Good Fruit Grower

July 1

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Grapes ROOTSTOCKS don't affect wine In a major study, no difference was found in wine quality between own-rooted vines and those on rootstocks. by Melissa Hansen "Rootstock trials have been conducted for major rootstock trial spanning more than a decade found that rootstocks gen- erally did not impact vine phenology, fruit set, and plant water status, nor did they impact wine quality when compared to wines from own-rooted grapes. Variety, location, and vintage are the driving factors of grape quality, say a pair of Washington State University researchers. In short, WSU viticulturist Dr. Markus Keller said the hundreds of years, but not at this level and scope." —Markus Keller research dispels the fear of using rootstocks in eastern Washington. "There's always been a fear of growers that rootstocks would induce too much vigor and the vine would have difficulty hardening off in the fall before cold temperatures hit," he explained. "But because the indus- try uses regulated deficit irrigation and can control vine growth through soil moisture, the research shows that such fears can go away. That was the big finding of the rootstock research." The rootstock research was unique in that it also evaluated wine quality, making wine from the rootstocks and own-rooted vines for three vintages. With regards to wine TREE SPREADERS Lowest possible prices on 4" to 48" nailed or notched spreaders Additional services: We assemble and repair new and old pallets for re-sale NATIONWIDE SHIPPING AVAILABLE! Markus Keller says growers in eastern Washington now have no reason to fear using rootstocks. quality, Dr. Jim Harbertson, WSU extension enologist, said that winemakers have no need to fear that grafted vines will impact wine quality. "We did all that winemaking—90 wine replicates each year for three years—and we didn't find anything to be that particularly different," Harbertson said. "We thought we would find some small difference because it was such a huge project. We certainly did our best to make sure that we got the right answers, but there just weren't a lot of differences in the wines." Monumental trial Keller's predecessor Dr. Bob Wample started the root- stock trial at WSU's Roza research vineyard in 1999 to evaluate a handful of rootstocks obtained from Cornell University and learn which might be best suited for east- ern Washington. When Keller took over Wample's project in 2001, he expanded the trial by field grafting three scion cultivars (Chardonnay, Merlot, and Syrah) onto the root- stocks and planted the same own-rooted varietals for side-by-side comparison. "Rootstock trials have been conducted for hundreds of years, but not at this level and scope," Keller said. "Most rootstock projects don't compare own-rooted vines because the research is in a location where they can't grow them because of issues like phylloxera. And almost none of the previous rootstock trials have carried the evaluations through to the wine quality aspect." The extensive trial included three scion varieties grafted on six rootstocks: 5C, 99R, 140Ru, 1103P, 3309C, and an unnamed Cornell University selection dubbed 101CU, plus the own-rooted vines. 101CU is thought to be a sibling or seedling of 101-14 Mgt. The experiment had ten field replicates, which meant that WSU enologist Harbertson made nearly 300 wine replicates from 2007 to 2009 in WSU's research winery. The research vines were irrigated in the same manner Yakima Specialties, Inc. P: 509.453.0386 32 JULY 2012 GOOD FRUIT GROWER F: 509.453.1279 Yakima Specialties Inc. I Non-Profit Agency Hiring Disabled Adults Visa and MasterCard Accepted I 1819 West "J" Street, Yakima, WA that eastern Washington growers follow, using regulated deficit irrigation. By carefully applying irrigation before veraison as Washington growers do, vigor of the grafted vines were kept in check and rootstocks were not invigorated as has been reported in other research. Keller said that if he were starting the rootstock trial today, his list of rootstocks would be different, including some that have been developed since the project began. One rootstock, 99R, was discarded early in the trial because of repeated scion dieback from cold injury. And though the trial was designed to include a drought- tolerant rootstock, two of the rootstocks sent by Cornell 48 years in business Photo by melissa hansen

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