新澳门六合彩内幕信息

When Smoke Gets In Your Wine

What Are the Solutions for Climate Change-Impacted Grapes?

Many wine lovers know that a hint of smoky flavors in Zinfandel or Pinot Noir are the perfect complement with grilled meats. They may also be familiar with the phrase, 鈥淪tressed vines make the best wines.鈥

But what if those smoky overtones go overboard as the grapes are exposed to destructive wildfires? And what if those stressed vines are the result of prolonged drought conditions?

As the effects of climate change are felt in California wine country and around the world, vintners are anxious about what the future holds. They wonder if some wine regions are becoming too warm to properly grow such signature grapes as Cabernet Sauvignon and Chardonnay. They鈥檙e concerned about prolonged droughts that decrease harvest yields and lead to dry conditions that set the stage for massive wildfires. Those fires can not only destroy precious vineyards but also damage fruit through prolonged smoke exposure.

Grapes growing in a vineyard
Oakville Station is a 40-acre research vineyard in the Napa Valley that has been utilized by 新澳门六合彩内幕信息 Davis for more than 50 years. It houses trials of rootstocks, irrigation, clones and other critical aspects of viticulture. (Gregory Urquiaga/新澳门六合彩内幕信息 Davis)

 

With so much at stake in the world鈥檚 wine industry, 新澳门六合彩内幕信息 Davis researchers are focused closely on mitigating the effects of climate change in viticulture. They鈥檙e working with the wine industry to study such pressing issues as smoke taint, drought-tolerant rootstocks and other ways that grape growers can adapt to warming temperatures.

鈥淲e鈥檙e seeing the impact of climate and climate change,鈥 said Megan Bartlett, a 新澳门六合彩内幕信息 Davis plant biologist and assistant professor. 鈥淓specially after the heatwaves and the megadrought a few years ago, we really saw, as an industry, declines in (crop) yield. These are really pressing problems, especially now.鈥

The spectre of smoke

The 2020 vintage was a lost year for Stuart Spoto. His premium brand, Spoto Family Wines, sources much of its Cabernet Sauvignon in the Oakville appellation in Napa Valley, on a plot of land that鈥檚 also used by 新澳门六合彩内幕信息 Davis researchers at Oakville Station.

As wildfires and hazardous smoke whipped around the Napa Valley in the fall of 2020, Spoto couldn鈥檛 help but fret. He鈥檇 been through this in 2017, when Napa was similarly engulfed in flames and smoke from the wine country fires.

While Spoto Family Wines was still able to release a 2017 vintage, this time was different. Early analysis showed that prolonged smoke exposure had most likely tainted the grapes that made the wine, leaving Spoto to scrap the 2020 vintage. Shafer Vineyards in Napa鈥檚 Stags Leap District and Somerston of St. Helena were among those who made the difficult decision to forgo the 2020 vintage due to smoke taint concerns.

鈥淧art of being in Oakville is we have a good team of fellow vintners, and 新澳门六合彩内幕信息 Davis is part of that,鈥 said Spoto 鈥82. 鈥淲e had a lot of data collected and we relied on other people鈥檚 information and sensory evaluations. Sitting down with 新澳门六合彩内幕信息 Davis, we had a pretty clear idea to not produce wine.鈥

Can you imagine licking an ashtray?

Anita Oberholster, a Cooperative Extension enology specialist at 新澳门六合彩内幕信息 Davis, has studied the effects of smoke taint over the past four years, as wildfires have become an annual event in California. She鈥檚 now one of the world鈥檚 leading experts in the issue.

If grapes are exposed to smoke, especially for extended periods of time, they can impart unwanted flavors into finished wine. That鈥檚 smoke taint, and it has the capability to ruin entire vintages of wine.

鈥淐an you imagine licking an ashtray?鈥 Oberholster said. 鈥淲hen wines are heavily impacted, it can taste like that.鈥

Anita Oberholster holds a pipette over a vat
Anita Oberholster uses a large pipette to grab a sample of smoke-exposed wine that鈥檚 been sitting in fermentation tanks. (Joe Proudman/新澳门六合彩内幕信息 Davis)

The impact of smoke taint isn鈥檛 always cut and dried. You can鈥檛 predict which grapes may have suffered damage based on anything intuitive, such as sight, smell or even the flavor of fresh grapes. Just because there鈥檚 smoke in the air doesn鈥檛 mean grapes are tainted.

鈥淭here are so many variables,鈥 Oberholster said. 鈥淔reshness of the smoke, number of times exposed, variety of grape 鈥 the list goes on. There鈥檚 so much we don鈥檛 know.鈥

Chemical analysis can help predict the likelihood of smoke taint, but time is of the essence. In the fall of 2020, as grapes hung heavy on the vine in Northern California, commercial labs were backed up for several weeks to test for possible smoke taint. Even if the grapes were unaffected, disruption could still be felt around the wine industry.

鈥淕rowers were in a tough position because buyers were cancelling contracts unless you could prove your grapes hadn鈥檛 suffered damage, said David Block, 新澳门六合彩内幕信息 Davis viticulture and enology professor and department chair, 鈥渁nd demand for analysis far exceeded supply.鈥

鈥淭here are so many variables. Freshness of the smoke, number of times exposed, variety of grape 鈥 the list goes on. There鈥檚 so much we don鈥檛 know.鈥 鈥 Anita Oberholster, 新澳门六合彩内幕信息 Davis enology specialist 

 

Mysteries and myths

Thus, the research related to smoke taint continues, with a long list of mysteries and myths to decipher.

鈥淣umber one, are we looking at the right molecules?鈥 Oberholster said. 鈥淲e can鈥檛 fully assess smoke-related issues if we don鈥檛 completely understand the nature of the compounds at play.鈥

Smoke barriers are also on Oberholster鈥檚 radar. She wonders if a spray could be developed that growers could use to protect grapes from the harmful compounds that burning woods emit.

Additionally, Oberholster hopes to see the development of low-cost sensors that support growers鈥 ability to estimate smoke-taint risk.

鈥淭hat would expand lab capacity because you鈥檇 only have to test grapes that were in a high-risk zone,鈥 she said.

As for myths, Oberholster wants to dispel the misconception that grapes and wine will automatically suffer in smoky conditions. 

鈥淐onsumers have no reason to shy away from vintage 2020,鈥 she said. 鈥淲inemakers will ensure the quality of the wine is what the consumer expects. They know that if consumers taste wine that is tainted, they won鈥檛 reach for it again.鈥

Rising temperatures, thirsty vines

2020 started on a worrisome note in terms of water. In February, the U.S. Drought Monitor classified nearly 60% of the state鈥檚 land as 鈥渁bnormally dry.鈥 That included the wine grape growing counties of Napa, Sonoma, Lake and Mendocino.

Meanwhile, a broader and equally troublesome trend was emerging in California鈥檚 wine country. Napa, for example, was moving into a warmer climate category according to the Winkler Index. Developed at 新澳门六合彩内幕信息 Davis by A.J. Winkler and Maynard Amerine, this system classifies the climate of wine growing regions based on a heat summation scale and serves as a guide for which grape varietals are best suited for a given area.

Grape vineyards under shade screens
Shade films are tested at Oakville Station to research their effectiveness in protecting grapes from heat and ultraviolet light. (Courtesy Kaan Kurtural)

Back at Oakville Station, Kaan Kurtural works directly with growers regarding climate change and wine. He鈥檚 a professor of viticulture at 新澳门六合彩内幕信息 Davis who researches rootstocks and clone combinations that show promise in being more drought-tolerant, along with farming practices that mitigate the effects of warming weather. Some future plots at Oakville Station will focus on varietals that are native to southern Italy and Greece and will be tested for plant-fitness in California鈥檚 warming climate.

鈥淚 don鈥檛 think there was ever a doubt with grape growers that it was happening,鈥 Kurtural said about climate change. 鈥淭his is bottom-line 鈥 grapes are money, it鈥檚 business.鈥

In response to warming temperatures, Kurtural is testing shade films that can be used in vineyards to filter certain types of ultraviolet light. Grapes can still be grown outdoors but have the potential to stay cooler and expand the growing season with these systems.

Two men stand between rows of wine grapes
Says 新澳门六合彩内幕信息 Davis viticulture specialist Kaan Kurtural, right, pictured with Miguel Guerrero of The Wine Group: 鈥淸Shade screens were] one of the first things that Napa Valley growers asked me to test when I came to 新澳门六合彩内幕信息 Davis in 2015." (Courtesy photo)

鈥淚t was one of the first things that Napa Valley growers asked me to test when I came to 新澳门六合彩内幕信息 Davis in 2015,鈥 Kurtural said. 鈥淣ow we have shades over the rows to block out the vineyards. It looks like you鈥檙e growing the grapes in a greenhouse but the site is open.鈥

Kurtural is also helping lead a trial that focuses on Napa鈥檚 most signature grape: Cabernet Sauvignon.

This red varietal, which likely accounts for slightly more than half of the Napa Valley鈥檚 grape plantings, requires very particular conditions to thrive. It needs warmth to ripen 鈥 but too much heat can make its flavors go flat and boozy. And without enough water supply, growers can face low crop yields.

Kurtural is now part of a research team that鈥檚 collaborating with Napa鈥檚 Beckstoffer Vineyards and Duarte Nursery in Stanislaus County in what鈥檚 been called 鈥渢he mother of all cabernet trials.鈥 It encompasses 3,600 plants with 10 clones of Cabernet Sauvignon crossed with different 10 rootstocks.

The trial鈥檚 goals are to find the hardiest rootstocks for Cabernet Sauvignon by identifying biomarkers for overexposure and water stress.

Explained Kurtural, 鈥淲e鈥檙e going to use these biomarkers to identify the most resilient rootstocks and clone combination for Cabernet Sauvignon. 鈥淚t鈥檚 unlikely that things will change overnight,鈥 he added, 鈥渙r the markets will accept a substitution for Cabernet or (Bordeaux varieties). This will buy us some time to find some breeding material to blend in.鈥

Bartlett, the plant biologist, also works to identify traits that can improve drought tolerance in rootstocks. She鈥檚 part of a 新澳门六合彩内幕信息 Davis project that鈥檚 looking at the characteristics of root cells that help the roots maintain water intake from dry soil. Once the genes with those traits are identified, they can screen across large populations for breeding.

鈥淲e鈥檙e trying to see how we can solve problems by improving these plants,鈥 Bartlett said. 鈥淲e want to see how we can scale up these traits for overall stress tolerance and performance from the plant.鈥

鈥淐onsumers have no reason to shy away from vintage 2020. Winemakers will ensure the quality of the wine is what the consumer expects. They know that if consumers taste wine that is tainted, they won鈥檛 reach for it again.鈥 Anita Oberholster, 新澳门六合彩内幕信息 Davis enology specialist 

 

So as the wine world looks to the 2021 vintage and beyond, questions remain about climate change and what the future may hold.

鈥淎 crystal ball would be nice in terms of climate change,鈥 said Spoto, the Oakville Station winemaker. 鈥淚 let the experts take the lead. Having 新澳门六合彩内幕信息 Davis in our backyard is beyond words for the benefit we get.鈥

Diane Nelson, 新澳门六合彩内幕信息 Davis College of Agricultural and Environmental Sciences, contributed to this story

Three people with masks stand in a smoky vineyard
Harvesting Cabernet Sauvignon grapes at Oakville Experimental Station under smoky conditions in 2017. From left to right are Ph.D. student Raul Girardello, M.S. student Arran Rumbaugh and Anita Oberholster, cooperative extension specialist in the Department of Viticulture and Enology. (Photo courtesy Anita Oberholster)

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Chris Macias, 新澳门六合彩内幕信息 Davis News and Media Relations, 530-752-9844, cjmacias@ucdavis.edu

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