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Grapes Don't Like Chilly Wet Mornings And Neither Do I

When I moved into my tent at the winery over a year ago I wondered why in the early morning I would hear what sounded like a fleet of helicopters landing in the vineyard. I now know that what I was hearing was the sound of vineyard owners battling the frost that threatened to destroy their grapes. If the temperature drops to below 32º F for more than 30 minutes there is a chance that ice crystals will form within the plants cells and destroy any green growth. During the spring when the buds are forming that will produce the fruit for harvest, the entire crop is vulnerable. In the fall early rains mixed with low temperatures can cause the grapes to shatter on the vine. Growers have developed a number of ways to combat this potentially disastrous scenario. Overhead sprinklers are one such technique. By covering the vines in water constantly the plant tissue will remain at 32º as long as the temperature is above 20º. The technique is effective but the systems are expensive, require maintenance and use about 55 gallons per acre per minute to be completely effective. That’s a lot of water. Heaters have also been used, though usually in conjunction with another method. Vineyard heaters for commercial use must comply with California emission standards but still can burn up to about a gallon of diesel fuel an hour per unit. Imagining the vast vineyards of California blanketed by these heaters makes the environmentalist in me cringe. The fans I mentioned earlier circulate the warmer air that is higher in the atmosphere. These can raise the temperature at the level of the grapes to 1/4th the difference between the temperature at 4 feet off the ground and 40 feet. So if there is a 4º temperature difference the fans will effectively raise the temperature at the height of the vines by 1º. The Department Of Agriculture’s Natural Resource Conservation Service is working with vineyards owners to switch to this method to conserve water. Maintaining soil that radiates heat effectively is an important component that can be utilized to bolster any frost protection strategy. Soil that is clean, firm and moist is best. Research recently done at the University of California, Berkeley indicates that the ice crystals that form in plant tissue must have a nucleus on which to form. Bacteria is what provides such a nucleus so by reducing the amount of ambient bacteria present on the vines the risk of frost should theoretically be reduced, though this strategy has yet to be implemented commercially. Frost damage is not a threat everywhere in California but in the Valley of the Moon where Deerfield Ranch Winery is located it is a threat that we contend with every year. We made it through spring without too much issue, though we did use our dual purpose irrigation system which makes use of water that is recycled by our on-site water treatment bioreactor. Usually, in Sonoma county, fall frosts which damage crops are rare because typically the fruit has been harvested. We can't seem to catch a break this year: A frost warning was issued for Wednesday morning. It looks like this time that the threat didn't materialize though. Deerfield is planning to pick its entire Syrah vineyard by mid next week. I'll let you know how it goes!

Global Warming? Not In Northern California Wine Country…

Controversy about climate change has swept the entire nation, with California wine country in tow. While record high temperatures have been searing cities across the country, Californians are complaining about another unseasonably cool summer. As these changes in temperature evolve into what seems to be a pattern, wine analysts and pundits are wondering if the esteemed growing regions of Northern California, like the Sonoma and Napa Valley, will be equally idyllic in the future. A report found in the journal, Environmental Research Letters, posited that as much as 50% of the North Coast and Central Coast growing regions would become unsuitable for winegrape production by the year 2039 due to higher temperatures. A myriad of publications including the L.A. Times, The Press Democrat and The Huffington Post wrote articles citing the report, prompting backlash from other journalists refuting the report’s claims. Notable wineblogger Steve Heimoff pointed out in this article that, in fact, this is the seventh year of cooling temperatures in Northern California. Deerfield’s winemaker, Robert Rex, asserts that the warming temperatures in the middle of North America are drawing the cool marine air further inland, across California. The unprecedented amount of fog in the valley for this time of year is a good indicator that he’s right. Global warming doesn’t mean that every area on the planet is getting warmer – some places actually get colder as other places get hotter.

As the end of August approaches, the buzz in the Sonoma Valley continues to revolve around the unusually cool summer. The record amounts of late rainfall and low temperatures probably would be more shocking if the previous two harvests had been any different. The reality is that what seemed like an anomaly in 2009 has developed into a steady pattern. Both the ’09 and the ’10 harvest in Northern California were among the most challenging years that growers and producers have seen in decades. Both years bore the same hallmarks: Cold nights, few days above 80 degrees and heavy rainfall before most grapes were optimally ripe, which then brought mold and mildew. Top that off with some erratic one-day heat waves that burnt the sensitive, normally sun-tanned, grape skins and you’ve got the Perfect Storm of poor growing conditions.

I’ve talked before about how these are the years when skilled winemakers stand out; these are the years when being selective about every single bunch of grapes is the key to producing quality wine. Now that the 2011 season is shaping up to be a repeat of the last two years, grape growers in Sonoma County are adapting to the shift in weather patterns. Growers were heavily culling formative grape clusters before fruitset even occurred, hoping to channel every ounce of captured sunlight into the remaining grapes. Last year many farmers cut most of the leaves off the vines, thinning the canopy to expose the grapes to more sunlight. That backfired when over two days in late August, a blistering heatwave scorched the rows of unprotected grapes. This year, the canopy is being left thicker, particularly on the sunny side and the plan is to lower the wires that hold the canes upright to provide emergency shade in case history repeats itself. Even though most grapes are as much 20 days behind, 2011 could be an ideal year if the sun continues to break through the fog and the fall doesn’t come early. The cooler, longer summer will produce great flavors at lower potential alcohol levels. Cautious optimism seems to be the prevailing sentiment, which is typical of growers and winemakers.

I believe that whatever the cause, climate change poses tremendous risk to our environment, yet our culture will shift with the weather. Winegrowing regions are quite diverse throughout the world; the arid plains of Spain are nothing like the chilly slopes of the Mosel Valley. It is possible that due to changing ecosystems, the terroir of renowned growing regions will be dramatically altered. Winemaker Robert Rex believes that the shift towards a cooler growing season is here to stay in the California North Coast. That doesn’t mean that we’re going to stop growing grapes or making world-class wine. No – it means that we’ll adapt to our new environment by producing wine that reflects the changing terroir. Only time will tell what the landscape will look like in 50 years, but whatever the outcome I’m sure that Sonoma will be famous for its wines for centuries to come. Perhaps Napa Valley will become famous for Pinot Noir instead of Cabernet.

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