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Graduate Research on Grapes Featured in Wine Trade Magazine

Plant Sciences Ph.D. student John Stenger’s research on cold-hardy grape cultivars was featured in an article in the Vineyard & Winery Management Magazine’s March/April 2015 issue. NDSU high-value crops project leader and professor Dr. Harlene Hatterman-Valenti oversees Stenger’s research.
Graduate Research on Grapes Featured in Wine Trade Magazine

John Stenger

The following article was written by Mark Ganchiff and Danny Wood and published in the Vineyard & Winery Management Magazine’s March/April 2015 issue ( The article is reprinted here with permission.

If you were a grapegrower arriving in the United States in the 1800s, the northern areas of the country would have seemed like a promising region for viticulture. The 45th parallel, which runs through several of the great grapegrowing regions of Europe, cuts through a wide swath of the northern U.S. and Canada.

But the area halfway between the North Pole and the equator is much colder in North America than in Europe. As a result, growing wine grapes commercially in USDA growing zones 4 and 5 has always been a dicey proposition. Growing them farther north in Minnesota and North Dakota was a near impossibility.

Now, through the combined efforts of a new generation of breeders, private and at universities, new cold-hardy wine grapes are being commercially developed and released. These new varieties are revolutionizing viticulture in areas that cannot reliably grow vinifera grapes, and pushing hybrid grapes to new levels of wine quality.

According to Bruce Reisch, a horticulture professor at New York’s Cornell University who has developed11 new hybrid varieties, “I think 20 years ago nobody would have predicted the success these (cold-hardy) grapes are having now.”

Reisch’s enthusiasm is evidenced by the explosive growth of wineries in the Midwest and Northeast. Hundreds of new wineries and vineyards have opened in the last two decades, even in states such as Vermont and Minnesota, once thought inhospitable to grapegrowing. Many of these startup wineries are selling wine made from newer hybrid grape varieties that can not only withstand subzero winter temperatures, but also have more nuanced flavors and aromas. One of them is Aromella, a white hybrid of Traminette and Ravat 34. J.F. Ravat is the French grape breeder who developed Vignoles in the 1930s.

“I think our new variety, Aromella, released in 2013, is one of the most winter-hardy grapes that we’ve developed from the Cornell-Geneva breeding program,” Reisch said. “It’s also spicy and has some beautiful aromatics, akin to its Gewürztraminer grandparent. Aromella is really a very high-quality hybrid.”

David Peterson of Goose Watch Winery, a 36,000-gallon-per-yearproducer with six locations in New York’s Finger Lakes region, released his first vintage of Aromella, the 2013, in 2014. He said it’s “a real attention-grabber in the tasting room.”

“Our Aromella is a balanced wine at 2% residual sugar with some Muscat characteristics, but not as sweet,” Peterson said.

He got a full crop of Aromella in 2014, despite a vineyard low temperature of minus 14°F. Measurements taken by Cornell indicate 50%bud kill for Aromella at between minus 16°F and minus 17°F.


Of course, one state’s cold-hardy variety is another state’s winter wimp. The general definition of “cold hardy” is whatever can survive the winter in a given grower’s vineyard.

For example, cold-hardy grapes developed by the University of Minnesota can survive even colder temperatures than Aromella. Frontenac, a University of Minnesota hybrid that has native Vitus riparia parentage, can survive chills as low as minus 33°F.

Peter Hemstad, a leader in grape research at the University of Minnesota, said the challenge of breeding wine grapes using riparia is retaining the cold hardiness and disease resistance while taming the less desirable native traits, such as high acidity.

According to Hemstad, the University of Minnesota will release a new white hybrid grape in 2015. The name of the grape – known temporarily as MN 1285 – had not yet been announced at press time.

“We’re very excited about this new grape,” he said. “The reaction has been very positive and it has excellent potential.” At a research update held at the University of Minnesota on Jan. 18, Hemstad reported that MN 1285 had very good primary bud survival during the harsh winter of 2013-14, and that it has lower acidity than the university’s existing varieties.

He noted that selected nurseries are already propagating the grape, and that he believes it will fill a niche that current white hybrid wine grapes don’t currently occupy.

Frontenac, Frontenac Gris, LaCrescent and Marquette, the four cold-hardy grapes already developed at the University of Minnesota, are sold at the rate of more than100,000 vines per year. Minnesota hybrids are being planted across the northern U.S. and in some parts of Canada.

“Quebec is a big believer in our varietals; they like dry wine in Quebec,” Hemstad said. “The Yakima Valley of Washington has introduced some hybrids, partially as insurance for those years when they don’t get a full vinifera crop.”

Frontenac was Minnesota’s first hybrid, released in 1996. Marquette, another red wine grape that is a cousin of Frontenac and a grandchild of Pinot Noir, has now surpassed Frontenac in sales. Marquette makes tannic, complex wines that stand out from older red French and American hybrids.

Philippe Coquard of Wollersheim Winery in Wisconsin, one of the most successful hybrid winemakers in the U.S., is a believer in Marquette. He uses Wisconsin-grown Marquette grapes and Wisconsin oak barrels to make a vinifera-like wine with notes of black cherry and blueberry.

According to Coquard, whose winery has more than 125,000 visitors and 250,000 gallons of production per year, there are two primary attributes he looks for in a cold-hardy hybrid. The first is cold tolerance. The second is the capacity to produce a “classy” wine.

“I like grapes that are rich and bold,” Coquard said, “but they must also have some finesse.”

Another more refined new red hybrid that’s attracting attention is Petite Pearl. It was developed by private Minnesota grape breeder Tom Plocher and was first bottled in 2012 by Bear Creek Winery in Fargo, North Dakota.

This hybrid is a cross between MN 1094 and ES 4-7-26. MN is the abbreviation for the University of Minnesota and ES stands for Elmer Swenson, the “godfather” of cold-hardy grape breeding.

Swenson, who died in 2004,became a mentor to Plocher, who has been involved with cold-hardy grapes since about 1980. Like many who knew Swenson, Plocher speaks of the Wisconsin dairy-farmer-turned-grape-pioneer in reverent terms: “Elmer was the trailblazer of cold-hardy grape breeding,” he said. “He started tinkering with grapes as a kid in the early 20thcentury and that gave him time to really perfect his work.”

Among the Swenson white cultivars one would likely find on a trip across the vast expanse of Midwest wineries are Brianna and St. Pepin. Brianna has just a background hint of labrusca grapiness, but the complex genetic mix of vinifera, rupestris, lincecoumi, berlandieri, riparia and yes, labrusca, is appealing to both serious wine drinkers and wine tourists.

Brianna is usually placed in the hybrid category at wine competitions, but it has also won top awards at major competitions against vinifera wines. Miletta Vista’s Nebraska Brianna won best white wine at the 2012 U.S. National Wine Competition in Sonoma County; Prairie Berry Winery in South Dakota won a gold medal at the 2012 San Francisco Wine Competition for its Brianna.

Like Swenson before him, Plocher is one of a small but devoted group of private grape breeders committed to creating cold-hardy grapes that can make quality wine. He does most of his crosses at his farm in Hugo, Minn.

Until 2013, Plocher thought the cold hardiness he had achieved with Petite Pearl was sufficient for south and central Minnesota and was setting his sights on improving wine quality.

“The widespread injury after last winter taught us that we are still not there yet with winter hardiness,” he said. “So I went back to work this past summer and made some backcrosses to hardier cultivars. Now I am pursuing both greater hardiness and better quality.”

He’s also tackling the issue of tannins – or the lack of them – in hybrid grapes used to make red wine.

“I think that’s traditionally where we’ve had a problem,” Plocher said. “Some of the crosses that have been done up to now have used French hybrids that really don’t have much tannin. So we ended up with grapes with a lot of acid, potentially a lot alcohol and no tannin. That’s a big deal for us in terms of quality.”

A few years ago, Plocher looked into the parent varieties of the grapes he was breeding and tested them for tannin. Now he knows which of the parents are high in tannin content, which facilitates a faster breeding process.

So far, Plocher’s Petite Pearl stands out among red hybrids for its vinifera-like phenolics and relatively high tannin levels.

“We can still do better,” said Plocher, who is now aiming to achieve a cold-hardy red balanced in alcohol, acid and tannin.

Andy Farmer of Northeastern Vine Supply in Vermont planted10,000 Petite Pearl vines when the variety was first released and sold between 12,000 and 13,000 of the vines in 2013. Farmer started his nursery in 2002 at age 26 and is now one of the nation’s leading providers of cold-hardy rootstock.

He said that Marquette is his top-selling red variety, but Petite Pearl is gaining quickly. “Petite Pearl buds late and has small leaves with not a lot of laterals,” Farmer said. “It’s also a late-ripening grape; the acids will drop and the tannins will keep developing right into October.”

Farmer is an hour down the interstate from Shelburne Vineyard in Shelburne, Vt. Shelburne is con-in the U.S. for cold-hardy wines, winning double gold at the 2013Finger Lakes International Wine Competition for its 2012 Marquette Reserve.


If Vermont seems an unlikely place to grow wine grapes, consider breeding grapes on the Wisconsin shores of Lake Superior. That’s the passion of Mark Hart, who has an experimental vineyard near Bayfield, the main entry point for the Apostle Island National Lakeshore. His vineyard is on a 350-foot-high,south-facing hill, a mile from Lake Superior, at 46.4° north latitude.

Hart now does about 150 crosses per year and has 16,000 to19,000 vines on 3.5 acres, all surrounded by Lake Superior. The main goal of his research is to create early-ripening grapes for areas that have around 1,800 to 2,000 growing degree-days. He has not released any grapes commercially yet, but his cultivars are currently being tested in Illinois, Vermont and Minnesota, as well as in Quebec and Europe.

Hart has emerged as a leader in the international grape-breeding community. He moderates an online grape breeders’ forum that has approximately 175 active members who share information about cultivating both new and rare grapes. Hart took over management of the forum from Lon Rombough, a respected Oregon grape breeder who died in 2012.

Hart is also one of the organizers of Vitinord, an international conference with a mission to promote the advancement of viticulture and enology practices in cold northern climates. Vitinord started in Latviain 2006. In November 2015, Vitinord will be in the U.S. for the first time, at the Lied Lodge and Conference Center in Nebraska City, Neb., including winemakers, academics and grapegrowers.

Experimental growers share a common passion for developing new grapes. While there is profit potential from expanding the range of commercial viticulture, most cold-hardy breeders are attracted by the creative process of composing new cultivars. “For me, it was the goal of trying to develop something that was better for the Illinois wine industry,” said Bill Shoemaker, a horticulturalist who retired from the University of Illinois in 2012 after 30 years of service.

Shoemaker said he believes that utilizing some of the many adapted grape species of North America could lead to a new viticultural paradigm for sustainability. “I think it’s an opportunity largely ignored and dismissed by the rest of the world,” he asserted. “Also, as I get older, working with these amazing plants is also a great way to keep myself happy and goal-oriented.”

The next generation of cold-hardy grape breeders is already at work. John Stenger, a plant sciences Ph.D. candidate at North Dakota State University, is breeding cold-hardy cultivars in a greenhouse, overseen by Dr. Harlene Hatterman-Valenti, who runs a high-value crops project.

Stenger, who is assisted by Plocher and a project team, said the greenhouse can produce 3,000-5,000 seedlings per year with a portion bearing fruit in 8-12 months. The project – a grape germplasm(living tissue from which new plants can be grown) enhancement program – was initiated in response to growers’ needs with financial assistance from the North Dakota state legislature and modeled after a method developed by Tyler Kabanat the University of Saskatchewan in Canada. The goal is to develop “super-cold-hardy” cultivars that can survive temperatures of at least 40 below zero.

In fall 2014, Stenger, Plocher and a panel of winemakers and researchers went to a local winery to evaluate wines made from 23 of their initial seedling selections –the first indigenous North Dakota wines ever made. The results were promising.

“The best ones from our winetasting will be moving to a replicated trial for yield tests,” said Stenger. “We’re saying we need at least five to 10 years of testing and replicated study after (the vines) start bearing fruit before we really know whether there’s something that truly is better than what we currently have available.”

Mark Ganchiff is the publisher of Midwest Wine Press in Chicago.
Danny Wood is a Kansas City-based Australian journalist who writes for Midwest Wine Press and works at Belvoir Winery. He was smitten by wine (and his American wife) while living in Spain, reporting for BBC News.

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