Evaluation of Eastern European Wine Grape Cultivars for Kentucky - UKREC - 2005
Joe Masabni, Dwight Wolfe, John Strang, Chris Smigell, June Johnston, and Hilda Rogers, Department of Horticulture

Interest in producing grapes for wine in Kentucky has increased dramatically, as the number of wineries has increased from 6 in 1997 to 24 in 2005. This was partially due to the cost-share program initiated by the Grape Industry Advisory Committee to help tobacco growers diversify their operations into other crops.

There are four types of grapes grown in the United States for wine: American (Vitis labrusca), Muscadine (Vitis rotundifolia), European (Vitis vinifera), and American French hybrids (Vitis labrusca x V. vinifera). Generally, Muscadine grapes are not well adapted to Kentucky’s climate, and European grapes can survive Kentucky weather only with extra care in vine management. American grapes grow well, but fruit quality for wine is usually substandard. Many American French hybrids grow well and fruit quality for wine is intermediate between the American and French parents. The majority of wines from Europe and the West Coast of the U.S. are made from European grapes.

European grapes are not well suited for the cold climate of northern Europe. Vines are usually buried with soil or mulch to prevent winter injury, a very labor-intensive operation. Northern Europeans have crossed the vinifera with different Vitis species, including some from China. The resulting cultivars have shown improved hardiness as well as outstanding fruit quality in Eastern Europe. The late Dr. Bob Goodman, of the University of Missouri, evaluated these cultivars in Eastern Europe and selected several, based on winter hardiness, disease resistance, and fruit quality. These selections were brought to the U.S. and grown in Missouri under post-entry quarantine. In 1998, the first of these selections were distributed to selected land grant institutions in the U.S., including the University of Kentucky. This project is being conducted in cooperation with the Missouri State Fruit Experiment Station of Southern Missouri State University, Mountain Grove, Missouri.

The objective of the project is to evaluate these selections in different regions of the U.S. To participate in this project, the University of Kentucky signed an agreement specifying that no one could collect bud wood from this planting.

Eighteen advanced selections were released from post-entry quarantine in the spring of 1998 and planted at the University of Kentucky Research and Education Center, Princeton, KY (UKREC). The vines were set 8 ft within rows spaced 12 ft apart. The planting stock was small-potted cuttings. These were trained to two leaders and tied to 5 ft bamboo canes during the first year. During the second year, vines were trained to a high bilateral cordon system. The planting is trickle irrigated and a 4 ft wide herbicide strip is maintained beneath the vines with mowed sod alleyways. The vines were balance-pruned according to the previous year’s yields. In brief, when balance pruning, the number of buds left on a vine is determined by the vine vigor and growth in the previous season, as measured by the weight of the wood removed.

Beginning in 2000 the yield, cluster weight, berry weight, pH, and Brix (% soluble solids) were recorded for each selection. The harvested grapes were then distributed to cooperating wine makers and the quality of the wines produced from these selections was evaluated beginning in 2001. Wines collected from these wine makers are all stored on their sides in constant darkness, at 55ºF. The American Wine Society evaluation form was used. Each white wine vintage was evaluated at one and two years after harvest, and the red wine vintages will be evaluated at one through five years after harvest. Vintages that do not rate well are omitted from future evaluations.

During the spring of 2001, an additional advanced selection of nine varieties was released from post-entry quarantine and planted at UKREC. The planting was established in an area previously used for a high-density apple planting. The remaining end posts were left in place, and used for the grape trellising. Consequently, vines were spaced 8 ft apart in rows 16 ft apart. Other aspects of planting and training were similar to those of the 1998 planting described above. A number of the vines were killed during a late spring freeze. The surviving plants were trained to two trunks and tied to 5 ft bamboo canes during the first year. Vines were not balance-pruned in 2003 because they didn’t have a crop in the previous season due to their poor growth after the late spring freeze.

Beginning in 2003, the same yield and berry measurements were recorded, and wines were made, as described for the vines planted in 1998.

Yield and fruit quality components for grapes harvested in 2004 and 2005 are listed in Tables 1 and 2 (1998 planting). In 2005, the varieties Iskorka, Liza, Petra, Rani Riesling, I-31/67 and M-39-9/74 were dropped from the project due to mediocre wine quality or poor vine growth. This planting is eight years old. Nearly all varieties harvested this year yielded acceptably, with a range of 4.6 tons/A to 10.9 tons/A. Interestingly, the three lowest yielding varieties have ranked among the best in the wine evaluations.

Yield and fruit quality components for the 2005 harvest of the 2001 planting are listed in Table 3. These vines are in their fifth year, and have been slow to produce economically viable yields. In 2004 only Bromariu and II 70/20 produced more than one ton per acre. This year their yields increased to 4.6 and 4.8 tons/A, respectively. Demetra, IR 26/5, Plai, and L4-9-18 also had yields of more than one ton/A this year. Wine was made from only Demetra, Nero, and II 70/20 in 2003. In 2004 Golubok, II 70/20, Bromariu and IR 26/5 yielded enough to make wines. This year eight of the nine (Golubok excluded) yielded enough to make wines. Table 4 compares the fruit yields, % soluble solids and pH for the years 2003-2005 of the 1998 planting and 2004 and 2005 for the 2001 planting. Malverina, Toldi, and Rubin Tairovski, averaged the highest yields for the last three years. Fruit sugar content averaged 19, 20, and 19 for the years 2003, 2004, and 2005, respectively. The average fruit pH at harvest was 3.2, 3.4, and 3.3, for 2003, 2004 and 2005, respectively.

Table 5 lists all the white wine tasting results. The 2000 vintage whites were tasted in 2001 and 2002, the 2001 vintages were tasted in 2002 and 2004, the 2002 vintages were tasted in 2004 and 2005, and the 2003 vintages in 2005. Table 6 lists all the red wine tasting results. The 2000 vintage wines were tasted in 2001, 2002, 2004, and 2005, the 2001 vintages were tasted in 2002, 2004, and 2005, the 2002 vintages were tasted in 2004 and 2005, and the 2003 vintages in 2005. Members of the Kentucky Vineyard Society have evaluated the wines. Average ratings for each wine are listed as well as the range of ratings between tasters and the comments from the most recent tasting. Comments for previous tasting evaluations are found in last year’s report.

Table 7 summarizes the wine evaluations. The two French-American hybrid wine standards, Chambourcin and Vidal Blanc, and the American Norton standard received the highest average cumulative rankings so far. They have been included for comparison, as they are some of the better non-vinifera grapes grown in Kentucky. They are followed by 34-4-49, Laurot, XIV-186, Malverina, Kozma 55, and Kozma 525. In this year’s evaluation, the three highest rated white wines were of the 2003 vintage (Seyval (hybrid standard), Malverina, 34-4-49). The Malverina and 34-4-49 were also among the three highest-rated whites last year. The three highest rated reds were the 2002 Norton, the 2003 II 70/20 and the 2003 Laurot. Last year, the same Norton and the 2002 Laurot were among the highest rated reds. Most red wines have received lower ratings as they have aged.

After three evaluations, the four highest-rated white wines are 34-4-49, XIV-186, Malverina and Vidal blanc (Table 7). The four highest-rated red wines are Norton, Chambourcin, Laurot and Kozma 55 (Table 7). Most of the top-ranked wines are the same as in last year's report. The XX-15-51 and Kozma 525 dropped out of the top rankings. Both bottles of 2003 XX-15-51 rated under 7 this year. The 2000, 2001, and 2002 Kozma 525 vintages all rated lower than in last year's evaluation. Their cumulative average in last year's tasting was 10.7, and only 6.8 in this year's evaluation.

The individuals that made these wines, and some professional winemakers, feel that some of these varieties could make decent wines, or at least good blenders.

The authors would like to express their appreciation for all the help that they received in this study from the many Kentucky Vineyard Society members who cooperated in making and evaluating these wines.

Table 1. 2004 yield and fruit quality results from the 1998 Eastern European wine grape cultivar trial at UKREC, Princeton, KY.

Table 3. 2005 yield and fruit quality results from the 2001 Eastern European wine grape cultivar trial at UKREC, Princeton, KY.