Chemistry Update Trevor Wicks WEB

8/3/2019 Chemistry Update Trevor Wicks WEB

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Fungicide control

Dr Trevor WicksSouth Australian Research & Development Institute

Waite Research Precinct, Adelaide



Control failures

• Why didn’t fungicides provide control

this season?



Control failures

• Fungicide type

• Low dosage

• Poor spray coverage

• Rain fastness

• Spray timing

• Fungicide resistance



Downy mildew disease

control evaluation 2010-11Number of replies Perceived fail

Agri-Fos 55 2

Ridomil 196 14

Acrobat 5 2

Amistar 9 0

Galben M 9 1

Chlorothalonil 28 4

Polyram 25 2

Rebound 5 0

Zineb 2 0

Flint 56 7

Cabrio 113 8Captan 137 24

Copper 218 40

Copper hydroxide 42 6

Copper sulphate tribasic 17 3

Delan 37 2

Mancozeb 111 23



November 2010

January 2011 April 2011

Downy mildew

Lenswood Research Centre

2010-11



Downy mildew Lenswood Research centre 2010-11



Downy

mildew



Powdery mildew curative

control 2010-11Number of replies Perceived fail

Filan 14 0

Amistar 3 0

Nustar 1 0

Prosper 48 2

Flint 39 2

Cabrio 70 5

Folicur 4 1

Topas 49 4

Domark 5 1

Legend 31 2

Rubigan 24 14

Mycloss 39 16

Bayfidan 27 11

Sulphur 130 14

Ecocarb 40 30



Powdery Mildew

Loxton 2011



Powdery mildew Loxton 15 Dec 2010



Sprayed vs Unsprayed – Loxton 2011



Botrytis bunch rot fungicides 2010-11

Number of replies Perceived fail

Filan 10 2

Amistar 4 1

Bravo 11 2

Teldor 17 4

Scala 29 7

Switch 36 8

Captan 48 18

Eco Protector (fatty acid) 2 1

Peratec (hydrogen peroxide +peroxyacetic acid)

26 12

Rovral 70 24



Botrytis bunch rot Coonawarra

April 2011



Control failures

• Fungicide type

• Low dosage• Poor spray coverage

• Rain fastness – Tenacity• Spray timing

• Fungicide resistance



Fungicide types

• Disease diagnosis

• Few fungicides control both downy and powdery mildew

– exceptions – strobilurins

– copper fungicides inhibit powdery

– Unknowns – Ecocarb/Oil on downy mildew– Peratec on mildews

– Others

• Compatibility - ?



Efficacy of common viticultural fungicides

Fungicide Powdery mildew Downy mildew Botrytis Phomopsis

Strobilurins Cabrio + + + + + + + + + - - - + + + -

Flint + + + + + + - - + - - - + ?

DMls Bayfidan, Mycloss + + + + - - - - - - - - ?

Others Acrobat - - - - + + + + - - - - - - - -

Agriphos - - - - + + + + - - - - - - - -

Bravo - - - - + + + - + + - - + + + -

Captan - - - - + + + - + + - - + + + -

Coppers + - - - + + + - - - - - + - - -

Delan - - - - + + + - - - - - + + + -

Dithane - - - - + + + - - - - - + + + -

Filan + + + + - - - - + + + + ?

Legend + + + + - - - - - - - - - - - -

Peratec ? ? + + - - - - - -

Polyram - - - - + + + ? + + - - + + + -

Prosper + + + + - - - - - - - - - - - -Rovral - - - - - - - - + + + + - - - -

Ridomil - - - - + + + + - - - - - - - -

Teldor - - - - - - - - + + + + - - - -

Scala - - - - - - - - + + + + - - - -

Shirlan - - - - + + + ? + - - - + + + -Sulphur + + + + - - - - - - - - - - - -

Switch - - - - - - - - + + + + - - - -



Dosage

• Rate/100L

• Concentration factors - ?

• Spray volume - ?

• Large canopies – underdosing



Rain fastness (Tenacity)

Influencing factors:

• Fungicide type - DMIs & Strobilurins rainfast

within 1 hour of application

• Formulation

• Deposit – droplet size

• Drying time

• Stickers/wetters

• Target surface – fixing in waxy cuticle• Rain intensity

• Rain duration



Impact of precipitation on the

performance of fungicides in grapes

Annemiek C. Schilder, Associate Professor, Department of Plant Pathology

Michigan State University, East Lansing, MI 48824



Spray coverage

• Important with protectant fungicides

e.g. sulphur ,coppers, mancozeb etc

• Less important with DMIs

e.g. myclobutanil (Mycloss) or tebuconazole (Folicur)

• Strobilurins also diffuse into grape tissue

• Rapid growth – dilution of chemical

– excessive foliage

– shingling



Spray timing

• Wet

• Windy

• Flooding

• Mechanical breakdown

• Chemical availability

• Contractor over committed

•Tractor bogged



1 Nil Nil Nil Nil 81

2 Exp Exp Exp Exp 65

3 Exp Cabrio Exp Sulphur 1 10 days before rain

4 Prosper Exp Cabrio Sulphur 67 3 days after rain

5 Prosper Cabrio Cabrio Sulphur 1

% leaves with downy mildewSpray Programs

T r e a t m e n t s

Block L Lenswood 2010/11



Spray timing

• Protectants – apply before rain

– regular sprays often ineffective if

applied after rain• Spray intervals – shorten with rapid growth or

excessive rain

• Eradicant sprays – most effective when applied beforesymptoms appear

•Systemic activity – phosohonates – only true systemic

fungicides•Established disease – powdery mildew difficult to wet

– downy mildew, reduced sporulation



Fungicide resistance

• Not widespread in Australian vineyards

• Downy mildew

– resistance to Metalaxyl (Ridomil)• Powdery mildew

– resistance to DMIs (Bayfidan, Topas)

– resistance to strobilurins (Amistar, Cabrio, Flint?)

• Botrytis

– resistance to Iprodione (Rovral)

Pyrimethanil (Scala)

Chemistry Update Trevor Wicks WEB

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