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38 WINES&VINES April 2016 GROUNDED GRAPEGROWING sarily the sole cause of smoke flavors, they are highly correlated to many other compounds that cause wine to taste bad and are easily detected in the lab. There are protocols in place to test fruit before picking, and anything found to have more than 0.5 parts per billion (ppb) guaiacol is considered likely to have smoke flavor problems. Sampling whole berries is recommended, as the skins of the berries have the highest concentration of guaiacol and 4-methylguaiacol compared to juice. Whole berry test results indicate that levels between 0.5 ppb and 2.0 ppb are moderately affected and will require special handling and treatment in the winery. Levels above that are almost certainly going to have major problems that may be cause for rejection by the winery, es- pecially for red fruit. Where does the smoke go? Research in Australia has shown that smoke uptake is most serious during the post-véraison period, but smoke damage also can occur at other times while fruit is growing. In the 2008 North Coast Lightning Complex, dense smoke occurred from June 21 to August in many areas while fruit was developing, and smoke-fla- vored fruit was widespread. The intensity and duration of smoke no doubt plays a factor. We noted locally that not all vineyards were equally affected, and why this occurred re- mains a mystery along with the pattern of smoke-affected vineyards. If your vineyard is close to a large fire and is inundated with intense smoke even for a relatively short period of time, it is likely that the fruit will be affected. In Australian re- search, ash settling on fruit was not found to contain very much guaiacol. Researchers were unable to remove guaiacol from the fruit by washing or rinsing with any solvents. However, removing the leaves from around the fruit, high-volume and high-pressure washing with water before harvest did seem to help reduce smoke flavors in the wine. By contrast, if you are in a confined valley and smoke settles as an inversion layer for a day or two from a distant fire, it is less likely that you will have issues with off-flavored fruit. If that smoke lasts for weeks, you may very well have smoke problems with your fruit. Grape varieties also differ in how much smoke they absorb and the extent of off flavors that result. Experiences in California, Canada and Australia suggest that the most affected varieties in decreasing order are Sangiovese, Pinot Noir, Cabernet Sauvignon, Chardonnay, Sauvignon Blanc, Syrah, Merlot and Petite Sirah. Processing white vs. red fruit affected by smoke Experience has shown that smoke-affected white fruit can be avoided and cleaned up by following these practices: •Harvest when the fruit is cool. • Hand harvest into smaller containers to avoid breaking skins as much as possible. Small vineyard blocks surrounded by flammable material are most susceptible to fire.