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Virus Fighters, Wild Yeast, Upcoming Classes

Posted by | April 17, 2008

The Virus Fighters

Naidu Rayapati has assembled an interdisciplinary team of virus fighters to help insure the longterm health of the Washington wine industry.
Naidu Rayapati has assembled an interdisciplinary team of virus fighters to help insure the longterm health of the Washington wine industry.

“Virus diseases like grapevine leafroll are firmly rooted here,” said Naidu Rayapati, WSU grape virologist. “It’s time to face reality and develop strategies to mitigate the problems caused by viruses.”

Grapevine leafroll disease, which is found world-wide, can cause a marked decline in grapevine vigor, grape quality, and productivity. The disease can reduce yields as much as 50 percent or even more, depending on the severity of infection.

A few years ago, it was estimated that nearly 10 percent of Washington’s vineyards have grapevine leafroll disease. Anecdotal evidence suggests that the disease is more wide spread than previously thought.

As part of an industry-led initiative, Rayapati was hired by WSU in 2004 to ramp up efforts to address virus diseases in wine grapes and set the direction of virus disease control programs.

Rayapati’s research for the past three years has documented many grapevine viruses occurring as single or mixed infections. “Knowing what is out there is part of dealing with the problem,” said Rayapati. “This information is critical for designing appropriate strategies to tackle virus diseases in our vineyards.”

He said the main objective of his research is to provide growers with best management practices to deal with diseases. “We will update growers and nurseries on what we are doing via the Web and other communications tools. We also will be promoting the planting of virus-tested materials as the best defense against virus diseases in grapes and small fruits.”

For more information on Rayapati’s research, please visit: http://wine.wsu.edu/virus/index.html

For more information about virus-tested plant material, please visit: http://nwgfs.wsu.edu/

Yeast Research Is No Spoiler

Without the proper precautions, Brettanomyces outbreaks may occur during the winemaking process.
Without the proper precautions, Brettanomyces outbreaks may occur during the winemaking process.

Washington State University professor Charles Edwards and his graduate student research team are helping Northwest wineries uncork the mystery behind a stinky epidemic.

Edwards and three graduate students focus their research on a type of wild yeast called Brettanomyces that produces foul odors and taste in some wines.

Brettanomyces’ smell has been likened to “barnyard,” “sweaty saddle,” “medicinal,” or “Band-aid.” Edwards said there are no adverse health effects, but the altered taste and smell of an affected bottle can deter consumers and, consequentially, cause problems for winemakers. Volatile chemicals produced by Brettanomyces are responsible for the off-odors. Some winemakers and wine drinkers believe that small amounts of these compounds provide complexity to red wines.

Brettanomyces primarily grows in red wine, but can be found in some white wines as well. Edwards is one of only a few researchers studying Brettanomyces and its effects on wine production and consumption.

“Wine is about quality, but it is also about marketing,” Edwards explained. “There is an emphasis on high quality red wines, and wineries are concerned about this particular type of yeast.”

Brettanomyces is extremely difficult to eradicate and involves significant sanitation efforts. It has been found in nearly all areas of the winery, most commonly in oak cooperage. The best line of defense for Brettanomyces is preventing initial contamination in the winery through a diligent wine sulfur dioxide program and limiting oxygen by keeping wine barrels topped. Inadequate additions of sulfur dioxide and the temptation to purchase used wine barrels to cut costs can increase winemakers’ risk of a Brett outbreak, Edwards said.

Edwards’ research pairs with efforts to train and assist new winemakers to carefully monitor their winemaking process for potential microbial contamination so they can identify a situation and take measures to control an outbreak.

— Katie Floyd, CAHNRS & WSU Extension Marketing and News Services Intern

Upcoming Viticulture and Winemaking Workshops

Learn how to grow grapes and make wine with WSU Extension viticulturists and enologists at two upcoming Westside workshops.

Learn the basics of growing cool-season wine grapes on the Olympic Peninsula at the Vine to Wine Workshop, April 25-26. For information and registration, visit http://tinyurl.com/53kcpv.

On June 30, WSU Extension is presenting a winemaking workshop with a maritime Washington emphasis. The workshop also covers the basics on how to start a winery. For more information and registration, visit http://tinyurl.com/3uzwkp.