Research Symposium in Pennsylvania
Penn State meeting features comparative tasting of wine grape trials
The program’s research committee provides funds for the USDA NE-1020 wine grape variety trials and grape pathology research at Penn State’s Fruit Research and Extension Center in Biglerville, Pa., and the Lake Erie regional grape lab as well as experimental wine trials conducted by state enologist Denise Gardner. On May 22, the program collaborated with the Penn State Extension to hold a research symposium in State College, Pa., that brought winegrowers and winemakers together to learn about the latest research that is advancing the wine industry as well as improving productivity and quality.
According to Mark Chien, viticulture educator with Penn State Cooperative Extension, conducting wine grape trials in Pennsylvania is not an easy task, given the diversity of climates across the state, which range from USDA regions 5a to 7b and growing degree-day regions from 1 to 4. Like most non-western states, the grape landscape is complicated by native, hybrid and vinifera varieties that are made into every conceivable style of wine.
When the two wine grape variety trials were established at the Penn State research stations in Biglerville, Adams County (southeastern Pennsylvania), and North East in Erie County (the northwestern corner of the state), varieties were selected with industry input that represented what was known to grow well in each area, and that may have market and viticultural suitability in Pennsylvania. Some highly adaptable varieties such as Vidal, Chambourcin and Pinot Grigio were planted at both locations, while Grüner Veltliner was assigned to Erie and Albariño to Adams County. Four core varieties—Vidal, Chambourcin, Cabernet Franc and Pinot Noir—were planted in each cool site (growing degree-days <2500) in Erie, while each warm site in Adams County (growing degree days between 2,501-3,500) was planted with Cabernet Sauvignon, Cabernet Franc, Merlot and Pinot Noir.
In addition to the vineyards in Adams and Erie counties, Dr. Rob Crassweller has established a cold-climate variety vineyard at the Rock Springs research farm near State College. This vineyard serves as a research and teaching vineyard for budding viticulturists at Penn State.
A highlight of the May 22 symposium was the opportunity to taste wines made from the variety trials at the research vineyards in Biglerville and North East. Led by Denise Gardner, Penn State Extension Enologist, a total of eight varieties were tasted including Pinot Grigio, Grüner Veltliner, Vidal Blanc, Albariño, Cabernet Franc Rosé, Chambourcin, Merlot and Cabernet Sauvignon.
Gardner had conducted yeast trials with two Grüner Veltliner wines from the 2012 harvest in North East, Erie County. The standard research white wine yeast is Lallemand’s EC 1118, and a second wine was fermented using Enartis Vinquiry’s yeast, Top Floral. The two wines were remarkably different in aromas and flavor: One Grüner Veltliner had cooked apple aromas while the other was floral and fruity. In addition, four Cabernet Franc rosé wines were tasted: the first two were fermented with Top Floral yeast, one wine from Erie and one from Adams County. Two other Cabernet Franc rosé wines, one from Erie and one from Adams, used ES 488 and Top Floral.
Color differences in the red wines produced from North East versus Biglerville grapes were clearly noted. Most of the 2012 red varieties from the Biglerville vineyard (including Chambourcin, Merlot and the Cabernet Franc rosé) lacked color intensity. Much of the discussion revolved around the issue of wine pH and its effect on wine color, as many of these red wines finished malolactic fermentation with a pH of 3.70 to 4.10. For the eastern United States, this is a high pH for red wines. Gardner noted that the pH has a direct effect on wine color, as free anthocyanins are altered in color as the pH of the wine changes. At pH of 2.60 or below, the majority of the free anthocyanins will exist in a colorless form. At a pH of 4.25, the majority of free anthocyanins will exist in a violet, or bluish, hue. Therefore, the closer to a pH of 4.25 the wine is, the more bluish in color the wine will appear.
The general lack of color intensity stimulated a thorough discussion of wine instability and the potential causes of high pH in wines produced during the 2012 growing season in Biglerville. Sulfur dioxide stripping was suggested as a potential cause of the higher pH wines, which require heavier doses of sulfur dioxide to manage a proper molecular (free) sulfur dioxide level for product stability.
Crop load research
Chien reported that the guest speaker at the symposium was Dr. Justine Vanden Heuvel, who has a 50-50 split viticulture research and teaching appointment at Cornell University. Her research at Cornell is focused on practical issues facing grapegrowers that can have a positive impact on quality and production. In her presentation, “Crop Load Adjustment: Does It Really Pay?” Vanden Heuvel presented data relating crop load to wine quality, with relative value and success of viticulture practices measured against wine consumers’ “willingness to pay” for a bottle of wine. The popular wine press often touts the necessity of low yields to make quality wines but she wanted to show that achieving a balanced vine supersedes the need to simply lower yield, and that costs involved in lowering yields—and loss of grape and wine revenue—are not always compensated by increased grape and/or wine prices .
Vanden Heuvel explained that the Ravaz Index is a good way to measure vine balance. The index is a ratio of 15-20 for hybrids (Reynolds) and 5-10 (Smart) for vinifera of weight of fruit to pruning weight of a vine. In fact, in a block of Noiret, she is considering removing vines to create a 16-foot gap between vines to get them in balance. Experimental wines from her trial were presented to a group of sommeliers, wine bloggers and other experts in New York City, and there was little correlation between low yields and perceived quality among these experts.
This is not to say that lowering yields cannot improve wine quality, Chien noted. In red wines especially, tinkering with yields can be very important, given site and vintage conditions; whites in general are more malleable in their tolerance of yield variation and can offer acceptable wine quality and style at different levels of ripeness. There is simply too much compelling evidence that yields, at the highest level of wine quality, are an important contributor to achieving the type and style of wine sought by these producers.
One participant suggested that the soil capacity likely influenced the outcome of these trials, but this work gives growers, especially on moderate to vigorous sites, ample food for thought.
Because education within the wine industry is a major goal of the Pennsylvania Wine Marketing and Research Program, similar meetings will be scheduled in the future, and more growers and winemakers will have the opportunity to taste the results of the wine trials across Pennsylvania.