Cold Hardy Grapes: University of Minnesota Releases the Itasca Grape
Chardonnay, Pinot Noir, Riesling and Gewürztraminer- what do they all have in common? They’re grapes that thrive in colder climates and sometimes survive long and arduous winters. In recent years, the University of Minnesota Grape Breeding and Enology Project has added Frontenac, Frontenac Gris, La Crescent and Marquette to that list. Now, they’ve added one more – Itasca.
University of Minnesota,
Grape Breeding and Enology Project
The University of Minnesota Grape Breeding and Enology Project specializes in research and grapevine cultivar development. According to their mission statement, they also focus on understanding the mechanisms of disease and pest resistance to incorporate these traits and improve sustainability for Minnesota and other cold climate viticulture areas. Lastly, they focus on developing and teaching enology best practices for cold-hardy grapes.
Project leader Matthew Clark, Ph.D., told The Grapevine Magazine that only the best seedlings make it to the university’s eleven-acre vineyard. The seedlings spend the first year of their lives in the nursery being DNA tested for particular traits, including disease resistance. The top performers then join the roughly 10,000 vines currently in all stages of “product development.”
“They are evaluated for cold hardiness, fruit quality, vine habit, disease and pest resistance, and eventually wine quality,” said Clark. “It can take three to five years after planting before we can taste the fruit for the first time.”
Throughout their lifecycle, vines will be considered for potential cross-breeding. This hybridization can sometimes lead to significant developments.
“We are using traditional plant genetic approaches to identify pest and disease resistance in the UMN breeding program. This involves making a cross-pollination of two parents of interest, one that shows the trait such as phylloxera resistance and one that is susceptible. We grow out all of the seedling offspring from that pollination and then evaluate the progeny for the trait of interest. Preferably for multiple years, and in the field, greenhouse or lab setting. We are then able to use genetic markers and statistics to help link regions of the genome with the trait. We have recently identified a new region of the grape genome that is associated with resistance to the foliar form of the insect pest phylloxera. Knowing where this resistance is, means that moving forward we can develop a DNA test to screen seedlings in the greenhouse rather than waiting three to five years for a field assessment to derive the same answer.”
The process takes a very long time, and success is not guaranteed. The release of the cold-resistant Itasca grape is fifteen years in the making, from original cross-pollination and testing to complete propagation and offering for sale in the marketplace, and is just one success out of the approximately 3,000-4,000 current hybridization projects at UMN.
Enology Specialist Drew Horton has been an active participant in the winemaking world for over 24 years. Starting his winemaking career in Santa Barbara, California, in 2010 he moved to Minnesota and began his current passion with cold-hardy hybrid grapes. Currently, Horton focuses on outreach to the wine industry as well as making wine with new grapes grown during the UMN enology project. He analyzes the taste, smell and mouth-feel of hundreds of test batches per year.
Horton is one of the first to make wine from the cold-hardy Itasca and has produced eighteen gallons of wine that he plans on sharing at the Minnesota Grape Growers Cold Climate Conference in March 2018.
“It has the flavor profile similar to a Pinot Grigio, Chenin Blanc, Sauvignon Blanc and some people say a Gewürztraminer,” Horton said. “It is an aromatic white wine with the aroma of pear as the predominant flavor. Also noted are hints of quince, violet and melon, lemon, apple and sweet herbs such as tarragon, basil and mint. It’s a complex white wine lower in acid than most other cold-hardy grapes.”
The new Itasca varietal was bred to be nearly resistant to common diseases like powdery mildew and phylloxera, allowing vineyard managers to reduce their spray inputs. Of course, it is also quite tolerant to cold. In the 2013-14 polar vortex, the UMN study only lost approximately 5 percent of their primary buds to freeze damage.
Notes from the Vineyard
Indian Island Winery in Janesville, Minnesota originated from the Winterhaven Vineyard and Nursery. The vineyard currently has over 6000 vines with seventeen different varieties and focuses on the newest cold-hardy grapes. They’re one of three certified grape nurseries licensed to propagate Itasca. Plus they’re thrilled to be the first wineries to release an Itasca wine on the market.
Vineyard manager and co-owner Ray Winter currently has twelve acres planted with the Itasca grape. “It grows very nice in the vineyard. It has nice vigor with very little disease issues. The Itasca has nice upward growth habits. We planted it four years ago. We didn’t crop it until the fourth year, but we could have cropped it in the third year. Production seems like it will be 5,000-8,000 pounds per acre. We have planted at six feet between plants and eight feet between rows. It has been very hardy with little to no bud damage in the spring, almost every bud shots in the spring.”
One area the UMN Grape Breeding and Enology program has become focused on is reducing the overall acidity of the juice of cold-hardy grapes. Some winemakers have mentioned frustration with the higher acids found in these varieties. The Itasca grape seems to break that pattern, with one-third the total acidity of its Frontenac Gris parents.
“The Itasca wine is definitely one to be very excited about,” Indian Island Winery winemaker Angie Netzke told The Grapevine Magazine. “The grape itself has lower acidity to start with than the other University of Minnesota varieties, which is a real advantage when it comes to making a drier white wine. I didn’t need to do any adjusting of the chemistry when it came in from the vineyard.” The grapes were picked at 24 Brix with 3.31 pH and 11.4 g/L.
To make a balanced wine, Horton offers some techniques, starting with allowing the grapes ripen as long as possible. This can be difficult in regions where the weather is an issue. You never know when a frost might happen or when a hail storm threatens to decimate a crop. “Higher sugar levels results in lower acidity. Let the grapevine work for you,” Horton said.
When it comes to yeast, he said that using a strain that metabolizes and lowers malic acid content is best. Pairing that with malolactic, or secondary, fermentation will convert malic acid to lactic acid, reducing total acidity and bringing a creamy component to the mouth-feel of the wine. Also, adding water before fermentation may help balance the wine.
Horton suggests using cold stabilization. This process of cooling the wine causes tartaric acid crystals to form. These crystals are referred to as “wine diamonds” and drop off in the bottom of the bottle. Be cautious, however. While there is nothing wrong with these crystals, some consumers find them unsettling
Blending with a lower acid wine will help cut the high acidity of cold-hardy varietals. Federal regulations allow for up to 25 percent of another wine to be added to the juice and not be disclosed on the label.
Finally, Horton suggests sweetening the wine with a little sugar. Food scientists have a term called “Bliss point” meaning that there is a point of perfect balance of feeling on your tongue. Balance the flavors, and you balance the integrated whole.
“Like a sculptor uses many tools to create the perfect piece of art, I encourage all winemakers to do just the same. Don’t just use one of these techniques, use them all in moderation to achieve balance,” Drew said.
Netzke took particular care during fermentation. “Not knowing exactly what to expect from the wine, I used SVG to ferment with and used a simple nutrition plan throughout fermentation. I let it ferment dry, and will be back sweetening slightly before we bottle it. Flavors that stand out the most from this wine are citrus (lots of lemon) and grapefruit. There were also very subtle notes of honey.”
Time Will Tell
“It is still too early to know how successful it is going to be. These vines may produce a small crop in 2018, but should be up to production in 2019-20 as the vines mature,” said UMN’s Clark. “The University of Minnesota varieties are grown across the US and Canada in cold climate areas and have resulted in new industries in many states, allowing grapes to be grown and wine to be made in regions where before it wasn’t thought possible. Even in Minnesota, we have an economic impact of over $80 million. Our goal is to produce wine grapes with improved disease resistance that are cold hardy and make superb wines.”
For more information, or if you wish to purchase any of the University of Minnesota’s grapevines go to https://mnhardy.umn.edu