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Colorado grape harvest early

By Dave Buchanan
Winemakers across the Grand Valley are in the midst of grape harvest, which this year comes a little earlier than in 2006. You can thank the hot but not too-hot summer for that, said Horst Caspari, viticulturist for the Colorado State University research center on Orchard Mesa. "We certainly are in the swing of things," Caspari said in a phone conversation today. "Some grape growers probably are getting into the chardonnay and merlots. The early whites like the sauvignon blancs and seyval blancs are already gone and the pinot gris is almost gone." Those white grapes normally are the first harvested in what can be a extended process depending on how the temperature holds in this change-of-season period. No matter what happens in the next month or so, this year's harvest is taking off, Caspari said. "It's an early year, I picked a lot of my stuff (on Orchard Mesa) already," he said. "I've heard that chardonnay is starting to mature and it's quite a bit earlier than last year." Winemakers the world over are reporting an early harvest, thanks mostly to warmer temperatures. In the Venetto region of northeast Italy, famed for its sparkling wines, grape growers started picking prosecco grapes nearly three weeks earlier than normal. In Sonoma County, Cal., a story in the Santa Rosa, Cal. Press-Democrat, said rising temperatures not only sped up the harvest but created the expected rush to crush at area wineries. "We're going faster than we've ever gone, by far," winemaker Bob Iantosca of Gloria Ferrer Champagne Caves told reporter Kevin McCallum. How do winemakers and grape growers know when to say when? Unless the promise of bad weather forces them to pick early, growers use several methods to determine if a grape is ripe enough to pick. Some growers rely on chemistry sets, using special tools to determine sugar and acid content in the grapes. Other rely on taste, actually going out into the vineyards and randomly tasting grapes to see where they are in terms of physiological ripeness. Rainer Thoma, winemaker for Garfield Estates Winery in Palisade, said he does both, taking samples to taste in the field and samples to test in the lab. "I'll go back and forth along the rows, even reaching up into the vines to make sure I get clusters I can't see, to make sure I get an even sampling," Thoma said recently. Warm but not too-hot temperatures all summer long pushed area grapes to early maturity, Caspari said. "The good thing about it is we didn't have that many really hot days, very few that went over 100 degrees," he said. Even so, August was more than 3 degrees warmer than average, including an average minimun temperature that was 3.5 degrees above average and and average maximum that was 2.6 degrees above average. That's based on 43 years of records kept at the Orchard Mesa research station. "Right up to the 20th of August we were on track for the hottest year on record," Caspari said. "It's certainly warmer than we've ever been." Warm days push grapes to ripeness but cool nights are needed to allow acid levels to stay high enough to balance the fruit sugars. When grapes respire at night, they give off malic acid, and on cooler nights respiration is less and more acid stays in the grape, Caspari explained. On warm nights, when respiration is more active, more acid is lost and that could mean a lack of balance between the sugar and acid levels. "I’m seeing, at least from some samples from our station, comparatively low acid levels in grapes, (which is) related to warmer nights and higher acid respiration," Caspari said, adding he has yet to conduct any detailed chemical analyses. When a white wine is out of balance with too much acid, it can be described as "flabby," while too much acid give a overly tart sharpness, neither of which makes for pleasant drinking. Sweet and semi-sweet white wines, such as riesling or gewurtztraminer, can hide a lot of acidity behind their sweetness and reach a balance that makes them appealing. Caspari once made a vintage of the French hybrid grape vignoles with 16 grams of residual sugar, which is quite high since most sweet dessert wines range from 5-15 grams. "It had very high sugar and high acid (so it was) tart yet incredibly sweet, and in that combination you can hide a lot of acid," Caspari said. "But you need it to reach the right balance." You can read more about balance in wine here