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Pesticide information box

© RPB
v. 4/5/2010

A Guide to Pesticides: grouped by
Modes of Action (MoA)

This page gives information plant protection/pest control agents grouped as:

Key to MoA tables

v. 24 November 2009

Fungicides

The term "fungicide" is also used for substances active against Oomycetes (e.g. Phytophthora spp.) that are no longer classified as fungi. MoA groups that include compounds active against oomycetes are marked with §O.

 

Multiple site of action (M): often protectant

MoA group

Chemistry

example(s)

Multi-site M1

Copper fungicides §O
Bordeaux mixture consists of equal parts of ~sulphate and lime (calcium hydroxide)

Copper: ~ammonium carbonate, ~hydroxide, ~oxide, ~oxychloride, ~sulphate, etc.

M2

Sulphur

sulfur

M3

Dithiocarbamates §O

ferbam, maneb, mancozeb, metam (also herbicide & nematicide), thiram, zineb, ziram (also a vertebrate repellent)

M4

Pthalimides

captan, captafol, folpet

M5

Chloronitriles

chlorothalonil

M6

Sulphamides

dichlofluanid, tolylfluanid

M7

Guanidines

dodine

Systemic - curative

MoA group

Chemistry

example(s)

A

Disruption of fungal nucleic acid synthesis:
A1: RNA polymerase (oomycete fungicides)

Four MoA groups

Phenylamides §O

benalaxyl, metalaxyl (resolved metalaxyl-M is mefenoxam)

  A2 Hydroxy-pyrimidines buprimate, dimethirimol
  A3-A4: DNA inhibition A3 Heteroaromatics §O
A4 Carboxylic acids
hymexazole, octhilinone
oxolinic acid
B Inhibition of mitosis and cell division  
 

B1-B3: Inhibition of beta-tubulin assembly

B1: Benzamidazoles
B2: N-phenyl carbamates
B3: Benzamides §O

benomyl, carbendazim, fuberidazole
diethofencarb
zoxamide

  B4-B5: cell division B4: Phenylurea
B5: Benzamide §O
pencycuron
fluopicolide

C

Respiration inhibitors - large group including:

 
 

C2: succinate dehydrogenase

Carboxamides: 6 classes including Oxathiins

boscalid
flutolanil
, oxycarboxin

C3: QoI - Quinone Outside (cytochrome) Inhibitors

Strobilurins etc.:
8 chemical classes

broad spectum incl. §O

azoxystrobin, pyraclostrobin, fluoxastrobin, trifloxystrobin
fenamidone

  C4: QiI - Quinone Inside Inhibitors 2 chemical classes §O cyazofamid, amisulbrom (newer a.i. for Phytophthora etc.)
  C5: uncouplers of oxidative phosphorylation 3 chemical classes including dinitrophenyl crotonates binapacryl (was also acaricide), dinocap
  C6: inhibitors of ATP synthase Organo-tin compounds fentin acetate
 

C1, C7

2 chemical classes  

D

Other mechanisms that inhibit protein synthesis

D1: Anilinopyrimidines

cyprodinil

  D2-D5

4 classes of antibiotics

kasugamicin

E

Signal transduction inhibitors

Quinolines, Phenylpyrroles, Dicarboximides


iprodione

F Lipid synthesis: cell membranes and walls  
 

F2: Inhibits phospholipid synthesis in membrane
(esp. Pyricularia oryzae)

phosphorothiolates,
dithiolanes

edifenphos, iprobenfos (IBP)
isoprothiolane

 

F3: lipid peroxidation

AH fungicides (aromatic hydrocarbons) §O

tolclofos-methyl, etridiazole

 

F4: cell membrane permability

Carbamates §O

propamocarb hydrochloride, prothiocarb

 

F5: cell wall deposition

Carboxylic Acid Amides (CAA) §O
- 3 chemical groups

dimethomorph (cinnamic acid amide), iprovalicarb, fluazinam
mandipropamid

G

Disruption of membrane function: sterol biosynthesis inhibitors (SBI)

 

G1: De-Methylation Inhibitor (DMI) fungicides

Pyridines, Pyrimidines
Imidazoles
and Triazoles

pyrifenox, fenarimol
imazalil,
procloraz
bitertanol, cyproconazole, difenoconazole, fluquinconazole, hexaconazole, myclobutanil, propriconazole, prothioconazole, tebuconazole, triadimefon, triadimenol

 

G2-G4

Morpholines and
6 other chemical classes

tridemorph, fenpropimorph fenhexamid, spiroxamine

H

Glucan synthesis antibiotic

2 classes of antibiotics

validamycin A (for Rhizoctonia solani)

I

Melanin synthesis in cell wall

6 chemical classes

tricyclazole (for Pyricularia oryzae)

Host plant defence induction (P) and other (sometimes unknown) mechanisms

P

Salicylic acid pathway

‘Plant activators’

acibenzolar

U

Other elicitors of Systemic Acquired Resistance (SAR)

phosphonate fungicides §O

fosetyl aluminium; potassium phosphonate

  microtubule disruption (poss.) U5: thiazole carboxamide §O ethaboxam

X

Unknown MoA

 

cymoxanil, triazoxide

Biological

   

Hyper-parasites

mycofungicide

Ampelomyces quisqualis

 

Typically antagonists

viral mosaic virus mild strains
  bacterial

Bacillus subtilis

  fungal §O

Trichoderma: many spp

Spray oils and Adjuvants

Various oils are known to have acaricidal, fungicidal, insecticidal, herbicidal and spray adjuvant properties in their own right or may enhance.  Examples include:

  • “dormant oils” or  “winter washes” are usually petroleum-based which are acaricides, insecticides and ovicides
  • fatty acid emulsions are used as broad spectrum contact insecticides
  • banana spray oil (BSO) is fungicidal for sigatoka disease (Mycosphaerella spp)
  • In N. America brush may sprayed with a herbicide in diesel oil as a carrier; many herbicide activators are emulsifiable light oils containing variable amounts of surfactants to emulsify the oil and penetrate waxy weed leaves.
  • a number of emulsified oils are used as spray adjuvants which are not very pesticidal themselves, but when added to the tank mixture, improve the performance of the pesticide; more information on: http://pmep.cce.cornell.edu/facts-slides-self/facts/gen-peapp-adjuvants.html.  Major functions are products that (examples of product names are for illustration and not necessarily recommendations) affect:

Adjuvant function

Examples

1. Formulation and tank mix
  Compatibility agents, Defoaming agents, thickeners, etc.

  Buffers (or pH modifiers)

Often containing phosphoric acid or a salt of phosphoric acid

2. Atomisation and drift
  a. droplet size spectrum
 
b. evaporation
 
(humectants affect droplet survival and
   deposit after contact)

Certain compounds can increase the viscosity and surface tension causing and increase in spray VMD and decrease the proportion of small droplets.

3. Retention and Deposit Modification on Plant surfaces

  Surfactants (wetting/spreading agents)

Alkyl-Aryl-Poly-Oxy-Ethylenates, ‘Activator’, ‘Agral

  Stickers (sometimes called extenders) to
   increase 'rain-fastness', etc.

Often polymers and organosilicones such as ‘Silwet

4. Plant cuticle penetrants
  (Often also enhance retention, as above)

emulsified oils (typically <5% emulsifier), ‘Codacide’, ‘Natur’l oil’

Plant Growth Modifiers (or ~ Regulators)

A number of non- pesticidal substances are frequently procured and stored together with pest control agents.  Since the term “pesticide” has become controversial, a number of products have been marketed as “plant tonics” or similar - that may have various modes of action and include mixtures containing micronutrients etc.

  •  Various chemicals encourage fruit set including: abscisic acid (ABA), gibberellic acid and carbaryl (which is also an insecticide).  1-napthylacetic acid and 4-indol 3-YL butyric acid are members of a group of synthetic auxins (and more active molecules are herbicidal) which prevents premature flower and fruit drop and stimulates root formation in cuttings.
  •  Foliar nutrient products may contain plant fertilizers such as N,P,K, minor nutrients such as Sulfur and Zinc, and a variety of trace elements such as Boron. They may also contain a relatively small amount of surfactant.
  •   Plant growth regulators (PGR) include 2-chloroethylphosphonic acid (CEPA or ethephon): which penetrates into plant tissues and decomposes into ethylene which affects various growth processes, including: ripening in fruits, latex flow in rubber, flowering and lateral branching in ornamentals.  Compounds such as chlormequat chloride regulate growth by inhibiting giberellin synthesis, thus shortening stems and producing more compact, sturdier plamtsPaclobutrazol is a triazole which inhibits sterol as well as giberellin biosynthesis so it also has some fugicidal activity (against mildews and rusts). Another PGR, daminozide ('Alar') was withdrawn in 1989, when it was withdrawn by the manufacturer in response to public fears over safety.
  •   Some molecules exhibit different effects at different concentrations.  For example, nonanoic acid is used for blossom thinning in apples and pears, but is herbicidal at higher dosages.

Herbicides

The HRAC system (http://www.plantprotection.org/hrac/) differs somewhat from that of the
Weed Science Society of America (WSSA), see: http://www.weedscience.com

Contact, desiccant

MoA group

Chemistry

example(s)

D

Photosystem I (electron transport): contact & desiccant action

Bipyridylium

diquat, paraquat

M

Cell membrane disruption, contact action

Dinitrophenol

DNOC

Z.

Unknown mechanisms, contact action

Organoarsenical

MSMA (methyl arsonic acid)

 

Multi-site soil sterilants
(also nematodes, fungi)

Various

dazomet, metam (methyl-dithiocarbamic acid): also ~ammonium, ~Na & K salts

 

Desiccants etc.

Inorganic

sodium chlorate, sulphuric acid

Systemic

MoA group

Chemistry

example(s)

A

Inhibits fatty acid synthesis (ACCase inhibitors)

3 chemical classes:
‘FOP’ hebicides

‘DIM’ herbicides

‘DEN’ herbicides

clodinafop-propargyl, diclofop-methyl, fenoxaprop-P-ethyl, fluazifop-P-butyl
clethodim, cycloxydim, sethoxydim, tralkoxydim

pinoxaden

B

Inhibits plant amino acid synthesis: acetolactate synthase (ALS)

Imidazolinones Sulfonylureas
+ 3 classes

imazapyr, imazethapyr,
amidosulfuron, bensulfuron- methyl, iodosulfuron-methyl-sodium, mesosulfuron-methyl, metsulforon-methyl,
pyriftalid, propoxycarbazone-sodium, trifloxysulfuron-sodium

C

Inhibits photosynthesis (photosystem II)

 
 

C1 

Triazines,
Triazinones

Phenyl-carbamates
+ 3 classes

ametryne, atrazine, simazine
hexazinone, metamitron, metribuzin
desmedipham
,
phenmedipham
bromacil

 

C2 

substituted ureas

diuron, isoproturon, linuron, propanil, tebuthiuron

 

C3 

nitriles + 2 classes

bromoxynil, ioxynil (also octanoate ester & Na+ salt)

E

Inhibits protoporphyrinogen oxidase, leading to irreversible cell membrane damage

Diphenylethers +
8 other classes of often selective herbicides with contact action and only limited translocation

oxyfluorfen
oxadiazon
fomesafen

F

Bleaching: inhibition of carotenoid biosynthesis

 
  F1:at the phytoene desaturase step (PDS) Pyridazinones + other classes norflurazon,
diflufenican, flurtamone
  F2:of 4-hydroxyphenyl-pyruvate-dioxygenase
(4-HPPD)
triketones + 3 classes mesotrione (for broad-leaved weeds in Maize)
  F3: inhibition of lycopene cyclase and unknown target

triazole
+ 3 other classes

amitrole,
clomazone

G

Inhibition of essential
aromatic amino acid synthesis (EPSPS) in chlororplasts

Organophosphate glycene

glyphosate: ~trimesium ~isopropylammonium, sulfosate

H

Glutamine synthetase inhibitor: accumulates ammonium ions, inhibits photosynthesis

Phosphinic acid

glufosinate-ammonium

I

Inhibition of dihydropterate synthase causing slow chlorosis

Carbamate

asulam

K

Inhibition of mitosis and cell division

CIPC etc. often used as potato sprouting inhibitors

 

K1 

Dintroanilines

pendimethalin, trifluralin

 

K2 

Carbamate

chlorpropham (CIPC)

 

K3 

Chloracetamides

+ 4 other classes

acetochlor, alachlor, dimethanamid, butachlor, pretilachlor, metolachlor, etc
flufenacet

L

Inhibition of cell wall synthesis

4 classes

dichlobenil, isoxaben

N

Inhibition of lipid synthesis (not A)

Thiocarbamates
+ 2 classes

ethofumesate, molinate, thiobencarb (benthiocarb)
dalapon (acid & sodium salt)

O

Synthetic auxins
(also plant growth modifiers)

Phenoxy-carboxylic-acids

2,4-D (acid & various salts: commonly ~amine & ~isopropyl ester), 2,4,5-T*, MCPA, MCPB, mecoprop-P (MCPP)

   
    Pyridine carboxylic acids aminopyralid, clopyralid, fluroxypyr, picloram, triclopyr
    + 3 other classes dicamba

P

Inhibits auxin transport

Phthalamate

naptalam

Herbicide safeners are admixed in order to selectively protect crop plants from herbicide damage without reducing activity in target weeds, and are usually used commercially to improve herbicide selectivity between crop and weed species.  They may also be applied as seed dressings.

cloquintocet-mexyl, cyometrinil, dichlormid, fenclorim, fluxofenim, flurazole, furilazole, oxabetrinil, naphthalic anhydride (NA)

       

Biological
Mycoherbicide

e.g. specific to Northern joint vetch: Aeschnomene virginica

Colletotrichum gloeosporioides f.p. aeschnomene

Insecticides, Acaricides, Nematicides, etc.

Neurotoxic

MoA group

Chemistry

example(s)

1

Acetylcholinesterase (AChE) inhibitors
Because the AChE mechanism in insect synapses are similar to that of mammals, group 1 compounds are often Extremely or Highly Hazardous although there are exceptions such as temephos).
This group contains a number of systemic compounds (e.g. carbofuran, carbosulfan, dimethoate, monocrotophos).

1A

Carbamates

aldicarb, bendiocarb, carbaryl, carbofuran (not GR), carbosulfan, dioxacarb, ethiofencarb, fenobucarb (BPMC), isoprocarb (MIPC), methiocarb (also a molluscicide), methomyl, metolcarb (MTMC), oxamyl, pirimicarb, promecarb, propoxur, thiodicarb (molluscicide), thiofanox

1B

Organophosphates:

acephate, azinphos (usu. ~methyl), cadusafos, chlorfenvinphos, chlorpyrifos (usu. ~ethyl), chlorpyrifos-methyl, demeton-s-methyl, diazinon, dichlorvos (DDVP), dicrotophos, dimethoate, disulfoton, ethoprophos, fenitrothion, fenthion, fosthiazate (nematicide), heptenophos, malathion, methamidophos, methidathion, mevinphos, monocrotophos, naled, omethoate, oxydemeton-methyl, parathion (usu. ~methyl), phenthoate, phorate, phosalone, phosmet, phosphamidon, phoxim, pirimiphos (usu. ~methyl), profenofos, quinalphos, temephos, thiometon, triazophos, trichlorfon, vamidothion

2

GABA-gated chloride channel antagonists

 
 

Cyclodienes and other organo-chlorines (OCs

HCH (lindane, gamma BHC), aldrin, dieldrin, chlordane, endosulfan

 

Phenylpyrazoles (Fiproles

fipronil

3

Sodium channel modulators

OC

DDT

 

pyrethrum & pyrethrins

bioallethrin, bioresmethrin, pyrethrum, resmethrin, tetramethrin

pyrethroids

bifenthrin, beta-cyfluthrin, cyhalothrin (unresolved), lambda-cyhalothrin, cypermethrin (and resolved alpha~), deltamethrin, esfenvalerate, etofenprox, fenpropathrin, fenvalerate, flucythrinate, silafluofen, tau-fluvalinate, permethrin, tefluthrin, metofluthrin

4

Acetylcholine receptor (nAChR) agonists

 

4A

Neonicotinoids

acetamiprid, clothianidin, imidacloprid, nitenpyram, thiacloprid, thiamethoxam

 

4B

nicotine

 

5

nAChR agonists: Allosteric (not group 4)

Macrocyclic lactones (Spinosyns)

spinosad

6

Chloride channel activators (insecticides & acaricides)

Avermectins, Milbemycins

abamectin, emamectin benzoate
milbemectin

14 nAChR channel blockers

Nereistoxin analogues

cartap, thiosultap (various anions), thiocyclam

22

Voltage dependent sodium channel blocker

Oxadiazine

indoxacarb

25 Neuroactive acaricide (unknown mode of action)   bifenazate
Group 11 etc. Microbial or derived disruptors of insect midgut membranes

Toxins produced by the bacterium Bacillus thuringiensis (Bt): Bt sprays and Cry proteins expressed in transgenic Bt crop varieties (specific cross-resistance sub-groups)

11A1 

For Diptera

Bacillus thuringiensis subsp. israelensis

11A2

For mosquito larvae

Bacillus sphaericus

11B1

Lepidoptera esp. Noctuidae

Bacillus thuringiensis subsp. aizawai

11B2

Esp. Lepidoptera: e.g. Plutella

Bacillus thuringiensis subsp. kurstaki

11C 

For Coleoptera

Bacillus thuringiensis subsp. tenebrionis

Other Microbial

EntomoPathogenic Fungi (EPF), nematodes (EPN) and viruses (EPV)

EPF

Beauveria bassiana, Metarhizium anisopliae, Paecilomyces fumosoroseus

EPN

Heterorhabditis megidis, Steinernema spp.

EPV

Various nuclear poly-hedrosis viruses (NPV) and granulo-viruses (GV): often highly specific, especially used against Lepidoptera
e.g. Spodoptera exigua nuclear polyhedrosis virus

Cuticle Synthesis, Moulting & Metamorphosis

MoA group

Chemistry

example(s)

7

Juvenile hormone mimics and analogues

fenoxycarb, methoprene, pyriproxyfen

Groups 15-17: Inhibitors of chitin biosynthesis
                          (insect growth regulators or IGRs)

15

for Lepidoptera,
Isoptera, etc. 

 Benzoylureas

bistrifluron, flucycloxuron, noviflumuron, diflubenzuron, teflubenzuron, chlorfluazuron, flufenoxuron, lufenuron, hexaflumaron, novaluron, triflumuron

16

for Hemiptera

buprofezin

17

for Diptera

cyromazine

18

Ecdysone agonist / molting disruptors

A. Diacylhydrazines

B. Azadirachtin

chromafenozide,methoxyfenozide, tebufenozide
azadirachtin

Disruptors of Various other Metabolic Processes
Many groups acting on a wide range of metabolic processes including:

MoA group

Chemistry

example(s)

12

Inhibitors of oxidative phosphorylation, disruptors of ATP formation (inhibitors of ATP synthase)

Diafenthiuron
Organotin acaricides

others

diafenthiuron
cyhexatin,
fenbutatin oxide

propargite, tetradifon

13

Uncouplers of oxidative phosphorylation via disruption of proton gradient

chlorfenapyr, DNOC

19

Octopaminergic (nervous system) agonist acaricide & insecticide (probably loss of feeding and adhesion)

amitraz

20

Mitochondrial complex III electron transport inhibitors

various

hydramethylnon, acequinocyl, fluacrypyrim

21

Mitochondrial complex I electron transport inhibitors

Rotenone,
METI acaricides

rotenone,
fenpyroximate, tebufenpyrad

23

Inhibitors of lipid synthesis

Tetronic acid derivatives

spirodiclofen, spiromesifen, spirotetramat

24 Mitochondrial complex IV electron transport inhibitors Precursors of fumigant:
phosphine (PH3)
(see also: rodenticides)
aluminium phosphide, magnesium phosphide,

28

Ryanodine receptor modulators: sustained contraction of insect muscle

Diamides

flubendiamide

Non-specific, Unknown and Miscellaneous MoA

MoA group

Chemistry

example(s)

8

Inorganic fumigants with non-specific MoA

see also: group 24

methyl bromide, chloropicrin, sulfuryl fluoride

9

Various compounds of non-specific mode of action
(selective feeding blockers)

cryolite, pymetrozine, flonicamid.

10

acaricidal growth inhibitors

various

clofentezine, hexythiazox, etoxazole

27

Synergists
27A: P450-dependent mono-oxygenase inhibitors

 

piperonyl butoxide

 

27B: Esterase inhibitors

 

tribufos (DEF)

un

Unknown mode of action

various

dicofol, pyridalyl

Repellents, attractants and other modifiers of insect behaviour

Insect repellents

 

DEET, citronella oil

Pheromones

Many, specific: also see Manual of Biocontrol Agents

Baiting attractants

 

methyl eugenol

Bird/rodent repellent

also a fungicide (FRAC M)

ziram

Molluscicides

RHS guide to slug control

MoA

Chemical Group

example(s)

     

Destruction of mucus cells: slugs secrete slime copiously and desiccate

tetramer of acetaldehyde

metaldehyde (contact and stomach action)

Neurotoxic (also insecticides)

carbamates

thiodicarb, methiocarb

Respiration inhibitor: probably oxygen uptake, and carbohydrate metabolism clonitralid-olamine (Germany) niclosamide (rice golden apple snail and WHO approved for vectors of schistosomiasis)

Pathological changes to slug digestive system

inorganic

ferric-III-phosphate

     
Biological
(with power of search)

pathogenic nematode

Phasmohabditis hermaphrodita

Rodenticides

       More information on: http://animalscience.ucdavis.edu/Avian/pfs23.htm

MoA group

Chemistry/type

example(s)

The older, acute toxicants rapidly became ineffective due to 'bait shyness': where rats learned to associate the food bait with the poison. Earlier chronic poisons (e.g. warfarin) have been replaced with a number of 'second generation' anti-coagulants that only require a single feed by the pest and have a delayed action; this reduces the problem of bait shyness. For obvious reasons, chemical rodenticides are highly toxic by nature, hence the interest in developing biological alternatives.

Acute toxin

reacts with stomach acids to produce phosphine
(see also: fumigants)

zinc phosphide,
magnesium phosphide

Hypercalcemia etc.

organic:
single dose

bromethalin,
cholecalciferol
(Vitamin D3)

Anti-coagulants

1st generation

chlorophacinone, pindone, coumatetralyl, warfarin

 

2nd generation
(single dose)

brodifacoum, difenacoum, bromadiolone, flocoumafen

Biological

 

Sarcocystis singaporensis: specific to Rattus & Bandicota spp

Barn owls


NOTE: these pages are for guidance only and no responsibility can be taken for any errors that may be present.  Likewise, inclusion of compounds or products does not imply recommendation or otherwise.

Key to MoA tables

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