Vinegar, nail polish and fruit flies: Keeping sour rot at bay. Wendy McFadden-Smith Cool Climate Oenology and Viticulture Institute, Brock university

Transcription

1 Vinegar, nail polish and fruit flies: Keeping sour rot at bay Wendy McFadden-Smith Cool Climate Oenology and Viticulture Institute, Brock university

2 Acknowledgements Ontario Grape & Wine Research Inc. Niagara Peninsula Fruit and Vegetable Growers Assoc. Grower cooperators Agrichemical companies Summer students Dr. Cristina Huber Dr. Deb Inglis

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5 So what? Wineries reject grapes when the VA exceeds their acceptance limit of acetic acid ( g/l) High VA indicates microbial contaminants not wanted in the winery Off-flavours in wines from affected grapes $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ Loads rejected in field or at winery Multiple fungicide sprays applied Labour costs of several passes to drop rotted fruit

6 Relationship between Sour Rot Severity and VA Volatile Acidity (g/l) y = x R² = y = x R² = Sour Rot Severity

7 What s causing it?

8 Isolations from rotted berries, 2010 Organic AA Bacteria Hanseniaspora Bacillus Aureobasidium

9 Isolations from rotted berries Pinot noir, AAbacteria Hanseniaspora Candida Pichia Bacillus Aureobasidium

10 Isolations from rotted berries Chardonnay, AAbacteria Hanseniaspora Candida Pichia Bacillus Aureobasidium

11 Isolations from rotted berries Riesling, AAbacteria Hanseniaspora Candida Pichia Bacillus Aureobasidium

12 Isolations from rotted berries, 2015 (with digital droplet PCR) Baco (9) Foch (2) P noir (5) Riesling (6) A. acetii A. malorum G. cerinus G. oxydans H. uvarum C. zemplinina S. ceravisiae

13 Day Day Day 581 Top 4 berries in each section were intact and the bottom 4 berries were wounded.

14 Sour Rot Severity Rating Scale

15 Disease Severity with Wounding 4 Mean Pathogenicity Rating (0-4) Gluconobacter oxydans Gluconobacter cerinus Acetobacter malorum Hanseniaspora uvarum Candida zemplinina Uninoculated

16 Mean Volatile Acidity (g acetic acid/l) Candida zemplinina Hanseniaspora uvarum Acetobacter malorum Gluconobacter oxydans 0

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18 Mean Sour Rot Severity with and without wounding Uninoculated G. oxydans H. uvarum C. zemplinina Wound inoculation Unwounded Pedicel inoculation

19 Infection with and without wounding

20 What Factors Promote Sour Rot?

21 Factors that Promote Sour Rot Tight clusters Thin skins Pinot noir, Pinot gris, Gamay, Chardonnay, Riesling, Gewurztraminer, Baco noir

22 Factors that Promote Sour Rot Grape Berry Moth

23 Factors that Promote Sour Rot Vinegar flies attracted by volatile compounds released during berry degradation

24 Why does it happen? Wasps Damaged berries leak juice and promote infection

25 Factors that Promote Sour Rot Diffuse powdery mildew infections? Slow-growing, sparse, non-sporulating Usually associated with minute patches of dead epidermal cells

26 Protect fruit during peak period of susceptibility, and continue protection until ontogenic resistance is fully expressed 3-4 weeks postbloom. Mildew-free Diffuse infection D. M. Gadoury

27 Factors that Promote Sour Rot It is known clusters infected with bunch rot are more prone to sour rot But Frequently find sour rot without bunch rot sporulation Frequently found sour rot in areas of clusters (shoulders) where no berry squeeze occurred Very weak correlation between severity of bunch rot and sour rot in 2008 with >1000 observations in 3 Niagara vineyards

28 Factors that Promote Sour Rot Avg Daily Temp (C) Frost Sour rot incidence C (54 F) mm Sept Oct Riesling

29 Factors that Promote Sour Rot Avg Daily Temp ( C) C (64F) Sour rot severity 129 mm (5 ) Aug Sept 2010 Riesling

30 Factors that Promote Sour Rot Avg Daily Temp ( C) 18.7 C (66 F) Sour rot severity 89mm (3.5 ) Aug Sept Oct 2011 Riesling

31 Factors that Promote Sour Rot Avg Daily Temp ( C) 16.6 C (62 F) Sour rot severity mm Aug Sept 2012 Riesling

32 What effect does temperature have on sour rot development?

33 Effect of Temperature on Sour Rot Mean Sour Rot Severity (0-4) <50 F 50 to 60 F 60 to 70 F 70 to 77 FC Days after Inoculation with acetic acid bacteria

34 Effect of Temperature on Sour Rot Mean Sour Rot Severity (0-4) <50 F 50 to 60 F 60 to 70 F 70 to 75 F Days after Inoculation with Hanseniaspora

35 Effect of Temperature on Sour Rot 4 Mean Sour Rot Severity (0-4) <50 F 50 to 60 F 60 to 70 F 70 to 75 F Days after Inoculation with Complex

36 Does berry maturity have an effect on sour rot development?

37 Brix and Sour Rot Avg Daily Temp (C) Brix Sour rot severity Aug Sept 2010 Riesling

38 Brix and Sour Rot Avg Daily Temp (C) Sour rot severity Brix Aug Sept Oct 2011 Riesling

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40 Brix and Sour rot Sour Rot Severity Lab Trial, Pinot noir, 2011

41 Brix and Sour Rot Pathogens Alone and in Complex 4 Sour Rot Severity (0-4) Pinot Noir Pinot Noir Riesling Riesling Complex Gluconobacter Acetobacter Hanseniaspora Negative

42 Summary Causal organisms Gluconobacter spp and Hanseniaspora AAB can cause sour rot with or without obvious wounds Hanseniaspora only with wounds AAB + Hanseniaspora synergistic effect re sour rot severity Capable of causing symptoms C; opt 25 C Fruit susceptibility Increases above 10 Brix

43 Strategies to Manage Sour Rot Loosen clusters Increase skin toughness Kill pathogens Manage vectors

44 Cluster Compactness ( Zab ) Scale

45 Treatments to Loosen Clusters Pre-bloom leaf removal Basal 6 leaves by hand

46 P noir Before Leaf Removal

47 P noir After Leaf Removal (4 leaves)

48 Pinot Noir, Basal 6 Leaves Removed

49 Riesling, Basal 6 Leaves Removed

50 Cluster Loosening Treatments Pre-bloom leaf stripping Pinot noir Riesling Sour rot severity (%) 57 31% Volatile acidity (g) Cluster looseness % *Inconsistent* Cluster weight (g) Including sour rot 8.1 Inconsistent

51 Leaf Stripping Basal 6 leaves removed by hand Timing 1 wk pre-bloom Immediate pre-bloom Fruit set Pea size berry Veraison

52 Untreated No leaf removal

53 Leaf removal Pre-bloom

54 Pea-sized berry Leaf removal

55 Veraison Leaf removal

56 Timing of Leaf Stripping prebl leaf fruit set leaf pea size leaf Sour rot Severity Botrytis Severity Cluster Looseness Sour rot Severity Botrytis Severity Cluster looseness PEC-1 PEC-2 PEC Riesling, 2013

57 Timing of Leaf Stripping wk prebl immed prebl immed post bl fruit set partial Sour rot Botrytis Cluster looseness Sour rot Botrytis Cluster looseness sour rot Botrytis Cluster looseness Pinot blanc Pinot noir Sauv blanc St. Catharines, 2013

58 Cluster Loosening Treatments Pre-bloom leaf stripping

59 Cluster Loosening Treatments Desikote Desikote polymeric terpene coating agent anti-transpirant 2.16 L/600 L/ha (0.5 gal/64 gal/a)to fruiting zone foliage Prebloom application

60 Prebloom leaf strip vs Desikote Sour rot severity (%) P noir Untreated P noir Pre-bl leaf P noir Desikote Ries Untreated Ries Pre-bl leaf Ries Desikote

61 Cluster Loosening Treatments Mechanical Leaf Removal Collard leaf blower 2 air speeds (high/normal) x 2 drive speeds (normal/slow) Immediate post bloom Follow-up removal across all plots

62 Mechanical Leaf Removal Air speed Drive speed untreated debris retained in cluster (g) 0.12 a Low Slow 0.07 b Low Normal 0.06 b High Normal 0.06 b High Slow 0.05 b

63 Treatments to Loosen Clusters Gibberellic Acid Falgro 5, 10, 20 ppm GroSpurt 7.5, 12.4, 20 ppm 600 L/ha (64 gal/a) in fruiting 50-80% bloom (post bloom in 2016 P. noir)

64 Cluster Loosening Treatments Giberrellic acid Pinot noir Riesling Low Med High Low Med High Sour rot severity (%) Volatile acidity (g) Cluster looseness (%) Cluster weight (g) Including sour rot

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66 GA Prebloom or Bloom? Sour rot severity, Pinot noir a 2017a 2017b untreated GroSpurt 7.5 prebl GroSpurt 12.5 prebl GroSpurt 7.5 bloom GroSpurt 12.5 bloom GroSpurt 20 bloom

67 GA Prebloom or Bloom? Sour rot severity, Riesling Untreated GroSpurt 12.5 prebl GroSpurt 20 prebl GroSpurt 12.5 bl GroSpurt 20 bl

68 Cluster Loosening Treatments Summary: Giberrellic acid sour rot and VA both P noir + Riesling No consistent rate effect Cluster loosening effect inconsistent Med and High rate looser Riesling Cluster wt Riesling High rate Both Prebloom and Bloom sour rot 2/3 yrs Bloom > Prebloom P noir

69 Treatments to Loosen Clusters Apogee (Regalis in Europe) prohexidione-ca Registered to reduce cluster compactness of Rhein Riesling, Sauvignon blanc, St.Laurent) 45, 90 and 180 g a.i/ha rates at 50-80% bloom (post bloom in 2016 Pinot noir)

70 Cluster Loosening Treatments Apogee Pinot noir Riesling Low Med High Low Med High Sour rot severity (%) Volatile acidity (g) Cluster looseness (%) Cluster weight (g) Including sour rot

71 Cluster Loosening Treatments Summary: Apogee Reduced sour rot and VA in both P noir + Riesling 45 g a.i. = 180 g a.i. 90 g a.i. inconsistent effect Cluster loosening inconsistent More effect in P noir than Riesling Cluster wt in P noir

72 Treatments to Loosen Clusters Stella Maris Liquid extract from seaweed 5L/400 L/ha prebloom 5 L/600 L/ha postbloom Timing 2-5 cm shoots cm shoots Immediate prebloom 3mm berry 50% Veraison (15 Brix)

73 Cluster Loosening Treatments Stella Maris: Pinot noir pre 2 post 4 app 3 pre 2 post 5 app Sour rot severity (%) Volatile acidity (g) Cluster looseness (%) Cluster weight (g) Including sour rot

74 Cluster Loosening Treatments Stella Maris: Riesling pre 2 post 4 app 3 pre 2 post 5 app Sour rot severity (%) Volatile acidity (g) Cluster looseness (%) Cluster weight (g) Including sour rot.8.9 1

75 Cluster Loosening Treatments Summary: Stella Maris Prebl apps reduced sour rot 3 prebl more effective than 2 VA reduced with 3 prebl not with 2 Clusters looser with 3 prebl than 2

76 Treatments to Loosen Clusters Ammonium sulphate 1.3 and 1.8% 50-80% bloom 400 L/ha fruiting zone

77 Cluster Loosening Treatments Ammonium sulphate: P. noir 0.13% 0.18% Sour rot severity (%) 11 3 Volatile acidity (g) Cluster looseness % *Inconsistent* Cluster weight (g) Including sour rot

78 Cluster Loosening Treatments Summary: Ammonium Sulphate 1.3% reduced sour rot slightly but minimal effect on VA 1.8% increased cluster looseness slightly

79 Effects on Return Fruitfulness % Fruitful shoots, Pinot noir untreated prebl leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180

80 Effects on Return Fruitfulness % Fruitful Shoots, Riesling 2009/ /11 Untreated prebloom leaf GA Low prebl GA Low bl GA Low 2X GA Low bl Apogee Apogee Apogee

81 Effects on Return Fruitfulness % Fruitful Shoots, Riesling, Check Prebloom leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180

82 Effects on Return Fruitfulness, Florets/Cluster, Riesling,

83 Effects on Return Fruitfulness Summary Gibberellic acid, Apogee, leaf stripping No effect on number of fruitful shoots at any rate or timing Gibberellic acid Riesling - # florets/cluster Effect on # berries/cluster????

84 Cluster Loosening Treatments Summary No significant effect on return fruitfulness No consistent effect on rachis length, berries/cm rachis Slight increase in % small berries for high rates of GA and Apogee

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86 Reduce Injury Leaf stripping in fruiting zone Early leaf stripping may help reduce incidence of sour rot Change berry skin and wax characteristics Change cluster compactness Reduce powdery mildew Reduce Botrytis bunch rot

87 Reduce Injury

88 Fluorescence micrographs of sweet cherry fruit surface. (A) Intact fruit surface with stoma. (B-C) Small microcracks; typical of fruit in early stages of development. (D-F) More and larger microcracks; typical of fruit in the latest stages of development.

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91 Reduce Mechanical Injury Suggestions for Cherry Cracking Osmoticum sprays Mineral salts (CaCl2) applied prior to or during rain Reduce absorption of water across skin Calcium Strengthen cell walls? Timing between fruit set and veraison Surfactants Raingard? (non-ionic surfactant) Desikote (new formulation of VaporGuard)

92 Reduce Injury Reduce skin cracking: Coatings Raingard Hydrophobic protective film decrease rain water absorption through cuticle 30 L/600 L/ha (8 gal/64 gal/a) in fruiting zone Pomcho cuticle supplement made from food grade, elastic and hydrophobic biopolymers 1 gal/a in 50 to 100 gallons 4 weekly apps Brix

93 Reduce Injury Reduce skin cracking: Coatings Pinot noir Riesling Raingard 2012 Pomcho 2015 Raingard 2011/12 Desikote Sour rot severity (%) Volatile acidity (g) Botrytis severity (%) 55 74

94 Reduce Injury Reduce skin cracking: Tougher skins Calcium 600 L/ha (64 gal/a) to fruiting zone biweekly starting at pea sized berry CaCl L/600 L (2.6 gal/64 gal) Calcium nitrate L/600 L (51 oz/64 gal) Calcium carbonate 10 L/600 L Silicic acid 300 ml/600 L (10 oz/64 gal) 5-15 cm shoot at 2 week intervals for 8 sprays

95 Reduce Injury Reduce skin cracking: Tougher skins Calcium and Silamol Results vs sour rot variable from one year to the next More consistent effect vs Botrytis

96 KMS KMS + TA bicarbonate Peroxiacetic acid Silver nitrate Fracture Timorex Gold Serenade Double Nickel Actinovate BlightBan A506 Regalia Maxx Vermicompost Cueva Switch Pristine

97 Increase host resistance? Regalia Maxx Extract of giant knotweed Induced systemic resistance response (ISR).54

98 Fungicides vs Sour rot

99 Sour Rot Management Potassium Metabisulphite? Used as anti-oxidant and anti-microbial (vs microbes) in vinification (40-60 g/tonne) Rengasamy & Poole (NZ): 5 kg per 1000 L water Botrytis-infected berries dry out Wicks (Australia): 3-4 g/l KMS killed Botrytis spores & inhibited growth of germ tubes If 4 g/l applied w/i 48 hr of infection, inhibits sporulation from infected berries

100 Sour Rot Management Potassium Metabisulphite (KMS) Concerns: Does it work? Rate? Timing? How does it work? (anti-oxidant/antimicrobial/both?) Excess sulphites & SO 2 in wine?

101 Kill the pathogens Potassium metabisulphite KMS Concentration 2.5, 5 and 10 kg/1000 L (5.5, 11 and 22 lb/100 gal) Volumes in fruiting zone 600, 800, 1000 L/ha (60, 80, 100 gal/a) +/- tartaric acid Formulation Food grade KMS, Solfobenton Weekly sprays starting veraison, 12, 14, 5, 17, 20 Brix, 3 and 1 day preharvest, when sour rot observed, after rain over 12 Brix

102 Antimicrobial Treatments KMS weekly from veraison Pinot noir Riesling Sour rot severity (%) Sour rot severity range (%) Volatile acidity (g)

103 Antimicrobial Treatments KMS Weekly Sprays, Riesling kg/1000 L 10 kg/1000 L Initiation Sour rot severity (%) VA (g) Sour rot severity (%) VA (g) veraison st sour rot wk preharv wk + 3 d preharv d preharv

104 Antimicrobial Treatments

105 Antimicrobial Treatments

106 Antimicrobial Treatments Solfobenton/Biobenton Sour rot severity (%) VA (g) Solfobenton dust weekly Solfobenton dust biweekly Solfobenton wet weekly Biobenton dust weekly Biobenton wet weekly

107 Effects of KMS on Vinification Treatments: 2 wk, 1 wk, 3 d, 1 d preharvest at 5 kg/1000l Each plot consisted of all rot-free fruit on 4 to 6 Riesling vines If no sulfur dioxide dissipated, expected concentration of SO 2 in juice would be 197 mg/l (based on a crop level of 4 tonne/acre)

108 Effects of KMS on Vinification Fermentations sampled every other day for cell count and ºBrix to dryness

109 Effects of KMS on Fermentation Total soluble solids (ºBrix) Added Nitrogen Control 2 weeks 1 week 3 days 1 day Days of fermentation Fermentation slower in untreated control compared to KMS

110 Effects of KMS on Fermentation 1.0E+08 Mean cell concentration (cells/ml) 9.0E E E E E E E E+07 Control 2 weeks 1 week 3 days 1 day Added Nitrogen 1.0E E Days of fermentation No effect on yeast growth

111 Effects of KMS on Fermentation Table 3. Wine parameters. Titratable acidity (g/l tartaric Treatment ph acid) Residual Sugar (g/l) Ethanol (% v/v) Total YAN (mg N/L) Free SO2 (mg/l) Total SO2 (mg/l) Control 2.86 ± ± 0.2a 1.1 ± ± ± ± ± weeks 2.87 ± ± 0.5b 1.2 ± ± ± ± ± week 2.82 ± ± 0.3b 1.3 ± ± ± ± ± days 2.81 ± ± 0.3b 1.6 ± ± ± ± ± day 2.86 ± ± 0.3b 1.6 ± ± ± ± ± 0.8 Mean values followed by letters are significantly different by LSD (p<0.05). Nsd in TA, residual sugar, ethanol Very low levels of SO 2

112 Effects of KMS on Fermentation KMS vineyard sprays did not adversely affect fermentation Sulfur dioxide sprayed in the vineyard is not detectable in juice processed from grapes only 1 day after KMS spray application Make sure to cold stabilize before bottling

113 Antimicrobial Treatments Biologicals Serenade Bacillus subtillus QST713 Fracture BLAD polypeptide Botector Aureobasidium pullulans Actinovate Streptomyces lydicus WYEC 108 BlightBan A506 Pseudomonas fluorescence Double Nickel Bacillus amyloliquefaciens D747 Sour rot Severity % difference

114 Antimicrobial Treatments Biologicals Oxidate hydrogen dioxide + peroxyacetic acid NeoBoost sodium percarbonate + tetraactetylethylenediamine + potassium silicate Agress silver nitrate Cueva copper octanoate Milstop potassium bicarbonate Timorex Gold tea tree oil variable

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116 Manage vectors Identify vectors Drosophila melanogaster Drosophila suzukii (Spotted Wing Drosophila)? When do they show up? Treatments to reduce introduction/spread of sour rot by vectors Insecticides Repellants

117 Manage vectors D. melanogaster Carries yeasts and bacteria associated with sour rot Can fly up to 4 miles upwind in 24 hrs Attracted to volatiles associated with rotting fruit Lay eggs on berries near stem end or on or near wounds in fruit Larvae hatch from berries and enter berries carrying yeast and bacteria

118 Manage vectors D. melanogaster Yeasts are major nutritional source, providing proteins, vitamins, and other nutrients for adults and larvae life span, reproduction AAB colonize gut carbohydrates, oxygen, and acidic ph,

119 Manage vectors D. suzukii Spotted wing drosophila Attracted to fruit as it ripens Does not require injury to lay eggs Serrated ovipositor Eggs deposited inside fruit Larvae feeds inside

120 Manage Vectors

121 Eliminate Vectors Bunches protected from vectors influence: Sound (SP) Sound with manually induced Wounds (SwP) Initial sour rot symptoms (SRP)

122 Manage Vectors grapes with sour rot symptoms protected with nylon nets spread of sour rot to remaining parts of clusters

123 Monitor Drosophila spp. in vineyard 1 L jars 50 ml apple cider vinegar 8 traps per location Collected 2x/week Brix at each date Counts of SWD vs Dm

124 Drosophila spp. in traps Drosophila\trap Brix D. melanogaster D. suzukii Brix

125 Drosophila spp. in traps 2014 Total % SWD % D. melanogaster Pinot noir Lincoln Riesling NOTL

126 Monitor Drosophila spp. on clusters Mesh bags on 12 clusters per week starting Aug 25 (12 Brix) 4 th week (18.7 Brix), bagged clusters removed and placed into 500 ml mason jars covered with mesh incubated at 20-25C for 1 week with ambient light for Drosophila spp. to emerge

127 Drosophila spp. on clusters, P. noir S Flies\bag Brix Brix D. melanogaster D. suzukii Sept

128 Drosophila spp. on clusters, P. noir N Flies\bag Brix Brix D. melanogaster D. suzukii Sept

129 Manage vectors Insecticides for SWD Delegate Malathion Permethrin (Ripcord) Bifenthrin (Capture)

130 5 weekly apps starting at Brix 14.3 (1 st fly catch) Volatile Acidity (g acetic acid/l) Capture + KMS Capture Delegate + 15ºB Delegate + 12ºB 15ºB 12ºB Botector PhD Cueva Serenade Max Oxidate NeoBoost Timorex Gold Fracture KMS 5 kg + Milstop KMS 10 12ºB KMS 5 15ºB KMS 5 12ºB Silamol Pomcho Leaf veraison Leaf cluster close Check Pinot noir St. Catharines, Sour rot Severity (%) Sour rot (%) VA

131 KMS 10 + Delegate KMS 5 + Delegate Apogee 180 post bl + Delegate GroSpurt 20 post bl + Delegate Delegate Apogee post bl + KMS 5 GroSpurt 20 post bl + KMS 5 KMS 10 Brix KMS 5 10 Brix Apogee InCa GroSpurt InCa 4 InCa 4 TopFlow Apogee 180 post bl GroSpurt 20 post bl GroSpurt 12.5 post bl Cluster close leaf Untreated Pinot noir St. Catharines, Sour rot Severity (%)

132 KMS 10 kg Volatile acidity (g acetic acid/l) KMS 5 kg Delegate/Delegate/Delegate Delegate/Malathion/Ripcord Leaf veraison + Delegate Leaf cluster close + Delegate leaf pea size berry + Delegate Delegate/Delegate/Delegate leaf veraison Leaf cluster close Sour rot VA Leaf pea size untreated Pinot noir St. Catharines, Sour rot severity (%)

133 Summary: Pathogen stuff Causal organisms Gluconobacter spp + Hanseniaspora Disease can occur C Fastest at 25 C Fastest with both organisms Symptoms rarely seen below 12 Brix

134 Summary: Management Reduce cluster tightness GA, Apogee, prebloom leaf stripping Exposure of clusters through leaf removal Earlier is better Calcium, Silamol 2 week intervals starting pea-size berry

135 Summary: Management Antimicrobials Variable efficacy Start Brix

136 Summary: Management Vectors D. melanogaster >>>> D. suzukii Start Brix

137 Summary: Management Use an INTEGRATED approach to sour rot management Host Pathogen Vector

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140 Cluster Loosening Treatments Rachis length Cl close, Pinot noir a 2016b Untreated pre-bl leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180 Stella Maris prebl Stella Maris postbl Stella Maris pre + post

141 Cluster Loosening Treatments Rachis length Cl close, Riesling a 2011a 2012a 2013b 2014b 2015b 2016d Untreated prebl leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180 Stella prebl Stella post bl Stella pre + post

142 Cluster Loosening Treatments Berries/cm Cl close, Pinot noir a 2016b Untreated pre-bl leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180 Stella Maris prebl Stella Maris postbl Stella Maris pre + post

143 Cluster Loosening Treatments Berries/cm Cl close, Riesling a 2011a 2012a 2013b 2014b 2015b 2016d Untreated prebl leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180 Stella prebl Stella post bl Stella pre + post

144 Cluster Loosening Treatments % Small Cl close, Pinot noir a 2016b Untreated pre-bl leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180 Stella Maris prebl Stella Maris postbl Stella Maris pre + post

145 Cluster Loosening Treatments % Small Cl close, Riesling a 2011a 2012a 2013b 2014b 2015b 2015c 2016d untreated prebl leaf GA Low GA Med GA Hi Apogee 45 Apogee 90 Apogee 180 Stella prebl Stella post bl Stella pre + post