Bunch Rot Disease Management

Your headlineLarry Bettigahere in Calibri. Advisor Monterey, Santa Cruz and San Benito Counties Simple text is best. Don’t read from your slides. Grapevine Disease Control

• Pathogen biology • Environmental factors • Vine susceptibility factors • Understanding how to optimize control tools Which Rot?

Botrytis rot Summer/Sour Rot • Most common in • More common in hotter coastal production areas of CA • cinerea • 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  Vine factors ✓ Varietal susceptibility ✓ Cluster architecture ✓ Berry maturation ✓ Bunch crowding ✓ density ✓ Berry wounds  Environmental ✓ Weather (and time interval) between and ✓ 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, , and damage  – 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, , 1989

Ratings 4 and 8 days following rain (Emmett et al. 1994) Resistance Botrytis Fungicides for Hydroxyanilides Phthalamides Anilinopyrimidines

Vangard Elevate Captan Scala (17) (M4) (9)

Combination Carbamates Dicarboximides Switch (9,12) Inspire Super (3, 9) Rovral Dithane Luna Experience (3, 7) (2) (M3) Luna Tranquility (7,9) Pristine (7, 11)

Benzimidazoles SDHI Biological

Boscalid Serenade Topsin Fluopyram Sonata (1) (44) (7) 2011 Botrytis Evaluation - Incidence Severity Treatment Timing % Rotten % Rotten Clusters 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 B 24 bcd 1.5 bc Serenade Max 2 lb PC, V 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 % Rotten Clusters 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 B, V 27 de 4.2 de Vangard 10 oz PC 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 B, V 27 efg 2.3 h Serenade Optimum 1 lb PC 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 B, V 66 b 10.5 b Elevate 1 lb PC Regalia 2 qt B, PC, V 65 b 10.8 b Pristine 23 oz B, V 64 b 12.2 b Elevate 1 lb PC Botector B, PC, V 64 b 9.6 b Luna Exp 8fl oz/ Serenade Opt B/ PC/ V 63 b 10.8 b 1 lb/ Luna Tranquility 16 fl oz Switch 14 oz B, V 61 b 8.9 b Taegro Eco 5.2 oz PC 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 B/ V/ PC 9 b 0.61 b 10 oz / Elevate 1 lb Luna Tranquility 12 fl oz B, V 7 bc 0.42 b Serenade Optimum 1 lb PC Vangard 10 oz / Fracture 24.4 B/ V/ PC 5 bc 0.42 b fl oz / Elevate 1 lb 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 B, PV 4 bc 0.40 b Switch 14 oz V 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