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CO VER S T OR Y Rolling With The Leafroll Punches Enological solutions for virus-affected fruit By Kerry Kirkham M aking wine with leafroll-affected fruit is not only possible, it's preferable in certain situ- ations. Some winemakers have managed to craft expressive wines from afflicted vines, while others eschew sourcing virused fruit en- tirely. Those in between the leafroll love and hate have a few enological solutions. Aside from reduced crop yield, the common symptoms of leafroll-affected fruit are under-ripe grapes, high acidity and color loss, which can lead to reduced complexity. Simple correc- tive steps can be taken to make the most out of leafroll fruit. Dr. Jim Harbertson, an associate scientist and extension enolo- gist at Washington State University, Prosser, will talk in depth about making wine from leafroll fruit during a full day leafroll virus semi- nar during the 62nd ASEV National Conference in Monterey, Calif. Harbertson's research interests include the phenolic com- pounds found in grapes and the relationship between tannin, polymeric pigments and astringency in red wine cultivars. Wines & Vines asked Harbertson for a sneak preview of his talk and also interviewed winemakers experienced with leafroll-affected grapes to get their advice on the matter. Due to the reduced photosynthetic capacity of the leafroll-affected ripening and acid respiration. A matter of style "Leafroll has been around for quite a long time," said Joel Peter- son, founder and winemaker of Sonoma's 950,000-case Ravens- wood Winery. Peterson sources fruit for one of his Ravenswood single-vineyard designate releases from Dickerson Vineyard on the west side of Napa Valley. The 20-acre vineyard consists of Merlot, Cabernet Sauvignon and 15 acres of Zinfandel planted prior to 1920 on St. George rootstock. Of the 15 acres of old vine Zinfandel, approximately 10-12 acres are affected by lea- froll type two. Highlights • Aside from reduced crop yield, the common symptoms of leafroll- affected fruit are under-ripe grapes, high acidity and color loss. • Saignée and co-fermentation can be the easiest, most cost- effective ways to address color loss. • Acid-reducing fining agents such as calcium carbonate or potassium carbonate can be used to attain acidity targets. 32 Wines & Vines JUne 2011 "My experience—and I have worked with a number of vineyards with various viruses—is that it tends to be site-related," he said. The leafroll virus impact hasn't worsened in Dickerson Vineyard since Peterson started working with it in 1982. Peterson noticed that leafroll made vineyards act as if their entire sites had shifted geographical positions. "Vineyards behave like they're closer to the coast: The wine has less color density, more acidity, and the fruit stays in a less-developed flavor state. Flavors stay in the red rasp- berry zone rather than the black cherry and plum zone." This is true of every leafroll-affected vineyard Peterson has ever worked in. "In some sites, it makes for interesting wines, and in others it makes for bland and anemic wines. Dramatic, interesting wines from affected vineyards are an exception rather than the rule. The vast majority of leafroll has not worked out. It's an 80/20 rule, depending on the site and stages of leafroll." Peterson allows each site to guide his winemaking with the vision of single-vineyard wines that convey a pure sense of place. Due to site and virus variations, it's difficult to make blanket state- ments about the impact of leafroll. "It's so site specific it's hard to define. Some of the leafroll viruses we have now are aggressive and can progress quite rapidly, leading to serious fruit and vine degradation. There are sites that you just can't go back to; the fruit View video in the Wines & Vines Digital Edition. Print subscribers can opt in via the Subscribe page on winesandvines.com