Grapes are the highest-value fruit crop grown in the U.S. Over 70% of the grapes grown are used in wine. As wine grape production expands to new areas in the U.S., growers need grape varieties suited to their growing conditions, which can differ environmentally and economically from traditional regions. Growers also need varieties that are more resistant to common pests and diseases. Wine producers are interested in new varieties they can use to create new wines and expand sales.
To find the best grapes for U.S. growers and wine producers, researchers at Land-grant Universities across the country are testing the performance and resulting wine quality of different grape varieties, including traditional, lesser-known, and new varieties. Researchers supported by USDA’s National Institute of Food and Agriculture also set up a database to store information on the characteristics of each variety and shared their findings with the industry through newsletters, farm tours and websites. This information is improving the economic viability of and respect for grape growers and wine producers nationwide.
As part of this collaborative project, researchers are growing different kinds of grape vines at more than 20 test sites across the country. Using rigorous standard protocols for collecting data at each test site, researchers are collecting high-quality data and compare results. At each site, researchers regularly collect weather data, record vine measurements, such as the number of grape clusters per vine, and note the presence of any pests, predators or diseases.
After harvest, researchers analyze grape color, acidity and other qualities. Establishing vines at a wide range of sites is helping distinguish how genetic factors, environmental conditions and management practices influence grape yield and wine quality. For example, at the University of Nebraska, researchers are evaluating whether reducing crop size improve wine quality. Other scientists showed the effects of grapes’ nitrogen nutrient supply on wine flavor.
Researchers have also identified grape varieties and management practices to prevent damage from cold weather and grapevine diseases, both of which affect many American grape-growing regions. In particular, Colorado State University researchers identified grape varieties with good cold hardiness and identified pruning and thinning practices that can improve yields and ensure profits even after severe cold damage.
In 2021, cold-hardiness information from Michigan State University helped grape growers prepare for cold weather events more proactively and minimize crop loss. Missouri researchers are establishing virus-free grape varieties, and Massachusetts researchers evaluated the efficacy of organic pesticides. These and other alternatives will help minimize chemical pesticide use and the human and environmental health risks.
Vineyards and wineries in many states regularly reach out to university programs for grape and wine data. Continued refinement of wine grape varieties and management recommendations has supported the production of desirable, competitive wines and led to an expansion of the grape and wine industries in several states. Many states have seen the economic impact of their wineries soar.
For example, Vermont had no grape or wine industry in the 1990s, but by 2016, the state had over 165 acres of wine grapes and wine was valued at over $5 million annually. In Kansas, Highland Community College operates a business incubator for wineries that continues to accelerate industry growth. In the last 10 years, Kansas added 650 acres of vineyards. The Cayuga White grape bred by Cornell University accounted for retail market wine sales of $4 million dollars annually in the years following its release.
The Multistate Approach
As the first-ever coordinated effort to improve wine grapes for U.S. growers, this project has created protocols, generated baseline data, and made advances that form a stable foundation for continued research. Working together capitalizes on the expertise and specialized facilities available at certain institutions to boost grape performance and winemaking in states with less capacity. Coordinating evaluations in multiple states at the same time also shortens the time it takes to evaluate grape traits and makes data collection more efficient. Collaboration also fosters other projects. Project participants have secured over $1.7 million in additional funding in just the last five years.
This project, NE1720: Multi-state Coordinated Evaluation of Winegrape Cultivars and Clones, is supported in part by the Hatch Multistate Research Fund through USDA-NIFA and by grants to project members from the following institutions: University of California-Davis, California Cooperative Extension, Colorado State University, Connecticut Agricultural Experiment Station, Cornell University, Cornell Cooperative Extension, Highland Community College (Kansas), Iowa State University, University of Kentucky, University of Maryland, University of Maryland-Eastern Shore, University of Massachusetts, Massachusetts Cooperative Extension, Michigan State University, University of Minnesota, University of Missouri, University of Nebraska, University of Nevada, New Jersey Cooperative Extension, New Mexico Cooperative Extension, North Carolina State University, North Dakota State University, Ohio State University, Pennsylvania State University, Purdue University, Rutgers University, South Dakota State University, Texas AgriLife Research, University of Vermont, Virginia Polytechnic Institute and State University, University of Wyoming, and the USDA-ARS.