My articles are usually warehoused in the articles section, but I though this one on Leafroll Virus in the vineyards of California was worth taking up space here. New story in the San Francisco Chronicle.
Leafroll: A quiet threat in the vineyard. You can click on this link right over HERE, and see the photos, or you can just scroll down.
It's not imagined. The blood-red leaves in California's vineyards are appearing earlier and spreading more widely. While pleasing to the eye, the colors indicate a shutting down of photosynthesis, often dangerously close to harvest. They can also be a signal for a virus that's giving the wine industry a migraine. The grape leafroll virus has been around and causing trouble for at least a century. It has about 10 variations. But the newest, V3 and V5, are causing panic, with some vineyard owners ripping out vines or blasting them with chemicals. "If I'm going to believe what I hear, it's going to be the next phylloxera," says Stuart Smith, owner of Smith-Madrone in St. Helena. "Worried? You bet." The virus is also affecting vines on the East Coast and in South Africa and New Zealand, and was the topic of an international conference at UC Davis in 2008. Like that other scourge, the European grapevine moth, lots of farmers have it. But if they are willing to discuss the moth, they are often fearful to fess up to the virus. Unlike some other afflictions, this virus won't kill the vineyard, but it will greatly affect the quality of grapes by preventing normal sugar development and greatly reducing yields. But not everyone views those effects as detrimental. Lower sugars were more acceptable 15 years ago, but now they conflict with today's bigger style of wine. "The virus causes a lack of (the) maturity that most of today's winemakers are looking for," says Paul Jackson, owner of Colinas Farming Co., which farms for such Napa Valley wineries as Grgich Hills, Round Pond and Frank Family. Hesitant to talk And why are those afflicted so hesitant to talk? "It is probably because they are fearful that their vineyard will be perceived as having inferior fruit and lose sales," says Dave Whitmer, Napa County agriculture commissioner. But speak to farmers and the situation becomes more complex. Where many see no option but to learn to live with the virus, others have immediately yanked out vineyards and replanted, only to have the virus reappear. The spread of these variants of leafroll was noticed in 2002 in the famed To Kalon vineyard. The late Ed Weber, Napa County's previous viticulture farm adviser, and Deborah Golino, director of Foundation Plant Services at UC Davis, began a four-year study of the phenomenon. During the study, there was a threefold increase in the number of infections in that vineyard alone. Oakville is still one of the hardest-hit areas. The study was disturbing. Previously, this virus was believed to be transmitted by grafting infected budwood in vineyards, which is why many farmers were terrified of using field cuttings instead of buying certified plant material from Foundation Plant Services. But it turns out that's not the only way the virus is transmitted. While grafting is one way - and cleaning up the virus in the vine is Golino's focus - the major spreader is the vine mealybug, which is native to Mediterranean countries. Golino says it probably arrived on lowly table-grape vines smuggled in from Israel to Southern California. Unhappy with that sandy soil, the bug moved steadily north. It tends to breed more quickly than other mealybugs and gets carried around by wind, vineyard machinery and vineyard workers. The pests do double damage: As they suck on a vine, they excrete a sticky substance called honeydew, leaving a tacky, candlelike wax on grape bunches, ruining them; as they feed on new vines, they pass along the virus. Yet there are those who happily live with the virus. These folks seem to have found a working mix of good farming and the right rootstock. Vines on their own roots, those on an old type known as St. George, or even phylloxera-prone AxR1, might carry GLRaV3 and 5, but don't seem to show a major impact. Vineyard manager Frank Leeds, who farms Frog's Leap in Rutherford, was working on a 20-year-old plot of Cabernet Franc that needed replanting because of rabbit damage. "I couldn't get St. George, so I got something called Freedom," he says. "I planted the same budwood on the root, and after four years those vines were showing virus, yet not in any of the other vineyards." Cathy Corison's Kronos vineyard in St. Helena has organic methods and solid, old rootstock going for it. Kronos is planted on St. George, which is one of California's old drought-resistant rootstocks. At 40 years old, the rubrum-colored leaves indicate that the virus is present, but Corison doesn't care. "Few people would tolerate the yields I get off the vineyard," she acknowledges, "but I love the flavor from those grapes." The virus seems to prevent her grapes from maturing too fast and getting too sugary, exactly what she wants. Tony Coturri, a longtime organic wine grower and winemaker, almost has a response of "What virus?" even though it exists in the Hanzell vineyard in Sonoma, which he helps farm. "We just have to live with it," he says. "Sometimes the weaker plants bring a complexity to the wine." He considers clean vine material too simple to make good wine. Controlling the situation with chemicals isn't a solution, warns Kent Daane, an entomologist at UC Berkeley. Daane found that spraying, which some fearful vineyard owners had done, was not effective because the bugs hide under the leaves. Solution A better solution, he says, is a new $54,000 pheromone mating-disruption program, funded by Napa County. Plastic packets measuring 2 by 3 inches impregnated with pheromones hung in vineyards in Napa and St. Helena. The idea: Keep the mealybug population down and avoid the spread of the virus, allowing young plants to grow large enough to fend off infection. Golino is adamant that growers must purchase new certified vines - "even when it means giving up field selections that have been a longtime part of a winemaking program" - in order to reduce the virus' impact. But even that won't eliminate it. "There is not going to be a fast fix," she says. Susceptible to infection And certified vines are susceptible to infection, too. Sebastopol consultant James A. Stamp is often called in as an expert witness when vineyards have taken nurseries to court for buying certified clones that came up positive for the virus. Stamp notes that the desire to keep the complexity of virused vines has led to some unusual farming notions. "We joked about the idea to clean up the vines and then add viruses back in, to add back the potential for complexity," he says. "It would have been a little bit like having unsafe sex." Curiously, organic and biodynamic growers haven't necessarily witnessed the same dangers. Grgich Hills has 25 biodynamically farmed acres in Yountville, adjacent to an afflicted Dominus vineyard. In 2001, Grgich saw the spread of red leaves into its vineyard. The fruit couldn't top 23 Brix, a measure of sugar. In 2003, they started biodynamic conversion. "We saw red leaf slow down and our ripeness increase," says winemaker Ivo Jermaz. "In fact, since going biodynamic, we have to watch so the grapes don't get too ripe." Monica Cooper, Napa County's viticulture farm adviser, couldn't comment on the impact of farming choices, though scientists like Daane suggest organic farming might help. Research in this area has been poorly funded, even though circumstantial evidence shows that organically farmed environments might have natural predators for the mealy bug. "We don't see the problem in our organic vineyards as we do in our conventional," says Jackson, who farms using a variety of protocols. "But I'm not prepared to say that's the reason." Viticultural consultant Steve Matthiasson, who consults for Napa's Araujo Estate, among others, is not alone when he jokes that less color, flavor, alcohol and ripeness might be blessings in disguise. This reaction raises Golino's ire. "I would love to see California produce less alcoholic wines," she says. "But virus isn't the way to do it."