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Micronutrients, Co-fermentation, Wine Auction

Posted by | August 20, 2009

A Pinch of This, a Dash of That – WSU Research Studies Micronutrients in Grapes

Doctoral student Suphasuk “Bird” Pradubsuck measures a Corcord grape vine prior to excavating it. Once excavated, she analyzed the plant's parts to determine Concord's micronutrient requirements.
Doctoral student Suphasuk “Bird” Pradubsuck measures a Corcord grape vine prior to excavating it. Once excavated, she analyzed the plant's parts to determine Concord's micronutrient requirements.

When humans don’t get enough Vitamin C, we can get sick with scurvy. The same is true of plants. Micronutrients such as boron, zinc and copper, although only a tiny part of a plant’s diet, can have a profound effect on the plant’s health.

WSU soil scientist Joan Davenport and her colleagues at the WSU Irrigated Agriculture Research and Extension Center in Prosser are studying micronutrient utilization in Concord grapes. Washington is the nation’s No. 1 Concord grape producer, so understanding what happens with micronutrients is important to the industry’s bottom line.

Kami Laffey, a freshly graduated Prosser High School student working with the WSU viticulture and enology program for the summer, assists Suphasuk “Bird” Pradubsuck in the excavation of a Concord grape vine.
Kami Laffey, a freshly graduated Prosser High School student working with the WSU viticulture and enology program for the summer, assists Suphasuk “Bird” Pradubsuck in the excavation of a Concord grape vine.

And micronutrient availability is an issue in Washington’s grape-growing region, with its high pH soils. The soil availability of micronutrients decreases as pH increases.

“Right now, growers apply micronutrients based on their experience and on what’s commercially available. We want to give them quantifiable data to work with,” said Davenport. “Then they’ll be able to supply plants what they optimally utilize without spending more than they need to on inputs.”

If the vine doesn’t get enough boron, Davenport said, pollen lands on the flower but doesn’t germinate. “That’s a disaster,” she said, “because if there’s no pollination, there’s no seed, and then there’s no fruit.” Copper and zinc don’t affect the plants so dramatically, but do affect the size of the canopy.

Excavating a Concord grape vine; L-R: Suphasuk “Bird” Pradubsuck , Kami Laffey and doctoral student Kyle Bair.
Excavating a Concord grape vine; L-R: Suphasuk “Bird” Pradubsuck , Kami Laffey and doctoral student Kyle Bair.

Davenport’s current project is based on one her doctoral student, Suphasuk “Bird” Pradubsuck, finished recently.

“Bird excavated Concord vines at various times during the growing season and then did detailed and comprehensive analysis of the plant parts in order to ascertain the amounts per acre of micronutrients the plants used,” Davenport explained.

Macronutrients, such as nitrogen, are measured in pounds per acre, while micronutrients are generally measured in parts per million. “A typical Concord yield is about eight tons per acre,” said Davenport. “To get that, the plants need about 50 pounds of nitrogen per acre, but only a third of a pound of boron.”

Davenport is running extensive field trials on micronutrient utilization with a cooperating grower. “We’re putting on micronutrient fertilizers as both ground and foliar applications,” she said, in order to determine whether vines take up the nutrients from the soil or through their leaves.

Davenport’s research has direct impact on wine-grape growing as well. She and her team are imposing nutrient deficiencies on Cabernet Sauvignon and Semillon grapes.

“All micronutrients have different M.O.’s. By depriving plants of individual nutrients, we’ll be able to see what affects they have and, with the field study data, compare the results in ways that inform wine-grape growers. It’s all about yield and quality,” said Davenport.

For more information on soil scientist Joan Davenport’s research, please visit: http://bit.ly/15e8iq.

Undergrad Researcher Experiments with Co-fermentation

Undergraduate enology research Landon Keirsey is interning this summer at Double Canyon Vineyard in the Horse Heaven Hills AVA near Alderdale.
Undergraduate enology research Landon Keirsey is interning this summer at Double Canyon Vineyard in the Horse Heaven Hills AVA near Alderdale.

The synergy created by co-fermenting black and white grapes together can create a truly wonderful wine. The winemakers of France’s Rhone Valley, where Syrah and Viognier have long been fermented together, are masters of this style of winemaking.

Unlike the more common art of blending already fermented wines, co-fermentation raises many questions. Do white grapes, for instance, dilute the color of black ones when added to a co-fermentation? And what about the aroma of a co-fermented wine? Is it the Viognier grapes that lend the wines of the Rhône Valley’s Côte Rôtie appellation their aromatic qualities?

These and other questions are being research by WSU viticulture and enology undergraduate Landon Keirsey and his faculty advisor, James Harbertson. Harbertson is an enologist based at WSU’s Irrigated Agriculture Research and Extension Center in Prosser and a designer of WSU’s research winery in Prosser.

This fall, and funded in part by a grant from the Rhone Rangers, Keirsey will make co-fermented wines in small batches at the research winery. The wines will be made with varying amounts of Viognier grapes and compared to two control wines, one made solely with Viognier, the other with only Syrah grapes.

Using sophisticated scientific techniques, Keirsey and Harbertson will analyze the aroma, color and tannin compounds in the wine. Keirsey hopes his research will be useful to winemakers, especially as Rhône-style wines become more important in the marketplace.

“I wanted to conduct this research because it’s important for winemakers to have hard data to reinforce their practices. It’s also a great opportunity for me to learn and get some experience doing science,” said Keirsey.

“The great thing about having the research winery is that it lets us answer so many questions important to industry,” said Harbertson. “It also gives undergraduate researchers a chance to get experience that reinforces their classroom learning and that gives them a leg up in terms of experience when they go looking for a job.”

For more information about educational opportunities in viticulture and enology at WSU, please visit http://bit.ly/iudP8.

Check out a short video about undergraduate research opportunities in WSU’s College of Agricultural, Human, and Natural Resource Sciences by visiting: http://bit.ly/crnff.

Celebrate Washington Wine

Thomas Henick-Kling
Thomas Henick-Kling

Mark your calendar! Join Thomas Henick-Kling, director of WSU’s program in viticulture and enology, as we Celebrate Washington Wine.

“Please join me in attending Washington State University’s ninth annual wine auction and dinner, featuring fine food, exceptional wines, interesting conversation, and silent and live auctions!

“With your support, we are building a world-class wine science research and education program at WSU. Our program supports the growth of the Washington wine industry and communities across our state.

“Thanks for being a part of this project!”

For more information about the ninth annual Celebrate Washington Wine gala event, please visit: http://bit.ly/3eesMd.