Viticultural Performance of Red and White Wine Grape Cultivars in

Viticultural Performance of Red and White Wine

Grape Cultivars in Southwestern Idaho

Krista C. Shellie

ADDITIONAL INDEX WORDS. grapevine, phenology, heat accumulation, germplasm,

Vitis vinifera

UMMARY. A collection of 23 red and six white wine grape (Vitis vinifera) cultivars

were evaluated for viticultural performance in Parma, ID. Vine yield, fruit compo-

sition, and vegetative growth were measured over four growing seasons, and data

were used to compare relative cultivar performance based on yield to pruning ratio

and fruit maturity. Relative differences among cultivars in budbreak day of year

[96 (6 Apr.) to 122 (2 May)] and days from budbreak to harvest (143 to 179 days)

varied from year to year. The earliest and latest maturing cultivars in 3 of 4 years

were ‘Blauer Portugieser’ (143 days), ‘Nebbiolo’ (177 days), ‘Barbera’ (179 days),

‘Orange Muscat’ (144 days), ‘Flora’ (149 days), ‘Muscat of Alexandria’ (166 days),

and ‘Viognier’ (168 days). Cultivars differed in yield (2.4 to 7.0 tons/acre),

vegetative vigor (4.6 to 20.4 yield/pruning weight), and harvest soluble solids

concentration (21.1 to 26.5), but differences in harvest pH (3.0 to 4.1) and

titratable acidity (2.48 to 13.03 gL

–1

) varied from year to year. Average heat unit

accumulation (1646) was 160 units higher than the 78-year site average. Few (less

than 150) units accumulated in April and October, most units accumulated in July,

and diurnal difference in air temperature was 15 C. Performance results from this

study can assist cultivar site selection by comparing climate data for an intended site

with that of Parma. For example, the low acidity and earliness of ‘Blauer Portugieser’

suggests it is best suited to a site with less heat unit accumulation than Parma, and the

high acidity and late maturity of ‘Barbera’, ‘Nebbiolo’, and ‘Carignan’ suggest these

cultivars are best suited to a site with more heat unit accumulation than Parma.

The inconsistent relationship between onset of budbreak and earliness observed

in this study suggests opportunity to match short-season cultivars late to break

bud such as Flora to short-season growing sites prone to late-season frost.

ew vineyard regions are

being tested and established

throughout North America

in climatic zones once considered

marginal or unsuitable for growing

grapes of European origin (Vitis vin-

ifera) for wine production (Evans

et al., 2005; Hamman, 1993; Kaps

and Odneal, 2001; Reynolds et al.,

2004; Wolf and Warren, 2000). Acre-

age expansion into marginal areas is

driven by the potentially high eco-

nomic value of associated agribusiness

and tourism as well as the high pro-

duction efﬁciency of wine grapes rel-

ative to other traditional agricultural

products. Determination of suitability

for cultivation of wine grapes based

on cold events or disease prevalence

is more easily accomplished than

matching of cultivars to particular

mesoclimates, yet districts of origin

in well-established production re-

gions demonstrate the importance of

cultivar site selection. When the Cal-

ifornia wine industry began growth in

the late 1800s, information from Old

World wine-producing countries pro-

vided limited assistance for determin-

ing cultivar suitability. After 50 years

of extensive cultivar testing con-

ducted in California under varied

environmental conditions, a climate

classiﬁcation system based on heat

unit accumulation was developed to

compare and describe production

regions (Winkler et al., 1974). Culti-

var site evaluation also played an

important role in Washington state

wine industry growth where cultivar

trials were initiated in 1937 and con-

tinued into the late 1980s (Ahmedul-

lah, 1985; Clore et al., 1976; Nagel

and Spayd, 1990; Powers et al.,

1992).

The uniqueness of Idaho’s viti-

cultural climate and youth of its in-

dustry warrant evaluation of cultivar

suitability for commercial production

(fruit quality and quantity sufﬁcient

to be competitive). Idaho’s principal

wine grape-growing district is located

in the western half of the Snake River

Plain, a crescent-shaped depression

that stretches roughly 600 km across

southern Idaho. The arid, continental

climate of the western Snake River

Plain is similar to other warm, arid

grape-growing regions in eastern

Washington, northern Nevada, west-

ern Colorado, and south central Brit-

ish Columbia, Canada, where the

growing season is delimited by spring

or fall frost events. In addition to

macroclimate, the diverse topography

within the grape-growing region cre-

ates distinct mesoclimates that greatly

impact cultivar suitability. The large

mesoclimate diversity offers opportu-

nities, but also poses additional chal-

lenges for cultivar site selection.

Wine grapes are Idaho’s second

largest fruit crop [U.S. Dept. Agr.

(USDA), 2007]. Acreage doubled

between 1993 and 1998 to 647 acres

in 27 vineyards, and the most recent

tree fruit census reported 1215 acres

in 49 vineyard operations. Cultivar

selection appears historically based

on a perceived need for cold

Units

To convert U.S. to SI,

multiply by U.S. unit SI unit

To convert SI to U.S.,

multiply by

0.4047 acre(s) ha 2.4711

29.5735 ﬂ oz mL 0.0338

0.3048 ft m 3.2808

3.7854 gal L 0.2642

2.5400 inch(es) cm 0.3937

0.4536 lb kg 2.2046

1.6093 mile(s) km 0.6214

28.3495 oz g 0.0353

0.001 ppm gL

–1

1000

2.2417 ton/acre mgha

–1

0.4461

(F – 32) O 1.8 F C (1.8 ·C) + 32

U.S. Dept. of Agriculture, Agricultural Research

Service, Horticultural Crops Research Laboratory,

29603 U of I Lane, Parma, ID 83660

I thank the Idaho Grape Growers and Wine Producers

and Essie Fallahi for planting the material evaluated in

this study and Jeff Acock, Chris Rennaker, David

Straley, Josh Gregersen, and Mark Redhead for their

technical assistance.

Mention of a trademark, proprietary product, or

vendor does not constitute a guarantee or warranty of

the product by the U.S. Dept. of Agriculture and does

not imply its approval to the exclusion of other

products or vendors that also may be suitable.

E-mail: kshellie@uidaho.edu.

•

October–December 2007 17(4) 595

hardiness and low heat unit require-

ment because an estimated 60% of

acreage is comprised of cool season,

cold-hardy white wine cultivars

[‘Riesling’, ‘Chardonnay’, and

‘Gewurztraminer’ (Gillerman et al.,

2006)]. More recent plantings

include the red cultivars ‘Cabernet

Sauvignon’, ‘Merlot’, and ‘Syrah’,

demonstrating industry interest in

expanding cultivar selection. Despite

the growing importance of wine

grapes in Idaho’s economy, little pub-

lished information is available on

cultivar performance under Idaho

growing conditions. The objective

of this study was to compare the

viticultural performance of red and

white wine grape cultivars

under similar cultural practices to

assist cultivar site selection for future

plantings.

Materials and methods

All of the cultivars evaluated in

this study have a history of commer-

cial production in well-established

viticulture regions but have either

never or only recently been planted

in southwestern Idaho. A description

of each cultivar with its correspond-

ing major area of production is pre-

sented in Table 1. The cultivars were

planted on their own roots in 1997

(Fallahi et al., 2004) or 1998 (Fallahi

et al., 2005) with planting material

purchased through Foundation Plant

Services, Davis, CA. Clonal designa-

tions are those used by Foundation

Plant Services. The cultivars were

evaluated at the University of Idaho

Parma Research and Extension Cen-

ter (lat. 4347# N, long. 11657# W,

elevation 750 m) in Parma, ID. Aver-

age annual precipitation for Parma is

9.7 inches of which 45% falls during

the growing season (1 Apr. through

31 Oct.) and provides 10% of pan

evapotranspiration (U.S. Dept. Inte-

rior, 2006). Climate data (1922–

2005) indicates a 90% probability of

a freeze (–1.46 C) event after 1 Apr.,

dropping to 20% by 1 May (USDA,

1972). The soil at the trial site was a

Turbyﬁll, ﬁne sandy loam with a pH

of 7.9 in the top 12 inches and 0.9%

organic matter. Eight vines of each

cultivar were planted next to one

another. The vine groups were

planted in a completely randomized

fashion within four ﬁeld replications.

The vines were spaced 7 ft apart in

north–south-oriented rows that were

Table 1. Region of major production for red and white wine grape cultivars

evaluated on their own roots in Parma, ID.

Cultivar (clone no.) Acronym Major acreage

Region

Red skin

Barbera (02) BA Italy

Piemonte

Blauer Portugieser (02) BP Germany/Austria Pfalz/Vienna

Cabernet Franc (04) CF France

Bordeaux

Cabernet Sauvignon (04) CS France

Bordeaux

Carignan (06) CG France

Midi

Dolcetto (01) DL Italy Piemonte

Grenache (03) GR Spain

Rioja

Lemberger (02) LE Germany

Wurttemberg

Malbec (06) MA Argentina

Mendoza

Merlot (08) ME France

Bordeaux

Pinot Meunier (01) MN France

Champagne

Nebbiolo (01) NB Italy Piemonte

Petit Verdot (01) PV France Bordeaux

Petite Sirah (03) PS California California

Pinot Noir (18) PN France

Burgundy

Pinotage (01) PT South Africa Stellenbosch

Primitivo (03) PR Italy Puglia

Sangiovese (04) SG Italy

Chianti

Souzao (01) SZ Portugal Douro

Syrah (07) SY France

Rhone

Touriga Nacional (02) TG Portugal Douro

Valdepenas (03) VP Spain

Rioja

Zinfandel (03) ZN U.S.

California

White skin

Chardonnay (38) CH U.S.

California

Flora (04) FL U.S. California

Muscat of Alexandria (02) MU Spain

Alicante

Orange Muscat (01) OM U.S. California

Pinot Gris (04) PG Italy

Lombardy

Viognier (01) VI France Rhone

Fegan, 2003.

Johnson, 1994.

One of the world’s 81 most widely planted grape cultivars (Fegan, 2003).

Table 2. Growing degree days and average daily maximum and minimum air

temperature at the University of Idaho Parma Experiment Station in Parma, ID.

Growing degree days

2002 2003 2004 2005 1922–2005

Growing degree days

April 36.0 41.3 82.2 45.8 35.5

May 151.4 168.7 149.5 158.5 139.9

June 305.6 329.3 298.5 222.7 245.3

July 465.9 503.5 434.4 431.4 383.5

August 346.9 427.1 395.5 410.6 350.2

September 227.2 247.8 200.2 194.3 180.4

October 46.9 133.5 83.8 47.3 35.5

Season 1579.9 1851.2 1644.1 1510.6 1486.8

Avg daily maximum temp (C)

July 35.9 36.1 34.2 33.7 33.4

August 31.0 33.7 32.8 33.7 32.5

September 28.5 27.9 26.1 26.1 26.8

Avg daily minimum temp (C)

July 14.6 16.0 14.1 13.2 12.6

August 10.9 13.7 13.3 12.6 11.2

September 7.9 7.9 7.4 5.9 6.2

Desert Research Institute, 2006.

Simple daily average 1 Apr. to 31 Oct. using a base of 10 C (50.0 F) with no upper limit (The Northwest Berry

and Grape Information Network, 2004).

(1.8 ·C) + 32 = F.

596

•

October–December 2007 17(4)

VARIETY TRIALS

9 ft wide. Vines were trained as two

trunks, each with a unilateral cordon

located 40 inches above the soil

surface. Cordons were spur-pruned

each year and shoots were positioned

vertically upright with the aid of trellis

foliage wires.

Vineyard and vine management

was according to commercial re-

commendations for eastern Wash-

ington (Watson, 1999) and included

early season mowing of a cereal rye

(Secale cereale) cover crop between

rows and periodic spot application of

in-row herbicide for weed control.

Conventional fungicide applications

were made throughout the season

for control of powdery mildew (Unci-

nula necator), and insecticides were

applied as needed. The vines were

irrigated twice weekly using drip tub-

ing suspended from the lower trellis

wire 18 inches above the soil sur-

face; 1 gal/h punch-in emitters were

located 6 inches on either side of

the vine. Vine management consisted

of shoot thinning to an average of

15 shoots per meter of canopy shortly

after budbreak and shoot positioning

and hedging as needed to maintain

an average shoot length of 1.2 m.

Dormant canes were annually pruned

to an average of eight spurs per meter

with two-bud spurs on red and three-

bud spurs on white cultivars.

Data collected each season

included dates of major phenological

events, yield components and fruit

chemistry at harvest, and cane prun-

ing weights. The day of year for bud-

break, bloom, and veraison was

determined by visual inspection for

stages 4, 23, and 35 using the modi-

ﬁed E-L system (Coombe, 1995).

Harvest date for each cultivar was

based primarily on berry soluble sol-

ids concentration (SSC) and seconda-

rily on titratable acidity (TA) and pH.

Target SSC was 24% for red and white

cultivars. The target TA and pH for

red and white cultivars, respectively,

was 7 or 8 gL

–1

and 3.6 or 3.45. Data

were collected from the middle vines

within each group of eight vines. The

number of clusters per vine was

counted at harvest and yield per vine

was used to calculate average cluster

weight. Berry weight and must TA

and SSC at harvest were measured

from a sample of 10 clusters harvested

equally from the east and west sides of

the canopy. Berry weight was deter-

mined from a 100-berry subsample

randomly selected from ﬁve locations

(four cardinal quadrants and one cen-

ter) on each cluster in the 10-cluster

sample. The remaining berries in

the 10-cluster sample were passed

through a hand-operated crusher,

ﬁltered, and a 40-mL must sample

was used to measure SSC with a model

RE40 temperature-compensating re-

fractometer (Mettler-Toledo, Colum-

bus, OH). Juice pH was measured

before titration as described by Shellie

(2006). Determination of maturity

for harvest was based on repeated

analyses of a 10-cluster sample from

nondata vines. The multiseason data

were analyzed separately for each skin

color using SAS GLM procedure

Table 3. Budbreak day of year for red and white wine grape cultivars

at Parma, ID.

Bud break (day of yr)

Cultivar

Avg 2002–2005 2002 2003 2004 2005

Red skin

Nebbiolo 106.0 109.0 105.4 96.5 113.3

Sangiovese 106.3 107.3 108.0 96.0 114.1

Grenache 106.7 109.0 105.9 96.8 115.0

Cabernet Franc 107.2 109.0 106.9 98.0 115.0

Pinotage 107.3 109.0 105.8 100.3 114.1

Lemberger 107.3 109.0 105.6 97.8 116.8

Merlot 107.4 109.0 108.2 97.3 115.0

Barbera 107.5 110.6 106.3 98.3 115.0

Blauer Portugieser 107.9 110.6 106.3 99.3 115.0

Malbec 108.2 109.0 109.1 100.5 114.1

Syrah 108.5 110.6 108.8 99.5 115.0

Touriga Nacional 108.8 109.0 110.5 100.8 115.0

Zinfandel 108.9 109.0 110.0 99.8 116.8

Pinot Noir 109.6 113.7 109.4 101.1 114.0

Valdepenas 110.4 109.0 109.1 101.5 122.0

Souzao 110.4 109.0 112.8 100.4 119.4

Petit Verdot 110.7 109.0 111.1 104.0 118.5

Petite Sirah 111.0 114.5 111.5 99.5 119.4

Primitivo 111.2 118.0 111.5 99.3 115.9

Carignan 111.4 115.5 107.5 103.8 119.4

Dolcetto 111.7 112.4 110.0 102.3 122.0

Cabernet Sauvignon 111.9 109.0 114.3 104.0 120.3

Pinot Meunier 114.6 122.0 112.9 103.1 120.3

Avg 109.2 111.0 109.0 100.0 116.7

MSD

8.1 3.8 2.1 3.9

White skin

Orange Muscat 104.9 ne

104.3 97.3 113.3

Chardonnay 106.5 111.6 102.5 97.0 115.0

Muscat of Alexandria 108.3 109.0 107.8 102.0 113.6

Viognier 109.0 111.5 111.4 98.0 115.0

Pinot Gris 110.7 110.6 111.9 100.8 119.4

Flora 113.2 122.0 111.8 100.8 119.4

Avg 108.8 113.0 108.3 99.3 115.9

MSD 9.1 2.4 4.2 6.7

P > F

Red skin

Cultivar (CV) <0.0001 0.0507 0.0171 0.0022 0.0448

Year (Y) <0.0001

CV · Y 0.0441

White skin

Cultivar (CV) 0.0036 0.3127 0.0101 0.6349 0.2043

Year (Y) <0.0001

CV · Y 0.1417

Cultivars within each skin type are listed in order of 2002–2005 average value.

Clonal designations are listed in Table 1.

Minimum signiﬁcant difference using Waller-Duncan k-ratio £0.05.

ne = not evaluated.

•

October–December 2007 17(4) 597

(SAS Institute, Cary, NC). Single-

season data were analyzed using the

SAS GLM procedure with the mini-

mum signiﬁcant difference generated

by Waller–Duncan k-ratio t test. The

calculated 4-year average ratios for

fruit maturity (SSC and TA) and vine

balance (yield to pruning weight

ratio) for each cultivar were graphed

as X, Y pairs in a scattergram using

SigmaPlot (SPSS, Chicago).

Results and discussion

The average (1922–2005) grow-

ing season heat unit accumulation

(GDD) at the Parma site (Table 2)

was within the upper range of

California Climatic Region II (Winkler

et al., 1974). Average heat unit accu-

mulation was 160 GDDs higher than

the 78-year site average with 2 years

(2003 and 2004) falling within the

temperature range for California

Climatic Region III. The coolest

growing season was 2005 (1511

GDD) and the warmest was 2003

(1851 GDD). Early and midseason

maturing cultivars are reported to

require a minimum of 1500 GDD

within a period of 150 d frost-free

(Weaver, 1976). The frost-free period

and heat unit accumulation at Parma

during the years of this study

exceeded these minimum values.

The Parma growing site accumulated

slightly more heat units than wine

grape trial sites in Reno, NV (Evans

et al., 2005), British Columbia,

Canada (Reynolds et al., 2004), and

Prosser, WA (Nagel and Spayd, 1990;

Powers et al., 1992) but was less

than Grand Junction, CO (Hamman,

1993) and Winchester, VA (Wolf

and Warren, 2000). Despite higher

seasonal heat unit accumulation in

Winchester, VA, average onset of

budbreak at Parma was 5 d earlier

and 10 d shorter between budbreak

and harvest (Wolf and Miller, 2001).

The monthly pattern of heat unit

accumulation in Grand Junction, CO,

and Prosser, WA, was similar to the

trial site in this study in that few (less

than 150) heat units accumulate in

April and October, and maximum heat

unit accumulation occurred during

July. Other similar climatic features

of growing sites in British Columbia,

Nevada, Washington, and Colorado

are low growing season precipitation,

high evaporative demand, high solar

radiation, and a large difference (15

C) in diurnal air temperature.

The timing of major phenolog-

ical events (budbreak, bloom, veraison,

and harvest) reﬂect genotype by envi-

ronment interaction and impact cul-

tivar site suitability because growing

conditions at different stages of berry

development uniquely impact fruit

production and quality. The environ-

mental conditions that induce release

from dormancy are known to vary

according to genotype, and in this

study, a range of 26 d was observed

among the cultivars. The 4-year aver-

age day of year (DOY) for budbreak

was 109 (19 Apr.) and was earliest

in 2004 (DOY 100) when heat unit

accumulation was approximately twice

the amount of other years (Table 2)

Table 4. Elapsed days from budbreak to harvest for red and white wine grape

cultivars at Parma, ID.

Bud break to harvest (d)

Cultivar

Avg 2002–2005 2002 2003 2004 2005

Red skin

Blauer Portugieser 142.6 131.4 144.4 152.8 142.0

Pinot Meunier 151.2 137.0 153.1 169.9 144.8

Dolcetto 152.3 139.6 156.0 170.8 143.0

Cabernet Sauvignon 155.4 143.0 151.8 169.0 157.8

Merlot 156.1 182.0 137.8 154.8 150.0

Valdepenas 156.2 174.5 137.9 169.5 143.0

Syrah 157.3 158.4 154.5 166.5 150.0

Pinotage 160.5 157.0 160.3 165.8 158.9

Malbec 161.1 157.0 150.9 165.5 170.9

Lemberger 161.5 157.0 145.4 175.3 168.3

Pinot Noir 161.7 166.1 156.6 173.9 151.0

Cabernet Franc 163.8 160.0 159.1 173.0 163.0

Petite Sirah 164.1 134.5 161.5 187.5 165.6

Petit Verdot 164.8 157.0 161.9 188.0 172.5

Primitivo 165.8 173.0 154.5 173.8 162.1

Souzao 168.2 166.0 160.3 174.6 171.6

Grenache 168.5 159.5 160.1 178.3 176.0

Touriga Nacional 168.9 157.0 162.5 186.3 170.0

Zinfandel 169.6 160.0 163.0 187.3 168.3

Carignan 171.3 159.5 165.5 188.6 171.6

Sangiovese 172.5 176.3 152.0 191.0 170.9

Nebbiolo 176.7 166.0 167.6 195.5 177.8

Barbera 179.2 180.4 166.8 193.8 176.0

Avg 163.0 158.8 155.8 176.1 162.0

MSD

6.1 4.9 1.7 2.7

White skin

Orange Muscat 144.8 ne

133.8 156.8 143.8

Flora 148.8 143.0 134.3 153.3 145.6

Chardonnay 153.5 161.4 144.5 161.0 147.0

Pinot Gris 159.3 164.4 154.1 165.3 153.6

Muscat of Alexandria 166.2 143.0 165.3 185.0 171.4

Viognier 168.2 167.0 161.6 180.0 164.0

Avg 156.8 159.9 148.9 166.9 154.2

MSD 12.4 2.3 3.8 6.5

P > F

Red skin

Cultivar (CV) <0.0001 <0.0001 0.0002 <0.0001 <0.0001

Year (Y) <0.0001

CV · Y <0.0001

White skin

Cultivar (CV) <0.0001 0.2412 0.0001 0.0013 0.041

Year (Y) <0.0001

CV · Y 0.0043

Cultivars within each skin type are listed in order of 4-year average.

Clonal designations are listed in Table 1.

Minimum signiﬁcant difference using Waller-Duncan k-ratio £0.05.

ne = not evaluated.

598

•

October–December 2007 17(4)

VARIETY TRIALS

and latest in 2005 (DOY 117) (Table

3). The 4-year average DOY for

bloom and veraison were 164 (160

to 172) and 225 (215 to 230), and

onset each year corresponded inver-

sely with growing season heat unit

accumulation. Budbreak DOY varied

more among cultivars within a skin

color group than between skin color

groups, and signiﬁcant cultivar-by-

year interaction indicates that relative

differences among cultivars varied

from year to year. The earliest culti-

vars to break bud in at least 3 of 4

years for each color group were:

‘Nebbiolo’, ‘Sangiovese’, ‘Grenache’,

‘Cabernet Franc’, ‘Lemberger’,

‘Pinotage’, ‘Merlot’, ‘Orange Mus-

cat’, and ‘Chardonnay’ (Table 3).

The cultivars last to break bud in at

least 3 of 4 years were: ‘Pinot Meu-

nier’, ‘Cabernet Sauvignon’, ‘Cari-

gnan’, and the white cultivar ‘Flora’.

‘Nebbiolo’, ‘Sangiovese’, and ‘Lem-

berger’ were also found to break bud

earlier than ‘Cabernet Sauvignon’ in

Winchester, VA (Wolf and Miller,

2001).

The number of days required

between budbreak and harvest (DTHV)

to produce fruit with optimum com-

position for wine production is

known to vary by genotype and by

growing site environmental condi-

tions. Red cultivars required 7 d more

between budbreak and harvest (163

DTHV) than white cultivars (156

DTHV), but the large range among

cultivars within each skin color group

(40 DTHV for reds and 29 DTHV

for whites) suggests sufﬁcient varia-

bility to identify relatively short-sea-

son red cultivars as well as long-

season white cultivars (Table 4). ‘Bla-

uer Portugieser’ stands out as

a relatively short-season (shortest

DTHV in at least 3 of 4 years) red

cultivar, and ‘Viognier’ and ‘Muscat

of Alexandria’ were the latest matur-

ing white cultivars. The longest sea-

son, red cultivars in at least 3 of

4 years were ‘Barbera’ and ‘Nebbiolo’,

and the shortest season white culti-

vars were ‘Orange Muscat’ and

‘Flora’. This long season trait of

‘Nebbiolo’ was not observed in Win-

chester, VA (Wolf and Miller, 2001)

where its maturity was similar to

‘Lemberger’ and earlier than ‘Caber-

net Sauvignon’. Onset of budbreak

did not always correspond with ear-

liness. For example, ‘Orange Muscat’

was early to break bud and short-

season. whereas ‘Flora’ was late to

break bud and also short-season. Cul-

tivars that break bud early would be

best suited for sites with low spring

frost risk and short-season cultivars

would be best suited for sites with

high risk of late spring and early fall

frost events.

Cultivars differed in yield com-

ponents, vegetative vigor, and har-

vest SSC (Table 5). All cultivars

produced fruit each year and the

Table 5. Yield components, pruning weight, and fruit harvest soluble solids

concentration (SSC) of red and white wine grape cultivars at Parma, ID.

Cultivar

Yield

(kg/vine)

Berry wt

(g)

Cluster wt

(g) SSC (%)

Red skin

VP 7.2 a 1.6 b 212.6 abc 24.0 cdefg

PT 7.1 a 1.1 ijk 151.4 defg 24.3 bcdef

CG 6.7 ab 1.7 ab 223.7 ab 22.9 h

PR 6.5 abc 1.6 b 207.1 abc 25.1 b

GR 6.3 abcd 1.4 ef 193.0 abcd 24.5 bcde

SG 6.3 abcd 1.5 bcd 179.5 bcde 23.5 fgh

MA 6.2 abcd 1.5 bcd 116.0 gh 23.6 efgh

BA 5.9 abcde 1.8 a 170.3 cdef 26.5 a

LE 5.8 abcde 1.3 fgh 187.7 abcd 23.5 fgh

TG 5.6 bcde 1.1 hij 134.2 efgh 24.5 bcde

DL 5.5 bcde 1.3 efg 211.7 abc 24.9 bc

PS 5.4 bcde 1.3 fgh 155.6 defg 23.79 defgh

NB 5.2 bcdef 1.5 cde 228.7 a 24.8 bc

CF 5.1 cdefg 1.2 ghij 167.4 cdef 24.1 cdefg

SZ 4.9 defg 1.4 def 127.7 fgh 24.4 bcdef

CS 4.8 defg 1.0 kl 115.3 gh 23.3 gh

BP 4.5 efgh 1.3 fghi 155.3 efgh 21.1 i

ME 4.5 efgh 1.1 jk 110.6 gh 24.2 bcdef

ZN 4.4 efgh 1.6 bc 209.4 abc 26.0 a

SY 3.7 fgh 1.2 ghij 136.0 efgh 24.3 bcdef

MN 3.6 gh 1.2 ghij 97.7 h 23.8 defg

PN 3.1 ih 1.1 ijk 98.1 h 23.7 efgh

PV 1.9 i 0.9 l 38.1 i 24.7 bcd

White skin

Muscat of Alexandria 7.9 a 3.6 a 182.3 a 23.5 a

Pinot Gris 6.5 ab 1.1 c 127.4 bc 23.7 a

Orange Muscat 5.5 bc 1.9 b 152.2 b 23.6 a

Viognier 5.0 bc 0.9 e 109.1 cd 24.3 a

Chardonnay 4.7 bc 1.0 d 106.1 cd 23.4 a

Flora 4.5 c 0.9 e 97.5 d 24.3 a

P > F

Red skin

Cultivar (CV) 0.0022 <0.0001 <0.0001 <0.0001

Year (Y) <0.0001 0.0004 0.0013 0.1565

CV · Y 0.6251 0.5874 0.1687 0.3493

2002 7.0 a 1.2 c 216.3 a 24.1 a

2003 5.2 b 1.4 ab 162.9 b 24.1 a

2004 5.3 b 1.3 b 151.1 bc 24.1 a

2005 4.3 c 1.4 a 141.6 c 24.3 a

White skin

Cultivar (CV) 0.0609 <0.0001 0.0245 0.8717

Year (Y) 0.2816 0.5063 0.9010 0.0400

CV · Y 0.5914 0.0852 0.4754 0.0784

2002 8.0 a 0.8 b 126.1 a 22.7 a

2003 4.7 c 1.5 a 126.6 a 24.3 a

2004 6.4 b 1.5 a 124.9 a 23.5 ab

2005 4.7 c 1.5 a 118.3 a 24.0 a

Cultivars within each skin type are listed in order of yield. Unless labeled otherwise, values are average of years

2002–2005.

Acronyms and clonal designations are listed in Table 1.

1 kg = 2.2046 lb, 1 g = 0.0353 oz.

•

October–December 2007 17(4) 599

4-year average yield ranged from

4.3 kg/vine in 2005 to 7.0 kg/vine

in 2002. The red cultivars ‘Zinfan-

del’, ‘Petit Verdot’, and ‘Souzao’

produced the least amount of fruit

per vine and ‘Valdepenas’, ‘Malbec’,

‘Pinotage’, and ‘Carignan’ produced

the most. The ratio of yield to prun-

ing weight is a measure of vine bal-

ance between vegetative and

reproductive growth. The yield to

pruning weight ratio for most culti-

vars was within the recommended

range of 5 to 10; however, ‘Petit

Verdot’ was 4.6, and ‘Dolcetto’,

‘Grenache’, ‘Pinotage’, ‘Pinot Gris’,

‘Flora’, and ‘Muscat of Alexandria’

were greater than 10. Berry weight is

an index of size and red wines made

from smaller berries are thought

to have more favorable character

(Kennedy, 2002). The weight of ber-

ries and clusters varied among culti-

vars with ‘Valdepenas’, ‘Carignan’,

‘Primitivo’, ‘Zinfandel’, and ‘Muscat

of Alexandria’ having the largest and

‘Petit Verdot’ the smallest.

Must SSC, TA, and pH are com-

mon indicators of fruit maturity and

known to vary by genotype and envi-

ronment. Cultivar differences in har-

vest SSC were consistent from year to

year (Table 5), but TA (Table 6) and

pH (Table 7) varied seasonally. The

4-year average must SSC at harvest of

all cultivars was 24%, but ‘Blauer

Portugieser’ was harvested at 21%

SSC because must TA was below

and pH was above target levels. ‘Bar-

bera’ was harvested at higher than

24% SSC because its level of TA was

higher and pH lower than target.

Growing season impacted the TA

and pH of red more than white

cultivars, and the relative difference

among red cultivars varied seasonally.

The average harvest pH of white

cultivars was 3.4 and was highest

in 2003, the warmest growing

season.

Evaluation of wine grape cultivar

performance requires interpretation

of fruit maturity in relation to vine

balance. The ratio of SSC to TA is an

index of quality for wine production

and higher than optimum values sug-

gest less desirable, advanced maturity.

The optimum ratio of SSC to TA

ranged from 2.7 to 3.5 for wines

produced from ‘Thompson Seedless’

(Ough and Alley, 1970). The opti-

mum ratio of SSC to TA for this

study, based on harvest criteria, was

3.4 for red and 3.0 for white cultivars.

Calculated values for fruit maturity

and yield to pruning weight averaged

over multiple growing seasons were

used to group cultivar performance

into one of three categories with three

outliers [‘Blauer Portugieser’, ‘Mus-

cat of Alexandria’, and ‘Petit Verdot’

(Fig. 1)]. Cultivars with closest to

optimum vine balance and fruit

maturity are assumed best suited to

the Parma growing site. Although not

part of the present study, one can

speculate that cultivars with advanced

fruit maturity under optimum or

higher than optimum vine balance

Table 6. Titratable acidity of must at harvest for red and white wine grape

cultivars at Parma, ID.

Titratable acidity (gL

–1

)

Cultivar

Avg 2002–2005 2002 2003 2004 2005

Red skin

Blauer Portugieser 3.48 5.00 3.75 2.48 3.83

Sangiovese 4.47 4.75 4.10 4.43 4.75

Dolcetto 4.94 5.95 4.93 3.70 5.70

Cabernet Franc 4.99 4.60 4.60 4.80 5.68

Merlot 5.02 5.38 6.15 3.90 4.65

Cabernet Sauvignon 5.06 5.40 5.45 3.78 5.78

Pinot Meunier 5.31 ne

5.40 4.18 6.35

Syrah 5.35 5.10 4.35 5.58 6.20

Pinotage 5.56 6.10 5.56 5.43 5.58

Touriga Nacional 5.57 6.10 5.60 5.03 5.95

Valdepenas 5.64 4.75 5.90 5.53 5.93

Pinot Noir 5.66 ne 4.97 5.20 6.53

Grenache 6.01 6.15 6.35 3.75 7.88

Primitivo 6.06 6.00 7.00 4.18 7.03

Lemberger 6.07 8.30 6.65 4.58 5.88

Malbec 6.34 5.63 6.35 7.30 6.10

Petite Sirah 6.36 6.20 5.80 6.05 7.33

Zinfandel 6.40 5.50 5.48 5.83 8.13

Souzao 7.44 8.50 6.15 5.93 9.20

Carignan 7.96 ne 7.65 6.05 10.20

Nebbiolo 8.01 7.60 7.50 6.05 10.70

Barbera 8.98 13.10 7.88 7.22 9.80

Petit Verdot 10.29 ne 11.75 6.10 13.03

Avg 6.13 6.32 6.06 5.09 7.05

MSD

2.26 2.49 0.69 1.25

White skin

Pinot Gris 5.67 6.70 4.70 6.03 6.03

Flora 5.92 5.60 5.68 5.18 6.98

Orange Muscat 6.23 ne 6.60 4.98 7.13

Muscat of Alexandria 6.68 ne 6.17 5.97 7.60

Chardonnay 6.76 7.50 6.53 5.78 7.80

Viognier 6.99 6.05 6.10 7.08 8.28

Avg 6.38 6.46 5.96 5.83 7.30

MSD 1.44 1.19 1.12

P > F

Red skin

Cultivar (CV) <0.0001 0.0390 0.0077 <0.0001 <0.0001

Year (Y) <0.0001

CV · Y 0.0165

White skin

Cultivar (CV) 0.0223 0.2705 0.5120 0.0999

Year (Y) 0.1620

CV · Y 0.8827

Cultivars within each skin type are listed in order of 2002–2005 average value.

Acronyms for cultivar names are explained in Table 1.

1gL

–1

= 1000 ppm.

ne = not evaluated.

Minimum signiﬁcant difference using Waller-Duncan k-ratio £0.05.

600

•

October–December 2007 17(4)

VARIETY TRIALS

may achieve better fruit composition

if harvested at a SSC lower than 24%,

cropped at a higher yield to pruning

weight ratio, or grown in a cooler

site. The advanced fruit maturity of

‘Blauer Portugieser’ when harvested

at 21% SSC (Table 5) at optimum vine

balance suggests that this cultivar is

better suited to a cooler growing site.

The high yield to pruning weight

ratio of ‘Muscat of Alexandria’ is

partly the result of large cluster and

berry size but may also be indicative

of dormant season desiccation and

sensitivity to cold injury. The clone

of ‘Petit Verdot’ evaluated in this trial

is known for low productivity. More

productive clones of this cultivar are

available but were not evaluated in

this study.

Data from this study as well

as other cultivar evaluation trials can

be used to further guide cultivar

selection within each of the groupings

depicted in Figure 1. ‘Malbec’, ‘Petite

Sirah’, and ‘Chardonnay’ were re-

ported best suited to California

Climatic Region II (Amerine and

Winkler, 1944), which is similar to

the Parma site. ‘Malbec’ and ‘Petite

Sirah’ produced well in Prosser, WA

(Nagel and Spayd, 1990) and ‘Petite

Sirah’ produced well yet was sensitive

to cold injury in Grand Junction,

CO (Hamman, 1993). Under similar

bud numbers, ‘Malbec’ yielded more

than twice the amount of fruit as

‘Souzao’ (Table 5), suggesting higher

potential for economic return. ‘Char-

donnay’ was rated cold-hardy (Ahme-

dullah, 1985; Hamman, 1993; Wolf

and Warren, 2000) and produced

good quality fruit over a wide range

of growing conditions, including

Prosser, WA (Powers et al., 1992),

Grand Junction, CO (Hamman,

1993), Winchester, VA (Wolf and

Warren, 2000), Reno, NV (Evans

et al., 2005), and British Columbia,

Canada (Reynolds et al., 2004). ‘Bar-

bera’, ‘Nebbiolo’, and ‘Carignan’

were reported best suited for California

Climatic Region III or IV (Amerine

and Winkler, 1944), which is warmer

than the Parma site, and our results

support this classiﬁcation. The high

acidity of these cultivars, despite

higher than average heat unit accu-

mulation during the years of this

study, suggests that these cultivars

may produce better balanced fruit

when grown in a site warmer than

Parma. ‘Barbera’ was reported as

cold-hardy and ‘Nebbiolo’ cold-

sensitive in Grand Junction, CO

(Hamman, 1993) and Winchester,

VA (Wolf and Miller, 2001). Basal

bud infertility was observed in ‘Neb-

biolo’ (Wolf and Miller, 2001).

‘Viognier’ grown in a site 250

GDDs warmer than Parma (Winches-

ter, VA) matured 11 d earlier but had

higher than optimum levels of pH

(Wolf and Warren, 2000), suggesting

it may be better suited to a cooler site.

‘Viognier’ was reported as cold-hardy

but had a high incidence of basal bud

necrosis (Wolf and Warren, 2000).

Pruning weight was not collected in

this study for ‘Orange Muscat’, but

its ratio of SSC to TA was 3.8,

Table 7. Must pH at harvest for red and white wine grape cultivars at Parma, ID.

Must pH

Cultivar

Avg 2002–2005 2002 2003 2004 2005

Red skin

Barbera 3.27 3.04 3.27 3.39 3.27

Nebbiolo 3.33 3.13 3.31 3.56 3.23

Souzao 3.33 3.13 3.33 3.61 3.25

Petit Verdot 3.38 ne

3.26 3.67 3.18

Lemberger 3.38 3.23 3.12 3.61 3.50

Petite Sirah 3.41 3.27 3.49 3.49 3.34

Carignan 3.43 ne 3.34 3.65 3.30

Grenache 3.46 3.36 3.24 3.90 3.30

Malbec 3.52 3.53 3.49 3.41 3.68

Primitivo 3.55 3.77 3.37 3.87 3.39

Dolcetto 3.55 3.37 3.41 3.81 3.55

Zinfandel 3.57 3.73 3.59 3.67 3.43

Cabernet Sauvignon 3.58 3.58 3.37 3.91 3.47

Pinot Noir 3.59 ne 3.51 3.81 3.49

Cabernet Franc 3.60 3.84 3.48 3.68 3.57

Pinotage 3.60 3.87 3.48 3.62 3.61

Touriga Nacional 3.61 3.61 3.45 3.76 3.62

Syrah 3.62 3.97 3.55 3.67 3.56

Sangiovese 3.63 3.53 3.59 3.69 3.65

Valdepenas 3.65 3.96 3.49 3.72 3.62

Pinot Meunier 3.67 ne 3.46 4.03 3.53

Merlot 3.70 3.81 3.58 3.71 3.71

Blauer Portugieser 3.89 3.95 3.72 4.09 3.86

Avg 3.54 3.56 3.43 3.71 3.48

MSD

0.39 0.29 0.15 0.12

White skin

Flora 3.31 3.51 3.57 3.14 3.21

Viognier 3.32 3.33 3.54 3.31 3.12

Chardonnay 3.33 3.51 3.47 3.18 3.29

Muscat of Alexandria 3.36 ne 3.47 3.35 3.30

Pinot Gris 3.40 3.48 3.51 3.33 3.37

Orange Muscat 3.40 ne 3.46 3.31 3.43

Avg 3.35 3.46 3.50 3.27 3.29

MSD 0.11 0.11 0.15

P > F

Red skin

Cultivar (CV) <0.0001 0.1095 0.1114 0.0055 0.0010

Year (Y) <0.0001

CV · Y 0.0296

White skin

Cultivar (CV) 0.3474 0.4215 0.1845 0.1591

Year (Y) 0.0003

CV · Y 0.0644

Cultivars within each skin type are listed in order of 2002–2005 average value.

Clonal designations are listed in Table 1.

ne = not evaluated.

Minimum signiﬁcant difference using Waller-Duncan k-ratio £0.05.

•

October–December 2007 17(4) 601

suggesting inclusion in this group.

‘Orange Muscat’ produced high-

quality wine in Prosser, WA (Nagel

and Spayd, 1990) and was rated

superior to ‘Muscat of Alexandria’

(Amerine and Winkler, 1944).

The majority of cultivars in this

study had optimum vine balance with

advanced fruit maturity. ‘Lemberger’,

‘Zinfandel’, and ‘Primitivo’ had closest

to optimum maturity. ‘Lemberger’ is

reported best suited to California Cli-

matic Regions I and II (Amerine and

Winkler, 1944), which is cooler or

similar to the Parma site. ‘Lemberger’

was found to be cold-hardy in Prosser,

WA (Ahmedullah, 1985), Grand Junc-

tion, CO (Hamman, 1993), and

Winchester, VA (Wolf and Miller,

2001) and produced fruit in Reno,

NV (Evans et al., 2005). ‘Zinfandel’

is best suited to California Climatic

Regions II and III (Amerine and

Winkler, 1944), which is similar to

the Parma site. ‘Primitivo’, a selection

from the same cultivar as ‘Zinfandel’,

was reported to have earlier fruit

maturity and superior production

attributes than ‘Zinfandel’ in the cen-

tral San Joaquin Valley (Fidelibus,

2005). ‘Zinfandel’ was found to be

cold-sensitive in Grand Junction, CO

(Hamman, 1993) and produced

mediocre quality wine in Prosser, WA

(Nagel and Spayd, 1990). In this study

under similar bud number, ‘Primitivo’

yielded twice the amount of fruit

as ‘Zinfandel’ (Table 5), suggesting

greater potential economic return.

The Bordeaux cultivars ‘Cabernet Sau-

vignon’, ‘Merlot’, and ‘Cabernet

Franc’ yielded similarly in this study

and performed well in Grand Junction,

CO (Hamman, 1993). ‘Cabernet

Franc’ produced fruit in Reno, NV

(Evans et al., 2005), and ‘Merlot’

performed well in Napa Valley, CA

(Benz et al., 2006), the Okanagan

Valley, British Columbia, Canada

(Reynolds et al., 2004), and Prosser,

WA (Powers et al., 1992). Mild cold

injury has been observed on ‘Cabernet

Sauvignon’ (Wolf and Miller, 2001)

and ‘Merlot’ (Ahmedullah, 1985;

Hamman, 1993). ‘Syrah’ performed

well in Grand Junction, CO, had

inconsistent quality in Winchester,

VA (Wolf and Miller, 2001), and

was sensitive to cold injury (Hamman,

1993; Wolf and Miller, 2001). ‘Pinot

Noir’ is best suited for California

Climatic Region I (Amerine and Win-

kler, 1944), which is cooler than the

Parma site. ‘Pinot Noir’ has been

evaluated in Prosser, WA (Ahmedul-

lah, 1985), the Willamette Valley, OR

(Castagnoli and Vasconcelos, 2006),

Reno, NV (Evans et al., 2005), Los

Carneros, CA (Mercado-Martin et al.,

2006), and the Okanagon Valley

(Reynolds et al., 2004) and is

reported as more cold-tolerant than

the Bordeaux cultivars (Ahmedullah,

1985; Hamman, 1993). ‘Sangiovese’

and ‘Valdepenas’ produced fruit of

mediocre quality and were less cold-

hardy than ‘Cabernet Sauvignon’ in

Winchester, VA (Wolf and Miller,

2001). No comparative trial results

were found in the literature for ‘Tour-

iga Nacional’.

Three red (‘Grenache’, ‘Pinot-

age’, and ‘Dolcetto’) and two white

(‘Flora’ and ‘Pinot Gris’) cultivars

produced fruit with advanced matur-

ity when cropped at higher than opti-

mum vine balance. ‘Grenache’ has

been reported best suited for Califor-

nia Climatic Regions I and II, which

is cooler or similar to the Parma site,

and to have low heat tolerance

(Amerine and Winkler, 1944). ‘Gren-

ache’ was rated cold-hardy (Ahme-

dullah, 1985) in Prosser, WA.

Comparative data were not available

for ‘Dolcetto’ or ‘Pinotage’. The

white cultivars ‘Flora’ and ‘Pinot

Gris’ produced high-quality wine

(Nagel and Spayd, 1990) and ‘Pinot

Gris’ produced fruit in Reno, NV

(Evans et al., 2005). In this study,

‘Pinot Gris’ yielded more fruit than

‘Flora’ (Table 5), suggesting higher

potential economic return.

Conclusions and grower

beneﬁts

Matching germplasm to site

location is a fundamental viticultural

practice to enhance yield and fruit

quality. Results from this study

describe the viticultural performance

of a diverse collection of red and

white wine grape cultivars as a guide

to aid cultivar selection for planting

sites. Knowledge of heat unit accu-

mulation and freeze events in an

intended new planting site is a critical

prerequisite for using the results from

this research. The vines evaluated in

this study were planted after the

last major cold event (Feb. 1989)

where temperatures reached a mini-

mum of –30 C. Future temperatures

may not be as moderate as the

years observed during this study and

reported cold-hardiness data from

other trial sites should be considered.

Fig. 1. Four-year average values for harvest fruit maturity [ratio of soluble solids

concentration (SSC) to titratable acidity (TA)] and yield to pruning weight ratio of

red and white cultivars evaluated at Parma, ID. Optimum values for vine balance

and fruit maturity are depicted as lines on each axis. Cultivar acronyms are listed in

Table 1.

602

•

October–December 2007 17(4)

VARIETY TRIALS

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•

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