Beating the Berry Shrivel Blues
The bright sunny days and cool nights of autumn so perfect for ripening wine grapes in Washington may also be fostering a vineyard villain — berry shrivel, according to Markus Keller, Chateau Ste. Michelle Distinguished Professor of Viticulture at WSU’s Irrigated Agriculture Research and Extension Center at Prosser.
Characterized by the sudden shriveling of berries while the stem remains green, berry shrivel can cost growers up to 40 percent of a crop, Keller said. “The berries start to ripen, then very suddenly decide they’ve had enough and start to shrivel,” he said. “The problem is it is very unpredictable — it only happens in some berries, in some bunches, in some vines, in some blocks, in some years. It is a moving target.”
Berry shrivel is most prevalent in certain varieties, such as Cabernet Sauvignon, Sauvignon Blanc and Petite Syrah. “We almost never see it in Merlot or Chardonnay grapes,” Keller said. Because it lowers sugar content, fruit with shrivel is very sour.
Unfortunately, the only way to remove the literally sour grapes is to remove the impacted clusters by hand. “So not only do growers lose the fruit, they have to pay people to clean the crop,” he said. “Economically, it’s a double whammy.”
Washington growers first alerted Keller to the problem in 2003-04. Working with grant dollars from the Wine Advisory Committee, he, fellow WSU faculty member Bhaskar Bondada and graduate student Geoffrey Hall have been exploring a number of possible causes for the phenomenon.
“We have followed berry shrivel throughout three entire seasons to see if there are any preliminary symptoms, early signs that berry shrivel is there,” Keller said. “We’ve tagged specific plants and specific clusters in blocks where berry shrivel has been prevalent in the past; but as is the case with these things sometimes, the clusters we tag are fine and the ones right next to them are shriveled.”
Based on an analysis of fruit composition of grapes with berry shrivel, Keller and Hall have confirmed that it includes an arrest of ripening. Bondada has reached the same conclusion based on his studies of the anatomy of impacted plants. Specifically, he is examining the physiology of vascular pathways in the plant that involve moving water and sugars into the berries.
“Thus far, my research has shown that most flesh cells of berries with berry shrivel have lost their membrane integrity, whereas the cell membranes were intact in the healthy berries,” Bondada said. He noted that both macro and micro nutrients — on a per fruit basis — were lower in the shriveled berries than in healthy berries.
Bondada also found that the vessels that make up the plant’s plumbing system in afflicted canes often were blocked with tylosis, a balloon-like obstruction, and that the stalk of clusters with berry shrivel showed a wavy architecture different than that of healthy plants.
The next step is to explore what causes it as well as possible preventives or treatments.
The team currently is focusing on the impact of temperature and light changes. “The bright, sunny days and cool nights have always been considered an advantage for Washington growers,” Keller said. “But, if the nights are too cool it could induce plants into thinking winter is just around the corner and they need to be focusing their energy on winter hardiness rather than fruit production. That’s our current working hypothesis.”
Some scientists in Europe and California also have spent a lot of time looking for a pathogen or disease that might cause berry shrivel. “They have run a lot of tests, but so far, no one’s been able to identify a pathogen,” Keller said.
Bondada noted that berry shrivel also has been reported in British Columbia, Chile, Austria, Germany and Italy.
For more information on berry shrivel research at WSU, please visit http://bit.ly/1ikr2a.
For more information on micro-nutrients in grapes, read the article in the August issue of Voice of the Vine http://bit.ly/9qPPEV.
The Wine’s Just Fine
Since WSU research enologist Jim Harbertson arrived in the heart of wine country five years ago, the number of wineries has doubled.
“We have a new population of winemakers making wine in the region,” Harbertson said from his base at the WSU Irrigated Agriculture Research and Extension Center in Prosser. “That means a lot of new winemakers with a need for basic problem-solving methods.”
Enter Harbertson’s latest publication, “A Guide to the Fining of Wine.” The booklet, available as a free download from WSU Extension Publications, provides suggestions (including convenient reference tables) for how winemakers can remove unwanted components that affect clarification, astringency, color, bitterness, and aroma in both red and white wines.
“I wrote this guide because I wanted winemakers to have a handy reference that lays out the basics of fining,” Harbertson said. “Winemakers should be aware that the need to fine may be an indication that they have a problem in the vineyard or in their winemaking technique. This guide doesn’t address those problems, per se, but rather gives winemakers some options if fining is the only solution available.”
Download your copy of “A Guide to the Fining of Wine” by visiting http://bit.ly/O0XqN. Via the same link to WSU Extension Publications, the publication is also available as an ink-on-paper booklet for $1.50.
Pour It On: Save the Date for Dad’s Weekend Wine Tasting
The Nov. 13 Dad’s Weekend wine tasting will be a first for the WSU V&E Club, which in the past has hosted successful wine tastings during WSU’s annual Mom’s Weekend. The club uses funds raised from such events for educational purposes in keeping with their mission to use and improve students’ knowledge of viticulture and enology and to promote the Washington wine industry.
“We’re planning a field trip for next spring,” Bailey said. “We want to tour several Washington wineries and network with growers and vintners, because talking to people in the industry is a good way for us to learn what it takes to succeed.”
The club is open to all students and faculty of both WSU and the University of Idaho.
Bailey said the club plans to charge $15 for five pours at the Dad’s Weekend tasting. Although the event is still in the planning stages, Bailey said the club will be pouring Washington wines and perhaps some from nearby Idaho.
“We have a bunch of students from Idaho in the club, so we’re exploring those connections, too,” she said.
Winemakers interested in helping viticulture and enology students raise funds for educational purposes should contact Bailey at rebecca.bailey@email.wsu.edu.
Scholarships to be Primary Focus for Wine Auction Proceeds
Scholarships and funding for student educational exchanges will be the primary applications for the proceeds raised by the 2010 “Celebrate Washington Wine” fundraiser to benefit the WSU Viticulture and Enology Program.
In its ninth year, the annual black tie gala reception, dinner, and auction has already raised more than $1 million dollars to help build the WSU program that provides scientific research to support Washington state’s growing wine industry, and educates the next generation of winemakers and grape growers.
The event will be held on Saturday, Jan. 30, 2010, starting at 6 p.m. in the intimate setting of the Chateau Ste. Michelle Winery in Woodinville. It will feature a reception, a multi-course dinner with wine pairings prepared by the winery’s award-winning culinary team, and both silent and live auctions with a multitude of exciting offerings.
The event has sold out in past years, so early registration is recommended. Tickets are $250 each, or $2,500 to sponsor a table of ten. Please join us for a fun-filled and exciting evening while contributing to student scholarships and WSU’s growing V & E program.
Information about becoming an event sponsor, donating auction items, and making reservations to attend can be found at http://www.wineauction.wsu.edu.