Frontenac - MN 1047.
Description: Introduced in 1996, Frontenac is the first in a
series of new wine grape varieties developed by the
University of Minnesota for Upper Midwest conditions. A
cross of V. riparia 89 (University of Minnesota 89) with the
French hybrid Landot 4511. The cross was made in 1978;
selected in 1983 and tested as MN 1047. Frontenac
combines many of the best characteristics of each parent.
Hardiness: -35F or colder. Frontenac is a very cold hardy
vine and has borne a full crop after temperatures as low as 33 F.
Viticultural Characteristics: The vine is described as
having moderately high vigor; a slightly upright growth habit
and arching canes. It produces only a moderate number of
tendrils, which facilitates vine management. Cane prune and
cluster thin to keep vine from overproducing. Several
training systems have been used by growers including high
bilateral cordon, vertical shoot positioning (VSP) and
Geneva Double Curtain (GDC). Bud break occurs early
midseason and cluster thinning and shoot thinning may be
needed in some years. It is advised that the grapes be
allowed to hang as long as possible to help reduce the
rather high acid. 100 days from bloom to harvest.
Disease/Pests: It is also a very disease resistant variety
with good resistance to powdery mildew and near-immunity
to downy mildew. Exhibits a tolerance to 2,4-D. Frontenac
is rated as moderately susceptible to black rot, Botrytis bunch rot and powdery mildew; slightly susceptible to
downy mildew and Phomopsis cane and leafspot . It
is also rated as slightly susceptible to anthracnose. It
is not sensitive to injuries from sulfur applications and
it is not sensitive to injuries from copper applications.
It is susceptible to foliar phylloxera.
Grape Characteristics: Initially acids are high, but
often drop dramatically late in the season.
Fortunately, the pH does not often rise to dangerous
levels. Frontenac ripens in late mid-season (mid-late
September). When grown in colder areas the berries
must be left on the vine long enough to mature fully
for the acidity to come down before picking. Average
harvest chemistry from the HRC vineyard (20032005):
°Brix: 25.1
TA: 15.4 g/L
pH: 2.9
The berry is described as small to medium in size
and bluish-black. The berries have high skin to pulp
ratios and colored pulp (these traits result in intense
juice color).
Clusters are medium sized; conical in shape and have a small shoulder. Clusters are loose and berry splitting
and bunch rot are rare, even in wet years. The typical cluster averages 152 g (.34 lb) in weight and 18 cm (7
in) in length.
Wine Profile: Frontenac's deep garnet color complements its distinctive cherry aroma and inviting palate of
blackberry, black currant, and plum. This versatile grape can be made into a variety of wine styles, including
rosé, red, and port.
Modifications in winemaking strategies are necessary to take advantage of Frontenac's four variations from
traditional wine grapes. It is more highly colored than
most V. vinifera, it has higher sugar and acid content at
harvest, and it tends to have low tannin.
Good canopy management practices are essential to
reduce acidity during veraison, and minimize herbaceous
character in the wine. Frontenac is also often mistakenly
harvested when the sugar level approaches 23° Brix. In
Minnesota, grapes harvested at 23° Brix can have acidity
levels >16 g/L (1.6%), which is extremely difficult to
correct in the winery. It is not uncommon for Frontenac to
reach 25° Brix or more prior to harvest. Proper vineyard
sampling and the testing of acidity is the best way to
determine the right time to harvest. Regardless of desired
style, letting the fruit hang until the acid falls below 15g/L
(if possible) is the best way to ensure palatable acidity in
the final product
Rosé and Sweet Red. Frontenac berries are small, have
high skin-to-pulp ratios, and tend to have colored pulp.
These traits result in intense juice color. For rosé
production, this means that immediate crushing and
pressing, without the few hours of skin time allowed in
traditional rosé production, results in an intense and
attractive rose-colored juice. It may be possible to fine to
produce a color more traditional and delicate. However,
fining trials are essential to minimize the risk of a sickly
salmon-colored result. For sweet red wines, 1-2 days of maceration are all that are necessary to achieve a
true red color.
Cool (55°F) fermentation with an aromatic yeast, like Cotes de Blancs, is recommended. Acid-reducing yeasts
(e.g. 71B) have reduced the post-fermentation titratable acidity (TA) 2-3 g/L while maintaining desirable
aromas and flavors. Malolactic fermentation is not a recommended acid-reducing strategy for rosé and sweet
red wines. If potassium sorbate, a yeast inhibitor, is used after MLF to prevent bottle fermentation, an intense
and unpleasant geranium odor develops. Cold-stabilization, followed by chemical reduction in acidity is
essential. The low pH of Frontenac enables significant chemical reduction of acidity without raising the pH to
an unsafe level. Slight amelioration can be used to reduce the alcohol below 14% while reducing the acidity
as well. The nose and palate showcase a bright cherry note that is enhanced by an off-dry finish and
moderate acidity. Depending on the fruit, sugar levels from bone dry to moderately sweet have shown
appropriate balance and customer acceptance.
Dry Red. Flavors and aromas of Frontenac table wines can range from simple to quite complex. Typical skin
time ranges form 5-8 days, with caps punched a minimum of thrice daily. The resulting color is a dark,
attractive garnet. Pre-fermentation pectinase addition is not recommended, as it inhibits good cap formation.
In research trials, high-extracting yeasts (Pasteur Red, RC 212, BM 45), with long maceration times have
produced the most complex wines.
Malolactic fermentation is essential for the production of a traditional red table wine. The combination of high
alcohol and low pH are difficult conditions for ML bacteria. Tolerant, aggressive strains should be selected
and added when the wine is about 2/3 finished with primary fermentation. Adding ML bacteria during primary
allow them to adapt to higher alcohol levels, and will reduce the potential for a sluggish secondary
fermentation. After the completion of MLF, cold-stabilization followed by chemical reduction of acidity is typical
to bring the wine into balance.
Oak chips, staves, spirals, and barrels interact well with Frontenac wine. All can increase aromatic and flavor
complexity, adding notes of vanilla, anise, clove, and other spices. Barrel aging also increases the
concentration of flavors in the wine and enhances the structure. Enological tannins are available, but can
create a disharmonious mouthfeel if too much is added. As more tannin products are available and more
winemakers experiment with them, this option may become more approachable, but the inexperienced should
approach it with caution.
Port. A few creative producers have used Frontenac to produce port-style wines of outstanding quality. In
port production, fermentation is stopped through the addition of grape neutral spirits while sugar content is still
high, resulting in a product with higher sugar and 15-20% alcohol. The higher acid levels balance the
increased sugar beautifully, deepening the typical fruit notes into lush shades of cherry, raspberry, black
currant, and stewed fruits. Some Frontenac ports exhibit pronounced chocolate notes, which seems
dependent on vineyard microclimate. This dessert wine is a showstopper; a Frontenac port won a consensus
gold at the 2004 Indy Wine Festival. It wouldn't be surprising to see an increase in commercial production in
the coming seasons.
Marquette - Minnesota 1211
Description: Marquette was officially introduced in 2006.
Cross originally made in 1989; selected in 1994, tested as
MN 1211, and released in 2006. Patent applied for in
2005. Marquette is a cousin of Frontenac and grandson of
Pinot noir. It originated from a cross of MN 1094, a
complex hybrid of V. riparia, V. vinifera, and other Vitis
species, with Ravat 262. Its open, orderly growth habit
makes vine canopy management efficient. Named after
Pere Marquette, a Jesuit missionary and explorer in
America in the second half of the 17th century.
Hardiness: -35F.. Very hardy (-20° F to -30° F). It’s been
reported to have withstood temperatures as low as -36° F
without serious injury.
Viticultural Characteristics: The vine has moderate vigor
with an open, somewhat upright and orderly growth habit,
which is desirable for efficient vineyard management and
fruit exposure to the sun conducive to maximizing wine
quality. Shoots typically have two small to medium clusters
per shoot, avoiding the need for cluster thinning. Bud
break is somewhat early, leaving it vulnerable to frost,
however it is moderately productive on secondary buds. It
is moderately susceptible to injury from 2,4-D and dicamba.
Disease/Pests: Based on observations compiled over four
years (2002-2005) at the University of Minnesota Horticultural Research Center, Marquette has a low
susceptibility to black rot, bunch rots (Botrytis, etc), downy mildew and powdery mildew. They report that it is
moderately susceptible to foliar phylloxera and crown gall has not been observed.
Grape Characteristics: Viticulturally, Marquette is outstanding. A high sugar and moderate acidity red wine
grape. Average harvest chemistry numbers from the HRC vineyard (2003-2005):
°Brix: 25.7-26.1
TA: 12.3-12.1 g/L
pH: 2.9-2.95
The berry is roundish in shape and small
to medium in size (average berry weight is
1.14 g); black skin with a bluish bloom and
light pink pulp. They report that neither
berry shelling nor splitting have been
problems.
Clusters are reported to be small to
medium (average cluster weighs .20 lb
and is 4.2 inches long); slightly conical;
and sometimes with one shoulder .
Wine Profile: Marquette’s high sugar and
moderate acidity make it very manageable
in the winery. Finished wines are complex,
with attractive ruby color, pronounced
tannins, and desirable notes of cherry,
berry, black pepper, and spice on both
nose and palate. As a red wine, Marquette
represents a new standard in cold hardy viticulture and enology.
Wine style. Marquette is best when utilized as a medium-bodied red table wine. Maceration (fermenting on
grape skins and seeds) for 7-8 days is recommended for optimal extraction of tannins. Marquette color is
typically moderate, and can endure longer maceration times without becoming dark and inky. Extended
maceration trials have not yet been conducted. High-extracting yeast strains have produced with intense fruit
and complexity, and moderate palate structure.
Management of acidity. While harvest acidity is lower than Frontenac, malolactic fermentation is highly
recommended for both acid reduction and increased wine complexity and mouthfeel. It is very important to
select a bacterial strain that can tolerate both low pH and high alcohol levels. Culture addition just after
maceration (after pressing), but while the juice is still fermenting, helps prevent sluggish or stuck secondary
fermentations. A slight acid reduction with potassium bicarbonate may be necessary as well to bring the wine
into balance. Final TAs of 6.5-7.5 g/L can be achieved without raising pH excessively.
Alcohol Management. High sugar levels at harvest often lead to high alcohol levels in the finished wine
(>14%), which may be a problem for some commercial wineries. Yeast strains exist which produce less
alcohol and more glycerol, which adds body. Amelioration is a possible solution, but the addition of water can
dilute the intensity of flavors and reduce body. Another solution is to blend a low-alcohol red wine into
Marquette to reduce total alcohol percentage below 14%. Blending has the added benefit of potentially
reducing wine acidity, and increasing overall wine complexity.
Cooperage. Studies on the interaction of oak aroma and flavor with Marquette have only recently begun, but
early impressions are very positive. Both French and American oak chips have been found to increase overall
wine complexity. Barrel aging additionally concentrates the wine aromas and flavors, increases body and
structure, and prolongs the lifespan of a wine in the cellar.
Swenson Red - Elmer Swenson 439
Description: Swenson Red was selected and introduced in 1978
by Elmer Swenson and the University of Minnesota when Mr.
Swenson was on the staff at the U of M Horticultural Research
Center. Minnesota #78 (‘Beta’ x ‘Witt’) x Seibel 11803.
Interspecific hybrid (includes V. labrusca and V. riparia). Crossed
in 1962; selected in 1967 (4, 8). Released jointly by Elmer
Swenson and the University of Minnesota in 1978. This
midseason, red, seeded grape is one of the highest quality
selections produced by Mr. Swenson with its large clusters,
refreshing flavor, tender skin, and crisp texture.
Hardiness: Hardy to -25F to -30F. It should be grown with
winter protection in USDA Hardiness Zone 4. Hardy (-15° F) but
less hardy than the other Swenson cultivars. Vines have survived
-25 to -30° F, without protection in the upper Midwest, but are not
considered hardy enough to fruit well without cover.
Viticultural Characteristics: Vigorous and with a procumbent
growth habit. Tends to be overly productive; cluster thinning may
improve fruit maturity.
Training: TWC.
Disease Resistance: Very susceptible to downy mildew in some
sites and years. Swenson Red is rated as highly susceptible to
downy mildew; moderately susceptible to Botrytis bunch rot and
powdery mildew; and slightly susceptible to black rot and crown
gall. It’s uncertain whether it is susceptible to anthracnose, crown
gall, Eutypa dieback or if it is sensitive to injury from sulfur or copper applications.
Black Rot - Slight
Powdery Mildew - Moderate
Downy Mildew - High
Bortrytis - Slight
Sulfer Sensitive - ?
Grape Characteristics: The berry is a medium to large; round to slightly ovate; dark red to lavender with a light bloom,
seeded table grape. Firm meaty texture with thin tender edible, non-slipskin, seeded, fruit keeps well in refrigerator.
Produces large bunches with large, red berries that may turn reddish-blue if harvested late. This cultivar is reminiscent of
a European table grape. It is capable of reaching high sugar levels. The cluster is medium in size; conical; slightly loose
to very compact, with a single shoulder. Primarily a seeded table grape, but suitable for wine. Keeps well in cold storage.
Wine Profile: Incredible strawberry-like flavor, much like a good seeded California table grape. Swenson noted the flavor
is rich, fruity but non-labrusca in character. Fermentation on the skins is not recommended.
White Grapes
Frontenac Blanc
The original 'Frontenac', introduced by the University of Minnesota in 1996, is a dark blue-fruited cultivar originating from a
cross of Vitis riparia x Landot 4511. 'Frontenac gris' was discovered in a University of Minnesota test vineyard as a
naturally occurring, single bud mutation of Frontenac back in 1992. More recently, several growers in Minnesota and
Canada have independently discovered white-fruited mutations of Frontenac and Frontenac gris that have now come to
be known as 'Frontenac blanc'. 'Frontenac gris' produces pigment (anthocyanins) only in the outer layers of cells of the
berry, just under the skin, giving the berry a grey or bronze color and producing a white or slightly pigmented wine. These
Frontenac blanc lines lack pigment and make white wine.
Initial trial vinifications of Frontenac blanc indicate that it produces wines that are distinctly different from Frontenac gris in
flavor and aroma. The University of Minnesota plans to evaluate and characterize Frontenac blanc lines as they are made
available and nurseries intend to sell Frontenac blanc in 2012.
Frontenac Gris – MN 1187.
Description: Frontenac gris was originally identified as a single
bud sport cane found growing on a Frontenac vine at the
University of Minnesota Horticultural Research Center. Frontenac
is an Interspecific hybrid (including V. vinifera and V. riparia)
derived from a cross between the French hybrid cultivar Landot
4511 and the University of Minnesota Vitis riparia selection #89,
found growing wild near Jordan, Minnesota.
Selected by the University of Minnesota and introduced in 2003.
Culturally, it is identical to Frontenac, having high vigor and yields.
Hardiness: Hardy to at least -38 F. Zone 3.
Disease Resistance: Disease resistance is good, with moderate
susceptibility to powdery mildew and black rot, and very low
susceptibility to downy mildew. Botrytis has not been observed.
Black Rot - Moderate
Powdery Mildew - Slight
Downy Mildew - Moderate
Bortrytis - Slight
Sulfer Sensitive - ?
Grape Characteristics: Small grey (thus named gris) berries
are born on medium sized, loose clusters. The berries have been
described as round; small to medium (average berry weight is
1.13 g/berry); grayish amber with a waxy bloom and clear juice.
Berry shelling and splitting have not been problems. The clusters
of Frontenac gris are loose and medium in size (averaging 131
g/cluster and 18 cm (7 in) in length); and are conical with a small
shoulder. Berry splitting has not been observed. Ripens late mid season, and are good sugar producers with 24-25° Brix
not uncommon. Average harvest chemistry from the HRC vineyard (2003-2005):
°Brix: 26.0
TA: 14 g/L
pH: 3.0
Viticultural Characteristics: Frontenac gris vines are considered to have moderately high vigor with a slightly upright
and open growth habit. Several training systems have been used for Frontenac, including high bilateral cordon, vertical
shoot positioning (VSP), and Geneva Double Curtain (GDC). Bud break
and bloom occur early to midseason and as it is typical for shoots to
produce three clusters, cluster thinning may be needed, especially on
young vines. VSP is preferred to reduce acidity. Arching canes and
minimal tendrils provide easy training and pruning to simplify vine
management.
Wine Profile: Frontenac Gris yields an amber-colored juice. Aromas
include peach, apricot, citrus, and pineapple with hints of enticing citrus
and tropical fruit. Unique and complex flavors make this an excellent
grape for table, dessert, and ice wines. A brilliant balance of fruit and
acidity creates lively, refreshing wines. Labrusca and herbaceous
aromas have not been detected.
Fermentation temperature and yeast. To retain fruity esters, Frontenac
gris is best fermented at cool temperatures (55°F) with aromatic yeasts.
Due to the high sugar, yeasts that can tolerate high alcohol levels are
necessary to ferment Frontenac gris to dryness. Acid-reducing yeasts have also been utilized successfully greatly
diminishing aromatic intensity.
Sweet and Dessert wine production. Frontenac gris benefits from residual sugar, which balances the high acid and
intensifies the rich fruit character. The key to successful palate balance in sweet wines is the retention or addition of
appropriate sweetening. This can be accomplished three ways: by stopping fermentation, by back-adding sugar, or by
reserving juice at harvest and blending it in following fermentation.
Stopping Fermentation: One means of achieving an appropriate acid:sugar ratio is by stopping fermentation, either by
filtration or cold-stabilization. Membrane filtration (not plate-and frame) at 0.45 or smaller should stop fermentation
instantly. Stopping fermentation via cold-stabilization is tricky, as it can take hours to days for the yeast to cease activity.
This delay is largely dependent upon the equipment and conditions available. Of these methods, filtration is much easier
for commercial wineries, as the lag between action and cessation of fermentaion is greatly diminished. Less aggressive,
aromatic yeasts are desirable, as these strains tend to slow down as alcohol levels increase. Preserving some of the
natural sugar in the wine can increase aromatic intensity and mouthfeel. This technique has the added benefit of keeping
alcohol levels
moderate.
Back-adding sugar
sweetening
to complete
technique has the
to perform bench
prior to adjusting the
tuned to a desired
or juice: The simplest way of
Frontenac gris is to ferment the wine
dryness, then back-add sugar. This
advantage of allowing the winemaker
trials of various sweetness levels
wine, so the final product can be finelevel of sweetness.
Another backreserving a portion
rest of the juice to
reserved juice to
character. Care
juice; usually this
clarified, treated
sweetening method involves
of juice at press time, fermenting the
dryness, then back-blending the
provide sweetness and intense fruit
must be taken in storing the reserved
portion (called sussreserve) is
with SO2 and frozen until needed.
In either case, it's
have been
inactivated with
much preferred, as
sorbate additions
chemical off-note in
important to make sure that yeast
removed, via sterile filtration, or
potassium sorbate. Sterile filtration is
the necessary inhibitory rate of
can vary, and may produce a
wines if overused.
"Faux" Ice Wine: Trials with faux ice wine have shown tremendous potential. This extremely sweet dessert wine can
produced two ways: by freezing grapes after harvest and pressing them frozen (which requires a specialized press) or
freezing juice after pressing and allowing slow thawing to control °Brix. Traditional ice wine (letting fruit freeze on the vine)
decreases overall vine hardiness and can result in significant injury in harsh winters.
Off-dry table wine. Frontenac gris table wines are best finished with some residual sugar, to boost the perception of fruit
and balance acidity. As with dessert wines, residual sugar can be achieved by stopping fermentation or back sweetening.
Attempts to reduce acidity with malolactic fermentation (MLF) have not been successful, as the diminished fruit tends to
leave the wine too acidic. Frontenac gris table wines are usually ameliorated to reduce alcohol and acidity, and often
treated with potassium bicarbonate or other chemical deacidification method to bring the wine into balance.
Brianna Grapevines - 7-4-76
Description: Elmer Swenson Variety. An interspecific hybrid
(includes V. labrusca and V. riparia) of Kay Gray x E.S. 2-12-13.
Cross made in 1983; selected in 1989 as a table grape and
2001 as wine grape. Named by Ed Swanson in 2002.
Introduced in 2001 but not patented.
Hardiness: Zone 4 Winter hardy in South Dakota
Training Method: VSP
Viticultural Characteristics: Brianna is vigorous and has a
semi-procumbent growth habit. It is easily managed in the
vineyard. It is productive on secondary buds and cluster thinning
is not necessary. It is somewhat susceptible to 2, 4-D,
moderately susceptible to dicamba and sensitive to endosulfan.
Disease/Pests: Brianna is reported to be highly susceptible to
crown gall; moderately susceptible to black rot and Botrytis
bunch rot; and slightly susceptible to downy and powdery
mildews. It is not sensitive to injury from sulfur applications, and
it is not known if it is sensitive to injury from copper. The foliage
is not normally affected by leaf phylloxera .
Grape Characteristics: The Berry is Medium-large in size and round in shape; thick-skinned greenish-gold berries
which turn gold when fully ripened. The clusters are medium-small tight clusters. The average cluster weight was .24 lb.
Wine Quality and Characteristics: Brianna can be made into a semi-sweet white wine with pronounced pineapple nose;
and hints of apricot, peach, and honey flavor when fully ripe. He also noted that for light table wines with more grapefruit,
tropical, and slight floral characteristics, Brianna is best harvested between 3.2-3.4 pH. The grapes are high in pectin, and
need extra enzymes for good juice yield. A lovely fruity nose. Also makes a good white juice
Louise Swenson - E.S. 4-8-33
Description: This selection is an interspecific hybrid (includes V. labrusca
and V. riparia) of E.S. 2-3-17 x Kay Gray. Cross made in 1980; selected in
1984; introduced in 2001.
Hardiness: -40F, Zone 3. This variety has shown little or no winter injury
even in the most severe (-40 F) winters.
Training Method: TWC
Viticultural Characteristics: Louise Swenson is moderately vigorous with
an orderly growth habit that is trailing to semi-upright which does well on a
VSP. It a smaller vine requiring closer spacing, and that it is somewhat slow
to become established. They also note that it has shown some sensitivity to
droughty conditions and may benefit from irrigation in dry, sandy soils in dry
years. Cluster thinning not needed. It buds out relatively late in the spring
compared to other interspecific hybrid grape varieties. The clusters hang
free of the tendrils. Perfect flowers. Mildew resistance and good winter
hardiness.
Disease/Pests: Disease resistance generally very good; some susceptibility to
anthracnose. Louise Swenson shows very good resistance to black rot, downy
mildew and phylloxera and hasmoderate resistance to powdery mildew.
Observations on very sandy sites suggest that Louise Swenson may be sensitive
to droughty conditions. On sites of this type, irrigation may be required in dry
years.
Grape Characteristics: The berry is medium sized and round averaging
around 3 g. Clusters are small to medium, conical, somewhat compact, and
average 105 g (range 70-130 g), (average cluster weight is .23 lb). Louise
Swenson rarely exceeds 20 Brix, even if left to hang past midseason. Yellowgold when fully ripe. The clusters hanging free of tendrils.
Wine Quality and Characteristics: The wine is without any negative hybrid
characteristics, and has a typical delicate aroma of flowers and honey. Said to be
reminiscent of a white burgundy. This wine’s only significant fault is that it is
rather light in body. Acidity is moderate and needs no reduction. This grape
should be grown much more widely in the North for its consistent wine quality,
outstanding winter hardiness, and good cultural behavior. Hardy white wine grape. Low sugar but moderate acidity. The
wine has a typical delicate aroma of flowers and honey. Wine is light in body. Blending with a variety such as Prairie Star
makes it a more complete wine.
Petite Amie - DM-8313-1 CV
Description: A white wine grape with muscat flavors. The Petit
Ami Grape is an interspecific hybrid (includes V. vinifera, V.
riparia) of ES 2-11-4 [ES 5-14 x Swenson Red] x DM P2-54
[Suelter x Morio Muscat]. Bred by David MacGregor. The cross
made in 1983; selected in 1987 and tested as DM 8313.1. Petite
Amie was named in late 2004 or early 2005 by Ed Swanson, with
the permission of David MacGregor . U.S. Plant Patent PP17,773
received on May 29, 2007.
Hardiness: Very hardy (-25° F). Shown to be hardy in milder
regions of zone 4.
Training Method: VSP
Viticultural Characteristics: Petit Ami Grape has a healthy vine
with average productivity, good sugar/acid levels. This grape
tolerates a wide range of soil conditions, but must have good drainage. Low to moderate vigor and a procumbent growth
habit. Grafting is recommended or planting on high vigor sites to reduce commercial size crops. Bud break occurs
midseason.
Disease/Pests: Good disease resistance. Under normal spray schedules, good disease control can be expected. ‘Petite
Amie’ may be slightly susceptible to black rot in wet years and anthracnose, and Muscat speckle occasionally on the
leaves.
Grape Characteristics: The berry is small (2 g/berry); round and yellowish green. The skin is thin and the flesh is soft
and juicy. The berries do not split following rains and adhere well to the fruit peduncle and do not shatter during harvest.
The cluster size is small to medium (10 inches long and 0.44 lb/cluster); and the shape as cylindrical to conical; and
moderately well-filled, but not compact. The clusters are capable of hanging in good condition for late harvest. Average
harvest parameters include:
soluble solids near 18° Brix
pH of 3.4
titratable acidity close to 9 g/liter.
Petite Amie is usually harvested before the pH gets above 3.4; this will vary with soils and climate.
Wine Quality and Characteristics: Vitis 'Petit Ami is a white grape that makes an excellent Muscat wine with just a hint
of rose petal in the nose. Petite Amie has produced excellent wines and describes the wine as having a fine Muscat
flavor similar to Muscat blanc. The wines have a wonderful smell of fresh roses and tend to develop tropical taste and
nose over time.
Prairie Star
-40F
Also known by the synonym name ES 3-24-7. Is a cross between ES
2-7-13 and ES 2-8-1. Developed by Elmer Swenson in 1980 and
released around 1994. Harsh-cold (to -40 deg. F) tolerant, this variety
is quite disease resistant other than a susceptibility to easily
controllable Anthracnose. Reported as capable of making a neutral
varietal wine in most years it is currently used to add body and finish
to such other white wines as Louise Swenson.
Hardy white wine grape. Neutral wine generally used for blending
with lighter white wines to add body to other white wines like Louise
Swenson. In some years the wine has floral nose allowing it to stand
alone as a varietal. Moderately resistant to powdery and downy
mildew.
Extremely winter hardy (to -40F), Disease resistant other than a susceptibility to easily controllable Anthracnose. Makes a
neutral varietal wine in most years it is currently used to add body and finish to such other white wines as Louise
Swenson.
Extremely winter hardy (to -40F), Disease resistant other
than a susceptibility to easily controllable Anthracnose.
Makes a neutral varietal win e in most years it is currently
used to add body and finish to such other white wines as
Louise Swenson.








Primary Use: Wine
Hardiness: Zone 3
Color: White
Harvest Season: Mid
Suggested Training Method: VSP
Disease Susceptibility:
o Black Rot - Moderate
o Powdery Mildew - Slight
o Downy Mildew - Slight
o Bortrytis - Slight
o Sulfer Sensitive - ?
 Synonyms: E.S. 3-24-7 (1, 5, 6).
 Pedigree: E.S. 2-7-13 x E.S. 2-8-1 (1, 5, 6).
 Origin: Osceola, Wisconsin. Developed by Elmer
Swenson (1, 5, 6).
 Cross/Selection/Test: Cross made in 1980;
selected in 1984, tested as E.S. 3-24-7 (1). Named by Tom
Plocher and Bob Parke in2000
 Introduction: 2000 (1).
Type: Interspecific hybrid (including V. vinifera, V. rupestris, V. labrusca, V. aestivalis) (1).
Color: White


Berry: Medium sized and round; yellow, and thick skinned (1). Average weight is 2.5 g/berry (6).
Cluster: According to Plocher and Parke (6), the clusters are long, slightly loose and have a very characteristic
“C” curve. They reported the average cluster weight is 177 g (or 0.39 lb) on heavy soils and on lighter or less
fertile soils, weight will be less (6). Prone to poor berry set when rain occurs during the early stages of bloom (4).
 Viticultural Characteristics: Domoto (2) described ‘Prairie Star’ as vigorous and having a semi-upright growth
habit. He added that bud break is mid-season and that secondary buds are moderately productive. Cluster
thinning is not necessary. Plocher and Parke (6) stated that early in the season, young shoots may have a
tendency to break off in strong winds and high cordon training systems should be avoided. They also reported
that poor fruit set has been seen in some seasons and this may be due to that fact that ‘Prairie Star’ tends to
have rampant shoot growth during flowering and fruit set. They suggest one method to counter this is to pinch off
the ends of the apical shoots just prior to flowering.
 Disease/Pests: Domoto (2) reported that ‘Prairie Star’ is moderately susceptible to black rot and anthracnose;
and slightly susceptible to downy mildew and powdery mildew. It is not known if it is prone to Botrytis bunch rot
and crown gall (2). Also, Domoto reported it to be moderately susceptible to injuries from 2,4-D and dicamba,
and it is not known if it is sensitive to injuries from sulfur. Some growers have reported using copper without
problems (7).
Wine Quality and Characteristics: Plocher and Parke (6) described the wine as being neutral, non-foxy and having a
fullness in the mouth and finish uncommon among hybrid grape varieties. They further stated that in some years it can
have a delicate floral nose and capable of standing alone as a varietal wine, but in most years it is an ideal blending
component to add body and finish to thin white wines. They noted that the fruit matures to excellent sugar and acidity for
winemaking. Sugar content typically runs 21° to 22° Brix.
Season: Early [mid-September in St. Paul, MN (6); mid- to late-August in Iowa (3)].
Cold Hardiness: Very hardy (-20° F to -35° F). (1, 2, 5) The original seedling had more than 50% bud survival after a
mid-winter low of -40° F (1)
Use: Wine, fresh eating
Notes: Plocher (7) shared that ‘Prairie Star’ was named at the same time as ‘Louise Swenson’ because the two go well
together as blending partners. He added that ‘Louise Swenson’ has the delicate aromatics and ‘Prairie Star’ has the body
and finish that ‘Louise Swenson’ lacks. Together they are better than either one alone.
St. Pepin
-26F
A sister seedling of LaCrosse but hardier, to around -26 F. This variety
is pistallite, meaning that it has only female flowers and must be planted
near other varieites to ensure proper fruit set. It should be pruned to a
high bud count to make sure there is adequate fruit production. Small
berries are formed on medium loose clusters. Ripens mid season to
about 20 brix and 1.0% total acidity. One row of St. Pepin next to one
row of another variety will do well. Excellent wines have been made
from St. Pepin as a varietal and also blended with LaCrosse. When well
ripened, fruit quality is similar to Reisling. Selected by Elmer Swenson.
Winter protection in most SD locations. White early ripening grape.
When well ripened, fruit quality is similar to Reisling. Also good juice or
table grape. This variety is pistillate (flowers female only) and must be
planted near other grape varieties that bloom at same time (LaCrosse)
for cross pollination.
Sister seedling to La Crosse the variety is pistallite (female flowers only) Other varieties are needed to get fruit set. When
well ripened has a style similar to Riesling.
Sister seedling to La Crosse the variety is pistallite (female flowers only) Other varieties are needed to get fruit set. When
well ripened has a style similar to Riesling.
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Primary Use: Wine
Hardiness: Zone 4
Color: White
Harvest Season: Early
Suggested Training Method: TWC
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Disease Susceptibility:
o Black Rot - ?
o Powdery Mildew - Slight
o Downy Mildew - Very
o Bortrytis - Moderate
o Sulfer Sensitive - ?
Synonyms: Elmer Swenson 282, E.S 282 (5).
Pedigree: (Minnesota #78 x Seibel 1000) x ‘Seyval blanc’
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(5, 6, 8).
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5, 6).
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Origin: Osceola, Wisconsin. Bred by Elmer Swenson (1,
 Introduction: 1983 (1) Plant patent 5771 assigned in
1986 to Swenson Smith Vines (7).
 Type: Interspecific hybrid (includes V. labrusca; V.
lincecumii; V. riparia; V. rupestris; V. vinifera) (5).
 Color: White
Berry: Spherical and small to medium in size; ripens evenly (8). Has a slipskin and tender flesh; pink juice (1).
Cluster: Medium to large in size and conical in shape; moderately loose (8).
Viticultural Characteristics: Swenson (8) described the ‘St. Pepin’ vine as vigorous with an upright growth habit
and somewhat open canopy. He also stated that ‘St. Pepin’ is productive and fruit holds well on the vine with no
shattering (shelling). The flowers are imperfect flowers (pistillate) and not self-pollinated so it needs to be planted
near perfect flowering vines for cross-pollination to occur (8). Fruit set and low yields can be an issue (2).
Disease/Pests: ‘St. Pepin’ is rated as highly susceptible to powdery mildew; moderately susceptible to Botrytis
bunch rot; and slightly susceptible to downy mildew (2, 7). Hart (3) reported that ‘St. Pepin’ is moderately
susceptible to downy mildew, powdery mildew; and a low susceptibility to anthracnose and black rot. He has not
seen Botrytis bunch rot (but does not typically see it on any cultivars at his location in northern Wisconsin) and
stated that crown gall has not been a concern. Also, Hart has not observed injuries from sulfur or copper spray
applications.
Wine Quality and Characteristics: Very fruity, comparable to many German style white wines and often has a
mild labrusca flavor (8). Some northern growers are also making quality ice wine from it. Swenson also reported
that ‘St. Pepin’ typically has low acidity and that average sugar content ranges from 17.6° to 21.0° Brix
(depending upon the location).
The 2006 harvest data from the University of Minnesota’s horticultural research vineyard show ‘St. Pepin’ had
somewhat high soluble solids at 21.8° Brix; moderate pH at 3.26; and had low titratable acidity at 6.28g/liter (4).
Season: Early Midseason. Mid to late September at Excelsior, Minnesota (8).
Cold Hardiness: Swenson (8) reported ‘St. Pepin’ as hardy (-15° F to -20° F). The predicted temperature of 50%
primary bud kill (LTF50) was -32° F., with no apparent injury to the trunks (8). Some bud injury can be expected
at temperatures below 25° F (6).
Use: Wine, table and juice.
Notes: Sister seedling of ‘LaCrosse’ (but not as hardy) (1).
Table and Juice Grapes
Bluebell
Minn. 158
Description: Bluebell was developed from the early 20th century
University of Minnesota breeding program. Bred by A. Wilcox
at the University of Minnesota Fruit Breeding Farm.
Selected in 1923. Introduction in1944. Derived from a Beta
cross with an unknown variety it is a high quality blue seeded
variety developed by Univ. Minnesota. Interspecific hybrid,
‘Beta’ x unknown variety of Eastern U.S. (likely V.
labrusca)
Hardiness: cold-hardy to -40 deg. F. Zone 3.
Viticultural Characteristics: Vigorous, with a procumbent
growth habit. Cluster thinning is not needed. May show iron
chlorosis on some soils where pH is above 7.0.
Training: VSP
Disease Resistance: Has good disease resistance. Only slight
susceptibility to black rot, Botrytis bunch rot, downy mildew
and powdery mildew. Anthracnose has been seen in very
wet fall seasons.
Grape Characteristics: Large blue berries with a dark blue
slipskin. Medium clusters, somewhat loose with a
pronounced shoulder. Ripens mid-September and is capable
of hanging on the vine until after the first frost. The flavor
is juicy with a pleasant, fresh flavor. Will have iron chlorosis
problems at pH levels greater than 7.5. Cracking of berries in
wet fall seasons can be a problem.
Wine Profile: Recommended as a table grape, juice production,
and jelly production in colder Mid-western states of USA. This
blue, seeded table grape has a delightful, fruity, mild labrusca, or
Concord-like flavor and thick skin.
Trollhaugen
-30F
Blue seedless table grape. Hardy to near -30 F. Medium to large blue berries are born on compact, medium sized
clusters. Sweet and mild Concord-like flavor. Ripens extremely early to high sugar but can hang in good condition until a
hard frost. Selected by Elmer Swenson.
Synonyms: E.S 3-24-7 (1).
Pedigree: MN #78 x ‘Venus’ (1).
Origin: Osceola, Wisconsin. Developed by Elmer Swenson, (1, 7) and named by David McGregor (4).
Selected: 1985 (1).
Release: 2000 (1).
Type: Interspecific hybrid (includes V. labrusca and V. riparia) (3, 5, 6).
Color: Blue
Berry: Small to medium in size and round in shape (1); thin slipskin; seedless with soft seed remnants (occasionally
woody) (8). Sugar content averages 22° Brix, and the flavor is sweet and mild Concord-like flavor (1). Berries are
somewhat susceptible to cracking (8).
Cluster: Small; cylindrical and compact (8).
Viticultural Characteristics: Moderately vigorous (8). Domoto (2) reported a procumbent growth habit. The fruit ripens
early, but is capable of hanging in good condition until a hard frost (4).
Disease/Pests: Good disease resistance. May be slightly susceptible to black rot and downy mildew (2).
Wine Quality and Characteristics: Not typically used as a wine grape.
Season: Early (September 10th in central Minnesota) (1).
Cold Hardiness: Very hardy to -22° F (1, 2) Elmer considered it hardy in southern part of Minnesota (7).
Use: Seedless table.
Notes: Sister seedling of Swenson Red and named by David McGregor (4).
Valiant
-50F
Claimed as extreme cold-hardy to -50F red wine grape cultivar developed
from Fredonia x Wild Montana (V.riparia) cross at South Dakota State
University. Requiring a dry climate it is very susceptible to the mildew
diseases. Unusual extreme cold tolerant cultivar in that it is capable of low
acids (>1%) and high sugars (up to 20%). Daylight sensitive, it commonly
goes dormant around September 1st. Currently grown in Minnesota, S.
Dakota and in some other US and Canadian midwest regions including
Manitoba, Canada where it reportedly needed no winter protection. Mostly used in blends, but can make agreeable jelly
and is recommended by some as a (small berry) tablegrape. Listed as ripening about three w eeks before Concord.
Possibly the hardiest grape available its claimed to be hardy to -50F Highly susceptible to the mildew diseases it
requires a good spray program. Makes outstanding juice and jam.
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Primary Use: Juice, Jam, Table
Hardiness: Zone 3
Color: Blue
Harvest Season: Early
Suggested Training Method: TWC
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Disease Susceptibility:
o Black Rot - ?
o Powdery Mildew - Very
o Downy Mildew - Moderate
o
o
Bortrytis - Moderate
Sulfer Sensitive - ?
\ Synonyms: SD7121, S.D.72S15 (5).
Pedigree: ‘Fredonia’ x S.D. 9-39 (V. riparia from NE Montana) (1).
Origin: Brookings, South Dakota. Bred by R.M. Peterson; South
Dakota State University.
Cross/Selection/Introduction: Cross made in 1967; selected in 1972;
tested as SD7121 or S.D.72S15 (1) 1982 (1, 5
Type: Interspecific hybrid (includes V. labrusca and V. riparia) (3, 5).
Color: Black
Berry: Small and round; blue slipskin (1). Sweet and tangy flavor
without a trace of tartness (7). Typically has low acid levels and high
soluble solids (3).
Cluster: Small and compact. Average cluster length is 4 inches (1).
Viticultural Characteristics: Vigorous and productive. Letting it overcrop when young may retard its maturity (3). Daylight sensitive, it
typically goes dormant around September 1st in Minnesota (3).
Disease/Pests: Susceptible to mildews (4).
Wine Quality and Characteristics: Sometimes made in a light rosé
style with minimum skin contact (2); or in blends, but used primarily for
jams and jellies.
Season: Early (late August or early September) (7).
Cold Hardiness: Very hardy. Has withstood -50° F in Manitoba, Canada and was not harmed (4).
Use: Jam, jelly, juice.
Notes: Does best in a dry climate. In moist climates, ‘Valiant’ is more susceptible to diseases (6).