- pernel,Anagallisarvensisc,Fieldbindweed,Convolvu- ringinwheatcrop. Saeedetal. (2010)alsoreported lusarvensis,Rumexdentatus,Seniberadidym,Broad thefrequentoccurrenceofdifferentweedsintheirex- leafdock,(Swinecress)andFumariaindica(fumatory), periments. Inasimilarstudy,Khanetal. (2012)also MelilotusalbaL.(sweetclover),(ShamsiandAhmad, narratedthehighestweedfrequencyforbroadleaved 1984). Therearenearly30,000weedsspeciesinthe weedsascomparedtograssyweeds.Themajorweed world,outofthese50to200mostlycauseconsider- werereportedtoinfestwheatcropinthenorthernPak- abledamagetothemajorfoodcrops(Mahmoodand istanwereCannabissativaHussainetal.(2007).Rela- Niaz,1992).Itisexpectedthatislossinwheatproduc- tiveweedfrequency(%)Therelativeweedfrequency tionisaboutfrom20%to40%isduetoweeds(Ahmad ofweedsisthebestwayofindicationforthepreva- andSheikh,2003).Thewheatgrowerenhancedwheat lenceofweedspeciesinthestudiedarea.Theresults cropqualitiesbyusingnewvariety,increasebiodiver- onrelativeweedfrequency(%)ofaparticularspecies sityandkeepawaywheatcropfromadverseeffectsof are shown in Table 2. On the basis of the data pro- pestandclimaticcondition.(Walburgeretal.,1999). vided the highest relative frequency was computed The weed density of dominated species (30.4 m-2) for Cannabis sativa (8.7%) followed by Stellaria me- wasrecordedforPhalarisminor(G.sokay)followedby diaandPhalarisminor(G.sokay)(8.3%respectively); Cannabissativa(28.4m-2).While,thelowestweedden- while,thelowest(5.9%)relativefequencywasrecorded sitywascalculatedforChenopodiumalbum(4.3m-2) for Chenopodium album. The remaining weeds in- sityandrelativeweedfrequencyandareoughtmost cludedintheTable-2wereofminorphytosociologi- importanttobemanagedproperlyontime.Theweeds calstatusandrelativelyunimportantasfaraswheat shouldbecontrolbeforethresholdlevel,sothatcould productioninthetargetareaisconcerned.Thehigh- not decrease wheat productivity. These results are estweedfrequencyinwheatfieldsmightbedueto supported by those of Saeed et al. (2010) who ob- lackofweedmanagementinthetargetareathat’swhy, servedthehighestimportancevalueindexforkharif weedsreproducemoreandarefrequentlyoccurring weeds in their investigations. Waheed et al. (2009) inwheatcrop. Saeedetal. (2010)alsoreportedthe concludedthatweedspeciessuchasCannabissativa, frequentoccurrenceofdifferentweedspeciesintheir Polypogon fugax, Melilotus indica, Cirsium arvense, experiments. In a similar study, Khan et al. (2012) ChenopodiumalbumandCynodondactylonwerealso alsonarratedthehighestweedfrequencyforbroad uniformlyobservedwithIVIrangingfrom6.70-44.45%. leavedweedsascomparedtograssyweeds.Hussain Freshbiomass(gplant-1)Dataregardingfreshweed etal.(2007)reportedthatthemajorweedinthenorth- biomassofofdifferentweedsduringthesurveyindi- ernPakistanwereCannabissativa. Kazietal. (2007) catedthatfreshbiomassvariedamongdifferentweeds reported that the relative density and frequency of speices(Table3).Thedatafurtherrevealedthatmaxi- Chenopodium album were 13.53% and 30% respec- mumfreshbiomasswasrecordedfromCannabissativa tively. While Heliotropium europacum showed less (142.6gplant-1)followedViciasativaandMedicago frequency (3.33%) and density (0.52). Qureshi et al. minima(128.3and128.2gplant-1)respectively.While, (2009)determinedthatCannabissativaandRanuncu- thelowestfreshbiomasswasnotedfromEuphorbia lusmuricatuswerethemostcommonanddominant helioscopiaandMedicagotruncatula(20.3and17.2 weed species with an average rate of 72% and 84% g plant-1) respectively. The more fresh biomass of respectivelyinwheatcropinDistrictTobaTakSingh. the weeds might be due to the avialibility of suffi- Muhammadetal. (2009)recordedthattheCynodon cientwater,nutrientsandnoweedmanagementtech- dactylon and Convolvulus arvensis were most com- niques. That’s why weeds grow vigoursley and pro- monweedspeciesinwheat,maizeandpotatocrops. ducemorebiomass. Theusedofproperweedman- Subedi(2013)studiedthathemajorweedspecieson agementtechniquecausedmaximumreductioninthe thebasisoffrequencyanddensitywereViciahirsutum, germinationandbiomassofhorsepurslane(Khanet Chenopodiumalbum, Oxalis 916 JournalofPhar- al.,2012).Thelowestweedbiomassintreatedfields macognosyandPhytochemistrycorniculata,Anagalis negativelyaffectedtheweedgrowthandbiomass(Pa- arvensisandPoaannuawhileChenopodiumalbum, teletal.,2006).Drybiomass(gplant-1)Dataregarding Polypogonfudax,Solanumnigrum,Gnaphaliumaffine dryweedbiomassofofdifferentweedsduringthesur- AnagalisarvensisandPolygonumplebijuminwheat veyindicatedthatdrybiomassvariedamongdifferent population. Whereas, Khobragade and Sathawane weedsspeices(Table3).Thedatafurtherrevealedthat (2014)studiedthatChenopodiumalbum,Parthenium maximumdrybiomasswasrecordedfromCannabis heterosphorus, Melilotus indica, Phaselous aconiti- sativa(59.1gplant-1)followedViciasativaandMed- folius,Tridaxprocumbence,Alternantheraspinosus, icago minima (44.1 and 37.9 g plant-1) respectively. Anagalis arvensi, Rumex dentatus, Cyprus rotunds, While,thelowestdrybiomasswasnotedfromEuphor- PortulacaoleraceaandEuphorbiathymifoliawerere- biahelioscopiaandMedicagotruncatula(20.3and17.2 portedtobethecommonweedspeciesinwheatcrop. gplant-1)respectively. Themoredrybiomassofthe Khanetal. (2012)foundsevenweedsinwheatcrop weedsmightbeduetotheavailabilityofsufficientwa- which were Cirsium arvense, Convolvulus arvensis, ter,nutrientsandnoweedmanagementtechniques. Conyza bonariensis, Cynodon dactylon, Cyperus ro- That’swhyweedsgrowvigourasliyandproducemore tundus,Partheniumhysterophorus,andSonchusas- biomass.Theusedofproperweedmanagementtech- pera. ImportancevalueindexTheimportancevalue niquecausedmaximumreductioninthegermination indexisimportantforunderstandingthestatusofa andbiomassofhorsepurslane(Khanetal.,2012).The givenweedspecieinaweedscommunity. Thedata lowest weed biomass in treated fields negatively af- in Table-3 exhibits the highest importance value in- fectedtheweedgrowthandbiomass(Pateletal.,2006). dex(25.1%)wasrecordedforPhalarisminor(G.sokay) followed by Cannabis sativa (24.3%), while the low- 2.Conclusion estimportancevalueindex(8.4%)forChenopodium Weedinfestationisamajorconstraintinwheatpro- albumandthesecondlowestbyAvenafatua(9.0%). duction, significantlyaffectingyieldandquality. In- Thehighestimportancevalueindexoftheaboveweed tegratedweedmanagementisthemosteffectiveap- speciesisduetotheirhighvalveofrelativeweedden- proachforsustainableweedcontrol.Futureresearch Category Weed ScientificName Grassy Littleseedcanarygrass Phalarisminor Grassy Wildoat Avenaludoviciana Broadleaf Bathua Chenopodiumalbum Broadleaf Senji Melilotusindica Broadleaf Scarletpimpernel Anagallisarvensis
WeedType Herbicide Dose Remarks Grassy Clodinafop 60g/ha Post-emergence Grassy Pinoxaden 50g/ha EffectiveforPhalaris Broadleaf 2,4-D 500g/ha Applyat30-35DAS Broadleaf Metsulfuron 4g/ha ControlsmanyBLW Mixed Sulfosulfuron+Metsulfuron 32g/ha Broadspectrum cost-effectiveness,over-reliancehasacceleratedresis- tance.Mechanicalandculturalmethods,thougheco- friendly, are less effective alone. Biological control ispromisingbutrequiresfurtherresearchandadop- tion.Integratedapproachesbalanceproductivitywith sustainability,aligningwithclimate-smartagriculture. Emergingtechnologiessuchasprecisionagriculture, AI-drivenweeddetection,andherbiciderotationstrate- giesofferfuturesolutions.PolicysupportforIWMadop- tion,farmertraining,andinvestmentinbiocontrolre- searcharecriticalforlong-termresilience.Weedman-
residuemanagement,andjudiciousherbicideuseare essential. Futuredirectionsshouldemphasizepreci- siontechnologies,climate-smartpractices,andeco- logicalsustainabilitytoensureyieldstabilityandfood security.