Iowa wine industry continues to change

AMES — The wine industry continues to change. New grapes are being introduced, and updated growing methods are improving fruit quality, sustainability and financial returns for producers.

A 2024 report on the Economic Impact of the Wine Industry in Iowa estimated that Iowa wine and winery-related tourism represented a value of $374 million in 2022, with a workforce of more than 1,590.

Iowa State University researchers Suzanne Slack, assistant professor of horticulture, and Aude Watrelot, assistant professor of food science and human nutrition, are working with colleagues at several north-central universities to nurture this steadily growing industry for the region.

They are investigating the best trellising systems for cold-hardy grapes and testing the potential of new cultivars to make wines that appeal to changing consumer preferences.

Slack focuses on grape production. This includes a trial evaluating the pros and cons of three types of trellising: a single high-wire system most widely used in Iowa and the Midwest; a vertical shoot positioning system more common in Europe and around the world, partly due to its compatibility with mechanization; and a Watson improved V-type system that can give cold-hardy grapes, which tend to grow large and vigorously, more room and may improve fruit quality and disease occurrence.

"One reason these systems are important to evaluate is because Midwestern grapes tend to have vines that grow downward, while many cultivars, especially those traditionally grown in Europe, tend to grow upward,” Slack said. "So, we can't assume that the same system will work the best here.”

Many of the newer grape cultivars being tested were planted two to seven years ago at the Iowa State Horticulture Research Station, where research tailored to Iowa grape and apple production is being revived. The effort has primarily been supported by USDA Hatch multi-state project “Coordinated Evaluation of Grape Cultivars and Clones (NE2220)” and recent “seed” funding from the College of Agriculture and Life Sciences.

“Most of these cultivars will not come to maturity for another couple of years,” Slack said. “Even so, a number are showing promise in terms of survivability and disease resistance. We are also evaluating unreleased cultivars from North Dakota State University where Iowa State alumna Professor Harlene Hatterman-Valenti has been breeding new grapes for the Midwest."

Watrelot’s work centers on how to make the best wines out of grape varieties well suited to Iowa’s climate and soils.

“A lot of different styles of wine can be made from the same grape cultivars,” she said. “The wine-making process, including the choice of fermentation conditions, can completely change the profile of the final product. Midwestern grapes are often very fragrant, so they can be a good base for lower alcohol wines that still offer a flavorful wine.”

White wines made from Clarion and Itasca grapes, have already resulted from the multi-state collaboration. Both are lighter styles, crisp and citrusy, with some notes similar to a Sauvignon Blanc and perfect for summer, according to Watrelot.

“The first releases of these vintages from Minnesota have quickly established a bit of a ‘cult’ following,” Watrelot said. “However, the Clarion grape would not have made it to production if not for its early success in Iowa, where it seems to grow much better.”

Among Watrelot’s projects is a study of a post-fermentation process used for red wines, which allows extended time for maceration of grape skins, seeds and berries to increase flavor, texture, and aging potential.

"In another project using different yeast strains for fermentation, we want to see if we can reduce acidity to improve the quality of our wines since wines from the Midwest tend to be acidic," Watrelot said. "The endpoint is always consumers."

Partner institutions on the USDA Hatch multi-state project include the University of Minnesota, North Dakota State University, South Dakota State University and Cornell University.