How to Grow Cold-Hardy Grapes
Northern Grapes Project details data from two years of vineyard trials in New York and Michigan
On April 8, Martinson and Paolo Sabbatini, associate professor of horticulture at Michigan State University, conducted a webinar to report two years’ worth of data (from 2012 and 2013) that was collected during vineyard trials in New York and Michigan as part of the Northern Grapes Project. More than 80 people from Quebec to Fargo, N.D., logged onto the webinar site to hear Martinson and Sabbatini discuss the topic “Impact of Crop Load and Training Systems on Viticultural and Enological Performances of Marquette and Frontenac Grown in Michigan and New York.”
Trained for quality
Training systems tested in the New York trial vineyards included Vertical Shoot Positioning (VSP), top wire cordon and umbrella kniffen for both Marquette and Frontenac. Martinson reported that umbrella kniffen, which is often used in the Finger Lakes with vinifera vines, and top wire cordon produced as much as twice the yield with lower costs for labor than VSP-trained vines. While the yields were lower in 2012 because of frost damage, the trend was the same in both years. Marquette in particular had a much better yield when trained on a high trellis.
Higher yields resulted in lower Brix levels but did not affect the level of total acidity. Since the total acidity in cold-hardy varietals is usually high, it was noteworthy that Frontenac clusters exposed to sunlight had higher Brix levels and lower titratable acidity, no matter which training system was used. Downward shoot combing was used on the Frontenac vines trained to top wire cordon to help increase the sunlight exposure on those vines.
Sabbatini noted that in Michigan, vinifera grapes are being grown successfully in a number of areas. However, the availability of cold-hardy varietals is expanding the state’s grape and wine industry, and Marquette represents 40% of the hybrids currently planted there. Consequently, vineyard trials in Michigan were conducted using Marquette vines that were trained on top-wire cordon (the training system most frequently used for Marquette in Michigan), Geneva double curtain and an experimental system known as moving trellis, which is described as “a new closing Y-shaped training system.”
Effect of frost events
While spring frost had an impact on the results in 2012, it also gave researchers the opportunity to compare how primary and secondary buds responded to the frost event in the subsequent growing season. Clusters on secondary shoots obviously got a later start than those on primary shoots, but by the time of harvest there were no differences in berry growth. There was no difference in canopy growth or size of the different training systems, and the fruit chemistry of clusters on primary and secondary shoots was similar for the three training systems.
In 2013, the yield per vine was modified by shoot thinning on all training systems at fruit-set, and by cluster thinning at fruit-set on high-wire cordon vines. The main conclusion was that fruit quality at harvest was related to cluster exposure, with grapes at 22.5° Brix and 6.7 total acidity at high yields. Overall, the trials in Michigan have shown that Marquette is very early to bud out, and therefore it is more susceptible to early spring frosts. It also ripens very early (three to five weeks before red vinifera varieties such as Pinot Noir and Cabernet Franc). In addition, while the yield per vine had little impact on fruit maturity at harvest, canopy-management practices may have an impact on wine sensory analysis.
Communicating with the industry
Education is a major focus of the Northern Grapes Project, both to communicate what is learned and to get feedback from producers about how the information has influenced their practices in the vineyard and the cellar. During and after the presentations by Martinson and Sabbatini, participants in the webinar posted questions and comments based on their individual experiences with cold-hardy varieties in different areas and on different soil types.
In addition to webinars, the Northern Grapes Project publishes a quarterly electronic newsletter and holds an annual “Northern Grapes Symposium” to provide yearly summaries of the progress of the overall project. The website northerngrapesproject.org includes a section titled “Recorded Webinars” where interested growers and winemakers can listen to past webinars or view pdf versions of the webinar slide sets. Most webinars last approximately one hour; the most recent one was 75 minutes.
Funding support for the Northern Grapes Project comes from the USDA’s Specialty Crops Research Initiative Program of the National Institute for Food and Agriculture, Project #2011-51181-30850, and the New York State Specialty Crops Block Program. The project includes 14 states: Connecticut, Illinois, Iowa, Maine, Massachusetts, Michigan, Minnesota, Nebraska, New Hampshire, New York, North Dakota, South Dakota, Vermont and Wisconsin.