Phenoxy Reference Guide - Pest Genie · 2005. 4. 14. · Damage to Cereal Crops from Incorrect Phenoxy Herbicide Applications 9 Salvage Spraying of Winter Crops 10 Cereal Tolerance

Phenoxy Reference Guide

www.nu f a rm . com .au 3

Introduction 4

Mode of Action 4

Cereal Crop Growth Stages (including Zadok’s guide) 5

A Numerical Cereal Growth Scale – Zadok’s 6

What Phenoxy Where? 6

Common Weeds Controlled 7

Using the Growth Stage of Cereal Crops to Time Herbicide Applications 8

Damage to Cereal Crops from Incorrect Phenoxy Herbicide Applications 9

Salvage Spraying of Winter Crops 10

Cereal Tolerance Guide 11-13

Plant Back Periods for Fallow Seed Bed Preparation 14-15

Spray Grazing 16

Withholding Periods 16

Reducing Off-Target Herbicide Drift 16-19

Herbicide Resistance Management 20

Contents

At Nufarm, we are committed to supporting Australian growerswith the highest quality crop protection and weed controlproducts so maximum outputs can be achieved.

Our commitment starts with the utilisation of world-leadingmanufacturing and environmental control technology. This isreflected in research and development, container management,and the establishment of regional service centres acrossAustralia.

Nufarm, an Australian company, is a global leader in themanufacture, supply and marketing of 'phenoxys', withmanufacturing plants in Australia (Melbourne), England(Belvedere), Austria (Linz) and the Netherlands (Botlek).

Phenoxys were first developed in the USA in the early 1940’sand used commercially in 1946. Today they remain amongstthe world’s most widely used herbicides, providing farmers andother users with broadleaf weed control in a multitude ofagricultural and non-agricultural uses. Phenoxys work bydisrupting plant cell growth and form a part of the Group Iherbicides.

Nufarm guarantees its Phenoxy products, which includeNufarm Amicide® 625, Nufarm Estercide® 800, Nufarm LVEstercide® 600, Nufarm Surpass® 300, Nufarm Buttress®,Baton®, Nufarm LVE MCPA and Nufarm MCPA 500.

Introduction

Mode of Action

Nufarm Phenoxy Reference Guide

4

Phenoxy herbicides mimic the plant growth regulator indol-3-acetic acid (IAA), or auxin in plants, thus it is necessary toreview the function of auxin in plants to properly understandtheir mechanism of action.

Role of Auxins in Plants – Auxin is a plant growthregulator that controls cell enlargement, division and plantdevelopment through the plant life cycle.

While much remains to be unravelled about the workings ofIAA, it is known that IAA binds to auxin binding proteins (ABPs)located in the following:

• The cell membrane

• The endoplasmic reticulum (an internal cellular membranesystem)

• The cell nucleus

• The cytoplasm

The control of growth that IAA exerts is multifunctional.Changes induced by IAA cause rapid changes in cellelongation and both rapid and slow changes in geneexpression. Auxins influence other growth regulators includingcytokinins, abscisic acid and ethylene (a gas that functions asa plant growth regulator).

The concentration of IAA in plant cells regulates cell growth.However, plant tissues differ in their sensitivity. Depending ontissue type and IAA concentration, IAA may either inhibit orstimulate a response.

IAA is a component of a carefully balanced system. IAA

concentrations are highly regulated in plants by synthesis,degradation and both reversible and non-reversibleconjugation. Synthesis increases the IAA content, whiledegradation decreases it. Conjugation, which is the linking ofIAA to another molecule, frequently an amino acid, inactivatesIAA. However, if conjugation is reversible, it may act as a slowrelease mechanism for maintaining relatively constant IAAlevels.

Auxin Herbicide Mode of Action – Auxinicherbicides (‘phenoxys’) presumably bind to some or all of thesame sites as naturally occurring IAA and cause similar effects.However, the amount of auxinic herbicides available to theplant is uncontrolled and, thus, auxin-like activity is unchecked.Plant growth becomes deregulated.

Metabolic reserves are mobilized and transported to the site ofgrowth, usually meristematic regions. Unregulated growthleads to twisting, thickening and elongation of leaves andstems. Auxinic herbicides are active primarily in growingplants. Plant death is gradual, due to the unconstrainedmobilisation of reserves, the breakdown of repair mechanismsand, finally, the loss of function.

Source: "How Herbicides Work: Biology to Application", AlbertaAgriculture, Food and Rural Development.

Cropgrowthstage

Zadok’sdecimalcode

Herbicidesprayingstage

2-leaf stageTwo leaves (L)have unfolded;third leaf present,yet to fullyexpand

2 leaves unfolded(Z12)

Suitable stage forspraying manyherbicides, but tooearly for 3 leafstage of application.

Start of tilleringFirst tiller (T1)appears frombetween a lowerleaf and the mainshoot. Usually 3 or4 leaves are on themain tiller.

4 leaves unfolded(Z14).Main shoot and 1tiller (Z21).

Suitable stage forspraying at the 3-4leaf stage. Too earlyfor the 5 leaf stageof application.

Tillering stageTillers come fromthe base whereleaves join thestem and continueforming, usuallyuntil there are 5leaves on the mainshoot. Secondaryroots developing.

5 leaves on mainshoot or stem(Z15). Main shootand 1 tiller (Z21).

Suitable forspraying manyherbicides at the 5 leaf tilleringstage.

Fully tillered stageUsually no more tillersform after the veryyoung head startsforming in the main tiller.Tillering completedwhen first node detectedat base of main stem.

6 leaves on the mainshoot or stem (Z16).Main shoot and threetillers (Z23).

Many herbicides can be sprayed up to theend of tillering. Suitablefor 2,4-D spraying.

Start of jointingJointing or nodeformation starts at theend of tillering. Smallswellings – joints – format the bottom of the main tiller. Headscontinue developing and can be seen bydissecting a stem.

First node formed atbase of main tiller (Z31).

Suitable for 2,4-Dspraying.

Early boot stageThe last leaf to form – theflag leaf – appears on topof the extended stem. Thedeveloping head can be feltas a swelling in the stem.

Z35-Z45.

No herbicide should beapplied at this stage. Toolate for 2,4-D applicationexcept harvest aidapplications.

Source: ‘Weed Control in Winter Crops 2004’, NSW Agriculture.

• There is no difference between spring wheat varieties sown on the same day in the rate of appearance of new leaves.• At the early boot stage, the last flowering part - the pollen - is being formed. This occurs earlier in barley than in wheat or triticale.


Cereal Crop Growth Stages (including Zadok’s guide)

Product

MCPA 500

LVE MCPA

Amicide® 625

LV Estercide®

600

Estercide® 800

Buttress®

Surpass® 300

SummerWeeds /melons

0

0

✔

✔

✔

0

0

Tank mixSpraySeed®2

0

✔

✔

✔

✔

0

0

TankmixRoundup®

X

✔

X

✔

✔

X

✔

Tankmixdiuron

✔

✔

✔

0

0

✔

0

Tankmixgrassherbicides

X

✔

X

X

X

X

X

Post-em tankmix with SUherbicides

✔

✔

✔

✔

0

0

0

Tankmix mosttraceelements

X

✔

X

✔

✔

X

X

Spray/Graze inpasture

✔

0

✔

X

X

✔

0

Early post-emin cereals

✔

✔

X

X

X

X

X

Late post-emin cereals

0

0

✔

✔

0

X

0

A decimal scale describing cereal crop growth stages is nowwidely used. This scale, called Zadok’s decimal code,describes the principal growth stages:

0 Germination 4 Booting 7 Milk Development

1 Seedling Growth 5 Ear Emergence 8 Dough Development

2 Tillering 6 Flowering 9 Ripening

3 Stem Elongation

Each primary growth stage is further subdivided into secondarystages extending the scale from 00 to 99.

The first number represents the growth stage and the followingnumber indicates the number of plant parts, e.g. Z12 indicatesa young plant with only two leaves fully unfolded, commonlyreferred to as 2 leaf stage. See the first diagram in Cereal CropGrowth Stages (p5).

A series of pairs of numbers can be used to further describe thegrowth stage. For example 14/21 indicates the main tiller with4 fully unfolded leaves, commonly referred to as the 4 leafstage, but this plant has the main stem and one more tiller. Notethat additional tillers are counted separately to the main tiller.See the second diagram in Cereal Crop Growth Stages.

The main stages of interest to cereal producers applyingherbicides are:

1 Seedling Growth 2 Tillering 3 Stem Elongation 4 Booting

Zadok’s scale is based on the individual plant, not the generalappearance of the crop. Therefore, to use the scale, arepresentative selection of plants should be examined from apaddock.

Other commonly referred to growth stages:

3 leaf: 3 fully unfolded leaves on the main shoot only. Zadok 13.

Double ridge – when the cereal plant changes from leafproduction to ear initiation, normally around 4-6 leaves on themain stem. Zadok 14-16.

5 leaf: 5 fully unfolded leaves on the main shoot only. Zadok 15.

Tillering: Tiller formation period. Plants past seedling stage andbefore stem elongation. Zadok 21 to 29. See the diagrams inCereal Crop Growth Stages.

Jointing: Crop becoming erect or booting up to the stage whenthe flag leaf is just visible. Zadok 31 to 39. See the fifthdiagram in Cereal Crop Growth Stages.

Boot: Head plainly felt in the stem before head emergence.Zadok 35 to 45. See the sixth diagram in Cereal Crop GrowthStages.


6

Recommended✔ Not preferred

option0 Not recommendedX

A Numerical Cereal Growth Scale – Zadok’s

What Phenoxy Where?

Variegated Thistle(Silybum marianum)


Note: These rates are a guide only and further information should be sought from the label for weed size, tankmix recommendations and stateregistrations. Further weed species and rates are included in the product label - for further advice or instructions refer to the product label.

Bathurst BurrBladder KetmiaCapeweedErodiumFat HenFlatweed / DandelionFleabaneFumitoryHeliotropeHexham ScentHoary CressHogweedHorehoundIndian Hedge MustardNoogoora BurrSaffron ThistleSalvation JaneSkeleton WeedSpiny EmexSt Barnaby's ThistleTurnip WeedVariegated ThistleVetchTaresWild MustardWild RadishWild TurnipWireweed

Amicide® 625800ml-2.2L

1.1-2.8L

1.4-3.2L

560ml-1.7L

1.1L

1.8-3.5L

560ml-1.7L

1.1L

1.1-1.7L

900ml-1.7L

1.4L

1.4-3.2L

1.1-1.4L

800ml-1.1L

560ml-1.7L

1.1-2.2L

1.4-1.7L

1.4L

560ml-1.1L

560ml-1.7L

1.1-1.4L

1.1-1.4L

800ml-1.7L

225ml-1.4L

1.4L

Buttress®

1.0-3.2L

2.1-3.2L

1-3.2L

2.1-3.2L

2.1-3.2L

1.0-3.2L

1.0-3.2L

2.1-3.2L

2.1-3.2L

1.0-3.2L

1.0-3.2L

2.1-3.2L

Estercide® 800700ml-2.8L

450ml-1.4L

700ml

350ml-700ml

350ml-2.8L

700ml-2.8L

700ml-1.4L

700ml-2.8L

700ml-2.8L

700ml-2.8L

1.0-1.4L

350-700ml

350ml-2.1L

550-700ml

550-700ml

350-700ml

180-700ml

700ml-1.4L

LVE MCPA1.6L

1.7L

1-1.6L

1.6L

1.1L

1.6L

1.1-1.9L

1.1-1.6L

700ml-1.1L

840ml-1.1L

1.1-1.6L

500ml-1.5L

LV Estercide® 600900ml-3.7L

600ml-3.7L

900ml

460ml-900ml

460ml-3.7L

900ml-3.7L

900ml-1.9L

900ml-3.7L

900ml-3.7L

900ml-3.7L

1.3-1.9L

460-900ml

460ml-3.7L

700-900ml

700-900ml

650ml-2.8L

460-950ml

240-950ml

900ml-1.9L

Surpass® 3001.6-2.3L

2.9-5.8L

2.9-6.6L

1.2-3.5L

3.6-7.3L

1.1-3.5L

2.3-3.4L

1.8-3.4L

2.9L

2.9-6.6L

465ml-2.9L

1.6-2.3L

2.3-4.6L

2.9L

1.1-2.3L

1.1-3.5L

2.3-2.9L

2.3-2.9L

1.6-3.5L

465ml-2.9L

2.9L

MCPA 5001.0-2.0L

2.1L

400-500ml (in mix)

1.0-2.0L

1.4-2.2L

1.4L

1.2-1.5L

2.1-4.5L

2.1-3.0L

1.0-2.0L

1-4L

1.5-2.0L

400-500ml (in mix)

1.0-1.1L

700ml-1.5L

700ml-2.0L

700ml-2.0L

Common Weeds Controlled

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8

It is important to consider the crop growth stage when timingherbicide applications.

Barley, oats and winter wheats sown in early autumn forgrazing develop much more quickly to the tillering stage thancereals sown in May-June. Given adequate moisture and warmweather, early development can be relatively quick.

The terms ‘early tillering’ and ‘late or fully tillered’ are notdefinitive and are commonly used in a very general sense. Thenumber of fully emerged main shoot or stem leaves, togetherwith the number of tillers when there is more than one, is theonly accurate, definitive description of the growth stage of acereal plant. See the diagrams in ‘Cereal Crop GrowthStages’, and ‘A Numerical Cereal Growth Scale – Zadok’s’.

In many cereal crops:

• 3 leaf (on main stem) stage is before tillering.

• 5 leaf (on main stem) stage coincides with early tillering.

• 6-7 leaf (on main stem) stage coincides with mid to fullytillered stage.

• Jointing or node formation indicates the start of thereproductive phase in the crop, and tillering can be said tobe complete.

The table below provides an indication of recommendedtimings for different phenoxy products.

The recommended timing of application has been determined after significant research, with the aim of minimising crop damageand maximising yield. Particular attention should be given to two vital stages of crop development - 3 to 5 leaf stage orcommencement of tillering and at the start of jointing.

Recommended and preferred timingLess preferred timing

Cereal growth stage

Product

MCPA 500

LVE MCPA

Amicide® 625

Estercide® 800

LV Estercide® 600

Buttress®

Chemical

ZadokCereal Code

MCPA 0.7L

MCPA 0.7 – 2.1L

MCPA 0.5L

MCPA 0.5 – 2.1L

2,4-D amine

2,4-D ester

2,4-D ester

2,4-DB

2 leaf

12

3 leaf

13

4 leaf

14

5 leaf –early till

15-21

Mid till

25

Late till

29

Full till-Jointing

30

Booting

40

Using the Growth Stage of Cereal Crops to Time Herbicide Applications

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Cereal crops are sensitive to phenoxy herbicide application atseveral growth stages throughout the season. The sensitivetimings usually coincide with periods of high growth orreproductive activity. Research has shown that applyingphenoxys in the incorrect application window or at an incorrectrate can result in yield losses of up to 30%.

The level of damage from incorrect application depends onseveral of the following factors:

Crop VarietyThere are variations amongst cereals with oats often displayingthe greatest sensitivity to many phenoxy herbicides.

Different varieties demonstrate different sensitivities – and oftendouble ridge at different timings.

Herbicide Type and Formulation• 2,4-D is often more damaging than MCPA • Ester formulations are often more damaging than amine

formulations• Higher rates usually result in more damage than lower rates• The addition of oils and wetting agents can aggravate the

effect of the herbicide

Variations in Crop DevelopmentCrops that experience uneven emergence or establishmentoften have variations in crop development at the time ofspraying.

Crop Development StageIt is critical to correctly identify stages of crop development toavoid damaging the crop with phenoxy herbicides.

Research has demonstrated that cereals are most sensitive atthe following growth stages:

a) The double ridge stage, which usually occurs between 4 and 5 leaf on the main stem in cereals (Z14-15). This iswhen the cereal plant changes from leaf production to earinitiation. Damage at this growth stage is affected byapplication rate and varietal characteristics.

b) Early boot (Z41-43) when the flag leaf sheaf is extending and swelling of the grain head can be seen in thestem.

c) Flowering / Anthesis (Z61-69)

The time taken for a crop to change from being safe to applyherbicides to being unsafe can be as little as 6 days.

Visual effects from each of these application timings can varywith the double ridge timing often appearing as distorted ortwisted heads later in the season when the grain heads emerge.This is normally accompanied by some missing grains in thehead. Early boot and flowering applications usually expresssymptoms as empty heads and missing grains with distortionbeing uncommon.

2,4-D Ester 0.75L/ha at Z14Carnamah

Untreated Carnamah head

Damage to Cereal Crops from Incorrect Phenoxy Herbicide Application


1 0

Situations may arise, due to late establishing weeds combinedwith wet and prolonged spring or harvest periods, wheresalvage spraying or pre-harvest desiccation may be necessaryto assist timely harvesting of winter crops.

Weeds such as skeleton weed, sowthistle, prickly lettuce, fathen and New Zealand spinach can interfere with harvesting.Weed seeds such as saffron thistle, rough poppy, Mexican

poppy, wild radish and black bindweed can contaminategrain.

Amicide® 625 and Roundup PowerMAXTM1 have a role insalvage spraying and pre-harvest desiccation of winter crops.The following table summarises the use patterns for Amicide®

625 and Roundup PowerMAXTM1.

Herbicide Product

Chemical

Registered

Crop

Rate

Crop safety

Harvest Withholding period

Application

Amicide® 625

2,4-D Amine 625g/L

Registered (All states)

Winter Cereals

1.2 – 1.7L/ha

Apply after late dough stage in wheat

Nil when used as directed

Ground / Aerial

Estercide® 800

800g/L

All states exceptTasmania

Winter Cereals

1.4L/ha

Apply after dough stage of crop

7 days

Ground / Aerial

RoundupPowerMAXTM1

Glyphosate 540g/L

Registered (All states)

Wheat

0.905 – 1.8L/ha

Apply after late dough stage in wheat

7 days

Ground / Aerial

Wild Radish (Raphanusraphanistrum)

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Salvage Spraying of Winter Crops

* For crops other than wheat refer to the product labels.

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Cereal Tolerance GuideTolerance of Barley Varieties to Post-Emergent HerbicidesVariety Bromoxynil Bromoxynil Bromoxynil MCPA + MCPA MCPA MCPA + 2,4-D

+ MCPA + MCPA + dicamba LVE Diflufenican aminedicamba

Bromicide® Bromicide® MA BroadsideTM Kamba® M MCPA 500 LVE MCPA Nugrex Amicide® 625200 (b) (b)

Product/ha 2.1L 2.1L 1.4L 1.4–1.7L 0.7L 1.2L 0.5L 1.0L 0.75L 1L 1.7L

Arapiles – – – – – – – – –

Barque S – – W S – – – – – S

Binalong W – – w – S – N W – S

Franklin S N – S S W S – – W S

Gairdiner W – – S S* N – S W – W

Grimmett N W W 0–15 N N N W – S –

Lindwall S – – – S S Q S – – S S

Mackay Q S – – S* S* W – – S* – W

Namoi – – – S – S – – – – S

Schooner W 0–15 N 0–15 S S W N S S W

Skiff S S – N N S N W – W S

Sloop W – – W S W S N W S W

Tantangara N – S N* S* W – – N S W

Tilga – – – – S S S S – S S

Yambla S – – S – – N S – – –

Wyalong N – – S S N – S – – S

Growth stage 3–4 leaf 5 leaf 3 leaf 5 leaf 5 leaf 5 leaf 3 leaf 5 leaf 5 leaf 3-4 leaf 5 leaf

Note: 1. Figures are the range of percentage yield reductions measured. 2. The occurrence of cold, wet seasonal conditions at or just after spraying a herbicide can result in significantyield loss in sensitive varieties.b = Not recommended, crop stage too early.– = Not tested.* = Tested one year only.W = Warning, damage possible – damage recorded only once at the recommended rate.Q = QDPI Data.N = Narrow safety margin – damage recorded at twice the recommended rate.S = Safe.



1 2

Tolerance of Wheat Varieties to Post-Emergent HerbicidesVariety Bromoxynil MCPA MCPA + LVE MCPA

+ MCPA + Dicamba Diflufenican

Bromicide® MA Kamba® M Nugrex LVE MCPA(a)

Product/ha 2.1L 1.7L 1.7L 0.5L 1.0L 1.2L Annuello* – – S – S –Babbler – – N – – –Bowerbird – – N – S –Bowie – – S – N –Braewood – – W – S –Chara – – S – S –Cunningham – – – S – WCurrawong S* – S* S S SDiamondbird – S N – S – Drysdale – S – – S* – EGA Bellaroi Q* – – – – – SEGA Hume Q* S – – – – SEGA Wedgetail – N – – – –Giles – – N – S –Goldmark – N N S S –H45 – – W – S –H Apollo S – S S S –H Mercury – – N S N –Janz S – S* N N NKamilaroi N S N – S –Kennedy Q* – – – – – SLang Q* – – – – – SLorikeet – – W – S –Pardalote – – S – S –Petrel – – S – S –Petrie Q – – – – – – QALBis Q* – – – – – S Rosella S W S S N S Snipe – – N – – – Strzelecki Q S* – – – – NSunbri – – – N – NSunbrook – – S S S – Sunco N – W S N NSunsoft 98 – – 0–15 – S –Sunstate S – – – – S Sunvale – – S S – – Thornbill – – S – W – Whistler – – S – S –Wollaroi S – S S S S Wylah – – W – S* – Yallaroi N – N S N SCrop stage at 5 leaf 3–4 leaf 5 leaf 3 leaf 5 leaf 5 leafapplication

Bromoxynil Picloram 2,4-D+ MCPA amine

Bromicide® Trooper® Amicide® 6252002.1L 1.0L 1.0L 0.2L 2.1LS – – – SW – S* – W*– – – – – S – S – W S – S – SS* – W* – S*S S – N NS – – S SS – W* – W*S – S – W– S – S SS – S – – S – S – W0–10 – W* – W*S – – – S S N – – – S N – S –S – – S –N – S* N N– N N S –S – S – SS – S – SS – – – SS – – – SS – – – –S S – – S– – S – –S N N N N– – – – –S – S – SS – – N N– – – – –– – N – –S – – – WW – – S NS – – – –S – – – S– – – – – S – – N SS – – – SS – N 0–10 N3 leaf 3 leaf 5 leaf 3 leaf 5 leaf

Note: 1. Figures are the range of percentage yield reductions measured. 2. The occurrence of cold, wet seasonal conditions at or just after spraying a herbicide can result insignificant yield reduction in sensitive varieties.a = Not recommended: crop stage too early. S = Safe.– = Not tested. Q = QDPI Data.W = Warning, damage possible – damage recorded only once at recommended rate. * = Tested one year only.N = Narrow safety margin – damage recorded at twice recommended rate. ** = +0.5% Uptake oil.



Tolerance of Oat Varieties to Post-Emergent HerbicidesVariety MCPA + Bromoxynil MCPA + 2,4-D Bromoxynil MCPA Metosulam +

Dicamba Diflufenican amine MCPA LVE MCPA LVE

Kamba® Bromicide® Nugrex Amicide® 625 Bromicide® LVE Eclipse®4M 200 MA MCPA MCPA LVE

Product/ha 1.7L 2.0L 1.0L 1.0L 2.0L 1.6L 5g + 0.5LBarcoo – S – 0–40 – – –Bimbil N W S – – – –Carrolup N 0–10 0–10 – – – –Cooba N W N – – – –Coolabah S W N – – – –Echidna 0–50 W W W W S SEurabbie W S S 0–55 S S SEuro N W N – – – –Gwydir S* N 0–20 0–20 – – –Mortlock N 0–10 N – – – –Possum* W W S S – – –Quall W* S N W – – –Taipan S W W W – – –Warrego* S S S W – – –Yarran 0–25 W W W W S SYiddah* N W S N – – –Crop stage at 5 leaf 3 leaf 3 leaf fully tillered 5 leaf 5 leaf 3-4 leaf application

N = Narrow safety margin – damage recorded at twice recommended rate. – = Not tested.S = Safe. * = Tested in 1 year only.W = Warning, damage possible – damage recorded only once at recommended rate.Figures are the range of percentage yield reduction measured.

Tolerance of Triticale and Ceral Rye Varieties to Post-Emergent HerbicidesVariety MCPA + MCPA + 2,4-D

Dicamba Diflufenican amine

Kamba® Nugrex® Amicide® 625M

Product/ha 1.7L 3.0L 1.0LAbacus W 0–15 SCredit S* 0–10 WEleanor 0–9 S SEverest S 0–10 SHillary W S WJackie W W WKosciuszko* S S SMaiden S – –Muir N S –Prime 322 S* S SRyesun S N –Tahara S S –Tickit* W W WTreat* W W WCrop stage at 5L 3L 5Lapplication

Tolerance of Field Pea Varieties to HerbicidesIn addition to the herbicides in the table below, most field pea varietieshave been tested for tolerance to the post-emergent grass herbicidesindicating that Aramo®1, Correct®3, Fusilade®2, Fusion®2,Targa®5, Select®6, Sertin®3 and Verdict®4 are safe.

Variety MCPA

MCPA 500

Product/ha 0.7LAlma NGlenroy –Dundale NExcel –Kaspa –Morgan –Mukta –Parafield –Snowpeak –

N = Narrow safety margin – damage recorded at twice recommended rate.S = Safe.W = Warning, damage possible – damage recorded only once at recommended rate.– = Not tested.* = Tested in 1 year only.Figures are the range of percentage yield reduction measured.

S = Safe.W = Warning, damage possible – damage recorded only

once at recommended rate.N = Narrow safety margin – damage recorded

at twice recommended rate.– = Not tested.



1 4

Nufarm Estercide® 800/Nufarm LV Estercide® 600

Estercide® 800

LV Estercide® 600

Balansa CloverBarley %Chickpeas #CottonFaba BeansField PeasLentilsLinseedLucerneLupins +MedicsNarbon BeansNavybeanOatsPerennial RyegrassPersian CloverPhalarisCanola / Rapeseed #RiceSafflower #Sorghum @SoybeanSub-CloverSunflower @TriticaleVetchWheat %White Clover

Up to440mL/ha

Up to580mL/ha

71710777777771037771477314771717

440mL –860mL/ha

580mL –1.15L/ha

7114147147771477103777217147147103737

860mL –1.31L/ha

1.15L –1.8L/ha

1032121101410141021101014710101028142110211014710710

Important: When applied to dry soils at least 15mm (1/2 inch) ofrain must fall prior to the commencement of the plant back period.

Notes:

% In Queensland, no rainfall is required to fall prior tocommencement of Plant Back Period for wheat, barley andtriticale.

# In Queensland, planting canola/rapeseed, chickpeas andsafflower must be delayed for at least 14 days followingrainfall of at least 15mm.

@ In Central Queensland, when using 830mL/ha or less of LVEstercide® 600, or 625mL/ha or less of Estercide® 800, the PlantBack Period for sorghum and sunflower is 1 day irrespective ofrainfall.

+ In WA the Plant Back Period for lupins at all rates is 28 days.

Important: When applied to dry soils at least 15mm (1/2 inch)of rain must fall prior to the commencement of the plant backperiod.

Notes:


# In Queensland, planting canola/rapeseed, chickpeas andsafflower must be delayed for at least 14 days following rainfallof at least 15mm.

@ In Central Queensland, when using 800mL/ha or less ofAmicide® 625, the Plant Back Period for sorghum and sunfloweris 1 day irrespective of rainfall.


Plant Back Periods (Days)

Nufarm Amicide® 625

Crop

Balansa CloverBarley %Chickpeas #CottonFaba BeansField PeasLentilsLinseedLucerneLupins +MedicsNarbon BeansNavybeanOatsPerennial RyegrassPersian CloverPhalarisCanola / Rapeseed #RiceSafflower #Sorghum @SoybeanSub-CloverSunflower @TriticaleVetchWheat %White Clover

Rates

Up to560mL/ha

71710777777771037771477314771717

560mL –1.1L/ha

7114147147771477103777217147147103737

1.1L –1.7L/ha

1032121101410141021101014710101028142110211014710710

Plant Back Periods for Fallow Seed Bed Preparation


Nufarm Surpass® 300

Crop

Balansa CloverBarley %Chickpeas #CottonFaba BeansField PeasLentilsLinseedLucerneLupins +MedicsNarbon BeansNavybeanOatsPerennial RyegrassPersian CloverPhalarisCanola / Rapeseed #RiceSafflower #Sorghum @SoybeanSub-CloverSunflower @Triticale %VetchWheat %White Clover

Rates

Up to 1.1L/ha

71710777777771037771477314771717

1.1L – 2.3L/ha

7114147147771477103777217147147103737

2.3L – 3.4L/ha

1032121101410141021101014710101028142110211014710710

Important: When applied to dry soils at least 15mm (1/2inch) of rain must fall prior to the commencement of the plantback period.

Notes:


# In Queensland, planting canola/rapeseed, chickpeas andsafflower must be delayed for at least 14 days followingrainfall of at least 15mm.

@ In Central Queensland, when using 1.6L/ha or less ofSurpass® 300, the Plant Back Period for sorghum and sunfloweris 1 day irrespective of rainfall.


Above: Wild Turnip (Brassica tournefortii)

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1 6

Nufarm Amicide® 625Pasture, Cereal Crops – Do not graze or cut for stock food for7 days after application.

Harvest Withholding Period: Not required when used asdirected.

In Tasmania, this product may only be used from 15 April to 15 September unless otherwise permitted by the Registrar ofPesticides.

Nufarm Buttress®

Do not graze or cut for stock food for 7 days after application.

Nufarm Estercide® 800 Nufarm LV Estercide® 600Pasture, Cereal Crops - Do not graze or cut for stock food for7 days after application.

Nufarm LVE MCPAPasture, Cereal Crops – Do not graze or cut for stock food for7 days after application.

Nufarm MCPA 500Cereals, Pasture - Do not graze or cut for stock food for 7 daysafter application.

Harvest Withholding Period not required when used as directed.

Nufarm Surpass® 300Pasture, Cereal Crops – Do not graze or cut for stock food for7 days after application.

Crop Harvest: Not required when used as directed.

In Tasmania, this product may only be used from 15 April to 15 September unless otherwise permitted by the Registrar ofPesticides.

The decision to spray graze depends on the composition of thepasture and the target weeds present. To warrant spray grazingthere should be at least 150 legume plants per m2 and greaterthan 30% broadleaf weeds.

The technique involves spraying low rates of Amicide® 625 orMCPA 500 onto the pasture. This is followed with a programof heavy grazing, at least five times the normal stocking rate.In normal seasons actively growing weeds are sprayed fromabout 6 weeks after the autumn break.

The effect from the herbicide over-stimulates weed growth. As aresult starch in the weeds rapidly converts to sugar, making theweeds more palatable to grazing stock.

MCPA 500 is often softer on pasture legume species thanAmicide® 625 and clovers are more tolerant than medics tothese herbicides.

Nufarm produces a separate pasture tolerance guide publication.

Spray Grazing

Withholding Periods

Reducing Off-Target Herbicide DriftIn areas where a range of agricultural enterprises co-exist,conflicts can arise, particularly from the use of pesticides. Amajor problem that can occur is damage to susceptible cropscaused by “off-target” herbicide drift. All herbicides arecapable of drift if applied in the wrong manner or wrongconditions, regardless of the active ingredient or theformulation type.

Herbicide users have a moral and legal responsibility toprevent herbicides from drifting and contaminating ordamaging neighbours’ crops. Sensitive crops may be up to10,000 times more sensitive than the crop being sprayed. Evensmall quantities of drifting herbicide can cause severe damageto highly sensitive plants.

How Many Types of Drift are There?Herbicides can drift as droplets (spray), as vapours or asparticles. Spray drift is the most common form of off-target effect.Vapour and particle drift are different to spray (droplet) drift.

Spray Drift (Droplet) – is the easiest to control becauseunder good spraying conditions, droplets are carried down byair turbulence and gravity, to collect on plant surfaces. Undernil wind conditions and very windy conditions, droplets,especially fine droplets, can be carried off-target. This canoccur regardless of the herbicide used. Spray drift is the majoroffender for off-target effects.

How to Minimise Spray Drift• Before applying any herbicide, always check for susceptiblecrops in the area

• Notify neighbours of your spraying intentions


• Always monitor meteorological conditions carefully and understand their effect on “drift hazard”

• Record weather conditions, wind direction, herbicide and water rates and operating details for each paddock

• Supervise all spraying even when a contractor is employed

• Spray when temperatures are less than 28oC

• Don’t spray if conditions are not suitable (use delta T)

• Maintain a down-wind buffer

• Minimise spray release height

• Use large droplets, where appropriate, to give adequate spray coverage

• If in doubt – then don’t spray

Vapor drift – arises directly from the spray or evaporation ofherbicide from sprayed surfaces. Changing to a less volatile ornon-volatile formulation reduces this risk.

Particle drift – occurs when water and other herbicidecarriers evaporate quickly from the droplet leaving tinyparticles of concentrated herbicide. This can occur to manytypes of pesticides. Vapours and minute particles float in the airstream and are poorly collected on catching surfaces. Theymay be carried for many kilometres in thermal up-draft beforebeing deposited.

What Factors Affect the Risk of Off-TargetDrift? The drift hazard, or off-target potential of a herbicide in aparticular situation, depends on the following factors:

• Proximity of susceptible crops to the particular herbicide being applied, and their growth stage. For example cotton and canola are more sensitive to phenoxy herbicides at the seedling 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.

Important Considerations for Avoiding Off-Target DriftReducing Spray Release Height

1. Operate the boom at the minimum practical height. Spraydrift hazard doubles as nozzle height doubles. Angling nozzlesforward can allow lower boom height with double overlap.Lower boom height can, however, lead to striping if the boom

is not stable and sways and dips below the optimum height.

2. Fit nozzles that don’t produce a fine droplet spectrum.Nozzles that produce larger droplets such as SprayingSystems, TurboTeeJet®8, DriftGuard or Air Induction nozzles (orsimilar from other manufacturers) are less prone to off-targetmovement and are still very satisfactory for optimum herbicidalperformance from the phenoxys.

3. 110o nozzles produce a higher percentage of fine dropletsthan 80o nozzles, however, they allow a lower boom heightwhile maintaining the required double overlap.

4. Operate within the nozzle pressure range recommended by thenozzle manufacturer. Lower volumes such as 30-40L/ha producea higher percentage of fine droplets than higher spray volumesapplied at the same pressure and from the same nozzle.

5. While not always the case, aircraft application generallyhas an inherently greater risk of spray drift than ground rigapplication. This is due to a number of factors including lowerapplication volume, small droplet sizes, height of application,and turning and wing tip vortices. An aircraft should not beused to apply herbicides in areas where highly susceptiblecrops are growing.

Use a Low-volatile FormulationEster-based formulations are recognised as the most volatilephenoxy formulations – changing to a non-volatile amine or saltformulation reduces risk. Even changing from an ethyl-ester toan iso-octyl ester can reduce volatility by 98.5%.

Size of Area TreatedWhen large areas are treated relatively large amounts of activeherbicide are usually applied and the risk of off-target effectsincrease due to the length of time taken to apply the herbicide.Conditions such as temperature, relative humidity and winddirection can change during spraying.

Capture SurfaceTargets vary in their ability to collect or capture spray droplets.Well-grown, leafy crops are efficient collectors of droplets.Turbulent airflow normally carries spray droplets down into thecrop within a very short distance.

Fallow paddock or seedling crops are generally poor catchingsurfaces. Drift hazard is far greater when applying herbicide inthese situations or adjacent to these poor catching surfaces.

The type of catching surface between the sprayed area and susceptible crops should always be considered in conjunction with the characteristics of the target area when assessing drift hazard.

Weather Conditions to Watch Out for:Inversions • The most hazardous condition for herbicide spray drift is an

atmospheric inversion, especially when combined with highhumidity.

• Do not spray under inversion conditions.

• An inversion exists when temperature increases with altitudeinstead of decreasing. An inversion is like a cold blanket ofair above the ground, usually less than 50m thick. Air willnot rise above this blanket, and smoke or fine spray dropletsand particles deposited within an inversion will float until theinversion breaks down.

• Inversions usually occur on clear, calm mornings and nights.Windy or turbulent conditions prevent inversion formation.Blankets of fog, dust or smoke and the tendency for soundsand smells to carry long distances indicate inversionconditions.

• Smoke generators or smokey fires can be used to detectinversion conditions. Smoke will not continue to rise but willdrift along at a constant height under the inversion ‘blanket’.

Midday Turbulence• Up-drafts during the heat of the day cause rapidly shifting

wind directions. Avoid spraying during this part of the day.

High Temperatures• Avoid spraying when temperatures exceed 28°C.

Humidity• Avoid spraying under low relative humidity conditions (less

than 35%) i.e. when the difference between wet and drybulbs (delta T) exceeds 8°C.

• High humidity extends droplet life and can greatly increasethe drift hazard under inversion conditions. This results inincreased life for droplets smaller than 100 microns.

Wind• Avoid spraying under still conditions.

• Ideal safe wind speed is 3–10 km per hour (kph). Leaves andtwigs are in constant motion.

• 11–14 kph (moderate breeze) is suitable for spraying ifusing low drift nozzles and/or higher volume application(80–120L/ha). Small branches move, dust is raised andloose paper is moving.

Relative Humidity or Delta T.The differential between a wet and dry bulb thermometerreading is known as “delta T”. Relative humidity is a measureof the amount of moisture in the air expressed as a percentage.Relative humidity and dry bulb temperature are used tocalculate delta T.

As temperature increases delta T becomes critical in predictingweed stress. Low relative humidity coupled with hightemperatures cause many common fallow weeds to “shutdown”. All plants have a self-preservation mechanism whichoften involves wilting and closing of the stomata causingnormal functioning in the plant to go into “hibernation”.

Intensive trial work indicates that a delta T value of 8°C or belowis preferable and if the delta T value is greater than 10°C weedcontrol will be reduced. Relative humidity and temperature can bemeasured with a device such as the Kestrel®73000 weather meter.

Consult the chart below to determine the best delta T conditionsto spray.

*It is important to note that ‘off-target drift’, regardless of thetype of drift, can be totally avoided through sound applicationdecisions and management.


18

X

X

X

X

X

XX

X

X

X


Nozzle SelectionSelecting the correct spray nozzles, pressure, speed, watervolume and spray release height are key factors impacting onproduct performance. Changing to nozzles that produce amedium to coarse spray quality is one way to minimise off-target spray loss.

An independent trial conducted in a wind tunnel by the Centrefor Pesticide Application demonstrated the difference in sprayquality that can be achieved by changing the nozzle setup ona spray boom when using phenoxy herbicides. Surpass® 300was applied through XR Teejet®811002, Turbo Teejet®811002and Agrotop Airmix®11110-02 nozzles at the same pressure(200kPa) and water volume (50L/ha). Measurement of thevolume mean diameter (VMD), which is the figure in micronswhere half the spray droplets (by volume) produced by thenozzle are smaller than this size and half are

larger, and the percentage of droplets less than 200 microns(droplets most susceptible to drift) was also conducted.

The data indicate that a shift in spray quality from fine to coarsewas obtained. The VMD varied from 213µm for the XR Teejet®8

nozzle (XR) to 333µm and 353µm for the TurboTeejet®8 (TT) andAirmix®11 nozzles (AM) respectively. The driftable componentwas reduced from 44% for the XR to 18% (TT) and 11% (AM).Although there has been a reduction in the driftable componentby changing nozzles, other parameters, such as release height,speed, pressure, water volume and meteorological conditionsneed to be considered when making a decision to spray. Driftreduction nozzles are available, including pre-orifice and airinduction nozzles, from local suppliers.

Nozzle Selection Guide for Ground Application

Risk

Distance downwind to susceptible crop

Droplet size (BCPC & ASAE)

Recommended nozzles (Examples only)

CAUTION

High

30 km

fine

ConventionalXR Teejet®8

Hardi®9S3110Hardi®9S4110Hardi®9150 F seriesLurmark Fan Tip®

High proportion of ‘driftable’droplets. Temperature andhumidity critical.

300®

µmµm

(µm

)

Nufarm


2 0


Know Your Herbicide Groups

High Risk

Moderate Risk

Low Risk

Group A

Group B

Group C

Group D

Group E

Group F

Group G

Group H

Group I

Group J

Group K

Group L

Group M

Group N

Inhibitors of fat (lipid) synthesis - ACC'ase inhibitors

Inhibitors of the enzyme acetolactate synthase - ALS inhibitors

Inhibitors of photosynthesis at photosystem II

Inhibitors of tubulin formation

Inhibitors of mitosis

Inhibitors of cartenoid biosynthesis

Inhibitors of protophyrinogen oxidase

Inhibitors of protein synthesis

Disruptors of plant cell growth (Phenoxy herbicides)

tba

Herbicides with multiple sites of action

Inhibitors of photosynthesis at photosystem 1

Inhibitors of EPSP synthase

Inhibitors of glutamine synthetase

Herbicide resistance is the inherent ability of a weed to survivea herbicide rate that would normally control it. This is not thesame phenomena as poor herbicide performance.

Why it is a Problem?If herbicide resistance develops, other herbicides or differentcontrol methods will have to be used to control a weed. Theseoptions may be more expensive or less effective. Oncedeveloped, herbicide resistance will persist for many years.

Understanding HerbicidesHerbicides act by interfering with specific processes in plants.This is known as the herbicide’s ‘mode of action’.

Watch your Paddocks• Keep accurate records.

• Monitor weed populations and record results of herbicides used.

• If a herbicide does not work, find out why.

• Check that weed survival is not due to spraying error.

• Conduct your own paddock tests to confirm herbicide failureand what herbicides are still effective.

• As soon as herbicide resistance is detected, prevent seed set.

• Have a herbicide resistance test carried out on seed fromsuspected plants testing for resistance to other chemicalgroups.

• Do not introduce or spread resistant weeds in contaminatedgrain or hay.

Aim to:• Reduce weed numbers by preventing seed set.

• Enter a cropping phase with low weed numbers.

• Use as many different control options (chemical and non-chemical) as possible in both crop and pasture phases.

When Using Herbicides:• Rotate herbicides from different groups.

• Reduce reliance on high-risk herbicides (Groups A and B)

• Make every herbicide application count – use the rate thatgives effective control.

Phenoxy Resistance ManagementFor weed resistance management phenoxys are Group Iherbicides. Some naturally occurring weed biotypes may beresistant to Group I herbicides through normal geneticvariability in any weed population.

Resistant individuals can eventually dominate a population ifthe same group of herbicide is used repeatedly.

These resistant weeds will not be controlled by Group Iherbicides.

Herbicide Resistance Management

Notes

2 1


2 2

For more information contact your Nufarm Regional Office:Northern Region QLD/NSW (07) 3893 8777. Southern Region VIC 1800 033 038 SA (08) 8444 6300.Western Region WA (08) 9411 4000.

®: Registered Trademark of Nufarm Australia Ltd. TM: Trademark of Nufarm Australia Ltd.TM1: Roundup PowerMAX is a registered trademark of Monsanto technologies LLC used under

licence by Nufarm Australia Ltd.

®1: Registered Trademark of BASF Ltd. used under licence by Nufarm Australia Ltd®2: Registered Trademark of Syngenta Ltd.®3: Registered Trademark of Bayer Ltd.®4: Registered Trademark of Dow AgroSciences Ltd.®5: Registered Trademark of Nissan Chemical Industries Ltd.®6: Registered Trademark of Arysta LifeScience Corp®7: Registered Trademark of Nielsen Kellerman Australia Pty Ltd.®8: Registered Trademark of Spraying Systems Company Ltd.®9: Registered Trademark of Hardi International Ltd.®10: Registered Trademark of Lurmark Ltd.®11: Registered Trademark of Agrotop Ltd.

This publication is a guide only and no substitute for professional or expert advice. The product label should be consulted before use of any of the products referred to in this publication. Nufarm Australia Ltd shall not be liable for any results, loss, or damage whatsoever, whether consequential or otherwise, through the use or application of products and/or materials referred to herein.

© Copyright 2005. Nufarm Australia Ltd A.C.N. 004 377 780

Phenoxy Reference Guide - Pest Genie · 2005. 4. 14. · Damage to Cereal Crops from Incorrect Phenoxy Herbicide Applications 9 Salvage Spraying of Winter Crops 10 Cereal Tolerance

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