Download - Chemistry Update Trevor Wicks WEB
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Fungicide control
Dr Trevor WicksSouth Australian Research & Development Institute
Waite Research Precinct, Adelaide
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Control failures
• Why didn’t fungicides provide control
this season?
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Control failures
• Fungicide type
• Low dosage
• Poor spray coverage
• Rain fastness
• Spray timing
• Fungicide resistance
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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
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November 2010
January 2011 April 2011
Downy mildew
Lenswood Research Centre
2010-11
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Downy mildew Lenswood Research centre 2010-11
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Downy
mildew
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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
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Powdery Mildew
Loxton 2011
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Powdery mildew Loxton 15 Dec 2010
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Sprayed vs Unsprayed – Loxton 2011
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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
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Botrytis bunch rot Coonawarra
April 2011
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Control failures
• Fungicide type
• Low dosage• Poor spray coverage
• Rain fastness – Tenacity• Spray timing
• Fungicide resistance
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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 - ?
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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 - - - - - - - - + + + + - - - -
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Dosage
• Rate/100L
• Concentration factors - ?
• Spray volume - ?
• Large canopies – underdosing
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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
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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
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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
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Spray timing
• Wet
• Windy
• Flooding
• Mechanical breakdown
• Chemical availability
• Contractor over committed
•Tractor bogged
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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
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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
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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)