Selecting Wine Grape Clones to

Improve Yield and Quality

Matthew Fidelibus

Department of Viticulture and Enology

University of California, Davis

Species, cultivars, and clones

• California’s wine industry based on a single species of grape, Vitis vinifera L.

• Most wines made from traditional (old) cultivated varieties of V. vinifera

• Old cultivars have accumulated many ‘clones’ due to mistaken identity, mutation, or both

• Variation among clones may be exploited to improve grapevine yield and quality

What is a grapevine clone?

• A population of vines propagated

asexually (e.g., by cuttings) from a single

mother vine.

• Virtually all propagated grapevines are

technically ‘clones’

• Of particular interest are clones or

‘selections’ having distinctive, beneficial,

characteristics

How to make a mammalian clone

How to make a grapevine clone

How can clonal selection

research benefit growers?• Nurseries offer many different clones of a

given cultivar

• These may differ dramatically with respect to

yield, yield components, fruit composition,

and susceptibility to pests and diseases

• The performance of a given clone can

depend on the climatic region where it is

grown

Materials and methods

• Chardonnay, Merlot, and Zinfandel/Primitivo vines planted in 1997

• Bilateral cordons, two-wire trellis, spur pruned

• Vine x row spacing = 7.5’ x 10’

• Ten single-vine replicates

• Randomized complete block design

• Within a year, all clones harvested on the same day

Chardonnay characteristics

• Most widely cultivated wine grape in CA

• > 70 different registered clones in CA

• Clone 4, industry standard

• High yields, good fruit composition

• 4 has large, heavy clusters—susceptible

to sour rot

Chardonnay clones

Clone Source

4 Martini 5V21, Olmo #66

6 Martini 3V4, Olmo #68

15 Prosser, WA, LR2V6

18 Rauscedo 8, Italy

20 Cornegliano 7, Italy

37 France, 95

Chardonnay yield components

Clone Clusters / vine Cluster wt.

(kg.)

Yield / vine

4 78 d 0.29 a 21.9 a

6 107 a 0.22 c 22.0 a

15 107 a 0.20 d 19.9 b

18 93 c 0.26 b 22.6 a

20 98 bc 0.25 b 22.1 a

37 105 ab 0.24 bc 23.2 a

Chardonnay berries

Clone Berries / cluster Berry wt

(g)

4 192 a 1.5 b

6 147 cd 1.5 b

15 138 d 1.4 c

18 172 b 1.5 b

20 153 c 1.6 a

37 158 c 1.5 b

Chardonnay fruit composition

Clone Brix pH TA

(g/100 ml)

4 23.7 a 3.60 c 0.584 a

6 22.9 b 3.70 a 0.555 b

15 22.8 b 3.69 ab 0.581 a

18 22.7 bc 3.67 b 0.534 c

20 22.4 c 3.68 ab 0.555 b

37 23.0 b 3.68 ab 0.534 c

Chardonnay, sour rot incidence

Clone Sour rot incidence

(%)

4 16 a

6 10 b

15 4 c

18 14 ab

20 13 ab

37 15 a

Chardonnay clones summary

• Clone 4 had good yields, large clusters,

and good fruit composition but was very

susceptible to sour rot

• Clone 15 had 10% lower yields than 4, but

had much less sour rot than 4

Merlot characteristics

• Merlot among the most important red wine

grapes in Calif.

• 20%, by area, and 45%, by yield, grown in

Central Valley

• Clone 3 is standard; consistent set, yield,

fruit composition

• Relative performance compared to other

clones in the valley has not been tested

Merlot clones

Clone Source

1 Inglenook, Calif.

3 Inglenook, Calif.

9 Rauscedo, Italy #3

10 Cornegliano, Italy ISV-V-F2

11 Cornegliano, Italy ISV-V-F5

14 Chamber d’Agriculture de al

Gironde, France

Merlot yield components

Clone Clusters / vine

(no.)

Cluster wt.

(kg)

Yield / vine

(kg)

1 90 b 0.24 19.83 c

3 91 b 0.25 20.75 bc

9 90 b 0.25 21.50 ab

10 103 a 0.24 22.21 a

11 92 b 0.26 21.08 abc

14 85 b 0.23 18.11 d

Merlot berries

Clone Berries / cluster

(no.)

Berry wt

(g)

1 150 1.57 c

3 148 1.66 b

9 149 1.65 b

10 145 1.57 c

11 145 1.73 a

14 146 1.54 c

Merlot fruit composition

Clone Brix pH TA

(g/100 ml)

1 23.6 c 3.91 b 0.377 cd

3 23.4 c 3.90 bc 0.374 d

9 23.7 c 3.90 bc 0.373 d

10 23.65 bc 3.87 c 0.398 a

11 24.0 b 3.94 a 0.391 ab

14 24.4 a 3.94 a 0.385 bc

Merlot clones summary

• Selection 10 performed best; consistently

higher yields of fruit with low pH and high

TA

• Selection 11 was undesirable; the largest

berries, was the most susceptible to rot,

and had high pH

• Selection 3 performed similar to selections

1 and 9 and was not superior to 10

‘Crljenak kastelanski’

• “The red grape of Kastela”

• Zinfandel and Primitivo are probably

selections of the “Red grape”

• Origin of Zinfandel is obscure, 1850s?

• Primitivo means “early” in Italian

• Primitivo has been grown in Italy for about

200 years

Zinfandel characteristics

• Big berries, large clusters, high

fruitfulness, high yields

• Very susceptible to “sour rot” in warm

climates

• Uneven ripening

• Yield declines as the season progresses

• Color can be poor, especially in warm

climates

Zinfandel & Primitivo Clones

Clone Source

Zinfandel 1A Lodi, CA, Handel

Zinfandel 2 Lodi, CA, Handel

Zinfandel 3 Livermore, CA, Ruetz

Primitivo 3 Bari, Italy

Primitivo 5 Calo, Italy

Primitivo 6 Calo, Italy

Zinfandel, cluster characteristicsClone Clusters / vine

(no.)

Cluster wt.

(kg)

Yield / vine

(kg)

1A 73 b 0.30 20.4 c

2 75 b 0.31 21.3 bc

3 75 b 0.35 23.4 b

P3 91 a 0.32 26.0 a

P5 79 b 0.30 22.2 bc

P6 80 b 0.31 22.1 bc

Zinfandel, berry characteristics

Clone Berries /

cluster

Berry wt

(g)

1A 104 2.77 a

2 107 2.75 a

3 126 2.76 a

P3 116 2.64 b

P5 117 2.57 b

P6 110 2.78 a

Zinfandel, fruit composition

Clone Brix pH TA

(g/100 ml)

1A 20.05 c 3.47 b 0.60

2 20.16 c 3.45 b 0.60

3 19.56 d 3.45 b 0.59

P3 21.10 b 3.46 b 0.61

P5 20.82 b 3.48 b 0.62

P6 22.00 a 3.52 a 0.60

Zinfandel, sour rot susceptibility

Clone Sour rot incidence

(%)

1A 50 ab

2 55 a

3 52 ab

P3 40 cd

P5 44 bc

P6 34 d

Zinfandel clones summary

• Few differences between the Zinfandel

selections tested

• Primitivo selections generally were better

• Earlier maturing

• Similar or higher yield

• Similar or less sour rot

Acknowledgements

• Thanks to L. Peter Christensen, Kimberley

Cathline, Jorge Aguilar Osorio, Don

Katayama, & Karin Kawagoe

• Viticulture Consortium & American

Vineyard Foundation

For more details…

• Email mwf@uckac.edu