Herbicides – Definition – Advantages & Limitations of Herbicide usage in India – Nomenclature of Herbicides – Herbicide label information – Presently available herbicides in the market

Define herbicides - advantages and limitations et

1. Lecture No 9
Herbicides –Definition –Advantages & Limitations of Herbicide
usage in India –Nomenclature of Herbicides –Herbicide label
information –Presently available herbicides in the market
1.What is meant by Herbicide?
2.Historical development of herbicides
3.Objectives of herbicide usage
4.Advantages of herbicide usage in Agriculture
5.Disadvantages of herbicide use/ Chemical methods
6.Nomenclature of herbicides
7.Authorities
8.Herbicide label information
9.Presently available herbicides in the market
Dr.G.Krishna Reddy
Professor [Agronomy]
SVAC, Tirupati
06.11.21

2. 1. What is meant by Herbicide
The word herbicide is derived from Latin
word Herbameans plantand
Caederemeansto kill
Herbicides are chemicals capable of killing
or inhibiting the growth of plants.

3. 2.Historical Development of Herbicides
•Commonsalt,ashetc.havebeenusedforcenturiestocontrolweeds
•Selectivecontrolofweedsin1896observedbyFrenchfarmerthat
BordeauxmixturesprayedonGrapevinetocontroldownymildew.
ItwasfoundthatCuSo4presentintheBordeauxmixturewas
responsibleforitsweedkillingeffect.
•Between1896and1908severalinorganicsaltsasalsosulphuricacid
werefoundselectivetosmallgraincrops.
•1945-2,4-D&MCPAinUSA&Englandindependentlyby
P.W.ZimmermanandHitchkock.werefoundhighlyselectiveforcereals
andphytotoxictobroadleavedweeds.
•InAgriculturallydevelopedcountries,herbicidesformover45%ofthe
totalpesticidesused.InIndia,shareofherbicidesisonly8%ofthetotal
pesticidesconsumed.TheaverageherbicideusageinIndiais
40g/ha/yearasagainst675-1350g/ha/yearinmanyadvancedcountries.

4. 3. Objectives of herbicides usage
•Toreplacethedrudgeryofmanualweeding.
•Thelabourpowercouldbesaved
•Increasingcostsofhiredlabourandlimitedsupply
offuelformechanicalweedcontroldemandsuse
ofherbicides
•Herbicidesarenotaimedatsubstitutingthe
Physical,Biologicalorgoodcrophusbandry
methods.
•Inwaterbodiesherbicidescanbeefficiently
employedtofreethemoftheirweedyvegetation.

5. 4. Advantages of herbicides
•Herbicidesareusefulinareaswhereincessantrainfallmay
hinderthephysicalweedingduringmonsoonalseason
•Herbicideusagereducethecompetitionforlabour
•Theycontrolgerminatingweedsandtherebymakethecrop
weedfree
•Theyareusefultocontrolweedsmimicweeds.
•Herbicidesdoesn’tdictatestrictrowspacing.
•Theyhavelonglastingeffectoncontrolofbrushweedsand
perennialweeds.
•Convenienttouseonthorny/spinyweeds.
•Controlweedsonerodiblesoilswheretillagemayaccelerate
soilandwatererosion

6. 4.Advantages of herbicides contd…….
•Theykilltheweedsinsituwithout
disseminationpropagules
•Sprayseasilyreachtheinaccessibleareas
•Reducethedemandforlabour
•Greaterpossibilityofmechanization.
•Easycropharvesting.
•Weedscontrolledincroprows
•IncreaseWUEindrylandsandlesscropfailures

7. 5.Disadvantages
•Noautomaticsignaltostopfarmerwhomay
applyingthechemicalinaccurately.
•Contaminatetheenvironment.
•Drifthazards/runoff/washoff
•Manyherbicidesareneededtocontrolweeds
dependinguponfarmdiversity.
•Skillisneededintheuseherbicides
•Insequencecropping-selectivityisamajorproblem.
•Neighboursfielddamagebywarfare

8. 8
6. Nomenclature of herbicides
Eachherbicidehasatradename(sometimesmore
thanone),acommonname,andachemicalname.
1.Commonname:Shortform-agreeduponby
acommittee.
2.Tradename:Offeredbythemanufacturer.
registered-several trade names.
Glyphosate:Glycel–Excel;–Monsanto
Roundup-Noweed-Dhanuka
3.Chemicalname:Fullmolecularstructure.

9. 9
S.
No.
Common
Name
Trade
name
Chemical name
12,4-D Fernoxone2,4-Dichlorophenoxyacetic
acid
2MCPA Agroxone2-Methyl-4-chlorophenoxyacetic
acid
3AlachlorLasso 2-Chloro-2,6-diethyl-N-
(methoxymethyl)acetanilide
4AtrazineAtrataf2-chloro-4-ethylamino-6-
isopropylamino-s-triazine
5BenthiocarbSaturn S-(4-chlorobenzyl)-N,N-
diethylthiocarbamate
Nomenclature

10. 10
7.Authorities to accept names
1.ANSI :AmericanNationalStandardInstitute.
2.BSI :BritishStandardInstitute.
3. IOS : International Organization for Standardization.
4.WSSA :WeedScienceSocietyofAmerica.
5.ISWS :IndianSocietyofWeedScience.
6.NRCWS : National Research Centre for Weed Science,
Jabalpur
6.DWS R : Directorate of Weed Science Research, Jabalpur
(MP)

11. 8.Herbicide label information
•Aherbicidelabelisalegaldocument
providingimportantinformationabout
aherbicide,itsappropriateuse,andthe
precautionsneededtoavoidoff-target
movementandtoprotectenvironmental
quality.Aherbicidelabelanswersthe
“what,where,when,”and“how”questions
abouttheproduct.

12. Herbicides of commercial importance

13. Herbicide label information
Toxicity
categories
LD50
[mg/kg
bodywt]
Colourof
thetriangle
Signal
word
Warning
symbol
Extremelytoxic0-50 BrightredPoison
Skulland
Cross
Highlytoxic 51-500
Bright
yellow
Poison -
Moderately
toxic
501-5000 BrightblueDanger -
Slightlytoxic>5000 BrightgreenCaution -

14. Herbicide label information to be noted
informationshouldbecollectedinthefollowingformat
1.Commonname
2.Tradename
3Formulation
4Activeingredient
5.Carrier
6Netweight
7.Antidote
8.Manufacturersaddress
9.Dateofexpiry
10.Recommendeddoseperacre

15. 9. Commonly
available
herbicides
in India
Commonnames Tradename Percentage
Alachlor Lasso 50EC
Anilofos Aniloguard 30EC
Atrazine Atrataf 50WP
Butachlor Machete 50EC
Clomozone Command 50EC
Ethoxysulfuron Sunrise 15WG
Fenoxaprop-p-ethyl Whipsuper 10EC
Glyphosate Glycel/Roundup 41SL
Metolachlor Dual 50EC
Imazethypr Persuit 10EC
Oxyfluorfen Goal 25EC
Oxadiargyl RaftSC,TopstarWG 6EC
Paraquat Gramoxone 24SL
Pendimethalin Stomp 30EC
Pretilachalor Rifit 50EC
Pretilacholar-S Sofit 30.7%EC
Pyrazosulfuron-ethyl Saathi 10WP
Quizalofop-ethyl Turgasuper EC
2,4-D Fernoxone 80WP
2,4-DEE Agrodon 48EC
Glufosinate Basta 15%SL
Isoproturon arelon 75%WP
Propanil StamF34 34%EC
Thiobencarb Saturn 50%EC
Trifluralin Tiptop 48%EC
Metaxuron Dosanex 80%WP
Cinmethylin Argold,Cinch
Bis-pyribacsodium
Metsulfuronmethyl Algrip 20%WP
Chlorimuron
+metsulfuron
methyl
Almix 20%WP
Chlorimuron-ethyl Kloben 25%WP
Nominee gold 10%SC

16. Dr.G.Krishna Reddy
Professor [Agronomy]
SVAC, Tirupati
06.11.21

17. Classification of Hb based on chemical nature and selectivity
1.Basedonchemicalstructure
i) Organic ii) Inorganic
2. Based on Selectivity :
i) Selective ii) Non selective
3. Based on mode of action
i) Contact ii) Translocated (Systemic)
4. Based on residual action in soil
i) Residual ii) Non residual herbicides
5. Based on Spectrum of weed control
i) Narrow spectrum ii) Broad spectrum herbicides
6. Based on duration of weed control
i)Soil sterilant ii) Fumigants
7. Based on Time of application
i) Pre planting herbicides ii) Pre Emergence iii) Post Emergence Hbs

18. 8. Based on method of application
i) Soil active herbicides ii) Foliage active herbicides
1. Surface application 1.Blanket application
2. Sub- surface layering 2. Directed spraying
3. Band application 3. Spot treatment
4. Soil fumigation 4. Protected spraying
5. Herbigation
9. Methods of treating brush and trees
i) Cut stump treatment
ii) Basal bark treatment
iii) Foliage treatment
10. Other methods of Herbicide Application

i) D.C.A. (Direct Contact Application
ii) Herbicide wax bars
iii) Herbicide cloth mulch
iv) Herbicide rouging gloves
v) Soil Injection

19. Classification of herbicides.
1) Classification based on chemical
nature [structure]
•Herbicidesareprimarilygrouped
into
•inorganicherbicides
•organicherbicides.

20. Classification of herbicides.
1.1Organicherbicides:
•Theseherbicidescontaincarbonatomsintheir
molecules.Theymaybeoilsornonoils.Eg.diesel
oil,xylenetypeofaromaticoils.
•Majorityofpresentdayherbicidesarenonoils.
•Thereareabout292(MACHRAC2010)herbicides
areavailable.
•Theydiffereachotherlikebehaviorinsoil,plants,
modeofactionetc.basedonthischemical
nature;theherbicidesaregroupedinto22
groups.

21. Classification of herbicides.
1.2Inorganicherbicidesdonotcontaincarbon
atomsintheirmolecules.Theywerethefirst
chemicalsusedforweedcontrol.
•Arsenicacid,sulphuricacidareacidtypeof
inorganicherbicides.
•Whereassodiumarsenate,sodiumchlorate,
coppersulphateetcareinorganicsalts

22. Based on chemical structure
Sl.NoGroup Herbicides
1 Aliphatic acids
Dalapon, TCA, Glyphosate, Methyl bromide
Cacodylicacid ,MSMA,DSMA
2 Amides
Alchlor, Butachlor, Propachlor,Metalachlor,
Diphenamide, Propanil
3 Benzoics 2,3,6, TBA, Dicamba, tricamba, Chloramben
4 By PyridillumsParaquat, Diquat
5 Carbamates
Propham, Chlorpropham, Barban, Dichlormate,
Asulam
6 Thiocarbamates
Butylate,Diallate,EPTC, Molinate,
Triallate, Benthiocarb, Metham
7 DithiocarbamatesCDEC, Metham
8 Nitriles Bromoxynil, Ioxynil, Dichlobenil

23. Based on chemical structure contd...
S.NoGroup Herbicides
9 Dintroanilins
Fluchloralin, Trifluralin, Pendimethalin, Nitralin
Isoproturon
10 Phenols Dinoseb, DNOC,PCP
11
Phynoxyalkanoic
acids
2,4-D, 2,4,5-T, MCPA, MCPB, 2,4-DB, Dichlorprop
12 Traizines Atrazine, Simazine, Metribuzine, Amytrin, Terbutrin
13 Ureas
Monuron, Diuron, Linuron, Metoxuron, Isoproturon,
Methabenzthiozuron
14 Uracils Bromacil, Terbacil, Lenacil
15 DiphenylethersNitrofen, Oxyfluorfen, Nitrofluorfen
16
Aryloxypheno
xypropionate
Diclopop, Fenoxaprop-p, Quizalofop-p, Haloxyfop-
p Fluazifop-p

24. Based on chemical structure contd…
S.NoGroup Herbicides
17Cyclohexanedione
Sethoxydim, Clethodim,
Tralkoxydim,Cycloxidim
18Imidazolines
Imazapyr, Imazamethabenz,
Imazaquin, Imazamax
Imazethapyr
19Isoxazolidinones Clomazone
20Oxadiazoles Oxadiazon, oxadiargyl
21Oxadiazolides Methazole
22N-phenylphthalamidesFlumiclorac
23PhenylpyridazonesSulfentrazone
24Phthalamates Naptalam

25. Based on chemical structure
Sl.NoGroup Herbicides
25 Pyrazoliums Difenzoquat, Metflurazone
26
Picolinic acids
Pyridine
Picloram, Dithiopyr, Pyrithiobac, Fluridone,
Thiazopyr
27 Quinolines Quinclorac
28 Sulfonylureas
Bensulfuron, Chlorimuron, Metsulfuron,
Sulfosulfuron
Triasulfuron, bispyriubacNa
29 TriazolinonesPyridates
30 Cineoles Cinmethylin
31 Others
Pichloram, Pyrazon, Endothal, Oxadiazon,
Amitrole, Anilofos

26. •Aselectiveherbicideisonethatwillkillsome
plantspecieswhenappliedtoamixedplant
population,withoutcausingseriousinjurytothe
otherspecies.Selectiveherbicidesareusedin
cropareas,lawns,gardens,andgrasslands.2,4-
D,atrazine,EPTC,trifluralin,alachlor,butachlor,
fluchloralinandpendimethalinareselective
herbicidesusedoncropland.
• Non-selectiveherbicide:Itisonethatkills
plantswithoutregardtospecies,forexample,
paraquat,Diquat,sodiumchlorate,weedoils,
andacrolein.Thenon-selectiveherbicidesare
employedforgeneralvegetationcontrolon
industrialsites,fallowland,andinaquaticsand
tenniscourts.*Certainselectiveherbicideswhen
appliedathighrates,canactasnon-selectiveplant
killers,forinstance,simazineanddiuron.

28. Contactherbicidekillsplantsbycomingincontactwiththeplanttissue
ratherthanasaresultofitstranslocation.Thus,acontactherbicide
appliedtothefoliageofaplantwillnotkillitsroots,thoughinsimple
annualstherootsofthetreatedplantsmaydiebecausetheywere
deprivedoftheirshoots.Theestablishedweedswillregrowfromtheir
crownbuds,roots,orrhizomes,shortlyaftertreatmentwithacontact
herbicide.Somecommoncontactherbicidesareparaquat,diquat,
Propanil,andpetroleumoil
Translocated(systemic)herbicidemoveswithintheplantfromthepoint
oftreatmenttoitsotherparts,tovariableextent.

29. Someherbicidesmayexhibitboth,contactandtranslocationactivities.For
example,atrazineisatranslocatedherbicidewhenabsorbedbytheweedfromthesoil,
butacontactherbicidewhenitissprayedontheplantshoots.

30. 4. Based on residual action in soil
i)Residualherbicides
itmaintainsitsphytotoxiceffectsinsoilforconsiderabletimeafterits
application.Thisresidueperiodmaybethreetofourweeksinsome
herbicides,suchas2,4-DandEPTC,andmuchlonger,uptoseveralmonths,
inothers.
ii)Anon-residualherbicideisinactivatedinsoilimmediately,orwithinafew
days,afteritreachesthesoil,Paraquat,diquat,amitrole,DSMA,andweed
oilsarenon-residualorveryshortpersistenceherbicides.
Thenon-residualherbicidesaregoodforaquickknockdownoftheexisting
weeds.Theydonotprovideanyextendedperiodofweedcontrol

31. i) Narrow Spectrum: -In a mixed population active
only on one weed species.
Ex: Metoxuron, Diclofop
Phalaris minor and Avenafatua
Disadvantage additional herbicides need to be
used.
ii) Broad Spectrum:-Wide spectrum of weed flora.
Most herbicides.

32. •Asoilsterilantpreventsthegrowthofplantswhenpresentinthesoil*.
i)Temporarysoilsterilantssterilizethesoilforupto16weeks,whereasthe
permanentsoilsterilantsremainactivefortwoormoreyears.Thetemporarysoil
sterilantsareusuallyvolatilecompoundswhichleavethesoilinvapourformaftera
fewdaystoafewweeksofapplication.Duringthisperiodthesearesupposedtohave
killedallliveplantpartsinthesoil.Suchsoilsterilantsarealsocalledsoilfumigants.
MB,Metham,anddazometaregoodexamplesofsoilfumigantsusedin
agriculture
andhorticultureforthetreatmentofseedbedsandpotsoil.
ii)Permanentsoilsterilantsusedincausingbaregroundinindustrialandothernon-
cropareasforoneormoreseasons.Sodiumchlorate,substitutedureas,several
symmetricaltriazines,arsenics,andboratesarethemajorpermanentsoilsterilantin
usecurrently.

33. 7. Based on time of application
1) Pre-sowing or pre-plant treatment: Anytime before the crop is
sown.
This is of 2 types
a) Pre-sowing or pre-plant desiccation: -
Applied to desiccate the standing weed vegetation.
eg:Paraquat & Glyphosate.
b) Pre-sowing or Pre-plant incorporation: -
Applied and incorporated before sowing.
eg: Fluchloralin, Pendimethalin, Trichloralin
2) Pre-emergence application:
Soon after sowing before neither the crop nor the weds
germinated.
Crop & weed have not emerged.
eg: Benthiocarb, Atrazine in maize,
Diuron in Cotton & Pendimethalin

34. Weed
Cropseedling
Crop seed
Weed seed
Weed seed Weed

35. 35
3) Post emergence application
Applied after the emergence of both crop and
weed.
Ex:Propanil in Rice at 25 DAT
2,4-D at 30 DAT of Paddy.
4) Lay by application ***VIMP
Application after ridging in sugarcane and cotton.
Eg.Atrazine in sugarcane after last interculture and
making ridges

36. 8.Classification based on methods of application of
herbicides
•Methodsofapplicationofherbicidesare
decidedlargelybytheirmodesofactionand
selectivity.Importantmethodsofapplication
ofherbicidestocropandnon-croplandsare
given,asfollows
•Soil-Active andFoliage-Active Herbicides

37. i) Soil-Active Herbicide
•Asoil-activeherbicideisonethatisappliedprimarily
tothesoilratherthantothevegetation.
•Theyinhibitsgermination/sproutingoftheirrhizomes/
tubers.
•Eliminatesearlyweed-cropcompetitionfortheperiod
of4to8weeks,dependingupontheherbicide/dose.
•Thesoil-activeherbicidesareappliedatthetimesof
planting.
•Weedfreeinter-rowsofestablishedcropstoobtain
extendedperiodofweedcontrol.
•EgSimazine,Alachlor,Trifluralin,andEPTC.
•Onnon-croplands,thesoil-activeherbicidesusedare
soilsterilantsandfumigantsEg.EPTC

38. 1.Surface Application
•Soilactiveherbicidesareapplieduniformlyon
thesurfaceofthesoileitherbysprayingorby
broadcasting,wheretheymaybeeitherleft
undisturbedorincorporatedintothesoil
physically.
Eg. Dinitroanilines, Triazines,

39. 2.Sub-Surface Layering
•Itistheapplicationofanherbicideina
concentratedband,about7-10cmbelowthesoil
surface
•Incorporationofsoilappliedherbicide
•Thetechniquehasprovedeffectiveincontrolling
perennialweedslikeCyperusrotundusand
Convolvulusarvensis.EgCarbamatefluchloralin,
trifluralinandnitralinherbicides,
•Theimmediateuseofthetechniqueisprobably
inorchardsandvineyards,besidescertainwide-
rowcropslikesugarbeetandtobacco.

41. iii) Band Application
•Thebandapplicationofaherbicide
constitutesitsapplicationtoarestrictedband
alongthecroprows,leavinganuntreated
bandintheinter-rows.
•Thebandapplicationofherbicidesisprimarily
acostsavingdevicesinceitreducesthe
quantityofherbicideintheratioofthe
treatedbandwidthtothecroprowwidth.

42. iv) Soil Fumigation
Herbicidesusedforfumigationarecalledas
fumigants.Dependinguponthenatureofthe
soilfumigant,itcanbeappliedeither
1)bysoilinjection(Chloropicrin)
2)byreleasingitundersealed,plasticcovers
(Methylbromide)or
3)bydirectsoilsurfaceapplication(Metham).

43. Soil fumigation under sealed plastic
covers

44. v) Herbigation
•Applicationofherbicideswithirrigationwater
bothbysurfaceandsprinklersystems.
•InIndiafarmersapplyfluchloralinforchillies
andtomato,
•whileinwesterncountriesapplicationofEPTC
withsprinklerirrigationwaterisverycommon
inLucerne.

45. ii) Methods of Application of Foliage-Active Herbicides
•AFoliage-activeherbicideisappliedtoweeds
aftertheiremergencefromthesoil.
•Theyareabsorbedbytheplantfoliageand
thesearetranslocatedtotheotherplant
parts.
Eg2,4,5-T,paraquat,diquat,MCPB,amitrole,
andherbicidaloils.
Theremaybesomeherbicidesthatareboth
soil-activeandfoliage-active,forexample,
2,4-D,picloram,andatrazine.

46. 1. Blanket Application
•Blanket(orover-the-top)itisuniform
applicationofherbicidestostandingcrops
withdisregardtothelocationofthecrop
plants.
•Onlyhighlyselectiveherbicidesareapplied
bythismethod,e.g.2,4-Dinwheat.rice,
MCPBinpea,2,4-DBinLucerne,andpicloram
insugarcanecf.surfaceapplicationof
herbicide

47. 2. Directed Spraying
•Itistheapplicationofherbicidetoweeds,which
aregrowingintheinter-rowsofcropavoidingthe
cropfoliageasmuchaspossible.
•Oneimportantpre-requisiteofdirectedspraying
isthatfarmermustgethisrowcropswellgrown
overtheweedsatthetimeoftreatment.
•Orchardsandplantationsaregoodvenuesof
directedherbicidesprays.
•Usually,thedirectedsprayingisadoptedwith
herbicidesthatarepartiallyselectivetothe
treatedcrops.

48. Post-emergence directed spray

49. 3. Spot treatment
•Spottreatmentistheapplicationofherbicides
tosmallpatchesofweeds,leavingtheweed-
freegapsuntreated.
•Thisisusedfortreatingpatchesofnoxious,
perennialweedsincertaincropfieldswith
potentherbicides.(Paraquattreatmentfor
cuscutainBlackgram)
•Spottreatmentinthenon-cropareasto
preventwastageofherbicide.

50. 4. Protected Spraying
•Non-selectiveherbicidescanbeemployedto
obtainselectiveweedcontrolindistantly
plantedvegetablesandornamentalseitherby
coveringthenon-targetplantsbefore
applicationoftheherbicidewithplasticor
metalliccoversorbysprayingherbicide
underneathahoodedorshieldedsprayer.

51. Glyphosate application underneath a hooded or shielded
sprayer that prevents spray contact with sugarcane foliage

52. 9.Methods of treating brush weeds and trees
•Brushweedsandunwantedtreesaretreated
withherbicidesbydifferentmethods.
i)Foliagetreatment
ii)Basalbarktreatment
iii)cutstumptreatment

53. i)Foliage treatment
Whenthebrushleavesarefully
expanded&growingactively.
-Groundsprayerscancoverupto2.5
mhighbrush
–Foliagetreatmentisthemost
commonmethodoftreatingbrush.

54. ii) Basal bark treatment
Abettermethodofdealingwith
tallbrushes.Basal30cmof
stembarkispeeledoffthen
sprayingisdonetothepointof
liberalrun-off

55. iii) Cut stump treatment
Cutthestumpfewinchesabovetheground
followedbyliberalapplicationoftheherbicideon
thecutsurface/Wickdippedinherbicidesolution
maybewrappedandappliedtwiceatanhour
interval.

58. 10.Other ways for treating brush and trees
•Otherwaysbywhichtheconcentratedherbicidesare
appliedtounwantedtreesare,frill,notch,andinjection
methods.
•Thefrill,notch,andinjectionmethodsareadoptedon
thickstemtreeswhichare8cmormoreindiameter.
•Thefrillsandnotchesaremadewithsharptoolsintothe
sapwoodatconvenientstemheightandfilledwith
herbicides.
•Theherbicideinjectionsaremadeintoholesmadeinthe
treetrunk.Usually,oneherbicideinjectionper2.5cm
stemthicknessisadequate.

59. Other methods of Herbicide Application
D.C.A.(DirectContactApplication:
D.C.Aincludesalltechniquesinvolvingwiping,rubbing,and
smearingofherbicideontothetargetplantsurfaces.
Itmaybeachievedbyusingherbicidewaxbars,herbicide
clothmulch,herbiciderouginggloves,etc.
Theherbicideladenwaxbarsaredraggedagainstweeds
growingmuchtallertothecropplants.
Herbicideclothmulchesarespreadinthecropinter-rows.
Therougingglovescarryarrangementtosmearherbicide
ontotheweedgrippedbytheworker.
ManyotherwaysofDCAofherbicidescanbedesignedtosuit
specificsituations.
Soilinjection:Herbicideslikeethylene,carbonbisulphideand
vernolateareappliedbysoilinjections,atprescribed
spacings,beforeplantingofthecrops.

63. Thank you