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Deficit Irrigation, Growers of the Year

Posted by | February 7, 2008
Voice of the Vine is watching water. This article is the first in a two-part series on vineyard irrigation research going on deep in Washington wine country at Washington State University’s Irrigated Agriculture and Research Center. Our article on soil moisture monitoring will run in the Feb. 21 issue.

Water, Water Everywhere?

I. Deficit Spending

“I wanted to focus my research on irrigation,” said recently graduated Master’s student Marco Biondi. “Water is the big thing, especially in the grape industry, one of the world’s most widely grown crops.”

Marco Biondi and enologist Kerry Ringer at a Seattle Enological Society event.
Marco Biondi and enologist Kerry Ringer at a Seattle Enological Society event.

Biondi hit U.S. shores from his native Italy a few years ago, proceeded to master English, and then to work with WSU viticulturist Markus Keller on an extensive Master’s of Science research project.

In much of Europe, Biondi explained, it’s illegal to irrigate wine grapes after veraison. Veraison, originally a French term, refers to the change of color that occurs in grape berries as they ripen. Because of ancient traditions, rather than science, growers aren’t allowed to irrigate post-veraison for fear of diluting Brix (the measure of the fruit’s sugar content).

For over 20 years, the working assumption has been that berries are hydraulically isolated after veraison, that is, that no water from the roots enters the berries. But assumption often wings far from fact, so Biondi and Keller set out to track the scientific truth of the matter.

Viticulturist Markus Keller served as Biondi's graduate advisor. Learn more about viticultural research at WSU's Irrigated Agriculture Research and Extension Center in Prosser:
Viticulturist Markus Keller served as Biondi's graduate advisor.Learn more about viticultural research at WSU's Irrigated Agriculture Research and Extension Center in Prosser:

Working with both vinifera and labruscana (wine and table) grapes, Biondi performed a variety of controlled, greenhouse experiments. He used high-tech sensors to measure change in berry size and color as the fruit ripened. He grew vines in a pressurized system in order to determine how water circulates within the plant and its berries. He put dye in water to visually inspect circulation.

The results of Biondi’s experiments are startling and fly in the face of viticultural tradition. “We proved that berries are not hydraulically isolated during ripening,” he said. Indeed, Biondi’s experiments show that berries absorb water in a variety of ways, including through the skin and not just through the root system, as commonly believed.

“Late season irrigation doesn’t decrease Brix,” Biondi said, “but irrigation does increase photosynthesis in the leaves, and photosynthesis in turn increases Brix.”

Markus Keller, Biondi’s advisor, said that this research will certainly result in changes in textbooks, which have long taught that deficit irrigation (starving the plant of water after veraison in order to increase Brix) is the way to go.

“We can now tell growers to keep irrigating very late in the season or maybe even increase water application,” Keller said. “They can maintain their crop at the same time as attaining the same quality. So, for the grower, that is a huge improvement. This could mean millions of dollars for Washington growers alone.”

Cougar Couple Win Grower of the Year Award

The Mrachek family: Allyson, Mike, Laura, and Bryan. Bryan is a student in WSU's V&E program; hear what Bryan and others have to say about the program in this short video: Visit the Mrachek's winery Web site:
The Mrachek family: Allyson, Mike, Laura, and Bryan. Bryan is a student in WSU's V&E program.

Laura and Mike Mrachek of Malaga, Washington, were named the 2007 Good Fruit Growers of the Year during the Washington State Horticultural Association’s annual convention in December. Since 1997, the award sponsored by Good Fruit Grower magazine has recognized farming families, a pair of brothers, and individuals for their commitment to fruit production and contributions to the industry. This was the first time a couple received the award. The recipients, chosen by the Good Fruit Grower’s Advisory Board, must be a commercial tree fruit or grape grower or orchard or vineyard manager within North America who is innovative, inspiring to others, and has contributed to the industry as a whole.

The couple, both WSU alumni, own cherry, apple, and wine grape acreage at three locations in Washington State, a winery and tasting room, a commercial laboratory, and an irrigation scheduling service.

The Mracheks began farming on their own in 1981 when they purchased a house and four acres of cherries. More than 25 years later, the Mracheks still live in the original house.

Through the years, the Mracheks have developed Lucky Bohemia Orchard and Vineyard to include about 270 acres of apples, cherries, and blueberries and 285 acres of wine grapes at Malaga, Quincy, and Mattawa. They released their first wine under their Saint Laurent label in 2001, and last fall, opened their own winery, St. Laurent, in Quincy.

The Mracheks’ son, Bryan, who will graduate from WSU’s viticulture and enology program this spring, eventually plans to join the family winery as general manager after first gaining outside experience.

Adapted from an article by Melissa Hansen originally published in the Jan. 1, 2008 issue of Good Fruit Grower magazine.

Hear what Bryan Mrachek and other students have to say about WSU’s program in viticulture and enology in this short video.