February 2014 Issue of Wines & Vines

The Potential of Hybrid Grapes

Hybrids offer an element of consistency in cold-climate wine regions

by Paolo Sabbatini and G. Stanley Howell
In “Vitis Hybrids: History and Current Status” (read the article here), we explored the necessity that led to hybridization of wine grapes in Michigan and the Great Lakes region of the eastern United States. But once hybrid cultivars are developed, what challenges and opportunities do growers face?

The Michigan experience, 1970 to date
Michigan soils are commonly sandy loams or loamy sands, and those soils are deep and well drained due to the state’s glacial history. Michigan’s climate is characterized by a short growing season (150 to 175 days) with cool-climate conditions (2,932 growing degree-days with standard deviation of ± sd 297) base 50°F. Yield and quality are often limited by several factors, namely spring freeze (50% chance of spring frost as late as May 15), early fall frost, high humidity and rainfall during the harvest season that promotes bunch rot. Hybrid cultivars used for wine in Michigan typically lack the strong flavors associated with Vitis labrusca and have a range of parental complexity from a simple crossing in Baco Noir to the very complex Traminette.

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Most hybrids are cultured as own-rooted (OR) vines, although there are exceptions. Chambourcin, Seyval Blanc and Valvin Muscat maintain vine size better when grafted. Because of the danger of winter freeze damage, graft unions require winter protection, and soil is mechanically mounded to cover the union while short spurs are maintained just above. That soil is mechanically removed the following spring to prevent scion rooting. Plant spacing is typically 8 feet within row and 10 feet between rows; own-rooted vines with less capacity to maintain vine size may be planted at closer within-row spacing, e.g., 6 feet.

Training systems are based on growth habit. Most hybrids produce a sessile, pendulous shoot habit resulting from larger leaves and longer internodes than typical for vinifera, and are trained to high systems as either cane-pruned, head-trained vines or as bilateral cordon-trained vines at the top wire. These systems employ canes as bearers (five to eight nodes per cane for cordon, and 12-15 nodes per cane for head). In both cases, the height of the head or cordon is 6 feet. Most hybrids employ minimal canopy manipulation other than shoot positioning as described by Nelson Shaulis et al. (1966) for cultivars with similar shoot growth characteristics.

Many hybrids possess the ability to produce fruitful shoots from “non-count” (Howell et al. 1987; Wolpert et al. 1983) base buds, giving them superior cropping ability, especially in years following severe winter cold, spring freezes or insect predation. This means cropping is different from the technique employed with most vinifera cultivars. A good example of this is Seyval Blanc (Smithyman et al. 1997). A full crop can be produced when the vine has been pruned to zero count buds, with the consequence that crop control can be difficult without crop adjustment via fruit thinning. Further, it means that spring freeze bud loss is of much less concern, since the base buds can add production to replace crop reduced by frost damage. Finally, it also means that fruit on a vine may have fruit of two maturity levels, requiring harvest at different times or with different fruit chemistry levels at the same time. The significance of this with regard to subsequent wine quality is dependent on cultivar and wine style sought.

From the outset of the Michigan efforts, there were problems related to attempts to produce and market quality varietally named hybrid wines. Those struggles continue, but several cultivars have succeeded in areas where wine is primarily marketed through tasting rooms. Among those with some success are Chambourcin, Chardonel, Seyval Blanc and Traminette. Most others are produced as multiple variety blends, especially reds (see table on page 80).

There are three primary wine grape-producing regions in Michigan. The two closest to Lake Michigan have the capacity to produce vinifera commercially, while the third does not. The third is nearly 100% hybrid and is successful because it consists of small operations that market the majority of their wine through tasting rooms.

Lessons learned, future opportunities and challenges
In locations where hybrid wine grapes have been cultivated and planted, each region’s experience has many of the following developments in common:

1. Where vinifera varieties were not common, natively grown non-labrusca-based hybrids were evaluated and, if deemed adequately cold hardy and devoid of lab­rusca’s strong flavor, were planted for dry table wine (e.g., the Great Lakes region of the United States).

2. In France, hybrids arose as a result of vinifera sensitivity to phylloxera and fungal disease introductions. These fungal diseases resulted in hundreds of thousands of acres of hybrids being planted for lower quality wine production (e.g., vin de France and IGP in France).

3. When vinifera culture regained its potential (France) or when it was shown to be culturally acceptable (U.S. Great Lakes region), the status of hybrid grapes was affected. Hybrids then declined in popularity, either because of economic protectionism (France) or new confidence in commercial viability of vinifera as a high-quality commercial crop (U.S. Great Lakes region).

4. The regions where vinifera are not commercially viable due to climate constraints continue to rely on hybrids. Further, once given the best viticulture and enology methods, many hybrid grapes produce wines of a quality and value that encourages further investment (e.g., Missouri and other continental regions where annual mid-winter temperatures fall below -25oF).

What are the lessons learned? The economics of wine grape production suggest that all regions must produce wine grapes of two types: 1) those upon which the region can build a positive reputation, and 2) those that can be relied upon to pay the bills and keep the operation solvent. In most historic wine regions these may be the same grape cultivars. In others they may be different. In young regions this is still an active dynamic, but in either case, both types are critical economically.

Future unknown
Cool- and cold-climate viticulture is aggressively pushing into new territory with the expansion of growing regions worldwide and the increasing recognition that successful cultivation and marketing is a boon to local economic growth and stability. This development raises two important questions:

1. Where will current developments in new cultivar breeding lead us? The innovative viticultural research conducted in very cold regions has stimulated strong interest in wine production. The recent efforts of Elmer Swenson and Peter Hemstad in Minnesota back-crossing to very hardy V. riparia selections have been successful and given rise to small but viable commercial vineyard and winery operations in Minnesota, Iowa, Nebraska and both North and South Dakota, where temperatures below -30oF occur annually. The new “super” hardy inter-specific cultivars tolerate these without special protection and possess varying degrees of disease resistance as well.

2. What are the potential impacts of more environmentally sustainable viticultural methods on traditional chemical methods used to control diseases and insect pests?

There is increasing interest among grape breeders worldwide in the development of cultivars that are more disease- and pest-resistant, even in areas where the public rhetoric speaks with derision when the word “hybrid” is used. We are not aware of all the efforts, but a few have been very good. Among these are the development and release of cultivars Regent, Phoenix and Hibernal from Germany. Other newly bred cultivars with American genes are showing multiple resistances to cold and pests while enjoying premium wine quality. While the EU has shown no interest, they should be welcome additions to new viticultural regions. With the attitudes prevalent in many sectors of the European continent regarding Biodynamic viticultural practices (Kirchmann, 1994) and “frankenfood” from GMO plants (Laudy, 2013), this image might arise once again and be encouraged should very high-quality wines of mixed-species grape cultivars be produced and serve to challenge established “noble” cultivars and regions economically.

Economic survival
In the Great Lakes region a strong argument can be made for the value of mixed viticulture. In the third week of January 1994, two winter freeze episodes below -18o F occurred in the largest grape production region of Michigan. As a result, all vinifera cultivars except Cabernet Franc and Riesling were killed to the snowline, and the productivity of these vines was significantly reduced. Because the graft unions were protected by soil coverage, no vines were lost and full production was regained in the 1995 growing season. However, the production for the 1994 season was non-existent. If Michigan had been 100% vinifera wine-grape culture, there would have been no Michigan grapes to put in tanks and zero cash-flow based on local grapes. Notably, all hybrid grape vines in the same research vineyard plot produced full crops in 1994.

In Michigan and the Great Lakes region, every winter poses the risk of such losses, and losses influencing vine productivity occur every winter. Consequently, hybrids play a significant role in the economic sustainability of the region’s wine industry. This episode has not been repeated, but it points to the efficacy of having some freeze-tolerant grape cultivars in the mix to moderate the economic downside risk. Ontario has recognized this and makes allowances for hybrids in their VQA system (see table on page 79) (Schiller, 2010).

Future pest control
It seems clear that the viticulture of the future will require the management of vine pests with fewer chemical inputs. The western section of the United States—particularly California, Oregon and Washington—already boasts very active sustainability movements among growers and producers alike. These programs are likely to continue to grow and spread geographically as consumers pay increasing attention to negative environmental impacts and growers experience rising application costs.

One way of coping with the sustainability movement is to employ advanced grapevine breeding, including mixed-species hybrids. The challenge will be to be ruthless in the selection of those mixed offspring, so that even the most critical wine aficionado will find the resulting wines of fine quality when bias is removed via blind tasting. One common argument against mixed-breed hybrids is the impact of “classic varieties,” the result of which is a selection based more on perceived marketability and less on wine quality.

Those who point to this “classic variety” phenomenon must also recognize the current reality in the U.S. wine market. Cultivars unknown in the U.S. 20 years ago—except to oenophiles—are now available and selling off supermarket shelves. Examples of such varieties include Tempranillo, Aglianico, Dolcetto, Vermentino, Verdicchio, Verdejo, Prosecco, Nero d’Avola, Montepulciano, Verdelho, Teroldego and Lagrein. Wines from districts previously unknown to consumers in the United States—Tuscan Sangiovese, Piedmont Barolo and Barbaresco from Nebbiolo, Asti’s Moscato—are now widely available.

Similarly, these new, quality inter-specific cultivars could find markets and also have the ability to call attention to their environmentally friendly culture, and they will do so at much lower costs of production than traditional freeze-susceptible cultivars prone to insects and diseases. A quiet but vigorous effort is under way in many European viticulture research facilities to select new wine cultivars with strong resistance to powdery and downy mildew, black rot, phylloxera, nematodes and numerous other vine pests. Meanwhile U.S. grape breeders continue to improve cold hardiness while also improving quality, especially in Minnesota and Wisconsin.

Dr. James A. Wolpert of the University of California, Davis, shared this anecdote from a trip to Missouri, where he met a winery owner from eastern Kansas who planned to open a tasting room and was requested not to do so by the local retail liquor store owner who was concerned about competition for wine sales. The winery owner apologized for the perceived attack on business but opted to open the tasting room. Ten years later there were six wineries, a mapped wine trail to help visitors find them all, and the concerned liquor store owner had expanded his wine section by 150%.

Wolpert explained, “I have used this commentary on the importance of local wineries to the general, not just local, wine culture. People learn about wine at a local tasting room and then feel comfortable consuming more wine—not just local Kansas wine, but Gallo and Yellow Tail and ultimately wines from Napa, Burgundy, Bordeaux and Tuscany as well. Most importantly, they become wine drinkers.”

He added, “I have shared this observation with many people, and all have agreed that the goal of making wine a national beverage in the U.S. hinges on the ability of local wineries to convince the 55% of the American population who drink alcohol, but very little wine, to make wine a part of their daily routine.”

Of the 50 states, only Alaska does not grow grapes for wine. Very cold-hardy cultivars have made commercial winegrowing possible in states in parts of the American heartland where the summers are hot and the winters bitterly cold, like Minnesota, Wisconsin, North and South Dakota, Nebraska, Iowa, Missouri, Kansas, Wyoming and Montana. These newly developing wine industries are possible because of hybrids or selections from local native American species such as Norton (Vitis aestivalis), and these local wineries are introducing new people to wine in their tasting rooms every day, which benefits every winegrowing region of the world.
Dr. Stan Howell is professor emeritus of viticulture and enology at Michigan State University. After arriving at MSU in 1969, Howell focused on cool-climate viticulture with the goal of assessing which cultivars were compatible with Michigan’s climate and evaluating the wines from those cultivars. Since he retired, he has been working with the VESTA (Viticulture and Enology Technology and Science Alliance) program to develop viticulture and enology courses.

Dr. Paolo Sabbatini is an associate professor of horticulture at Michigan State University with research (60%) and extension (40%) responsibilities in viticulture. His primary objective is to identify environmental, physiological and cultural factors that limit vine growth and development, fruit maturity and quality of grapes grown in Michigan. Sabbatini received his Ph.D. in 2002 from the University of Ancona (Italy).

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