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Larry Bettiga Viticulture Advisor

Monterey, Santa Cruz and San Benito Counties

Bunch Rot Disease Management

Grapevine Disease Control

• Pathogen biology

• Environmental factors

• Vine susceptibility factors

• Understanding how to optimize control tools

Which Rot? Botrytis rot

• Most common in coastal vineyards

• Botrytis cinerea

Summer/Sour Rot • More common in hotter

production areas of CA • A complex of several

organisms Aspergillus Alternaria Cladosporium

Rhizopus Penicillium

• Becomes sour when yeast and bacteria colonize the rot

Botrytis Bunch Rot Botrytis cinerea

Botrytis Germination and Infection

• Temperature range • 0-30 ºC (32-86 ºF) - can occur • 15-25 ºC (59-77 ºF) - broadly optimal • 18-20 ºC (64-68 ºF) - ideal

• Favored by the presence of free water • Can occur in the absence of water when

RH is above 93% for extended periods • Requires a nutrient source

Botrytis Bunch Rot Cycle

Overwintering Botrytis

Botrytis Spring Infections

Pinot Leaf Curl

Photo: M Longbottom, University of Adelaide

Points of Infection for Botrytis

Factors Critical in Botrytis Severity Pathogen factors

✓ Inoculum as influenced by sources within the vineyard

Vine factors ✓ Varietal susceptibility ✓ Cluster architecture ✓ Berry maturation ✓ Bunch crowding ✓ Canopy density ✓ Berry wounds

Environmental ✓ Weather (and time interval) between veraison and

harvest ✓ Microclimate in the fruit zone ✓ Practices that influence canopy density and berry

compaction

Bunch rot: Botrytis cinerea

Management Canopy management – trellis design; shoot

thinning, leaf removal and hedging Sanitation – removal of sclerotia Nutrient management Irrigation management Manage insect, powdery mildew, and bird

damage Fungicides – apply at the appropriate times

based on seasonal conditions

Optimum timing for leaf removal for Botrytis control

After fruit set is complete – Optimizes the wax development – Reduces sunburn risk – Improves spray coverage

Botrytis Bunch Rot, Chardonnay, 1989

Ratings 4 and 8 days following rain

Percent rotten clusters

Sept 21

Sept 25

Non-positioned

51

85

Positioned

12

71

Positioned-leafed

1

29

(Emmett et al. 1994)

Resistance

Dithane (M3)

Captan (M4)

Boscalid Fluopyram

(7)

Serenade Sonata

(44)

Elevate (17)

Topsin (1)

Phthalamides Hydroxyanilides

Benzimidazoles

Carbamates

Biological SDHI

Botrytis Fungicides for Grape

Rovral (2)

Dicarboximides Switch (9,12)

Inspire Super (3, 9) Luna Experience (3, 7) Luna Tranquility (7,9)

Pristine (7, 11)

Combination

Vangard Scala

(9)

Anilinopyrimidines

2011 Botrytis Evaluation - Riesling Incidence Severity

Treatment Timing % Rotten Clusters

% Rotten berries per

cluster Untreated Control - 56 a 6.1 a

Inspire Super 20 fl oz B, PC, V 34 b 3.5 b

Pristine 23 oz B, PC, V 29 bcd 1.5 bc

Vangard 10 oz B, PC, V 28 bcd 2.0 bc

Switch 14 oz B, PC, V 24 bcd 1.6 bc

Elevate 1 lb Serenade Max 2 lb

B PC, V

24 bcd 1.5 bc

Scala 18 fl oz B, PC, V 21 bcd 1.5 bc

Elevate 1 lb B, PC, V 18 cd 1.4 bc

Luna Experience 8 fl oz B, PC, V 16 d 1.0 c

2012 Botrytis Evaluation - Riesling

Incidence Severity

Treatment Timing % Rotten Clusters

% Rotten berries per

cluster Untreated Control - 58 a 14.4 a Rovral 1 lb + Stylet Oil 1% B, PC, V 60 a 13.3 a Vangard 10 oz B, PC, V 40 bcd 9.8 abc Pristine 23 oz B, PC, V 45 abc 9.2 abcd Inspire Super 20 fl oz B, PC, V 39 bcd 8.1 bcd

Elevate 1 lb B, PC, V 36 bcd 6.9 bcde Luna Experience 8 fl oz B, PC, V 36 bcd 4.2 de Merivon 8 fl oz Vangard 10 oz

B, V PC

27 de 4.2 de

Switch 14 oz B, PC, V 18 e 2.1 e

2013 Botrytis Evaluation - Riesling Incidence Severity

Treatment Timing % Rotten Clusters % Rotten berries per cluster

Untreated Control - 62 a 12.6 a Inspire Super 20 fl oz B, PC, V 45 abcd 7.6 bcd Vangard 10 oz B, PC, V 36 bcdefg 5.2 cdefgh Pristine 23 oz B, PC, V 34 bcdefg 4.9 cdefgh

Switch 14 oz B, PC, V 27 efg 3.3 efgh Luna Experience 8 fl oz B, PC, V 26 fg 3.2 efgh

Elevate 1 lb B, PC, V 24 g 2.9 fgh Luna Tranquility 16 fl oz B, PC, V 25 fg 2.4 gh Luna Tranquility 16 fl oz Serenade Optimum 1 lb

B, V PC

27 efg 2.3 h

2014 Botrytis Evaluation - Riesling Incidence Severity

Treatment Timing % Rotten Clusters % Rotten berries per cluster

Untreated Control - 92 a 20.4 a Taegro Eco 5.2 oz B, PC, V 74 b 12.6 b Serenade Optimum 1 lb B, PC, V 68 b 12.6 b Vangard 10 oz Elevate 1 lb

B, V PC

66 b 10.5 b

Regalia 2 qt B, PC, V 65 b 10.8 b Pristine 23 oz Elevate 1 lb

B, V PC

64 b 12.2 b

Botector B, PC, V 64 b 9.6 b Luna Exp 8fl oz/ Serenade Opt 1 lb/ Luna Tranquility 16 fl oz

B/ PC/ V 63 b 10.8 b

Switch 14 oz Taegro Eco 5.2 oz

B, V PC

61 b 8.9 b

Luna Experience 8 fl oz B, PC, V 58 b 9.0 b

2015 Botrytis Evaluation - Riesling Incidence Severity

Treatment Timing % Rotten Clusters % Rotten berries per cluster

Untreated Control - 16 a 1.30 a Fracture 24.4 fl oz / Vangard 10 oz / Elevate 1 lb

B/ V/ PC 9 b 0.61 b

Luna Tranquility 12 fl oz Serenade Optimum 1 lb

B, V PC

7 bc 0.42 b

Vangard 10 oz / Fracture 24.4 fl oz / Elevate 1 lb

B/ V/ PC 5 bc 0.42 b

Luna Tranquility 12 fl oz B, V, PC 5 bc 0.32 b Luna Experience 8 fl oz B, V, PC 5 bc 0.32 b Luna Tranquility 12 fl oz B, V, PC 4 bc 0.25 b Pristine 23 oz Switch 14 oz

B, PV V

4 bc 0.40 b

Vangard 10 oz B, PC, V 4 bc 0.24 b Luna Tranquility 16 fl oz B, PC, V 3 bc 0.16 b Elevate 1 lb B, PC, V 2 c 0.07 b

Your headline here in Calibri.Grapevine Disease ControlWhich Rot?Slide Number 4Slide Number 5Botrytis Germination and InfectionSlide Number 7Slide Number 8Slide Number 9Pinot Leaf CurlSlide Number 11Slide Number 12Slide Number 13Factors Critical in Botrytis SeveritySlide Number 15Slide Number 16Optimum timing for leaf removal for Botrytis controlBotrytis Bunch Rot, Chardonnay, 1989Slide Number 19ResistanceSlide Number 212011 Botrytis Evaluation - Riesling2012 Botrytis Evaluation - Riesling2013 Botrytis Evaluation - Riesling2014 Botrytis Evaluation - Riesling2015 Botrytis Evaluation - RieslingSlide Number 27