Herbicide Group Classification by Mode of Action

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 Pesticide Resistance
The problem
Agricultural pests can develop resistance to fungicides, herbicides or insecticides. Resistance is the result of repeated use of one or more similar pesticides over a number of years. In Alberta, the potential exists for resistance to develop to a number of products. Producers should follow agronomic practices that both prevent or minimize the development of resistance and prevent the spread of existing resistant populations.

Pest biotypes resistant to one or more chemical pesticides occur naturally. Repeated use of either one pesticide or of pesticides with a similar mode of action can result in a build-up of resistance and a loss of control. Pesticide resistant biotypes do not differ in appearance from the susceptible biotypes. Therefore, it is extremely difficult to observe the progression of resistance until a loss of control is observed.

Identifying resistance
  • Loss of control is observed. One pest may escape control while other pest species are controlled.
  • Was pesticide performance adversely affected by weather conditions or misapplication?
  • Does the field history indicate repeated use of one or more pesticides with a similar mode of action?
  • Did the pest infestation occur after pesticide application?
Mode of action
Chemical family
Active ingredients
Found in*
Group 1
Inhibitors of acetyl CoA
carboxylase ACCase.
These chemicals block
an enzyme called
ACCase. This enzyme
helps the formation of
lipids in the roots of
grass plants. Without
lipids, susceptible
weeds die.
Aryloxyphenoxy propionate
clodinafop-propargylFoothills SG, Harmony K, Harmony Max, Harmony SG, Horizon SG, Ladder, MPower Aurora, NextStep SG, NuFarm clodinafop,Signal D, Signal M, Signal F, Signal FSU, Traxos
fenoxyprop-p-ethylBengal, Cordon, MPower Hellcat, Puma Super, Puma Advance, Tundra, WildCat, Vigil
quizalofop-p-ethylAssure II, Yuma
clethodimArrow 240 EC, Centurion, Select, Shadow RTM
sethoxydimPoast Ultra, Odyssey Ultra
tepraloxydimEquinox, Odyssey DLX
tralkoxydimLiquid Achieve, Bison, Marengo, Nufarm, Tralkoxydim
Phenylpyrazolin (Den)pinoxadenAxial, Axial iPAK, Axial Xtreme, Broadband, Traxos
Group 2
ALS/AHAS inhibitors. These chemicals block
the normal function
of an enzyme called
acetolactate (ALS)
actohydroxy acid
(AHAS). This enzyme
is essential in amino
acid (protein) synthesis.
Without proteins, plants
starve to death.
ImidazolinonesAC 299, 263, 120 ASAltitude FX
imazamethabenzAssert 300, Assert FL, Avert
imazamoxAres, Salute, Solo, Tensile, Viper
imazamox + imazethapyrOdyssey, Odyssey DLX, Odyssey Ultra
imazapyrArsenal, Ares, Salute
imazethapyrGladiator, Multistar, Pursuit, MPower Kamekaze
flucarbazone sodiumEverest, Inferno Duo, Pace
SulfonylureaschlorsulfuronTelar, Truvist
ethametsulfuron methylMuster
metsulfuron-methylAlly Toss-N-Go, Escort, Accurate,
Express Pro, Reclaim
rimsulfuronPrism, Titus Pro
thifensulfuron-methylBarricade, Broadside, Deploy, Harmony K, Harmony Max, Harmony SG, MPower R, Nimble, Pinnacle SG, Refine SG, Retain SG, Triton C
tribenuron-methylBarricade, Broadside, Deploy, Express Pack, Express SG, Express Pro, FirstStep Complete,Harmony K, Harmony Max, Harmony SG, Inferno Duo, Inferno WDG, KoAct, Nimble, MPower R, MPower X, Nuance, Refine SG, Refine M, Retain, Signal FSU, Triton C, Triton K
triflusulfuron methylUpBeet
TriazolpyramidinesflorasulamAssert FL, Benchmark, Broadband, Frontline, Frontline XL, Frontline 2, 4-D, Korrex, Paradigm, PrePass, Priority, Spectrum, Spitfire, Stellar, Topline
pyroxsulamSimplicity, Tandem
Triazolonesthiencarbazone-methylVelocity m3, Varro
Group 3
Microtubule assembly
inhibitors. These
chemicals inhibit the
cell division in roots.
trifluralinBonanza, Fortress, Rival, Treflan
Group 4
Synthetic auxins. These
chemicals disrupt plant
cell growth in the
newly forming stems
and leaves; they affect
protein synthesis and
normal cell division,
leading to malformed
growth and tumors.
Benzoic acidsdicambaBanvel II, Distinct, DyVel, DyVel DSp, Glykamba, Harmony K, Hawkeye Power, Korrex, Oracle Dicamba, Pulsar, Rustler, Sword, Target, Takkle, Tracker XP, Triton K, Vanquish, VMD 480
Carboxylic acidsclopyralidCurtail M, Eclipse lII, Lontrel, Momentum, Prestige, Prestige XC, Salute, Spectrum, Tensile
aminopyralidReclaim, Restore II
fluroxypyrAltitude FX, Attain XC, Axial Xtreme, Barricade, Enforcer D, Enforcer M, Fluorex 24, Harmony Max, Momentum, Pixxaro, Prestige XC, Pulsar, Retain SG, Signal F, Signal FSU, Stellar, Tandem, Trophy
picloramGrazon, Tordon 22K
Picolinic acidHalauxifenParadigm, Pixxaro
Phenoxy2,4-D2,4-D, Approve, Attain XC, Benchmark, Calmix Pellets, Desormone, DichlorpropDX, DyVel DSp, Enforcer D, EstapropXT, Fluorex 24, Frontline 2,4-D, Grazon, KoAct, Leader, Reclaim, Restore II, Retain SG, Signal D, Thrasher, Thumper, Triton K, Turboprop 600
dichlorprop (2,4-DP)Desormone, Dichlorprop-DX, Estaprop XT, Optica Trio, Turboprop 600
2,4-DB2,4-DB, Caliber 625, Cobutox 625,
Embutox 625
MCPAAltitude FX, Assert FL, Badge, Broadside, Buctril M, Clovitox Plus, Curtail M, DyVel, Enforcer M, Frontline, Frontline XL, Horizon BTM, Logic M, MCPA, Mextrol, Optica Trio, Pixxaro, Prestige XC, Refine M, Signal M, Spectrum, Stellar, Sword, Target, Topline, Tracker XP, Topside, Trophy, Tropotox Plus
MCPBClovitox Plus, Topside, Tropotox Plus
mecoprop (MCPP)DyVel DSp, Mecoprop-P, Optica Trio, Sword, Target, Tracker XP
quincloracTriton C
aminocyclopyrachlorNavist, Truvist
Group 5
Photosynthetic inhibitors
at Photosystem II,
Site A. These
chemicals interfere
with photosynthesis
and disrupt plant
growth, ultimately
leading to death.
Phenyl-carbamatesdesmediphamBetamix, Betamix
phenmediphamBetamix, Betamix
TriazinesatrazineAatrex, Laddok, Primextra II Magnum
simazinePrincip Nine-T, Simazine 480
TriazinoneshexazinoneVelpar DF, Velpar L
metribuzinSencor, Titus Pro
UracilsbromacilCalmix Pellets, Hyvar X/X-L, Krovar I
Group 6
inhibitors at
Photosystem II, Site II
BenzthiadiazolesbentazonBasagran, Basagran Forte, Laddok, Viper
NitrilesbromoxynilApprove, Axil iPAK, Badge, Bromotril II, Brotex 240, Buctril M, Enforcer D, Enforcer M, Infinity, Koril, Leader, Logic M, Mextrol, Pardner, Thrasher, Thumper, Titanium, Tundra, Velocity m3
Group 7
inhibitors at
Photosystem II, Site B.
UreasdiuronDiurex 80W, Karmex XP, Krovar I
linuronLinuron, Lorox
Group 8
Lipid synthesis
inhibitors (not ACCase
inhibition). These chemicals inhibit the cell division and
elongation in the
seedling shoots before
they emerge above
triallateAvadex (Extra Strength) BW/MicroActiv, Fortress.
Group 9
Inhibitors of EPSP
synthesis. These
chemicals inhibit the
amino-acid synthesis.
NoneglyphosateCheminova Glyphosate, Clearout 41, Cleanstart, Credit, Credit 45, Eclipse III, FirstStep Complete, Glyphogan Plus, Glyfos, Glykamba, Knockout Extra, Matrix, Maverick III, MPower glyphosate, Pace, Prepare, Prepare Complete, PrePass, Renegade, Roundup Transorb HC, Roundup Ultra2, Roundup WeatherMax, Rustler, R/T 540, Sharpshooter, Sharpshooter Plus, StartUp,Takkle, Touchdown Total, Traxion, Vantage Plus Max II, Vector
Group 10
Inhibitors of glutamine synthetase.Noneglufosinate-ammoniumLiberty 150 SN, MPower Good Harvest
Group 11
These chemicals inhibit the carotenoids biosynthesis.TriazoleamitrolAmitrol 240
Group 14
Inhibits an enzyme of chlorophyll and heme biosynthesis.Aryl triazonecarfentrazoneCleanstart, Aim, Authority Charge
sulfentrazoneAuthority, Authority Charge
flumioxazinChateau, Payload, Valtera
Group 15
Inhibitors of cell growth
and division.
Chloroacetamidesmetolachlor propyzamideDual II Magnum, Primextra II Magnum
Kerb 50W
Group 16
UnknownBenzofuranyl alkylsulfonateethofumesateEthos SC, Nortron
Group 19
Auxin transport inhibitor allowing buildup in the meristem areaSemicarbazonediflufenzopyrDistinct
Group 20
Inhibits actively dividing merestems in roots and shoots as well as seed germination.NitrilesdichlobenilCasoron
Group 22
Cell membrane
disrupters. Chemicals
that disrupt the internal
cell membrane and
prevent the cells from
manufacturing food.

Reglone Desiccant, Reglone Ion, Reward
Group 27
Inhibits plant pigment biosynthesis and photosynthesis.BenzopyrazolepyrasulfotoleAxial iPAK, Infinity, Tundra, Velocity m3

* A herbicide may appear in more than one group if it contains more than one active ingredient
For more information about the content of this document, contact Harry Brook.
This document is maintained by Mary Ann Nelson.
This information published to the web on April 15, 2003.
Last Reviewed/Revised on March 31, 2015.