28
A guide to phenoxy herbicides PHENOXIES
A guide to phenoxy herbicides
PHENOXIES
Contents
Introduction
Mode of Action
Formulation Types
Phenoxies
Weed Charts
Getting the Best Results
Application Timing Guidelines
Water Stewardship
2
PHENOXY HERBICIDES70 YEARS OF SUCCESS
3
Introduction
Nufarm, Built on Phenoxies
• Phenoxies is a general term to describe a group of herbicides that mimic the effect of natural plant hormones called auxins.
• First developed in USA & UK in 1940’s - First used commercially in 1946.
• Remain amongst the world’s most widely used herbicides.
• Nufarm is a global leader in manufacture, supply and marketing of phenoxy herbicides. With manufacturing plants in the UK, Australia and Austria.
• Nufarm manufacture from raw material so we can guarantee the quality of finished product.
• Phenoxy herbicides play a special role in managing resistance because they have the lowest risk of fostering the development of resistance.
• The phenoxy herbicides are often mixed with resistance prone broad leaf weed herbicides or used in rotations to delay resistance.
• Postponement of resistance by the phenoxy herbicides lengthens the time before resistant prone herbicides becomes truly non-renewable.
Nufarm believes that within the current agricultural climate in the UK, phenoxies have an important role to play. With growing resistance to other herbicide groups, along with phenoxies unique mode of action, you could say phenoxies are more relevant than ever. This guide was written in the mind that whilst we at Nufarm know how useful phenoxies can be, due to their longevity in the market place some of their key benefits may have been forgotten over time. We encourage a new generation of agronomists and growers to learn more about phenoxies, as well as invite those already established in the industry to rediscover how to best utilise phenoxy herbicides.
Nufarm is a global manufacturer and supplier of crop protection chemicals. We synthesise and manufacture a wide range of chemicals including MCPA, 2-4 D, CMPP-P 2,4-DB, MCPB, 2-4 Dichlorprop-P.
An Australian company, we have grown from humble beginnings over 50 years ago at our Laverton site in Melbourne to be the eighth largest crop protection company in the world. Nufarm has prided itself on its production of phenoxies over the years and operates the largest flexible phenoxy production site in the world, right here in the UK.
Our site at Wyke (near Bradford), which was established in 1877 as a Picric Acid manufacturer, now produces Phenoxy herbicides, Glyphosate, intermediates and inhibitors.
Mode of ActionPhenoxy herbicides mimic the plant growth regulator indol-3- acetic acid (IAA), or auxin in plants, thus it is necessary to review the function of auxin to properly understand their mechanism of action. Auxin is a plant growth regulator that controls cell enlargement, division and plant development through the plant life cycle. While much remains to be explored about the workings of IAA, it is known that IAA binds to auxin binding proteins (ABPs) located in the following:
• the cell membrane.
• the endoplasmic reticulum (an internal cellular membrane system).
• the cell nucleus.
• the cytoplasm.
The control of growth that IAA exerts is multifunctional. Alterations induced by IAA cause rapid changes in cell elongation, and both rapid and slow changes in gene expression. Auxins influence other growth regulators including cytokinins, abscisic acid and ethylene (a gas that functions as a plant growth regulator). The concentration of IAA in plant cells regulates cell growth. However, plant tissues differ in their sensitivity. Depending on tissue type and IAA concentration, IAA may either inhibit or stimulate a response.
IAA concentrations are highly regulated in plants by synthesis, degradation and both reversible and non-reversible conjugation. Synthesis increases the IAA content, while degradation decreases it. Conjugation, which is the linking of IAA to another molecule, frequently an amino acid, inactivates IAA. However, if conjugation is reversible, it may act as a slow release mechanism for maintaining relatively constant IAA levels.
4Source: ‘How Herbicides Work: Biology to Application’, Alberta Agriculture, Food and Rural Development.
Mode of Action
• Phenoxies are acids, normally formulated as salts, sometimes as esters.
• Well tolerated by cereal crops within specific GS limitations.
• Foliar activity, absorbed into leaf within 4 - 6 hours.
• Concentrates in the actively growing regions of a plant (meristematic tissue).
• Over stimulate plant cells causing abnormal plant growth and death.
• Interferes with plant metabolism, protein synthesis, cell division and transportation of nutrients within the plant.
• However, the plant has no mechanism to control the concentrations of these ‘imposters’.
5
These herbicides are capable of moving from leaves (sources of sugar production) with sugars to sites of metabolic activity (sites of sugar utilization) such as underground meristems (root tips), shoot meristems (shoot tips), storage organs and other live tissues. Since movement to sites is essential for continued plant growth, these herbicides have the potential to kill simple perennial and creeping perennial weeds with only one or two foliar applications. Symptoms are evident on new growth first. Pigment loss (yellow or white), stoppage of growth, and distorted new growth are typical symptoms. Most injury appears only after several days or weeks. Herbicides in this group are usually non-charged at low pHs found in the cell walls and negatively charged at higher pHs encountered in the cytoplasm of leaf sieve cells of the phloem (the ionization inside the cytoplasm of the phloem accounts for trapping and movement of these herbicides).
• Translocated within plant to growing points in stems and roots.
• MOA Classification: Group O (Synthetic auxins).• Phenoxies may be used solo but are more often
used in mixtures with other phenoxies, dicamba or other selective herbicides such as SU products.
• Almost all plants can be affected.
• Phenoxys do affect most monocots, but only at specific growth stages.
• Selectivity most likely due to: - Restricted translocation - Morphological / structural differences - Ability to metabolise toxin
How Do Auxins Work?
Reference: A Brief Guide to Biology. Peatson, Prentice, Hall, Inc.
When sunlight is overhead the IAA molecules (auxins) produced by the meristem are distributed evenly in the shoot.
Once the sunlight shines on the shoot at an angle, the IAA molecules move to the far side and induce elongation of cells on that side.
Cell eglonation results in the bending of the shoot towards the light.
Phenoxy Symptoms
• Epinastic growth eg. twisting & bending (1-3 days)
• Leaf cupping and curling (1-3 days)
• Thickening and elongation of leaves (7 days)
• Chlorosis at the growing point (7-10 days)
• Finally, wilting and death (21+ days)
Observations in the field include: The twisting effect of a phenoxy treatment on docks.
6
Ester Formulations
Formulations
• Esters are not very water soluble but dissolve readily in organic solvents (EC).
• Ester can be applied in relatively hardwater.
• Ester formulations tend to resist washing from leaves following rain.
• Work better under challenging conditions.
• Little to no root absorption.
• May be more volatile than other Phenoxies and higher odour level.
• Quickest uptake through leaves, trichomes and glands, plus stomata uptake of vapour.
• Higher activity per g ai of 2,4-D - controls harder to kill weeds.
Amine Formulations
Comparison Summary
• Formulated as solutions which makes them more water soluble.
• More prone to water quality effects (high pH and salts).
• Water solubility increases susceptibility of being washed from leaves by rain.
• Less compatible than Esters with many other product eg. foliar fertilisers and trace elements.
• Non-volatile & less odour than esters.
• Intermediate uptake through leaves - must be actively transpiring.
• Some root uptake possible.
• Intermediate activity per g ai of 2,4-D, not as high as Ester but greater than salts in stressed conditions.
Esters Amine
Root Uptake Low Low - Moderate
Shoot Uptake High Moderate - High
Volatility Low Non-volatile
Activity per gram active ingredient Highest High under good growing conditions.
Moderate under stressed conditions.
Speed of Uptake Quickest Moderate
Compatibility High Moderate
Chemistry Matrix
Raw Materials“Acetics”
MCA(Acetic acid + Chlorine)
“Propionics” L-Chloro-propionic Acid
“Butyrics”L-Chloro-propionic Acid
Gamma-Butyrolactone (GBL)
O-Cresol MCPA CMPP-P/Mecoprop-p MCPB
Phenol 2,4-D 2,4-DP-P/Dichloroprop-p 2,4-DB
Some products such as 2,4D can be formulated as either an Amine or Ester formulation. Esters tend to have better uptake into plants especially in cooler conditions while Amines generally have a much lower risk of volatilisation and therefore less risk to nearby sensitive crops.
7
The World of HerbicidesAccording to HRAC classification on mode of action 2010
HERBICIDES AFFECTING: Light Processes Cell Metabolism Growth/Cell Division
C2
C3
C1 C Inhibition ofphotosynthesis at PS II
B Inhibition of ALS (branched)chain amino acid synth.)
K1Inhibition of
microtubule assembly K2Inhibition of
microtubule organisation
M Uncoupler (membrane disruption)
E Inhibition ofprotoporphyrinogen oxidase
D PS-I-electron diversion
F Inhibition of pigmentsynthesis (bleaching)
N Lipid synthesis inhibition(not ACCase)
A Lipid synthesis inhibition(inhibition of ACCase)
K3Inhibition of cell division
(inhibition of VLCFAs)
L Inhibition ofcellulose synthesis
F1 Inhibition of PDS
F4Inhibition of
DOXP synthase
F3 Unknown target
F2Inhibition of
4-HPPD
I DHP-inhibition
Z Unknown modeof action
O Synthetic Auxins
P Auxin transportinhibition
H Glutamine synthetase inhibition
G Inhibition ofEPSP synthase
Phenyl-pyridazines
Diphenyl ethers
Thiadiazoles
Diphenylether
Pyrimidinediones
Cyclohexanediones (DIMs)
Chlorocarb. acids
Others
Glycines
Others
Others
Ureas
Uracils
Amides
Triazolinone
Triazines
Phenylpyrazoles
Imidazolinones
Triazolopyrimidines
Chloroacetamides
Pyridine-carboxylic acids
Benzoic acids
Phenoxy-carboxylic acids
Tetrazolinones
Acetamides
Semicarbazone
Phthalamate
Benzamide
Alkylazines
Nitriles
Pyridines
Phosphoroamidates
DinitrophenolsBipyridyliums
Phosphorodithioate
Benzofuranes
Quinolinecarboxylic acids
Phosphinic acids
Carbamate
Sulfonylamino-carbonyl-triazolinones
Sulfonylureas
Pyrimidinyl (thio) benzoates
Oxadiazoles
Triazinones
Triazolinones
Pyridazinone
Nitriles
Phenylcarbamates
N-Phenyl-phthalimides
Oxazolidinedione
Benzothiadiazinone
Benzoic acid
Carbamates
Dinitroanilines
Benzamides
Oxyacetamides
Aryloxyphenoxy-propionates (FOPs)
www.hracglobal.com
Thiocarbamates
Phenylpyrazoline (DEN)
Arylaminopropionic acid
Triazolocarboxamide
O
O
NH
Cl
Cl
Clomeprop
O
OH
O
Cl
Cl
Dichlorprop=2,4-DP
O
OH
O
Cl
Cl
2,4-D
O
OH
OCl
MCPA
O
Cl
Cl
OH
O
2,4-DB
OCl
OH
O
MCPB
OCl
OH
O
Mecoprop = MCPP = CMPP
FF
N
NN
ONH2
Cl
OFF
F
Flupoxam
NCl
Cl Cl
OOH
O
Triclopyr
NCl
Cl
O
OH
Clopyralid
NF
Cl Cl
OOH
O
NH2
Fluroxypyr
NCl
Cl Cl
NH2
O
OH
Picloram
NCl
Cl
NH2
O
OH
Aminopyralid
NH
NOO
O
O
Isoxaben
Cl
Cl NH2
OHO
Chloramben
OHO
O
Cl
Cl
Dicamba
OHO
Cl
Cl
Cl
TBA
Cl ClCN
Dichlobenil
Cl Cl
SNH2
Chlorthiamid
NH
O
OH
O
Naptalam
N
OOH
Cl
Quinmerac
N
Cl
OOH
Cl
Quinclorac
O
O
NNNH
NH
O
F
F
Na
Diflufenzopyr-sodium
N
SO
Cl
O
O
Benazolin-ethyl
+
N
N
N
NH2
F
NH
O
Triaziflam
Indaziflam
N N
N
NH2
F
CH3
CH3
NH CH3
N
N
N
NH NH
S
Desmetryne N
N
N
Cl
NH
NH
Propazine
N
N
N
NH
NH
S
Ametryne
N
N
N
NH
NH
Cl
Atrazine
N
N
N
NH
S NH
Dimethametryn
N
N
N
NH
NH
Cl
Simazine
N
N
N
NH
NH
Cl
Terbuthylazine
N
N
N
NH
NH
S
Terbutryne
N
N
N
NH
NH
S
SimetryneN
N
N
NH
NH
O
PrometonN
N
N
NH
NH
Cl
CN
Cyanazine N
N
N
NH
NH
S
Prometryne N
N
N
NH
NH
O
Terbumeton
N
N
N
N NH
Cl
Trietazine
NH
N
O
Fenuron
S
NN
NHO
Methabenzthiazuron
NH
ClN
O
Chlorotoluron
NH
ON
OCl
Chloroxuron
NH
N
O
FF
F
Fluometuron (also F3)
Cl
Cl
NH
NO
Neburon
NH
N
ClN
O
O
N
O
Dimefuron
NH
N
O
Isoproturon O
Cl
NH
ON
Metoxuron
NH
NH
O
Siduron
NH
Cl
Cl
N
O
Diuron
NO
NH N
O
Isouron
Cl
NH
N
O
O
Monolinuron
N N
S N
O
NH
Tebuthiuron
Br
Cl
NH
NO
O
Chlorobromuron
S
NN
NS
O
O
NH
O
Ethidimuron
Cl
Cl
NH
NO O
Linuron
N
SNH
O
OO
Bentazone
N
NH
O
Br
O
BromacilN
NH
O
O
LenacilN
NH
O
Cl
O
Terbacil
NH
ONH
O
O
OPhenmedipham
NNCl
O
O
S
Pyridate
N N
OH
Cl
Pyridafol
NN
OCl
NH2
Chloridazon/Pyrazon
N N
NN
O
O
Hexazinone
N
NN
O NH2
MetamitronN N
NO
NH2
S
Metribuzin
N
NN
O
NH2
O
NH
Amicarbazone
N+
N+
Br Br
N+
N+
Cl Cl
Diquat
Paraquat
Cl
Cl
NH
O
Propanil
Cl
NH
O
Pentanochlor
Br
OH
Br
N O
NO2
O2N
Bromofenoxim (also M)
I
OH
I
CN
Ioxynil (also M)
Br
OH
Br
CN
Bromoxynil (also M)
O
NHO
O
NH
ODesmedipham
Br
NH
O
N
O
Metobromuron
O NNH
O
F
FF
F
Picolinafen
N
O
FF
F
Fluridone
NN
OCl
NH
FF
F
NorflurazonN
OCl
ClF
FF
Flurochloridone
O
ClNH2
O2N
AclonifenNH
NO
FF
F
Fluometuron(also C)
NO
Cl
O
Clomazone
ON
O
Cl
S
O
O
Isoxachlortole
NN
OO Cl
Cl
O
Pyrazoxyfen
NN
OOH S
F
FF
OO
Pyrasulfotole
O
O
O Cl
SO
O
O O
Tefuryltrione
ONH
O
FF
F
Flurtamone
ON
O
NH
F F
FF
F
DiflufenicanBeflubutamid
F
F FF
OO
NH
Isoxaflutole
ON
O
F
FF
SO
OBenzofenap
NN O
O
OCl
Cl
PyrazolynateN
N OS
O
OCl
Cl
O
Sulcotrione
ClOO
O
O
SO O
Mesotrione
O O
O
N+O O
SO O
Benzobicyclon
S O Cl
SO O
Tembotrione
O
O
O Cl
OF
F
F
SO O
Topramezone
O
NN
OH
ON
SOO
O
OH O
N
FF
F
OO
Bicyclopyrone
Amitrole (Inh. of lycopene cyclase)
NH
N
N
NH2
NH
ONH
Dymron = Daimuron
NH N
O
Methyldymron
NH
NH
OCl
Cumyluron
OH
O
Pelargonic acid
N N
S S
Dazomet
(CH2)7CO2H
(CH2)7CH3
Oleic Acid
O
N
Cl
ClO
Oxaziclomefone
NH2
PO
O
O
OH
Fosamine
ClCl
NH
O
OO
Etobenzanid
O
O
CinmethylinN NO
S
O
Pyributicarb
DSMA
AsO
O
O
Na+
Na+
MSMA
As
O
OH
O Na+Metam
S
S
NH
Na+
Bromobutide
NH
O
Br
DifenzoquatMetilsulfate
NN
+CH3SO-4
Indanofan
OO
O
Cl
Chlorflurenol
OH OH
O
Cl
N
NO
O
NH
NH
OS OO
NS O
O
Amidosulfuron
N
NO
O
NH
NH
OS OO
N N
N
NNN
Azimsulfuron
N
NO
O
NH
NH
OS OO
OO
Bensulfuron-methyl
N
N
O
NH
NH
OS OO
OO
Cl
Chlorimuron-ethyl
NN
NO
NH
NH
OS OO
Cl
Chlorsulfuron
NN
NO
O
NH
NH
OS OO
OO
Cinosulfuron
N
NO
O
NH
NOS O
O
N
O
FF
F
Na+
Trifloxysulfuron-sodium
N
NO
O
NH
NH
OS OO
NHO
Cyclosulfamuron
NN
NO
NH
NH
NH
OS OO
OO
Ethametsulfuron-methyl
N
NO
O
NH
NH
OS OO
O
O
Ethoxysulfuron
N
NO
O
NH
NH
OS OO
N
FF
F
Flazasulfuron
N
NO
O
NH
NOS O
O
N
OO
FF
FNa+
Flupyrsulfuron-methyl-sodium
N
NO
O
NH
NH
OS OO
N N
ClOO
Halosulfuron-methyl
N
N
NO
O
NH
NH
OS OO
N
Cl
Imazosulfuron
NN
NO
NH
NOS O
O
I
OO
Na+
Iodosulfuron-methyl-sodium
NN
NO
NH
NH
OS OO
OO
Metsulfuron-methyl
N
NO
O
NH
NH
OS OO
NH
ON
O
H
Foramsulfuron
N
NO
O
NH
NH
OS OO
N
ON
Nicosulfuron
N
NNH
NH
OS OO
OOO
Oxasulfuron
N
NO
O
NH
NH
OS OO
O
F
F
F
F
O
Primisulfuron-methyl
NN
NO
NH
NH
OS OO
FF
F
Prosulfuron
N
NO
O
NH
NH
OS OO
OO
NH
SO O
Mesosulfuron-methyl
N
NO
O
NH
NH
OS OO
N N
OO
Pyrazosulfuron-ethyl
N
NO
O
NH
NH
OS OO
N
S OO
Rimsulfuron
N
NNH
NH
OS OO
OO
Sulfometuron-methyl
N
NO
O
NH
NH
OS OO
N
N
SO
O
Sulfosulfuron
NN
N
O
NH
NH
OS OO
FF
F
FF
F
Tritosulfuron
NN
NO
NH
NH
OS OO
S
OO
Thifensulfuron-methyl
NN
NO
NH
NH
OS OO
OCl
Triasulfuron
NN
NO
NNH
OS OO
OO
Tribenuron-methyl
NN
NO
NH
NH
OS OO
O
N
O
FFF
Triflusulfuron-methyl
N
NO
O
NH
NH
OS OO
OO
NO
F
Flucetosulfuron
N
NO
O
NH
NH
OS OO
NHN O
Orthosulfamuron
NH
NO
N
OOH
Imazapic
NH
NO
N
OOH
Imazapyr
NH
NO
OONH
NO
OO+
Imazamethabenz-methyl
NH
NO
N
OOH
Imazaquin
NH
NO
N
OOH
O
Imazamox
NH
NO
N
OOH
Imazethapyr
OH
NO2
NO2
DNOC
OH
NO2
NO2
Dinoterb
OH
NO2
NO2
Dinoseb
O ON
N N
N
O
O
O
O
O O Na+
Bispyribac-sodium
O ON
N N
N
O
O
O
O
O ON
Pyribenzoxim
S
N
N
O
O
O O
Cl
Na+
Pyrithiobac-sodium
S
N
N
O
OO O
Pyriftalid
O
N
N
O
O
O O
NO
Pyriminobac-methyl
NH
N
N
O
OOH
O
SOO
FF
Pyrimisulfan
S NOO
ON
N
NO
O
OO
Na+
O S NOO
ON
N
NO
O
FF
F
Na+
Flucarbazone-sodium
Propoxycarbazone-sodium
S
S NH
N
O
NN
O
O
OO
O O
Thiencarbazone-methylN
N
NNS
NH
Cl
OO
OO
F
O
Cloransulam-methyl
N
N
NNS
NH
Cl
Cl
OO
F
O
Diclosulam
N
N
NNS
NH
F
F
OO
O
F
Florasulam
N N
NNS
NH
F
F
OO
Flumetsulam
N N
NNS
NH
Cl
Cl
OO
O
O
Metosulam
N
N
NNNH
S
O
OO
O
O
FF
FF
FPenoxsulam
N N
NNNH
SN
O
O
OO O
FF
F
Pyroxsulam
OHP N
H
OH
O O
OH
Glyphosate
OHP N
H
OH
O O
O
(CH3)3 S+
Sulfosate
POH
O
ONH2
O
NH4+
Glufosinate-ammonium
NH2 SNH
OO
O
O
Asulam
Propyrisulfuron
N
N
S NH
NHO
NNN
Cl O
OOO
Bialaphos
CH3PO
OH NH2
HNH
O CH3
HNH
O
CH3
H O
OH
SNH
SP
O O
S
OO
Bensulide
S N
O
Tiocarbazil
S N
O
Cl
Thiobencarb = Benthiocarb
S N
O
Esprocarb
S N
O
Cycloate S N
O
EPTCNS
O
Dimepiperate
N S
O
Molinate
S N
OCl
Orbencarb
S N
O
Pebulate
S N
O
Prosulfocarb
S N
O
VernolateS N
O
Cl
Cl
Cl
Tri-allate
OH
O
Cl
Cl Cl
TCA
OH
O
ClCl
Dalapon
OH
O
FF
F
F
Flupropanate
O
O
O O
NO
Alloxydim
O
O
O
N O
Butroxydim
Clethodim
O
OS
N O ClCycloxydim
O
O
NO
S
Sethoxydim
O
O
NO
S
Profoxydim
S
O
O
N OO
Cl
Tepraloxydim
O
OO
N O Cl
Pinoxaden
O NN
O
O
O
Tralkoxydim
O
O
NO
Cyhalofop-butyl
OF
N OO
O
CH3
H
Diclofop-methyl
Cl Cl
O
OO
O
Fluazifop-P-butyl
N
F
FF
O
OO
O
CH3
H
Fenoxaprop-P-ethyl
Cl O
N O
O
OO
CH3H
Metamifop
O
N
Cl
O
OO
NFCH3
Haloxyfop-P-methyl
N
F
FF Cl
O
OO
O
CH3
Propaquizafop
N
N
O
Cl O
CH3
O
OON
Quizalofop-P-methyl
N
N
O
Cl O O
O
CH3
Quizalofop-P-tefuryl
N
N
O
Cl O
OCH3OO
Ethofumesate
OO
OS
O OBenfuresate
O
OSO O
Butylate
S N
O
Clodinafop-propargyl
N
Cl F
O
OO
O
CH3
N
Cl
O
ClN
O
O
Oxadiazon
O
Cl
Cl
N
ON
O
Oxadiargyl
NN
O
OO
O
O
O
FF
F
Benzfendizone
Cl
O N
F
O
O
O
Pentoxazone
NN
F
H O
O
F
Cl
NH
SCl
OO
Profluazol
NN O
F
O
Cl
O
OF
F
F
Flufenpyr-ethyl
SN
NN
O
NO
F
Thidiazimin
N
ClF
OCl
ONN
O
F
F
Carfentrazone-ethyl
NN
N
O Cl
Cl
O
Azafenidin NCl
OO
Cl
O
O
Cinidon-ethyl N
O
Cl
O
O
F
OO
Flumiclorac-pentyl
N
O
O
F
N
O
O
Flumioxazin
O
Cl
F
FF
OO
N+
O
ONa+
Acifluorfen-sodium
O
Cl
Cl
OO
N+
O
O
Bifenox
OCl
F
FF
N+
O
O
OOO
O
Fluoroglycofen-ethyl
O
Cl
Cl
ON
+O
O
Chlomethoxyfen
O
F
FF
O
N+
O
O
NH
SO O
Cl
Fomesafen
OF
F
FF Cl
NH
OS
O O
N+ O
O
Halosafen
O
Cl
F
FF
N+
O
O
OOO
O
Lactofen
O
ClF
FF
O
N+ O
O
Oxyfluorfen
OF
FF Cl
O
O CH3
HO
OCl
Ethoxyfen-ethyl
NN
O
O
FF
FCl
OO
O
O
Butafenacil
NNN
N
ClCN
N
Pyraclonil
N
F
Cl
S
OO
NN
S
O
Fluthiacet-methyl
ClCl
N
N
NNH
SO
O
O
FF
Sulfentrazone
N N
FCl
O
OF
FF
Br
Fluazolate
N N
FCl
OO
ClF
FO
O
Pyraflufen-ethyl
Bencarbazone
NN
N
O
FFF
F
NH
NH2
S
SO
O
Saflufenacil
N
N
O
OF
FF
F Cl
O
NH
S NO O
N
O Cl
O
Acetochlor
N
O Cl
O
AlachlorN
O Cl
PropachlorN
O Cl
O
Butachlor
N
O Cl
O
Dimethachlor
N
O Cl
S
OThenylchlor
S
N
O
Cl
O
Dimethenamid
N
O Cl
NN
Metazachlor
N
O Cl
O
MetolachlorN
O Cl
O
Pretilachlor N
O Cl
O
Propisochlor
N
O
Cl
O
Pethoxamid
Cl Cl
ClCl
O
OO
O
Chlorthal-dimethyl = DCPA
N
NO2
NO2
SNH2
O
O
N
NO2
NO2
FF
F
Ethalfluralin
NH
NO2
NO2
Pendimethalin
NH
NO2
NO2
Butralin
Oryzalin N
NO2
NO2
FF
F
Trifluralin
N
NO2
NO2
FF
FNH2
Dinitramine
NH
OO
Cl
Chlorpropham NH
OO
Propham
N
NO2
NO2
FF
F
Benefin = Benfluralin
S
PNH
OO
NO2
S
PNH
OO
NO2
Amiprofos-methyl
Butamifos
NH
OCl
ClPropyzamide = Pronamide
NO
Tebutam
PS
OSO
N
OCl
Anilofos
N PS
OSO
O
Piperophos
SO O
NN
N
N
O
Cafenstrole
O
NH
O
Naproanilide
N
O
Diphenamid
N
S
O
S
O
FF
F F
F
Dithiopyr
N
O
O
FF
F F
F
S
N
Thiazopyr
ON
NN
S
O F
FF
F
Flufenacet
ON
N
S
O
Mefenacet
N NNN N
OO
Cl
Fentrazamide
Carbetamide
NH
O
O
NH
OH
Napropamide
O
O
N
SNN
ON
OOO
FF
FFF
Pyroxasulfone
Ipfencarbazone
F
F
N
OO
N NN
CI CI
Flamprop-m
N
Cl
F
C H3O
H
O
O H
A (1) Lipid synthesis inhibition (inh. of ACCase)B (2) Inhibition of ALS (branched chain
amino acid synthesis)C (5, 6, 7) Inhibition of photosynthesis PS IID (22) PS I electron diversionE (14) Inhibition of protoporphyrinogen oxidaseF Inhibition of pigment synthesis (bleaching)F1 (12) Inhibition of PDSF2 (27) Inhibition of 4-HPPDF3 (11, 13) Unknown targetF4 Inhibition of DOXP synthaseG (9) Inhibition of EPSP synthase
H (10) Inhibiton of glutamine synthetaseI (18) Inhibition of DHPK1 (3) Inhibition of microtubule assemblyK2 (23) Inhibition of microtubule organisationK3 (15) Inhibition of cell division (VLCFA)L (20, 21) Inhibition of cellulose synthesisM (24) Uncoupler of oxidative phosphorylationN (8, 26) Inhibition of lipid synthesis (not ACCase)O (4) Synthetic auxinP (19) Auxin transport inhibitionZ (17, 25,) Unknown mode of action
( ) WSSA Group
A free copy of this poster can be downloaded from www.hracglobal.com Designed and produced by Syngenta 2010
8
The World of HerbicidesAccording to HRAC classification on mode of action 2010
HERBICIDES AFFECTING: Light Processes Cell Metabolism Growth/Cell Division
C2
C3
C1 C Inhibition ofphotosynthesis at PS II
B Inhibition of ALS (branched)chain amino acid synth.)
K1Inhibition of
microtubule assembly K2Inhibition of
microtubule organisation
M Uncoupler (membrane disruption)
E Inhibition ofprotoporphyrinogen oxidase
D PS-I-electron diversion
F Inhibition of pigmentsynthesis (bleaching)
N Lipid synthesis inhibition(not ACCase)
A Lipid synthesis inhibition(inhibition of ACCase)
K3Inhibition of cell division
(inhibition of VLCFAs)
L Inhibition ofcellulose synthesis
F1 Inhibition of PDS
F4Inhibition of
DOXP synthase
F3 Unknown target
F2Inhibition of
4-HPPD
I DHP-inhibition
Z Unknown modeof action
O Synthetic Auxins
P Auxin transportinhibition
H Glutamine synthetase inhibition
G Inhibition ofEPSP synthase
Phenyl-pyridazines
Diphenyl ethers
Thiadiazoles
Diphenylether
Pyrimidinediones
Cyclohexanediones (DIMs)
Chlorocarb. acids
Others
Glycines
Others
Others
Ureas
Uracils
Amides
Triazolinone
Triazines
Phenylpyrazoles
Imidazolinones
Triazolopyrimidines
Chloroacetamides
Pyridine-carboxylic acids
Benzoic acids
Phenoxy-carboxylic acids
Tetrazolinones
Acetamides
Semicarbazone
Phthalamate
Benzamide
Alkylazines
Nitriles
Pyridines
Phosphoroamidates
DinitrophenolsBipyridyliums
Phosphorodithioate
Benzofuranes
Quinolinecarboxylic acids
Phosphinic acids
Carbamate
Sulfonylamino-carbonyl-triazolinones
Sulfonylureas
Pyrimidinyl (thio) benzoates
Oxadiazoles
Triazinones
Triazolinones
Pyridazinone
Nitriles
Phenylcarbamates
N-Phenyl-phthalimides
Oxazolidinedione
Benzothiadiazinone
Benzoic acid
Carbamates
Dinitroanilines
Benzamides
Oxyacetamides
Aryloxyphenoxy-propionates (FOPs)
www.hracglobal.com
Thiocarbamates
Phenylpyrazoline (DEN)
Arylaminopropionic acid
Triazolocarboxamide
O
O
NH
Cl
Cl
Clomeprop
O
OH
O
Cl
Cl
Dichlorprop=2,4-DP
O
OH
O
Cl
Cl
2,4-D
O
OH
OCl
MCPA
O
Cl
Cl
OH
O
2,4-DB
OCl
OH
O
MCPB
OCl
OH
O
Mecoprop = MCPP = CMPP
FF
N
NN
ONH2
Cl
OFF
F
Flupoxam
NCl
Cl Cl
OOH
O
Triclopyr
NCl
Cl
O
OH
Clopyralid
NF
Cl Cl
OOH
O
NH2
Fluroxypyr
NCl
Cl Cl
NH2
O
OH
Picloram
NCl
Cl
NH2
O
OH
Aminopyralid
NH
NOO
O
O
Isoxaben
Cl
Cl NH2
OHO
Chloramben
OHO
O
Cl
Cl
Dicamba
OHO
Cl
Cl
Cl
TBA
Cl ClCN
Dichlobenil
Cl Cl
SNH2
Chlorthiamid
NH
O
OH
O
Naptalam
N
OOH
Cl
Quinmerac
N
Cl
OOH
Cl
Quinclorac
O
O
NNNH
NH
O
F
F
Na
Diflufenzopyr-sodium
N
SO
Cl
O
O
Benazolin-ethyl
+
N
N
N
NH2
F
NH
O
Triaziflam
Indaziflam
N N
N
NH2
F
CH3
CH3
NH CH3
N
N
N
NH NH
S
Desmetryne N
N
N
Cl
NH
NH
Propazine
N
N
N
NH
NH
S
Ametryne
N
N
N
NH
NH
Cl
Atrazine
N
N
N
NH
S NH
Dimethametryn
N
N
N
NH
NH
Cl
Simazine
N
N
N
NH
NH
Cl
Terbuthylazine
N
N
N
NH
NH
S
Terbutryne
N
N
N
NH
NH
S
SimetryneN
N
N
NH
NH
O
PrometonN
N
N
NH
NH
Cl
CN
Cyanazine N
N
N
NH
NH
S
Prometryne N
N
N
NH
NH
O
Terbumeton
N
N
N
N NH
Cl
Trietazine
NH
N
O
Fenuron
S
NN
NHO
Methabenzthiazuron
NH
ClN
O
Chlorotoluron
NH
ON
OCl
Chloroxuron
NH
N
O
FF
F
Fluometuron (also F3)
Cl
Cl
NH
NO
Neburon
NH
N
ClN
O
O
N
O
Dimefuron
NH
N
O
Isoproturon O
Cl
NH
ON
Metoxuron
NH
NH
O
Siduron
NH
Cl
Cl
N
O
Diuron
NO
NH N
O
Isouron
Cl
NH
N
O
O
Monolinuron
N N
S N
O
NH
Tebuthiuron
Br
Cl
NH
NO
O
Chlorobromuron
S
NN
NS
O
O
NH
O
Ethidimuron
Cl
Cl
NH
NO O
Linuron
N
SNH
O
OO
Bentazone
N
NH
O
Br
O
BromacilN
NH
O
O
LenacilN
NH
O
Cl
O
Terbacil
NH
ONH
O
O
OPhenmedipham
NNCl
O
O
S
Pyridate
N N
OH
Cl
Pyridafol
NN
OCl
NH2
Chloridazon/Pyrazon
N N
NN
O
O
Hexazinone
N
NN
O NH2
MetamitronN N
NO
NH2
S
Metribuzin
N
NN
O
NH2
O
NH
Amicarbazone
N+
N+
Br Br
N+
N+
Cl Cl
Diquat
Paraquat
Cl
Cl
NH
O
Propanil
Cl
NH
O
Pentanochlor
Br
OH
Br
N O
NO2
O2N
Bromofenoxim (also M)
I
OH
I
CN
Ioxynil (also M)
Br
OH
Br
CN
Bromoxynil (also M)
O
NHO
O
NH
ODesmedipham
Br
NH
O
N
O
Metobromuron
O NNH
O
F
FF
F
Picolinafen
N
O
FF
F
Fluridone
NN
OCl
NH
FF
F
NorflurazonN
OCl
ClF
FF
Flurochloridone
O
ClNH2
O2N
AclonifenNH
NO
FF
F
Fluometuron(also C)
NO
Cl
O
Clomazone
ON
O
Cl
S
O
O
Isoxachlortole
NN
OO Cl
Cl
O
Pyrazoxyfen
NN
OOH S
F
FF
OO
Pyrasulfotole
O
O
O Cl
SO
O
O O
Tefuryltrione
ONH
O
FF
F
Flurtamone
ON
O
NH
F F
FF
F
DiflufenicanBeflubutamid
F
F FF
OO
NH
Isoxaflutole
ON
O
F
FF
SO
OBenzofenap
NN O
O
OCl
Cl
PyrazolynateN
N OS
O
OCl
Cl
O
Sulcotrione
ClOO
O
O
SO O
Mesotrione
O O
O
N+O O
SO O
Benzobicyclon
S O Cl
SO O
Tembotrione
O
O
O Cl
OF
F
F
SO O
Topramezone
O
NN
OH
ON
SOO
O
OH O
N
FF
F
OO
Bicyclopyrone
Amitrole (Inh. of lycopene cyclase)
NH
N
N
NH2
NH
ONH
Dymron = Daimuron
NH N
O
Methyldymron
NH
NH
OCl
Cumyluron
OH
O
Pelargonic acid
N N
S S
Dazomet
(CH2)7CO2H
(CH2)7CH3
Oleic Acid
O
N
Cl
ClO
Oxaziclomefone
NH2
PO
O
O
OH
Fosamine
ClCl
NH
O
OO
Etobenzanid
O
O
CinmethylinN NO
S
O
Pyributicarb
DSMA
AsO
O
O
Na+
Na+
MSMA
As
O
OH
O Na+Metam
S
S
NH
Na+
Bromobutide
NH
O
Br
DifenzoquatMetilsulfate
NN
+CH3SO-4
Indanofan
OO
O
Cl
Chlorflurenol
OH OH
O
Cl
N
NO
O
NH
NH
OS OO
NS O
O
Amidosulfuron
N
NO
O
NH
NH
OS OO
N N
N
NNN
Azimsulfuron
N
NO
O
NH
NH
OS OO
OO
Bensulfuron-methyl
N
N
O
NH
NH
OS OO
OO
Cl
Chlorimuron-ethyl
NN
NO
NH
NH
OS OO
Cl
Chlorsulfuron
NN
NO
O
NH
NH
OS OO
OO
Cinosulfuron
N
NO
O
NH
NOS O
O
N
O
FF
F
Na+
Trifloxysulfuron-sodium
N
NO
O
NH
NH
OS OO
NHO
Cyclosulfamuron
NN
NO
NH
NH
NH
OS OO
OO
Ethametsulfuron-methyl
N
NO
O
NH
NH
OS OO
O
O
Ethoxysulfuron
N
NO
O
NH
NH
OS OO
N
FF
F
Flazasulfuron
N
NO
O
NH
NOS O
O
N
OO
FF
FNa+
Flupyrsulfuron-methyl-sodium
N
NO
O
NH
NH
OS OO
N N
ClOO
Halosulfuron-methyl
N
N
NO
O
NH
NH
OS OO
N
Cl
Imazosulfuron
NN
NO
NH
NOS O
O
I
OO
Na+
Iodosulfuron-methyl-sodium
NN
NO
NH
NH
OS OO
OO
Metsulfuron-methyl
N
NO
O
NH
NH
OS OO
NH
ON
O
H
Foramsulfuron
N
NO
O
NH
NH
OS OO
N
ON
Nicosulfuron
N
NNH
NH
OS OO
OOO
Oxasulfuron
N
NO
O
NH
NH
OS OO
O
F
F
F
F
O
Primisulfuron-methyl
NN
NO
NH
NH
OS OO
FF
F
Prosulfuron
N
NO
O
NH
NH
OS OO
OO
NH
SO O
Mesosulfuron-methyl
N
NO
O
NH
NH
OS OO
N N
OO
Pyrazosulfuron-ethyl
N
NO
O
NH
NH
OS OO
N
S OO
Rimsulfuron
N
NNH
NH
OS OO
OO
Sulfometuron-methyl
N
NO
O
NH
NH
OS OO
N
N
SO
O
Sulfosulfuron
NN
N
O
NH
NH
OS OO
FF
F
FF
F
Tritosulfuron
NN
NO
NH
NH
OS OO
S
OO
Thifensulfuron-methyl
NN
NO
NH
NH
OS OO
OCl
Triasulfuron
NN
NO
NNH
OS OO
OO
Tribenuron-methyl
NN
NO
NH
NH
OS OO
O
N
O
FFF
Triflusulfuron-methyl
N
NO
O
NH
NH
OS OO
OO
NO
F
Flucetosulfuron
N
NO
O
NH
NH
OS OO
NHN O
Orthosulfamuron
NH
NO
N
OOH
Imazapic
NH
NO
N
OOH
Imazapyr
NH
NO
OONH
NO
OO+
Imazamethabenz-methyl
NH
NO
N
OOH
Imazaquin
NH
NO
N
OOH
O
Imazamox
NH
NO
N
OOH
Imazethapyr
OH
NO2
NO2
DNOC
OH
NO2
NO2
Dinoterb
OH
NO2
NO2
Dinoseb
O ON
N N
N
O
O
O
O
O O Na+
Bispyribac-sodium
O ON
N N
N
O
O
O
O
O ON
Pyribenzoxim
S
N
N
O
O
O O
Cl
Na+
Pyrithiobac-sodium
S
N
N
O
OO O
Pyriftalid
O
N
N
O
O
O O
NO
Pyriminobac-methyl
NH
N
N
O
OOH
O
SOO
FF
Pyrimisulfan
S NOO
ON
N
NO
O
OO
Na+
O S NOO
ON
N
NO
O
FF
F
Na+
Flucarbazone-sodium
Propoxycarbazone-sodium
S
S NH
N
O
NN
O
O
OO
O O
Thiencarbazone-methylN
N
NNS
NH
Cl
OO
OO
F
O
Cloransulam-methyl
N
N
NNS
NH
Cl
Cl
OO
F
O
Diclosulam
N
N
NNS
NH
F
F
OO
O
F
Florasulam
N N
NNS
NH
F
F
OO
Flumetsulam
N N
NNS
NH
Cl
Cl
OO
O
O
Metosulam
N
N
NNNH
S
O
OO
O
O
FF
FF
FPenoxsulam
N N
NNNH
SN
O
O
OO O
FF
F
Pyroxsulam
OHP N
H
OH
O O
OH
Glyphosate
OHP N
H
OH
O O
O
(CH3)3 S+
Sulfosate
POH
O
ONH2
O
NH4+
Glufosinate-ammonium
NH2 SNH
OO
O
O
Asulam
Propyrisulfuron
N
N
S NH
NHO
NNN
Cl O
OOO
Bialaphos
CH3PO
OH NH2
HNH
O CH3
HNH
O
CH3
H O
OH
SNH
SP
O O
S
OO
Bensulide
S N
O
Tiocarbazil
S N
O
Cl
Thiobencarb = Benthiocarb
S N
O
Esprocarb
S N
O
Cycloate S N
O
EPTCNS
O
Dimepiperate
N S
O
Molinate
S N
OCl
Orbencarb
S N
O
Pebulate
S N
O
Prosulfocarb
S N
O
VernolateS N
O
Cl
Cl
Cl
Tri-allate
OH
O
Cl
Cl Cl
TCA
OH
O
ClCl
Dalapon
OH
O
FF
F
F
Flupropanate
O
O
O O
NO
Alloxydim
O
O
O
N O
Butroxydim
Clethodim
O
OS
N O ClCycloxydim
O
O
NO
S
Sethoxydim
O
O
NO
S
Profoxydim
S
O
O
N OO
Cl
Tepraloxydim
O
OO
N O Cl
Pinoxaden
O NN
O
O
O
Tralkoxydim
O
O
NO
Cyhalofop-butyl
OF
N OO
O
CH3
H
Diclofop-methyl
Cl Cl
O
OO
O
Fluazifop-P-butyl
N
F
FF
O
OO
O
CH3
H
Fenoxaprop-P-ethyl
Cl O
N O
O
OO
CH3H
Metamifop
O
N
Cl
O
OO
NFCH3
Haloxyfop-P-methyl
N
F
FF Cl
O
OO
O
CH3
Propaquizafop
N
N
O
Cl O
CH3
O
OON
Quizalofop-P-methyl
N
N
O
Cl O O
O
CH3
Quizalofop-P-tefuryl
N
N
O
Cl O
OCH3OO
Ethofumesate
OO
OS
O OBenfuresate
O
OSO O
Butylate
S N
O
Clodinafop-propargyl
N
Cl F
O
OO
O
CH3
N
Cl
O
ClN
O
O
Oxadiazon
O
Cl
Cl
N
ON
O
Oxadiargyl
NN
O
OO
O
O
O
FF
F
Benzfendizone
Cl
O N
F
O
O
O
Pentoxazone
NN
F
H O
O
F
Cl
NH
SCl
OO
Profluazol
NN O
F
O
Cl
O
OF
F
F
Flufenpyr-ethyl
SN
NN
O
NO
F
Thidiazimin
N
ClF
OCl
ONN
O
F
F
Carfentrazone-ethyl
NN
N
O Cl
Cl
O
Azafenidin NCl
OO
Cl
O
O
Cinidon-ethyl N
O
Cl
O
O
F
OO
Flumiclorac-pentyl
N
O
O
F
N
O
O
Flumioxazin
O
Cl
F
FF
OO
N+
O
ONa+
Acifluorfen-sodium
O
Cl
Cl
OO
N+
O
O
Bifenox
OCl
F
FF
N+
O
O
OOO
O
Fluoroglycofen-ethyl
O
Cl
Cl
ON
+O
O
Chlomethoxyfen
O
F
FF
O
N+
O
O
NH
SO O
Cl
Fomesafen
OF
F
FF Cl
NH
OS
O O
N+ O
O
Halosafen
O
Cl
F
FF
N+
O
O
OOO
O
Lactofen
O
ClF
FF
O
N+ O
O
Oxyfluorfen
OF
FF Cl
O
O CH3
HO
OCl
Ethoxyfen-ethyl
NN
O
O
FF
FCl
OO
O
O
Butafenacil
NNN
N
ClCN
N
Pyraclonil
N
F
Cl
S
OO
NN
S
O
Fluthiacet-methyl
ClCl
N
N
NNH
SO
O
O
FF
Sulfentrazone
N N
FCl
O
OF
FF
Br
Fluazolate
N N
FCl
OO
ClF
FO
O
Pyraflufen-ethyl
Bencarbazone
NN
N
O
FFF
F
NH
NH2
S
SO
O
Saflufenacil
N
N
O
OF
FF
F Cl
O
NH
S NO O
N
O Cl
O
Acetochlor
N
O Cl
O
AlachlorN
O Cl
PropachlorN
O Cl
O
Butachlor
N
O Cl
O
Dimethachlor
N
O Cl
S
OThenylchlor
S
N
O
Cl
O
Dimethenamid
N
O Cl
NN
Metazachlor
N
O Cl
O
MetolachlorN
O Cl
O
Pretilachlor N
O Cl
O
Propisochlor
N
O
Cl
O
Pethoxamid
Cl Cl
ClCl
O
OO
O
Chlorthal-dimethyl = DCPA
N
NO2
NO2
SNH2
O
O
N
NO2
NO2
FF
F
Ethalfluralin
NH
NO2
NO2
Pendimethalin
NH
NO2
NO2
Butralin
Oryzalin N
NO2
NO2
FF
F
Trifluralin
N
NO2
NO2
FF
FNH2
Dinitramine
NH
OO
Cl
Chlorpropham NH
OO
Propham
N
NO2
NO2
FF
F
Benefin = Benfluralin
S
PNH
OO
NO2
S
PNH
OO
NO2
Amiprofos-methyl
Butamifos
NH
OCl
ClPropyzamide = Pronamide
NO
Tebutam
PS
OSO
N
OCl
Anilofos
N PS
OSO
O
Piperophos
SO O
NN
N
N
O
Cafenstrole
O
NH
O
Naproanilide
N
O
Diphenamid
N
S
O
S
O
FF
F F
F
Dithiopyr
N
O
O
FF
F F
F
S
N
Thiazopyr
ON
NN
S
O F
FF
F
Flufenacet
ON
N
S
O
Mefenacet
N NNN N
OO
Cl
Fentrazamide
Carbetamide
NH
O
O
NH
OH
Napropamide
O
O
N
SNN
ON
OOO
FF
FFF
Pyroxasulfone
Ipfencarbazone
F
F
N
OO
N NN
CI CI
Flamprop-m
N
Cl
F
C H3O
H
O
O H
A (1) Lipid synthesis inhibition (inh. of ACCase)B (2) Inhibition of ALS (branched chain
amino acid synthesis)C (5, 6, 7) Inhibition of photosynthesis PS IID (22) PS I electron diversionE (14) Inhibition of protoporphyrinogen oxidaseF Inhibition of pigment synthesis (bleaching)F1 (12) Inhibition of PDSF2 (27) Inhibition of 4-HPPDF3 (11, 13) Unknown targetF4 Inhibition of DOXP synthaseG (9) Inhibition of EPSP synthase
H (10) Inhibiton of glutamine synthetaseI (18) Inhibition of DHPK1 (3) Inhibition of microtubule assemblyK2 (23) Inhibition of microtubule organisationK3 (15) Inhibition of cell division (VLCFA)L (20, 21) Inhibition of cellulose synthesisM (24) Uncoupler of oxidative phosphorylationN (8, 26) Inhibition of lipid synthesis (not ACCase)O (4) Synthetic auxinP (19) Auxin transport inhibitionZ (17, 25,) Unknown mode of action
( ) WSSA Group
A free copy of this poster can be downloaded from www.hracglobal.com Designed and produced by Syngenta 2010
9
Group 4’sSynthetic auxins
Carboxylic acids
Clopyralid, fluroxypyr, triclopyr etc.
Halauxifen-methyl (Arylex)
Phenoxies
MCPA
2,4-D
2,4-DB
Dichlorporp
MCPB
CMPP-P
Benzoic Acids
Dicamba
Group 4 HerbicidesPhenoxies
The mode of action in herbicides is the way an active ingredient controls the plant. It describes the physiological process that is interrupted in the plant which ultimately affects the plants growth and development. In other cases, the mode of action may be a general description of the injury symptoms seen on susceptible plants.
There are 7 different mechanisms listed below and Herbicide Resistance Action Committee (HRAC) use groups from A-Z to class different types of modes without these mechanisms.
1) ACCase inhibitors 2) ALS inhibitors 3) EPSPS inhibitors 4) Synthetic auxins5) Photosystem II inhibitors 6) Photosystem I inhibitos 7) HPPD inhibitors Phenoxy herbicides are in Group 4 “Synthetic auxin” category and are in HRAC group O. Knowing mechanisms and groups of herbicide is important in order to manage resistance. Herbicide resistance is the inherent ability of a weed to survive a herbicide rate that would normally control it. This is not the same phenomena as poor herbicide performance. If herbicide resistance develops, other herbicides or different control methods will have to be used to control a weed. These options may be more expensive or less effective. Once developed, herbicide resistance will persist for many years.
10
With its roots extending back to investigation of auxins in 1936, MCPA was first synthesised in 1945 and has been used as a powerful selective herbicide ever since. Nufarm manufactures MCPA from its state of the art production facilities in Wyke Bradford.
MCPA (2-methyl-4-chlorophenoxyacetic acid)
MCPA Weed Control
• Formulated as a salt or an ester, MCPA offers a good broad-leaved spectrum in cereals and grassland.
• Rate response depends on species and size but generally you need 500-750g active in mixtures in cereals minimum.
• Use in cereals is increasing to control SU resistant weeds such as Poppy.
• Easel is approved up to the later time of GS39 in Winter Wheat.
• Boosts Thistle, Fat hen and Hempnettle control in cereals.
• Controls Thistles and Buttercups in grassland.
Brand straights: Agritox, EaselBrand co-formulations: CloverMax, PastureMaster, Mircam Plus, TurfMaster
More SusceptibleLess Susceptible
Chickweed Soft Rush Docks Thistles
ButtercupDandelions Ragwort Nettles
11
2,4-D (2,4-Dichlorophenoxyacetic acid)
2,4-D Weed Control
2,4-D is Systemic
• One of the most widely used herbicides in the world.
• Developed during World War II at Rothamsted Experimental Station with the aim to increase crop yields for a nation at war.
• 2,4-D typically applied as an amine salt, but more potent ester versions exist.
• Radio labelled 2,4-D is sprayed on oilseed rape at 4 leaf stage.
• 48 hours after treatment, the amount of radiolabelled 2,4-D is observed in the plants through radioactivity in liquid scintillation.
• The 2,4-D has migrated from leaves to roots.
• 2,4-D has a similar weed spectrum to MCPA Cereals less tolerant than to MCPA.
• Early tillering in winter cereals can result in severe ear damage. No later than before first node otherwise ear damage Better control of docks in grassland than MCPA.
Chickweed Docks Buttercup
Dandelions
Ragwort
2,4-D has systemic activity this means the herbicide will move both up and down the plant and into the roots giving a faster speed of kill than that of a contact product. This is especially important when it comes to controlling perennial weeds such as docks or ragwort.
Like MCPA, 2,4-D was developed in the 1940’s and has been a vital component of British Crop protection since. It is now one of the most widely used herbicides in the world. It has proven to be systemic which is ideal for perennial weed control.
Brand straights: DepitoxBrand co-formulations: Kyleo, Thrust, PastureMaster
More SusceptibleLess Susceptible
Soft Rush Nettles Thistles
12
Mecoprop-P (methylchlorophenoxypropionic acid)
• New technologies in the 1980s allowed for the creation of products with higher concentrations of the optically active isomer.
• Boosts Cleaver and Fat hen control, which are not well controlled by many SUs. Also strong on Chickweed, and killing leguminous volunteers but generally boosts the weed control of anything it is mixed with.
• Works in cooler weather than the other phenoxies.
• Rate response. Activity falls off quickly below 1.0 l/ha.
Mecoprop-P Weed Control
Cleaver
Soft Rush Docks Chickweed
ButtercupDandelions
Ragwort
Nettles
Thistles
Discovered by Boots Agrochemicals in 1953, registered in 1957. This initial formulation consisted of two chemical isomers in equal proportion, only one of which is the active herbicide.
Brand straights: Duplosan KV, Compitox PlusBrand co-formulations: Mircam Plus, High Load Mircam, Duplosan Super, TurfMaster
More SusceptibleLess Susceptible
13
2,4-DB (4-(2,4-dichlorophenoxy)butyric acid)
• Butyric phenoxies are about half as active as Acetics.
• 2,4-DB is the key active in CloverMaster, and one of the key actives within Clovermax.
• 2,4-DB is safe to Clover when applied before 4th trifoliate leaf stage because young Clover can’t convert 2,4-DB to 2,4-D.
• If applied when Clover (or Lucerne) is more mature, it will damage, or kill the crop.
• Clovermax and CloverMaster can be applied to cereal crops (wheat, barley or oats) under-sown with Red or White Clover.
• Other legume crops, such as Peas and Beans are not tolerant to 2,4-DB as they have the ability to convert it to 2,4-D, which causes the damage.
Clover safe weed control in established grassland and new sown leys. An ideal mixing partner with Squire Ultra.
Brand straights: CloverMasterBrand co-formulations: CloverMax
2,4-DB Weed Control
Black Bindweed
Field Penny Cress
Redshank
Charlock
More SusceptibleLess Susceptible
Speedwell species
Shepherds Purse
Fat Hen
14
MCPB (4-(4-chloro-o-tolyloxy)butyric acid)
• Some legume crops, notably peas and clover lack the conversion mechanism and therefore are tolerant, however others are not e.g lucerne, beans.
• Weed spectrum similar to MCPA but less than half as active.
• Tropotox is approved for use in Combining and Vining Peas.
Discovered at Wye College, London University in 1955 by Professor Louis Wain. It is converted within the plant by susceptible weeds into MCPA. As a butyric phenoxy it is generally about half as active, but has some unique selective properties.
Brands: Tropotox
MCPB Weed Control
Chickweed Docks
Buttercup
Ragwort Fat Hen
More SusceptibleLess Susceptible
Orache NettlesThistles
15
Dichlorprop-p (2,4-dichlorophenoxy propionic acid)
• Improved control of polygonum weeds such as Black bindweed & Redshank over CMPP.
• Ideal product for spring barley.
• More temperature dependant than CMPP-P.
Discovered by Boots Agrochemicals in 1945. It was initially a mix of two isomers, now single isomer Dichlorprop-p. Dichlorprop-p is not available for use as a straight active.
Dichlorprop-p Weed Control
Brand co-formulations: Duplosan Super
16
CleaverSoft RushBlack
BindweedRedshank
ButtercupDandelions
Ragwort
Nettles
More SusceptibleLess Susceptible
Thistles
Dicamba
• Adds control of most of the Polygonums including Redshank and Knotgrass and improves control of Docks. Will boost Chickweed and control of most Mayweed species and also gives good control of Fumitory in mixtures. Kills clover.
• Safe in cereals up to about 100g/ha ai but can be used at higher doses up to about 300g/ha in grassland.
• An effective mixing partner for phenoxy actives.
As with Dichlorprop-p, Dicamba is not available for use as a straight active in cereals and grassland. This compound was discovered in 1965 by Velsicol. Dicamba is not a phenoxy and is more closely related to clopyralid but its acts in a similar way to phenoxies. Effective at a far lower dose than phenoxies.
Dicamba Weed Control
Groundsel Mayweed Black BindweedKnotgrass
More SusceptibleLess Susceptible
Brand co-formulations: High Load Mircam, TurfMaster, Mircam Plus, Thrust
17
Chickweed
CMPP-P CMPP-P + Dicamba MCPA MCPA + CMPP-P
+Dicamba Bromoxynil Tribenuron -methyl
Duplosan KV H Load Mircam Easel/ Agritox Mircam Plus Maya Thor
Cleavers
Chickweed
Charlock
Fat hen
Small Nettle
Mayweed
Fumitory
Docks
Knotgrass
Speedwell
Thistles
Redshank
Groundsel
Spring Cereal Product Spectrum
CMPP-PMCPA +
CMPP-P + Dicamba
Fluroxypyr MCPA Florasulam Bromoxynil Tribenuron -methyl
Duplosan KV H Load Mircam Tomahawk Easel/ Agritox Lector Maya Thor
Cleavers
Chickweed
Speedwell
Mayweed
Charlock
Knotgrass
Poppy
Vol OSR
Groundsel
Thistles
Cranesbill
Fools parsley
Fumitory
Winter Cereal Product Spectrum
18
Susceptible
Moderately Susceptible
Moderately Resistant
Resistant
Am
aran
thus
Amar
anth
us li
vidu
sAmaran
thaceae
Bind
wee
d, b
lack
Fallo
pia
conv
olvu
lus
Polygo
naceae
Bugl
oss,
vip
ers
Echi
um v
ulga
reBo
ragina
ceae
Cam
pion
Sile
ne a
lba
Caryop
hyllaceae
Char
lock
Sina
pis a
rven
sis
Crucife
rae
Chic
kwee
dSt
ella
ria m
edia
Caryop
hyllaceae
Clea
vers
Gal
ium
apa
rine
Rubiaceae
Cran
esbi
ll, c
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Ger
aniu
m d
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Geran
iaceae
Dea
dnet
tle, h
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mpl
exic
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Labiatae
Dea
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edLa
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Labiatae
Fat h
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Chen
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Flix
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escu
rain
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phia
Crucife
rae
Forg
et m
e no
tM
yoso
tis a
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sis
Boragina
ceae
Fum
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Fum
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offi
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lisFu
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Gro
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Hem
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tetr
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Labiatae
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lygo
num
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cula
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lygo
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Mar
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Chry
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hem
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May
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Trip
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Compo
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Mer
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Mer
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Mou
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Mug
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tAr
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vul
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Compo
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Mus
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sym
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Crucife
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Net
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Urticaceae
Nig
htsh
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bla
ckSo
lanu
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Nip
plew
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Laps
ana
com
mun
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Ora
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Atrip
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patu
laCh
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Shep
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Caps
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bur
sa-p
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risCrucife
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Runc
hRh
apha
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apha
nist
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Crucife
rae
Reds
hank
Poly
gonu
m p
ersi
caria
Polygo
naceae
Popp
yPa
pave
r rho
eas
Papa
veracae
Pim
pern
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carl
etAn
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lis a
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isPrim
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Pers
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ia, p
ale
Poly
gonu
m la
path
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mPo
lygo
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Pars
ley
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Pars
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fool
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umUmbe
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Pans
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Viol
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Sow
this
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lySo
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s asp
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mpo
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Sow
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Spee
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Vero
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Spur
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phor
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scop
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Spur
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cor
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la a
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Caryop
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Thor
n ap
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Dat
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stra
mon
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Solana
ceae
Venu
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g-gl
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Lego
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hyb
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Wild
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Dau
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lliferae
Broa
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Nuf
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19
Getting the Best Results
• Weed must be growing. Avoid cold frosty conditions.
• Phenoxies take about 4-6 hours rain free to get into the plant.
• Check the species is actually susceptible.
• Get the timing right – ideally young plants.
• Make sure the crop is not under stress due to poor nutrition, drought or disease otherwise weed control will be reduced and there is the possibility of damage to the crop.
Understand your Weed Target
Dicot weeds will more often than not be either hairy eg thistle or waxy eg Vol OSR. Knowing what the target is will help to make decisions on spray quality, rate and whether an adjuvant is required.
Most dicot weeds have amorphous (layer) wax however there are some exceptions, fat hen for example has a crystalline wax (hairy in appearance under the microscope and more commonly found in grasses.
Crystalline waxes tend to be harder to penetrate as the spray droplet will sit on top of the ‘hairy’ waxes.
Waxy and hairy. Difficult to penetrate leaves
Small fine shoot system big root system = hard to control.
Dock - Big root system but also many leaves = Spray when enough foliage but not too much as unlikely to get a lethal concentration.
Small root, big leaves and susceptible species = Easy to kill.
Very small target. Finer spray. Big droplets may bounce off or miss the target
Best Use:
20
Application Guidelines – Know your waxes!
21
Application Timing Guidelines
Cereal Growth Stages• The BBCH cereal growth Stage key does not run
chronologically from GS00 to GS99, for example when the crop reaches 3 fully unfolded leaves (GS13) it begins to tiller (GS20), before it has completed 4, 5, 6 fully unfolded leaves (GS14, GS15, GS16).
• It is easier to assess main stem and number of tillers than it is the number of leaves (due to leaf senescence) during tillering. The plant growth stage is determined by main stem and number of tillers per plant e.g. GS22 is main stem plus 2 tillers up to GS29 main stem plus 9 or more tillers.
• Later autumn sown or spring sown crops will very rarely reach GS29 (main stem & 9 tillers or more) before the main stem starts to elongate at GS30.
• After stem elongation (GS30) the growth stage describes the stage of the main stem only, it is not an average of all the tillers.
Cereal crops are sensitive to phenoxy herbicide application at several growth stages throughout the season. The sensitive timings usually coincide with periods of high growth or reproductive activity.
GS 00 - 09 GS 10 - 19 GS 20 – 29 GS 30 - 39 GS 40 - 49
Development Germination Seedling growth Tillering Stem elongation Booting
GS 50 - 59 GS 60 - 69 GS 70 – 79 GS 80 - 89 GS 90 - 99
Development Ear emergence Flowering Milk Development (grain fill period
Dough Development
(grain fill period)Ripening
Safe Timing• Critical period is the ‘double ridge’
- Shoot apex changes from leaf production to spikelet formation.
• Safety period occurs 1 leaf after the ‘double ridge’ stage.
• Timing can be determined by leaf number in spring cereals.
• Spikelet initiation occurs later in winter varieties - Plant has more leaves by the time it has occurred. - Safe stage is when the crop reaches Leaf sheath erect GS30. - Can only be determined exactly by dissection.
• GS30 - The tip of the developing ear is 1 cm or more from the base of the stem where the lowest leaves attach to the shoot apex.
• GS31 - The first node can be seen 1 cm or more above the base of the shoot (with clear internode space below it) and the internode above it is less than 2 cm.
• Spikelet initiation is delayed in dry seasons.
• Ear distortion doesn’t always translate through to a yield reduction.
• Can sometimes be mistaken for frost damage.
Incorrect Timing in Cereals Risks Damage• Symptoms of phenoxy damage include:
- Ear deformities - Rachis (stem of the ear) thinning - Missing spikelets - Increased shattering at harvest
• This doesn’t always translate through to a yield reduction.
• Can sometimes be mistaken for frost damage.
22
Cereal Application Timing with Phenoxies
Product Active Ingredient Cereal crops
Cereal Growth Stage BBCH
1 leaf 5 leaf Leaf sheath erect
First node
Second node
Third node
Before flag leaf
extending
01 15 30 31 32 33 39
Easel MCPA
Winter wheat
Winter barley
Spring cereals
Depitox 2,4-DWinter cereals
Spring cereals
Duplosan KV
MCPP-P Winter cereals
Spring cereals
Recommended timing
23
Water and Phenoxies
Herbicide Application Requires Careful Management to Protect our Water Sources
The challenge• They are all very soluble.
• They don’t get locked up much in the soil.
• Easy for them to leach into field drains and ground water.
The good• The half life varies but is relatively short i.e. less than
a month.
• If there is a reasonably thick crop canopy it can be intercepted.
• They can be taken out by water companies if plant was put in place prior to the water framework directive.
• Measures to remove oestrogen in the future will actually remove phenoxies too.
Water Stewardship
In areas where a range of agricultural enterprises co-exist, conflicts can arise, particularly with the use of pesticides. A major problem that can occur is damage to susceptible crops caused by “off-target” herbicide drift. All herbicides are capable of drift if applied in the wrong manner or conditions, regardless of the active ingredient or the formulation type.
Herbicide users have a moral and legal responsibility to prevent herbicides from drifting and contaminating or damaging neighbouring crops or environmently sensitive areas. Off-target crops may be up to 10,000 times more sensitive than the crop being sprayed. Even small quantities of drifting herbicide can cause severe damage to highly sensitive plants.
Over 50% of phenoxy which gets into water is point source.
Reducing Off-Target Herbicide Drift
Factors that Affect the Risk of Off-Target Drift
• Herbicides can drift as droplets (spray), as vapours or as particles. Spray drift is the most common form of off-target effect. Vapour and particle drift are different to spray drift.
• Vapour Drift - arises directly from the spray or evaporation of herbicide from sprayed surfaces. Changing to a less volatile or non-volatile formulation reduces this risk
• Physical Drift - occurs when water and other herbicide carriers evaporate quickly from the droplet leaving tiny particles of concentrated herbicide. This can occur with many types of
The drift hazard, or off-target potential of a herbicide in a particular situation depends on the following factors:
• Proximity of susceptible crops to the particular herbicide being applied and their growth stage.
• The method of application and equipment used - air, ground, mister and their specific configurations can affect off-target drift.
• Size of the area treated and the amount of active herbicide applied.
• Efficiency of the capture surface, bare soil versus crop.
• Volatility of the formulation applied; ester-based formulations are recognised as the most volatile phenoxy formulations - changing to a non-volatile amine or salt formulation reduces risk.
pesticides. Minute particles float in the air stream and are poorly collected on catching surfaces. They may be carried for miles in thermal up-draft before being deposited.
• Spray Drift (Droplet) - is the easiest to control because under good spraying conditions, droplets are carried down by air turbulence and gravity, to collect on plant surfaces. Under nil wind conditions and very windy conditions droplets, especially fine droplets, can be carried off-target. This can occur regardless of the herbicide used Spray drift is the major offender for off-target effects.
How to Minimise Spray Drift• Before applying any herbicide, always check for
susceptible crops in the area.
• Do not use unless wind speed is more than 3 kilometres per hour and less than 15 kilometres per hour as measured at the application site.
• Restrict sprayer forward speed and limit boom height to that recommended for nozzles.
• Notify neighbours of your spraying intentions.
• Always monitor meteorological conditions carefully and understand their effect on “drift hazard”.
• Supervise all spraying even when a contractor is employed.
• Record weather conditions, wind direction, herbicide and water rates, and operating details for each field.
• Spray when temperatures are less than 28°C to reduce vapour drift risks.
• Maintain a down-wind buffer.
• Minimise spray release height (50cm above the target).
• Use 3* rated Drift reduction nozzles and minimize spray pressures.
• If in doubt – do not spray.
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25
PROTECT YOUR WATER
Use Plant Protection Products safely.
Observe all product buffer zones.
Ensure only certificated spray operators and equipment apply the products.
Do not fill or wash down sprayer in yard unless measures to collect washings for safe disposal in place.
Clean and wash down your sprayer at the end of the day, well away from water bodies or open drains.
Do not use on waterlogged fields, if tyre marks are visible the field is too wet.
Do not exceed the maximum application rate.
Do not use if rainfall is expected. Apply on a calm day when weather conditions are good.
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NOTES
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NOTES
Nufarm UK Ltd Wyke Lane, Wyke, Bradford, West Yorkshire BD12 9EJ
