(Wines&Vines) - Shelburne Vineyard is one of just two wineries in Vermont to grow vinifera grapes. Instead, winemaker Ethan Joseph focuses largely on Marquette, a hybrid grape less than a decade old. Developed by Peter Hemstad at the University of Minnesota and released in 2006, Marquette is a complex hybrid of V. riparia, V. vinifera and French hybrid cultivar Ravat 262. One of its grandparents was Pinot Noir.

In many ways, Joseph treats Marquette like a vinifera grape, and the resulting wines have garnered critical praise including four Best of Show awards at the International Cold Climate Wine Competition.

Joseph spoke Feb. 6 at the Cold Climate Grape Conference in Minneapolis, Minn., where he shared his winery’s approach to growing and vinifying Marquette.

Joseph says Marquette “is a premium variety, and we need to treat it as such. From a wine-quality perspective, it’s very important to our industry.”

Training Marquette

Planted entirely in north-south rows and almost exclusively trained on high-wire cordons (8 by 10 feet and 6 by 9 feet) that are replaced often, the mature vines get balanced pruning and then leaf pulling shortly after bloom.

“We call it ‘vine swimming’ because we’re doing this,” Joseph said, churning his arms like a freestyle swimmer. “This is an arduous task, but the benefits are enormous. You’re going to get much better clusters, and they’ll have their own microclimate.

Joseph said he gets soil tests every five years and petiole tests every other year. He and his crew do spraying based on disease history. Marquette is most prone to black rot and phomopsis, he said, “And it’s really important to rotate (herbicide) materials.” As for weed control, “We want the native plants to dominate, to keep vine vigorousness down.”

Canopy management is “more like a typical vinifera than a hybrid. We don’t have an option.” While many growers emphasize high yields on hybrid grapevines, according to Joseph, Shelburne’s Marquette grapes are “managed to optimize cluster exposure, heat accumulation and ripening. That requires a big labor expense, but it is justified in the end product.”

Marquette is proving quite vigorous, Joseph said, with the winery getting 4 to 5 tons per acre, almost double the output of four years ago, and “with a big improvement in grape quality.” It is usually picked in late September, after about 2,300 growing degree-days.