Crop Load Adjustment - PA Wine Grape Growers Network

Crop Load Adjustment:
Does It Really Pay?
Justine Vanden Heuvel
Associate Professor of Viticulture
Trent Preszler
Gavin Sacks
Qun Sun
Tim Martinson
Tyler Berkey

Clos des Papes
Châteauneuf-du-Pape 2005
98 points / $80
At 98 points, the 2005 is
Avril's best wine yet,
displaying an enormous core
of fruit and minerality along
with massive structure. Avril
keeps yields low….

Columbia Crest, founded in 1978, is part of Ste. Michelle
Wine Estates, which accounts for more than half the
wine produced in Washington. With an excellent
growing season in 2005, winemaker Ray Einberger, who
worked at Château Mouton‐Rothschild and Napa's Opus
One, crafted an exceptional wine. He used grapes from
six low‐yielding vineyards…. This wine belongs in the
company of the world's great Cabernets and, with its
low price and significant production, earns our 2009
Wine of the Year.

“The Hermann J. Wiemer winery…Quick math tells
you that yields here are low…an eye-opening
number… which distances them from most of the
wines currently produced in the Finger Lakes. (Low
yields, anyone?) If a broader base of consumers is
going to change its perception of Finger Lakes
wines, the region will need more winemakers who
understand how critical low yields are to making
quality wine.”
– James Molesworth, Editor
Wine Spectator

The yield/quality relationship
Yield
Quality
Quality
Cluster
thinning
Traditional view
Yield
Modified view

↔
Economic
sustainable,
labor, lost
yields
↑
Soluble
solids,
ripening
CLUSTER
THINNING
pros/cons
↑
Air flow,
light
environ
↔
Flavor
chemistry,
Wine
Quality
↑
Vine
balance

How does CT affect costs & returns?
• Input
• Total costs per acre to manage Riesling
• Labor costs per acre to thin clusters
• Yield (t/ha) before CT and after CT
• Ouput
• Calculation of minimum price needed to
maintain constant net returns at varying crop
levels

Applying the model to a field study
• Three year study: 2008 - 2010
• King Ferry Winery, east side Cayuga Lake
• Well-drained Cazenovia series silt loam
• 224m elevation,1.5 x 3.0 m spacing, North-South
• Vitis vinifera L. cv. Riesling cl. 239/RS3309 (1984)
• Winter pruned to consistent bud number, spring
thinned to 36 shoots per vine
• Vertically shoot positioned “Pendelbogen”

Experimental Treatment
• 4 experimental treatments replicated 4 times:
• Low crop (1 cluster remains per shoot)
• Medium crop (1.5 clusters/shoot)
• High crop (2 clusters/shoot)
• Non-thinned control
• Distal clusters removed first, basal left intact
• Cluster thinning at E-L stage 31 (pea-sized)
• Harvested 3 weeks after typical harvest date

Non-thinned

High crop

HIGH CROPLOAD
Medium crop

Low crop

Data Collection
• Canopy characterization & light environment
• Enhanced Point Quadrat Analysis at veraison
• Yield components at harvest (3 weeks late)
• Yield/vine, cluster number, cluster weight
• Pressed juice composition at harvest
• Dissolved soluble solids, pH, Titratable Acidity
• Production economics
• Costs, price, yield analysis for net returns
• Wine sensory analysis
• Preference ratings and willingness to pay
(WTP) elicitation among NYC professionals

Table 1 Significant impacts* of cluster thinning on yield components of late
harvest Finger Lakes Riesling, 2008-2010. Measurements are the average of
four field replicates.
Clusters per shoot Clusters per vine Cluster weight (g)
Treatment 2008 2009 2010 2008 2009 2010 2008 2009 2010
Low 1.0 c 1.0 c 1.1 c 27.9 c 37.0 c 41.3 c 91.4 a 59.6 a 53.4 a
Medium 1.5 b 1.6 b 1.4 b 39.3 b 56.5 b 49.8 b 75.7 b 51.6 a 51.1 a
High 2.1 a 2.0 a 1.9 a 57.8 a 72.3 a 69.7 a 63.7 b 47.3 a 36.0 b
Control 2.2 a 1.9 a 1.7 a 59.0 a 67.6 a 62.0 a 67.7 b 54.3 a 43.0 b
Berry weight (g) Yield/hectare (t) Yield/vine (kg)
Treatment 2008 2009 2010 2008 2009 2010 2008 2009 2010
Low 1.83 a 1.28 a 1.52 a 5.5 c 4.7 b 4.7 a 2.5 c 2.2 b 2.2 a
Medium 1.73 a 1.17 b 1.50 a 6.4 b 6.3 a 5.5 a 3.0 b 2.9 b 2.5 a
High 1.41 b 1.07 b 1.34 b 7.9 a 7.3 a 5.4 a 3.7 a 3.4 a 2.5 a
Control 1.48 b 1.04 b 1.22 b 8.4 a 7.8 a 5.8 a 3.9 a 3.6 a 2.7 a
* Means analyzed by SAS GLM PROC and significance indicated by different letters at p ≤ 0.05.

Table 1 Significant impacts* of cluster thinning on late harvest Finger Lakes
Riesling, 2008-2010. Measurements are the average of four field replicates.
Crop load
(yield/pruning wt) Pressed juice Brix CEFA
Treatment 2008 2009 2010 2008 2009 2010 2008 2009 2010
Low 3.3 c 3.2 c 2.9 b 19.6 a 19.9 a 21.4 a 0.18 a 0.28 b 0.21 a
Medium 4.1 b 4.8 b 4.1 a 19.4 a 19.5 a 20.3 b 0.23 a 0.29 b 0.25 a
High 5.7 a 6.6 a 4.2 a 17.5 b 18.2 b 19.5 b 0.23 a 0.32 b 0.24 a
Control 6.3 a 7.0 a 4.6 a 17.1 b 17.8 b 19.1 b 0.26 a 0.39 a 0.32 a
* Means analyzed by SAS GLM PROC and significance indicated by different letters at p ≤ 0.05.

Table 1 Significant impacts* of cluster thinning on late harvest Finger Lakes
Riesling, 2008-2010. Measurements are the average of four field replicates.
Crop load
(yield/pruning wt) Pressed juice Brix CEFA
Treatment 2008 2009 2010 2008 2009 2010 2008 2009 2010
Low 3.3 c 3.2 c 2.9 b 19.6 a 19.9 a 21.4 a 0.18 a 0.28 b 0.21 a
Medium 4.1 b 4.8 b 4.1 a 19.4 a 19.5 a 20.3 b 0.23 a 0.29 b 0.25 a
High 5.7 a 6.6 a 4.2 a 17.5 b 18.2 b 19.5 b 0.23 a 0.32 b 0.24 a
Control 6.3 a 7.0 a 4.6 a 17.1 b 17.8 b 19.1 b 0.26 a 0.39 a 0.32 a
* Means analyzed by SAS GLM PROC and significance indicated by different letters at p ≤ 0.05.

Table 2 Production costs, price, yield and revenue parameters for late harvest
Finger Lakes Riesling, 2008-2010, as expressed by metrics of previously
published cluster thinning economic model.
Market price ($/t) Yield after CT (t/ha) Revenue ($/ha)
Treatment 2008 2009 2010 2008 2009 2010 2008 2009 2010
Low 2660 2350 2400 5.5 4.7 4.7 14,630 11,045 11,280
Medium 2660 2350 2400 6.4 6.3 5.5 17,024 14,805 13,200
High 2660 2350 2400 7.9 7.3 5.4 21,014 17,155 12,960
Control 2660 2350 2400 8.4 7.8 5.8 22,344 18,330 13,920
Total production
cost ($/ha)
Grower net returns
($/ha)
Treatment 2008 2009 2010 2008 2009 2010
Low 6,369 6,357 6,344 8,261 4,688 4,936
Medium 6,338 6,320 6,326 10,686 8,485 6,874
High 6,301 6,301 6,307 14,713 11,225 7,030
Control 5,930 5,930 5,930 16,414 12,029 7,613

Dollars per hectare
18,000
16,000
14,000
12,000
10,000
8,000
6,000
Grower Net Returns
Low
Medium
High
Control
4,000
2,000
0
2008 2009 2010
Year

Price differential after
CT ($/bottle)
Treatment 2008 2009 2010
Low 3.03 3.36 1.33
Medium 1.83 1.27 0.42
High 0.44 0.43 0.51
Control 0 0 0

Winemaking
• Fruit combined from field replicates of each
treatment, whole cluster pressed, split in
duplicate 19L carboys
• Juice adjusted to 22Brix before fermentation at
16°C (equivalent potential alcohol)
• Fermentation stopped with 6-10% residual sugar
for “medium sweet” by Int’l Riesling Foundation
• Bottled after 3 months w/o adjustments, filtering

Wine basic analysis
pH TA (g/L) Alcohol (%v)
Treatment 2009 2010 2009 2010 2009 2010
Low 2.87 a 3.07 a 11.1 a 9.8 a 9.3 a 10.0 a
Medium 2.86 a 3.09 a 11.0 a 10.0 a 9.8 a 10.2 a
High 2.85 a 3.09 a 11.2 a 10.0 a 9.6 a 10.3 a
Control 2.86 a 3.07 a 11.3 a 9.9 a 9.5 a 10.1 a

• NYC #1 wine market in US
• Consumes 30% of total imports
• Driven by market gatekeepers
• Evaluate price premiums on
wine attributes at WSET HQ

Wine sensory WTP trial in NYC
• No up-front training or attribute selection
• 27 panelists all working in wine sales and
distribution, writers, bloggers, PR
• 21 graduated WSET Level 4 Diploma or M.W.
• Wine poured in 30mL samples, ISO glass
• Panelists asked to free-scale rate (0-10cm)
fruitiness, petrol, mouthfeel, likability, likelihood
of purchase
• Provide everyday LH Riesling WTP and max.
WTP for each wine tasted

Average Rating (0 to 4)
2.50
2.00
1.50
1.00
0.50
0.00
Low
Medium
High
Control
a
a
a
a a a a
a
b b a a
Purchase Petrol Like Fruit Structure
Sensory or Preference Attribute
Figure, 2009 wines: Sensory evaluation and preference rating by New York City wine industry
professionals of late harvest Finger Lakes Riesling wines made in 2009 from vines cluster thinned
to varying levels. Response means for 27 panelists followed by different letters differ at p ≤ 0.05.
a
b
a
a
b
a
a
a

Average Rating (0 to 4)
3.00
2.50
2.00
1.50
1.00
0.50
0.00
Low
Medium
High
Control
a
a
a
a
a
a
a a a a a
Petrol Purchase Like Structure Fruit
a
b
b
b
a
a a a
a
Sensory or Preference Attribute
Figure, 2010 wines: Sensory evaluation and preference rating by New York City wine industry
professionals of late harvest Finger Lakes Riesling wines made in 2010 from vines cluster thinned to
varying levels. Response means for 27 panelists followed by different letters differ at p ≤ 0.05.

Dollars per Bottle
20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0
Willingness to pay by NYC Wine Professionals
for Late Harvest FL Riesling
Low
Medium
High
Control
a a
a
a a
a
a
a
4.0
2.0
0.0
2009 2010
Year

Shoot and cluster thinning for hybrids
How much does it cost?
What are the benefits?

Marechal foch
Control
Shoot-thinned
Early harvest: Sept. 11
Late harvest: Sept. 18

Tannins in wine improved with ST
b
a
b
a
b
b
a
a
CE = control, early harvest, CL = control, late harvest
STE = shoot thinned, early harvest, STL = shoot thinned, late harvest

Unpleasant aromas decreased with ST
fruit,
banana,
apple,
rose
solvent,
fruit,
potato,
chocolate
sweat,
cheese
flower,
apple
sweet,
clove,
smoke,
bandaid
grass,
green

To maintain revenue $2,460 (2007) and
$4,662 (2008) per acre in Foch vineyard:
Control
(2007)
ST (2007)
Control
(2008)
Yield (t/a) 4.1 3.3 7.0 5.3
ST (2008)
Add. costs
per acre
Add. cost
per ton
Req.
price/ton
Add. Bottle
price
$0 $54 $0 $54
$0 $16.36 $0 $10.18
$600 (avg) $761 $666
(avg)
$890
$0 $0.22 $0 $0.31
ST wine significantly different than control in 2007 by 24-member sensory panel

To maintain revenue of $7,356 per acre in
Seyval vineyard:
Control ST CT ST+CT
Yield (t/a) 12.0 9.6 8.1 6.6
Add. costs
per acre
Add. cost
per ton
Req. price
per ton
Add. bottle
price
$0 $54 $62 $116
$0 $5.62 $7.65 $17.57
$613 (avg) $772 $915 $1,132
$0 $0.22 $0.42 $0.72
CT wine significantly preferred over control by 26-member consumer panel

To maintain revenue of $6,499 per acre in Corot
noir vineyard:
Control ST CT ST+CT
Yield (t/a) 10.35 9.39 7.97 7.02
Add. costs
per acre
Add. cost
per ton
Req. price
per ton
Add. bottle
price
$0 $54 $62 $116
$0 $5.75 $7.77 $16.52
$628 (avg) $698 $823 $942
$0 $0.10 $0.27 $0.44
ST+CT “fruitier” than control and ST by 16-member sensory panel

Labor time and cost (@$15/hr)
for thinning
Vine
spacing
Vines per
acre
Hr per
acre
$ per
acre
Hr per
acre
$ per
acre
15 sec per vine 30 sec per vine
4 x 9 1210 5.0 $76 10.1 $151
5 x 9 968 4.0 $61 8.1 $121
6 x 9 807 3.4 $50 6.7 $101
7 x 9 691 2.9 $43 5.8 $86
8 x 9 605 2.5 $38 5.0 $76

Original
tons
Additional $ per ton required to
maintain gross revenue with
Tons left
thinning
Required additional price per ton
$300 $500 $1,000 $1,500
3 2 $150 $250 $500 $750
4 3 $100 $167 $333 $500
5 4 $75 $125 $250 $375
6 5 $60 $100 $200 $300
7 6 $50 $83 $167 $250

Additional $ per bottle required to
Original
tons
maintain gross revenue with
Tons left
thinning
Price per ton
$300 $500 $1,000 $1,500
3 2 $0.32 $0.35 $0.69 $1.04
4 3 $0.14 $0.23 $0.46 $0.69
5 4 $0.10 $0.17 $0.35 $0.52
6 5 $0.08 $0.14 $0.28 $0.42
7 6 $0.07 $0.12 $0.23 $0.35

Does it pay to reduce cropload?
• Wines from lower cropped vines are not always
preferred by consumers, and they often won’t pay a
premium for it
• For a grower, only if winery will pay a premium
(unless vines are overcropped)
• For a winery, maybe – required premium for
preferred wines generally low ($0.44 per bottle)