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Rootstock Research Reaches for Drought Resistance

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Canopy of vines on GRN2 rootstock, close to harvest in 2021 drought year. Rootstocks like GRN2 are good at mining water from the soil (photo courtesy Tian Tian, UCCE.)

Vineyard rootstocks find water, scions spend water.

The relationship between the two needs to work to produce grape yields and quality, but researchers know if drought conditions persist, rootstocks that can perform on less water must be developed.

Most grapevines are grafted on a rootstock, the underground part of the plant that supports growth aboveground. Grapevines are deeply rooted with more than 25% of root biomass typically distributed below one meter.

Luis Diaz Garcia, assistant professor in grape breeding in the Department of Viticulture and Enology at UC Davis said drought resistance research is ongoing, exploring different adaptive strategies in a variety of grape germplasm and developing novel approaches to screen drought tolerance traits more efficiently. Diaz Garcia said his laboratory is using genomics, robotics, proximal sensing and artificial intelligence to increase the efficiency in identifying superior-performing vines.

These approaches, he said, can increase the number of plants evaluated in the program and reduce the time it takes to find and test the new rootstocks.

Diaz Garcia explained there are several mechanisms by which a grapevine can tolerate drought. Those include closing its stomata (small pores on the surface of the leaves that facilitate gas exchange and transpiration) to prevent water loss, limiting growth and modifying its root architecture to explore more soil area and extract water.

“The challenge is not all of these adaptive mechanisms are compatible with vineyard production systems. Therefore, understanding these mechanisms is crucial for selecting the best/most informative traits to screen in breeding programs,” he said.

The goal of the UC research, Diaz Garcia explained, is to develop new rootstocks with improved water-use efficiency and other adaptive traits such as nematode tolerance and good grafting and rooting capabilities. New root traits that help with drought resistance have been identified by UC researchers.

Drought Responses
Megan Bartlett, Department of Viticulture and Enology, said with identification of these traits, they can be amplified in new grape varieties. A UC publication outlined her study findings. Contributing to her study were researchers from University of British Columbia and the USDA-ARS Crops Pathology and Genetics Research Unit.

Bartlett’s research focused on drought responses in living root cells. Capitance, a measurement of how much roots shrink as they dehydrate, is an important trait for drought tolerance. Water stress can cause roots to shrink and pull away from the soil, losing access to any soil water. When the scion is unable to replace the water lost to evaporation, the stomata are closed to prevent severe dehydration. However, this stops photosynthesis. Rootstocks with lower capitance maintained greater gas exchange under water stress, suggesting adjustment in root structure and biochemistry to retain greater root volume could improve belowground hydraulic function under drought conditions. Bartlett’s study was the first to test whether traits measuring root shrinkage and cell collapse can capture differences in rootstock drought tolerance.

Canopy size of different rootstocks tested for drought resistance. UCCE Viticulture Advisor Karl Lund notes there is a lot of variation among rootstocks in how they handle water stress (photo courtesy K. Lund.)

Karl Lund, UCCE viticulture advisor in Madera, Merced and Mariposa counties, said most of the work in drought tolerant rootstock development is focused on the winegrape segment as there is funding available. Bartlett’s study was supported by the American Vineyard Foundation, UC Davis and by private donations.

“What does drought tolerance mean?” Lund asked. “Is it when a rootstock is good at dealing with low irrigation like 70% of ET over the season, or is it the ‘broken pump’ problem where there is no water available for a period of time, and when it is, will the rootstock recover?”

Lund explained there is a lot of variation among rootstocks in how they handle water stress. Some, he noted, are good at mining water from the soil or can find water in the soil. An example is the GRN3 rootstock’s ability to find water.

One challenge to development of a new rootstock is time. Lund said with drought tolerance in mind, first you have to grow the plant, then it takes multiple years to determine its value as drought-tolerant. Field trials for drought tolerance are also difficult to do in wet years.
In comparison, a rootstock trial for nematode resistance takes six months to two years.
Use of genetic markers to make crossbreeding selections for rootstocks can speed up the process, but the rootstock’s performance in the field for crop yield and quality also must be considered.

Scion Plays a Part
The scion grafted to the rootstock also plays a part in drought tolerance. The rootstock may find the water needed for production, but it is the scion that decides when to open stomata for transpiration. Canopy size is also controlled by both the rootstock and the scion. Larger root systems handle drought by finding water, but they also support a larger canopy.
Lund said he has found situations where a drought-resistant rootstock develops a large canopy that can still handle water stress when the rootstock and scion work as a team. Some incompatibility issues between rootstocks and scions have arisen, but Lund said viruses may play a part in that.

When choosing a grapevine rootstock, Lund said the first question is how much tonnage do you want? That figure varies depending on the region. In the San Joaquin Valley, desired winegrape tonnage is high. In the wine country to the north, lower tonnage is preferred, he said. 7 tons to the acre is too much for winegrape growers in the Napa and Sonoma growing regions; they prefer about 3 to 5 tons per acre and desire a lower-vigor rootstock.

Wine and Food Pairings Can Be a Complex Art

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Martha Stoumen’s Negroamaro Rosato goes well with salami and cheeses (photo by Andrew Thomas Lee.)

Conventional wisdom will tell you beef goes best with red wine, and white wine is best with fish. The truth, however, is pairing the right wine with your meals, desserts and cheeses is much more complex.

“In my experience of preparing food to be enjoyed with wine, I’ve learned that it’s not about finding the ‘perfect pairing,’” said Sarah Scott, executive winery chef at Opus One Winery. “These can be elusive. Rather, it’s about consistently cooking with excellent, seasonal products and mindfully balancing the umami, salt and acid ingredients within each dish. This allows the wine to taste as the winemaker intended.”

“We consider body and texture when considering food pairings for our wines,” said Nina Kravetz, head of marketing and direct-to-consumer sales at Martha Stoumen Wines. “Lush and textural wines like our historic Out to the Meadow field blend or aged Negroamaro Rosato keep us craving salty foods with a compelling char. When bright and brooding wines like carignan and pinot noir are on the table, we lean on more decadent dishes that could use a companion to cut through the fat.”

“When you’re doing food pairings, there are some basic rules,” said William Allen, owner and winemaker at Two Shepherds, who provided an example. “Try to avoid completely opposite wine pairings. Generally, if you’re matching wines with acidity, you typically want to pair them with foods that have acidity.

“One of the things in pairing that is often very difficult is spicy foods,” he said. “Most wines will clash with spicy foods. That’s why a lot of people drink beer with spicy food. Big bold fruity wines don’t work because you’re clashing fruitiness with spiciness.”

Opus One wine paired with seared Sonoma duck breast with sautéed spinach, cremini mushrooms and a crispy polenta cake (photo courtesy Opus One Winery.)

Seafood Pairings
“Penfolds BIN 311 Chardonnay has vibrant citrus fruits and pronounced minerality,” said Ellie Farrell, public relations manager at Treasury Wine Estates, which has more than 40 wine brands including Beringer Vineyards. “For the same reason, we love a squeeze of lemon on crab legs, shrimp and oysters. The crisp citrus flavors are the perfect foil for briny shellfish.”

“Some of our lighter reds like our pinot meunier go great with salmon,” said Allen. “But we’re not talking about white steak fish. We also have the vermentino that would definitely pair with summer foods, summer salads, oysters for sure and other kinds of seafood.”
But pairing wine with seafood can be a challenge.

“It depends on your seafood,” said Allen. “What’s the sauce on it? Is it a cream sauce? Is it just grilled with nothing on it? You can take a fish dish and make it completely different depending on how you’re preparing it.”

Martha Stoumen’s Post Flirtation White can be paired with sliced vegetables and dip (photo by Emma K. Morris.)

Meat and Pasta Pairings
“We often recommend barbecue,” said Gillian Balance, Beringer Bros spokesperson and master sommelier, about food pairings with their cabernet. “Sweet, smoky, tangy sauces really play up the toasty oak characters, while the dark berry fruits and tannins provide the perfect contrast to savory meat platters.”

“The Beringer Knights Valley Cabernet Sauvignon is a delicious cabernet-driven blend with ample dark fruits,” said Farrell. “The well-integrated tannins and fruit-driven profile are the drivers of the wine’s versatility, allowing it to pair beautifully with any number of dishes, including roasted chicken, grilled beef tenderloin and pasta dishes with meat or mushroom sauce.

“The spicy, charred flavors from heavily toasted bourbon barrels add another dimension to the dark fruits in our Beringer Bros Red blend, which pairs well with smoked meats and barbecue,” she added.

Roasted lamb chops, duck and Wagyu New York Strip are among the meals that go best with Opus One, according to Christopher Barefoot, vice president of communications and guest relations at Opus One Winery.

Overture, the other wine produced by Opus One Winery, pairs best with “risotto with mushrooms, or any pasta with hearty mushroom sauce and a truffle or two on top,” said Barefoot, who also suggested meats with chimichurri and roasted root vegetables, and “even a grilled burger with sharp cheddar cheese and a medley of summer vegetables like summer squash or summer beans.”

Opus One wine paired with roasted lamb shop with celery root purée and summer vegetables (photo courtesy Opus One Winery.)

Martha Stoumen’s cabernet blends like Another Shore 2021 go well with hearty dishes, those that are fattier and meatier such as sausage and schmaltzy chicken, according to Kravetz, adding Honeymoon goes well with continental fare.

“Our white Honeymoon blend is also a holiday favorite,” she said. “It’s fun to cook while you drink the wine.”

Allen, who describes his Rosé of Cinsault as a complex wine to be served with a little chill, said, “You can pair it with things that are savory. Duck is good, so is lamb. You would also pair it with typical summer fare, particularly hamburgers, hot dogs and barbecue ribs. It’s got a nice freshness and a little bit of structure.”

Cheese Pairings
“Sharper cheeses are best, harder vs soft, and with a good amount of age, including aged gouda, ewephoria, seascape, fiscalini cheddar, comet and toma,” said Barefoot about Opus One pairings, adding the recommended cheeses with Overture are similar to Opus One since they are both cabernet wines.

“What you want to avoid is soft rind, creamy cheeses like French bries, and triple cream such as Brillat-Savarin, St. André, etc.,” he added.

“With so many wines in our portfolio, and the incredibly diverse world of flavors and textures in cheese, I often will recommend a delicious ‘bridge’ wine, something that will work with almost any cheese,” said Farrell. “A great example is our Etude Pinot Noir from Grace Benoist Estate in Carneros. The wine offers subtle red fruits, earthy tones and silky texture, making if the perfect backdrop for mild, earthy cheeses like tomme, manchego, gouda and mild cheddars.”

Dessert Pairings
“Many popular desserts have one or all of the following: nuts, caramel, butterscotch, chocolate or dried fruits,” said Farrell. “When describing our Penfolds Club Tawny Port, all these flavors are mentioned. There is also enough sweetness to match desserts like sticky toffee pudding, crème brulée or ice cream with caramel sauce.”

Allen, however, is not as enthusiastic about pairing wines and desserts.

“For me, generally, pairing dry wines and desserts is a challenge,” he said. “Maybe in the summertime, like a watermelon or a fruit salad, but definitely not a typical sweet dessert like cake or brownies. This is why typically dry red wines and chocolate don’t go very well even though people try to sell you red wines and chocolate at Valentine’s Day. It’s actually one of the worst kinds of pairings there is.”

Temperature vs Wine Flavor
“Think about temperature,” said Allen. “You wouldn’t have a dinner party and serve a carrot soup out of the refrigerator. You would heat it up.

“I always tell people, if you don’t have a wine cellar, which a lot of people don’t, take your red wine off the counter and put it in the fridge for 15 minutes, and take your white wine out of the fridge for 15 minutes,” he continued. “Remember the temperature of the wine dramatically impacts the flavor of the wine and thus the food pairing as well.

“95% of people drink their red wines too hot and their white wines too cold. So, you’re completely throwing off the food pairing because the temperature of the bottle characteristics changes. When your red wine is hot or warm at 70 degrees [F] on your counter, it’s not the proper serving temperature for an elegant red. You’re going to make the alcohol really stand out.

“On white wine, most people do the exact opposite. They pull them out of the fridge, which is 38 degrees [F]. If you’re buying ‘Two Buck Chuck,’ you would never put ice cubes in it and put it in a blender.”

‘Be Creative’
Winemakers are always learning about new pairings for their wines.

“Don’t stick to the old adages,” said Allen. “That’s a very outdated thing, white wine with fish, or red wine with meat. There’s a whole row of things in between that. Just be diversified.

“It’s fun to be creative,” he added. “I think people fixate too much on getting the food pairings exactly right. We will often have two bottles open and try them with both courses of the meal. Sometimes you’re pleasantly surprised.”

Martha Stoumen’s webpage offers visitors an opportunity to be part of the Cookbook section of its Field Notes by reporting and describing the new food and wine pairings they have discovered.

“We get a lot of reminders that wine pairings don’t need to be Eurocentric,” said Kravetz. “There are many flavors to be trying such as tacos and Middle Eastern food.”

But if you aren’t feeling especially creative, please note that wineries often include suggested food pairings on their websites.

Masters of the Vineyard

All Sangiacomo vineyards have received 100% sustainable certification from the California Sustainable Winegrowing Alliance (photo by Brennan Spark.)

The winegrape harvest has been finished for a week when brothers Steve and Mike Sangiacomo meet in their Sonoma office to catch up on some overdue indoor business.
Outside, the vineyards are quiet, their leaves turning to shades of gold and burgundy. There’s a sense of relief in the air on this November morning, and it’s not coming only from the fields.

“It was a successful harvest that definitely tested the resiliency of us as growers,” said Steve. “It even tested the resiliency of the grapes themselves. It was one of our longest growing seasons since 2005.”

Multiple rain events and unusually cool temperatures threatened the crop early on. But things began turning around after heat spikes in September and October enhanced ripeness and bolstered grape quality.

“It’s shaping up to be an exceptional vintage,” Steve added.

That’s good news for the Sangiacomos and for the 90 wineries who source their grapes from this third-generation farming operation. For more than 50 years, Sangiacomo Family Vineyards has been growing premium Chardonnay and Pinot Noir grapes for winery partners. Today, the Sangiacomos farm 1,600 acres across 15 vineyards in the Carneros, Petaluma Gap, Sonoma Coast and Napa Valley regions. Their vineyard expertise in one of the world’s premier wine areas has earned them a long list of loyal customers and a litany of industry awards.

“To put it simply, they are one of the best growers of Chardonnay in the world and a pleasure to work with,” said Richie Allen, senior director of winemaking for Rombauer Vineyards in St. Helena, in nearby Napa Valley.

He’s not alone in his estimation of the Sangiacomo operation. In 2020, the Sonoma County Farm Bureau honored the family with the Luther Burbank Conservation Award for balancing economic viability with environmental stewardship. In 2019, the Sonoma County Harvest Fair presented the Sangiacomos with its Sustainable Farmers Award.

Most recently, the California Association of Winegrape Growers (CAWG) named Sangiacomo Family Vineyards its 2024 Grower of the Year. In announcing the award, CAWG paid tribute to the Sangiacomos’ “pioneering spirit, commitment to sustainable practices, innovation and community engagement.”

The family’s goal is to maintain winegrape quality while farming more efficiently, says Mike Sangiacomo (photo courtesy Sangiacomo Family Vineyards.)

Family Roots
The Sangiacomos’ success didn’t happen overnight. The family has been farming in Sonoma County since 1927 when Italian-born Vittorio Sangiacomo purchased a 52-acre fruit-tree ranch just 2.5 miles from Sonoma’s historic city square. For years, the family grew pears on its home ranch.

Vittorio may not have been thinking of viticulture back then, but he had chosen land perfect for what his grandsons call “amazing vineyard sites.” In 1969, the Sangiacomos planted their first vineyard. By the 1980s, the conversion from orchards to vineyards was complete. Over time, the family expanded its acreage. Today, Vittorio’s grandchildren, Mike, Steve and their sister Mia Pucci, lead the operation, helped by other family members and 120 employees.

The 2023 growing season “definitely tested the resiliency of us as growers,” says Steve Sangiacomo (photo courtesy Sangiacomo Family Vineyards.)

In 2016, the Sangiacomos took on winemaking, launching their own estate brand. The label bears the “Sangiacomo Wines” name on its bottles of Pinot Noir, Chardonnay and Cabernet. Five years later, they began offering wine tasting and vineyard tours on the home ranch, now part of the Carneros American Viticultural Area. A recent wine tasting on the “Home Ranch Terrace” featured the Sangiacomo 2021 Sonoma Coast Chardonnay, which earned a 93-point, or “excellent,” score and an Editors’ Choice recognition from Wine Enthusiast magazine.

Yet the addition of winemaking is only a small part of the family’s business, amounting to about 4,000 cases a year, or just 2% of the fruit they grow. The rest of their winegrapes are custom grown for wineries whose annual volumes range from a thousand to hundreds of thousands of cases. The Sangiacomos work collaboratively with their clients, discussing varietals, clones, farming practices and appellations. Together they then select a match from over 300 small vineyard blocks. The Sangiacomos’ pride in their winery partners shines in the foyer of their Sonoma office, where a wall lined with dozens of their customers’ wine bottles dominates the room.

Staying Ahead of Challenges
As custom farmers, it makes sense for the Sangiacomos to have a broad customer base to minimize their farming risks. And there are plenty of those.

“You can do everything right in the vineyard, but Mother Nature can come in and take your success away in one vintage,” said Mike.

Like other grape growers, the Sangiacomos wrestle with weather and climate change, emerging plant viruses, labor shortages, water uncertainty, increasing regulations, energy needs, rising input costs, shifting market conditions and the lingering impacts of the pandemic.

Dozens of customers’ wines line the foyer wall in the Sangiacomos’ Sonoma office (photo by C. Merlo.)

“In our dad’s, uncles’, aunts’ and grandparents’ age, it was really more about just producing the best quality product you could,” said Mike. “Today, the challenge is continuing to evolve and stay ahead of all the issues.”

Added Steve: “We feel the responsibility to deliver a premium product. If we do not, a lot of these wineries are not going to have wine to sell, which is going to affect their businesses along with ours. So, we’re going to do everything we can to achieve that.”

As a result, the Sangiacomos have made sustainable winegrape growing a priority. In 2015, all Sangiacomo vineyards received 100% sustainable certification from the California Sustainable Winegrowing Alliance. That year, too, the family’s vineyards were also certified under the Fish Friendly Farming program for land management practices that protect fish habitat. Among their vineyard sustainability practices, the Sangiacomos have adopted water conservation, soil management and erosion control (e.g., planting cover crops and riparian strips).

An overview of the Sangiacomos’ home ranch near Sonoma. The large building at lower right houses their offices and wine tasting space (photo courtesy Sangiacomo Family Vineyards.)

Increasingly, the Sangiacomos also are seeking ways to use less energy, and they’re going electric where they can. They’re already using electric pressure washers, for example, and next year, one of their vineyards will use an electric tractor for the first time. They also plan to expand the use of solar panels for additional electric power. They’re investing in mechanized weed management for vineyard floors and canopies.

But this farming family relies on other strengths too. The brothers cite the family’s longevity, consistency and work ethic, handed down from what Steve called “an amazing example” set by previous Sangiacomo generations. The business also cultivates “a trust element” with its winery partners that also began with past family members, “who built our business on integrity and fairness,” Steve said.

The brothers maintain confidence that demand for good quality wine will continue to grow, even as certain consumer demand categories trend downward.

This sign welcomes visitors to the Sangiacomo headquarters, located in the Carneros AVA near Sonoma (photo by C. Merlo.)

“I’m optimistic,” Steve said. “Consumers want authenticity. They want to know where their food comes from. We believe if you take care of the land, it will take care of you.”

Looking ahead, the Sangiacomos will continue to grow their vineyard brand and their own wine brand simultaneously. They plan to remain in farming and to successfully transition the next generation into the family business. And they want to continue learning even more about winegrapes and making wine. They’re eyeing their grandfather’s homeland, where grapes and wine have gone hand in hand for more than 4,000 years.

“It’s on our list to go back to Italy, not as a vacation, but like a business reconnaissance mission, to learn more about winegrape growing from them,” Mike said. “It’s long overdue.”

A recent offering during a tasting at the family’s Home Ranch Terrace (photo by C. Merlo.)

Eye in the Sky

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This King Air B200 aircraft flew over California vineyards imaging them with an AVIRIS instrument from NASA’s Jet Propulsion Laboratory (photo courtesy K. Gold.)

A group of researchers have tapped NASA Jet Propulsion Laboratory’s hyperspectral imaging equipment and machine learning expertise to see if they can detect virus-infected grapevines before they exhibit visible symptoms. Although similar technology has been used to identify bacterial and fungal infections in asymptomatic plants and trees, it had not been used to detect viruses in asymptomatic vines until now, said Katie Gold, an assistant professor of grape plant pathology with Cornell University’s AgriTech in Geneva, N.Y. She is leading a Cornell research group collaborating with the Jet Propulsion Lab.

The theory is that by identifying asymptomatic grapevines infected with grapevine leafroll-associated virus complex 3, growers would be able to remove them earlier in the disease cycle.

GLRaV-3 has a latent period of about 12 months, and often times more, depending on the variety, where vines are infected but don’t express symptoms. The longer infected vines remain in a vineyard, the greater the potential for them to spread GLRaV-3 to nearby plants.

Based on two years of work with 300 acres of grapevines in the Lodi production area, Gold said they were able to identify asymptomatic red varieties with 87% accuracy. Although she said they were “very pleased” with the results, she also pointed out it wasn’t perfect.
For example, the machine learning model at times misidentified vines affected by the drought or other abiotic stressors mostly along vineyard edges.

“What we will work on is maintaining accuracy but reducing misclassification,” Gold said. “This is the low-hanging fruit, and we know we can improve our methods because we can improve our corrections.”

She also said she doesn’t see remote sensing technology replacing the need for PCAs and crop scouting but instead helping them be more efficient.

A drone captured a grateful message written among grapevines by collaborators in the hyperspectral imaging research in the Lodi region (photo by Aaron Lange, courtesy Lodi Winegrape Commission.)

A Promising Tool
Charlie Starr IV, a Lodi-area PCA who was part of the research project, said while hyperspectral imaging holds promise, it still has several unanswered questions.

He has been working with a vineyard client for several years to try to reduce the number of GLRaV-3-infected vines in a young vineyard by rouging. Unlike some areas of the state where grapevine red blotch disease is the predominant virus, Starr said GLRaV-3 is the leading one in the Lodi area.

Mealybug, which are endemic to the region, are the main GLRaV-3 vectors. Since it would be nearly impossible to try to eradicate mealybugs, he said they are focusing on eliminating infected vines.

“We know we can’t eliminate the vector, so that only leaves one other option: Try to get rid of the virus,” Starr said.

But that doesn’t mean they ignore mealybug. He and his client have taken an integrated approach that uses insecticides as well as mating disruption to bring pest numbers down as low as possible.

“It’s correct that we know we will not eradicate the mealybug. However, if we let the populations build, we’re only allowing more bugs to vector the virus quicker,” Starr said. That’s where he said a neighborhood mealybug effort that enlists nearby growers is important since the pest can move and be transported between vineyards.

Image A (left) shows the full extent of the AVIRIS-NG flights in 2020 over vineyards. Image B (right) zooms in on the the flight lines that collected hyperspectral imaging over Lodi-area vineyards (photo courtesy NASA/Cornell).

Depending on the season and other environmental factors, GLRaV-3-infected red varieties near harvest typically express visual symptoms compared with white varieties, which usually don’t.

Over the years, the client’s scouting crew has become skilled at identifying red varieties infected with the virus. But white varieties typically go unscouted because of a lack of visual symptoms.

“If we can refine [the technology] to where we can actually identify viruses in white and in red varieties, but more importantly in white varieties, that will be a game changer for us to get an upper hand on viruses,” Starr said.

He and his vineyard client’s efforts took on new urgency with the advent of sudden vine collapse several years ago.

UC researchers conducted PCR testing of affected vines to try to solve the mystery in 2019 at the request of the Lodi Winegrape Commission. They identified co-infections of leafroll virus and grape vitiviruses and believed the combination was responsible for what has been dubbed “sudden vine collapse.”

Certain rootstocks like Freedom also appear more sensitive. And like leafroll virus, grape vitiviruses can be vectored by mealybugs and scale insects.

Plant pathologist Katie Gold, an assistant professor at Cornell University, inspects diseased grapes in a field. Gold’s team used a JPL-developed instrument to detect infected crops from the air in one of California’s most important winegrape-producing regions (photo by Allison Usavage.)

Remote Sensing 101
At the basic level, remote sensing involves measuring how much light, or electromagnetic radiation, an object or area reflects or absorbs. This is known as its spectral signature.
The electromagnetic spectrum includes all the kinds of light, both visible to the human eye and the larger portion that is not visible.

Our eyes can only see the visible portion (red, green and blue). Healthy vegetation typically appears green because it absorbs more blue and red light and reflects more green.

But vegetation reflects even more light in specific near-infrared channels. As a result, many growers and consultants have begun flying off-the-shelf drones equipped with near-infrared sensors to measure light reflectance and plant health. By imaging an area and creating a map, they can identify stressors including diseases symptoms that may not be visible just by walking a crop.

Gold and her group have taken that concept to an entirely new level and are using hyperspectral imaging to assess grapevine health. Any digital image, whether viewed on a cellphone or high-powered computer, is made up of pixels, the smallest unit in a digital display.

Instead of assigning just red, green or blue to each pixel, hyperspectral imaging analyzes a wide spectrum of light. It also breaks down the light striking each pixel into several different spectral bands, providing significantly more information about what was imaged.
Specifically, Gold and her group are using NASA’s Airborne Visible and Infrared Imaging Spectrometer Next Generation, or AVIRIS-NG.

Driving their work is the assumption that diseases affect plant chemistry and physiology, and this would change molecular composition. That in turn may change how cells react to light waves.

Imaging Vineyards by Plane
The imaging was done with a specially equipped twin-engine plane flying about 1,000 meters or about 3,280 feet above the vineyard floor. About 11,000 acres total were captured in 2020 and 2021 just before harvest when disease symptoms are the most pronounced. But collecting the images was just part of the project.

In the Lodi area, the Cornell researchers collaborated with Stephanie Bolton of the Lodi Winegrape Commission, its grower members and local PCAs including Starr.

Shortly after the 2020 flight, specially trained scouts scoured 300 acres of the vineyards to visually identify symptomatic vines.

They also collected samples from 100 vines in 2020 for GLRaV-3 laboratory testing to verify diseased and non-diseased vines. Testing the entire vineyard would be too labor-intensive and expensive since each lab test typically costs between $40 and $100 each.

All the samples the scouts identified as diseased tested positive, and those identified as non-diseased tested negative.

The diseased vines were removed that winter, and the vineyards were again scouted just before harvest in 2021 and sampled from 10 vines.

As a result of the latent period, the researchers went back to the 2020 images and geotagged those vines that were symptomatic in 2021 as asymptomatic in 2020.

Researchers turned to machine learning to differentiate slight nuances in each of millions of pixels that make up the image. The computer program “learns” the spectral signature of uninfected, asymptomatic and symptomatic vines.

By rerunning the 2020 images that were geotagged as asymptomatic vines, they “taught” the computer model how to identify vines with early infections using spectral signatures. And each time data was run through the computer model, the accuracy of the results improved.

The best performing models had 87% accuracy differentiating between noninfected and asymptomatic vines, suggesting the importance of nonvisible wavelengths in detecting disease-inducted changes to plant physiology.

A Few Caveats
Calling the Lodi research a case study, Gold said they also want to test the hyperspectral imaging on varieties other than cabernet sauvignon, which was used in their subset. That’s because white varieties like chardonnay exhibit few symptoms when infected with GLRaV-3. In addition, some hybrids have better tolerances to higher viral loads, which could affect their biological responses.

Geography along with soil type, cultural practices and climate likely play a role in remote sensing applications too. This research was conducted only in the Northern San Joaquin Valley, but Gold said she’d like to expand it to other production regions within the state as well as elsewhere in the United States.

Based on what she’s seen so far, Gold said the technology also has the potential to be used to diagnose other viral diseases in asymptomatic vines, although they’re not there yet.
She said the results lay a foundation for using NASA’s upcoming hyperspectral satellite mission, dubbed Surface Biology and Geology, to monitor regional diseases of grapevines and other crops.

The End of Open Ag Burning in the Central Valley and the State

Under SB 703 (Florez) Chapter 481, Statutes of 2003, open burning for agricultural crops is phased out under a prescribed schedule. This schedule will result in the near-complete prohibition of agricultural open burning in the Central Valley beginning Jan. 1, 2025 (all photos courtesy Fowler Brothers Farming.)

In the next two years, California’s Central Valley will experience a transformational change in agriculture: the end of open agricultural burning. It is likely that other regional air districts around the state will adopt a similar prohibition of open agricultural burning in the years to follow.

Under SB 703 (Florez) Chapter 481, Statutes of 2003, open burning for agricultural crops is phased out under a prescribed schedule. This schedule will result in the near-complete prohibition of agricultural open burning in the Central Valley beginning Jan. 1, 2025.
In preparing for this, the California Association of Winegrape Growers (CAWG) worked with other agricultural industry associations in 2021 and successfully advocated in the State Legislature for nearly $180 million in funding for the San Joaquin Valley Air Pollution Control District. This one-time influx of money in part provides funding for the District’s Alternatives to Agricultural Open Burning Incentive Program. This stipend program is intended to help growers pay the high costs of alternatives to open agricultural burns during the phaseout.

For decades, the disposal of old orchards and vineyards has commonly involved burning. For vineyards, the materials used in trellising, such as end posts, t-posts and wire have created unique challenges in how to dispose of vines when removed. That is why up and down the Central Valley, you may see piles of pulled vineyards left sitting waiting to be disposed of.

In 2003, opponents to SB 703 warned of the very situation in which we now find ourselves. The analysis by the Assembly Committee on Natural Resources, dated June 30, 2003, stated, the following:

“Bill opponents state that while the agricultural community is willing to pursue means to reduce or eliminate burning when feasible, it is important that alternatives to burning be established BEFORE the prohibition is enacted.”

Unfortunately, that advice was not heeded.

CAWG will be advocating in the legislature in 2024 to obtain additional funding to develop viable alternatives, like the air curtain burner pictured here, for disposing of vineyards.

Alternatives
To address this situation, CAWG will be advocating in the legislature in 2024 to obtain additional funding to develop viable alternatives for disposing of vineyards. However, this will be difficult as almost every alternative comes with unique challenges. The alternatives and associated challenges are outlined as follows:

Chipping and Mulching: This alternative involves the grower to either hire a company to chip or mulch the piles of vines on-site or ship those piles to a facility equipped for chipping and mulching.

There are three specific challenges with this alternative:
Economics. Most of the machines used to chip, mulch or grind vines don’t work well with metals. This means all metal would need to be removed first, which can be a very costly endeavor. Additionally, if the vines are being shipped to a facility, shipping costs can also be expensive.

Disease. When old vines are removed due to disease, chipping and mulching is not a viable option as this would potentially result in putting disease back into the soil or spreading the disease to nearby vineyards. The federal Tree Assistance Program (TAP) provides financial assistance to eligible growers to replant. A condition of the TAP program is the diseased vine cannot be reincorporated into the soil and best practices prioritize burning.

Market Demand. Increased forest management (preventing fires) and the recent prohibition of putting food and other organic waste into landfills has resulted in a substantial increase in the supply of compost, mulch, wood chips and other similar groundcover. This means if a grower decides to dispose of old vines through chipping and mulching, no one may be waiting to buy that material. So, what is the grower to do with that material? While there is a beneficial use of this material in a new vineyard, there is only so much a grower can use.

Air Curtain Burners, also called FireBoxes: These act as an air pollution control device by reducing the particulate matter, smoke or black carbon created by burning wood waste. This alternative to traditional open burning mitigates the amount of smoke released from open agricultural burning. This also creates a valuable byproduct that can be tilled into the soil. The downside is that while some growers can afford this equipment, most cannot. Additionally, there is limited availability of these burners.

Low-Smoke Ag Burning: This is an important option (for 2024 only) in dealing with vineyard management waste. Low-smoke agricultural burning, when using best practices, takes into consideration concerns of public health as well as climate change. The challenge here is how long a grower needs to wait for approval of a burn day. Depending on several meteorological factors and how many people want to burn in that area, a grower with a permit to burn could wait for several months to get approval, and that grower is not guaranteed to be able to burn their full permitted amount in one day.

Biochar: This is one of the smartest alternatives that also offers incredible benefits. One ton of biochar is equivalent to three tons of CO2 sequestered. By turning old vineyards into biochar, carbon remains trapped in its solid form, thus creating a carbon-negative cycle. However, few Pyrolysers (an oven that creates biochar through pyrolysis) exist in the Central Valley. Additionally, there are economic challenges in shipping.

Biomass: Vines can be used as alternative fuels within energy conversion chains, driving renewable energy exploration as an alternative to traditional agricultural biomass burning. The ability to convert grapevine biomass residues into energy is potentially a valuable alternative to explore in the future. However, there would need to be an expansion of markets and availability. Unfortunately, policymakers in Sacramento currently do not see biomass as an effective tool in fighting climate change and protecting clean air.

CAWG has created a hotline for its members who find they have reached a dead end in getting approval to burn. It is recommended that CAWG members diligently go through the steps provided on cawg.org’s Ag Burn Hotline Webpage (under the Resource Tab) before completing the form for CAWG’s assistance.

Fire Insurance a Moving Target

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Some owners of vineyards and wineries in high-fire-risk areas are finding it difficult to keep themselves on fire insurance plans as providers continue to pull out and prices increase.

Driving up Soda Canyon Road on Napa’s east side, the neighborhood under the Vaca mountains looks different these days. Gone are many of the old wood frame houses, replaced today with new, boxy homes built of fire-resistant materials.

The October 2017 Atlas Fire was the big changemaker. The fire destroyed 781 buildings and over 51,057 acres of vegetation.

Chris Vandendriessche remembers what life was like before the fire when his family’s winery, White Rock Vineyards, had just one insurer. In 2017, the family lost all the structures on their property, including the 1870’s stone winery that had been converted into a family home for his parents (who founded the family winery), the modern winery a few hundred yards away and the small tasting room adjacent to it.

With money from their insurance claims from Travelers Insurance, the stone house innards were built anew, preserving the stone structure on the building’s outer shell. The winery caves were restored.

But today, Travelers no longer provides their coverage.

“Before the fire, we could have one carrier that insured the entire property, liability, equipment, all the houses, caves, the entire thing was at one company,” said Vandendriessche. “After the fire, nobody wanted to take on that much risk because that meant you were exposed to all the potential damages in a fire. And since then, we’ve had to take eight or nine companies, each one taking a little tranche of the insurance needs of our business.”

But each year, the family still must seek new coverage and new insurers.

“Every year since the fire, two or three of those companies have backed out, and we have to find new ones. The prices have tripled for less coverage. So, that’s our insurance picture.”

The Vandendriessche’s insurance agent, Jim Stetson, Agency co-owner of Leavitt United Insurance Services, deals with properties all over the state. He says the rising rates are highly localized and that insurance rates for vineyard and winery owners in other parts of the state have not been affected by the wildfires.

“For somebody with little to no wildfire exposure, we can still get basically the same kinds of programs that we had in the past,” he said. “It depends on the wildfire risk, the property values and loss control, and brush mitigation. If you’re in American Canyon or Lodi or Sacramento or somewhere like that, the wildfire concern isn’t going to be really an issue. But in a lot of the other areas, you are going to be exposed to that.”

Wine Warehouse Insurance Affected
It also depends on where wine is stored, Stetson said.
“Aggregation can be an issue; that’s where carriers only want to have a certain amount of limit in one area so that if there’s some kind of catastrophic wildfire event, they’re not losing it all in one event. So, they don’t want to have too much value, say over $100 million, in one five-mile area.

“We see that at the wine warehouses in American Canyon right now, where there’s aggregation issues with certain carriers where they have too many clients storing wine or producing wine in one location.”

Insurance Tied to Bank Loans 
The insurance issue is complicated because it isn’t just about insurance. Insurance is linked to winery finance since banks require insurance to lend money.

“2017 brought increased awareness of the problem, and that’s when the insurance industry started pulling out,” said Michael Miiller, director of government relations at the California Association of Winegrape Growers (CAWG).

“Basically, where our growers are is they have a property that has a structure on it. And if they have any kind of line of credit already lending at all, they have to have proof of insurance as a condition of that lending, which means they have to have insurance.”
“We’re in a crisis situation,” he said.

Mixed Reviews for the FAIR Plan
The state of California has stepped in to create the insurer of last resort: the FAIR Plan. FAIR Plan’s policy numbers more than doubled between 2018 and 2022 from 127,000 to 272,000 (including homeowners as well as businesses.)

“Right now, it’s the only option available to people, to many, many people,” said Miiller. “And when your safety net is all you have, that’s not sufficient. They have a limit to how much they can cover.”

In March 2023, the California Department of Insurance announced it would up FAIR Plan caps for commercial businesses coverage amounts “from $8.4 million to $20 million per location, and under its Division II Business Owners Program, from $7.2 million to $20 million per location,” according to a department press release.

Stetson explained that the FAIR Plan is not a state run program but is run by the insurance companies themselves. “A lot of people think it is [state-run], but it’s a pool of all the admitted carriers doing business in California.”

That means each new change requires negotiations between the department and the FAIR Plan.

Reducing on-property fire risks may improve coverage options in the eye of the insurer, but there is no guarantee of return on investment.

By summer 2023, the department had still not implemented the increases announced in March and said in an email to Grape & Wine the higher limits would most likely be available by end of 2023. That leaves many businesses exposed again during the 2023 vintage.

“The FAIR Plan does not cover things like faster water damage or falling objects, freezing pipes,” said Stetson, “so there’s some gaps there.”

He said commercial insurers are starting to fill in some of the gaps. “That’s starting to come back online and provide a little bit of relief.”

Miiller pointed out that even when the $20 million limit is implemented, the amount is per policy, not per structure. “It would be better if it were per structure,” he said.

The CAWG official criticized the state’s insurance regulators for being slow to act.
“We’re looking at how they set rates, we’re looking at the expediency of rate approvals and those kinds of things. There’s a lot that can be done at the Department of Insurance to speed things up. And they’re just not doing it. When you look at when Lara expanded the FAIR Plan, it took them forever to approve their rates.”

“When there’s no product on the market, growers have no options,” he said.

Still, despite wildfires in Oregon, the situation is quite different there, Miiller said.

“You can find growers in Oregon who aren’t having near the problems that they’re having in California. Their regulatory system is entirely different.” That’s because Oregon does not set commercial insurance rates.

The Crisis Continues… for Some
Miiller warned that the crisis, however unevenly distributed it is, is far from over.
“If we don’t start looking at this like the emergency situation that it is, we are quickly going to see a bunch of industries that are going to pay some serious consequences because they can’t buy insurance. Insurance isn’t an option. You have to have it to be in business. If it is not available, the dominoes start falling.”

“So, from my perspective, I think there really needs to be somebody to step up and say, ‘Hey, we have an emergency. And I’m going to implement these emergency actions to start to address this problem.’”

Yet, when it comes to insurance, some areas of the state are stable, said Stetson. “For folks in the Central Valley, if there’s no wildfire risk, the options are pretty much what they were [before 2017]. If there’s wildfire risk, then we have to start getting more creative.
“If there’s no wildfire risk, that’s the carrier’s main concern. We have seen a little bit of a rate increase, but there’s still a lot of carriers playing in the space.”

Reducing Risk
What can property owners do to reduce risk in the eyes of insurers?

“It’s a moving target,” Stetson said. “Defensible space is always the first thing that people do, cutting back brush, removing low hanging branches and getting ladder fuels off the property or away from the buildings. That’s definitely helpful.

“Some people have contracted private firefighting companies to consult. Some will spray fire retardant seasonally around the production buildings, and then they sometimes have them on a retainer to come in…so if there’s a wildfire event, they will help defend the property.”

Sprinklers make sense, he said, but there’s no guarantee installing them will bring a return on the investment. “Unfortunately, it’s difficult to ask somebody to spend that much money because it’s not necessarily a guarantee of an offer of coverage. The insurance companies can make somebody put in a six-figure sprinkler system, and then that same carrier that asked him to do that next year could pivot,” he said.

“A lot of people in the brushy areas are stuck in the process,” he added.

Another limitation of the FAIR Plan: It doesn’t cover wine in tanks. “Anything not bottled yet is excluded from coverage,” said Stetson. “So that’s a pretty big issue for people because typically, once it’s case goods, they can move it to a third-party storage location and find palatable, affordable coverage from an admitted carrier.”

According to the California Department of Insurance, counties where 25% or more homes are in high fire risk, these are the top-ranked counties, by highest exposure first: Tuolumne, Trinity, Nevada, Mariposa, Plumas, Alpine, Calaveras, Sierra, Amador, El Dorado, Mono, Lake, Mendocino, Siskiyou, Butte, Lassen, Shasta, Tehama, Santa Cruz, Humboldt, Napa, Del Norte, Modoc, and Placer.

Water-Wise Winemaking: How Sustainable Wine Brands Reduce Their Water Footprint

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From water application tools and strategies in the vineyard to capturing, treating and reusing winery wastewater, sustainable wine brands use practices that minimize their water use, optimize efficiency and reduce groundwater pumping (all photos courtesy Shale Oaks Winery.)

While our planet’s nickname “the Blue Planet” might imply that water resources are plentiful and available, this is not actually the case. Over 97% of Earth’s water is unusable salt water, and 2% is unavailable freshwater stored in glaciers and ice caps. This means less than one percent is freshwater that is accessible to humans to fulfill our daily water needs.

USDA’s Erika Cross gave this staggering analogy: “…if the world’s water supply were 26 gallons, our useable supply of freshwater would be half a teaspoon” (Cross 2022).
Of all our water daily uses, from hydrating ourselves and our pets to washing our hands and our cars, water for agricultural crops is one of the most important and demanding.
With the country’s population growth of nearly 100 million between 1980 and 2015, how can it be that water withdrawals for irrigation were relatively steady during that time span? The USGS posits the effects could be attributed to water conservation efforts and greater water use efficiencies (USGS 2018).

Managing agricultural water use in a responsible way can have a positive impact on water conservation while also maintaining a stable food supply for years to come. Growers can use responsible water management strategies that conserve and optimize their use, ones that increase water efficiency without decreasing crop yield. The sustainable winegrowing community does just that.

When rain falls on the roofs of Shale Oak’s winery and tasting room, it is directed through a water passage that flows to a water feature. When it fills up, the overflow goes to a sump pump, where it begins its journey to the vines.

Water Sustainability in Viticulture
From water application tools and strategies in the vineyard to capturing, treating and reusing winery wastewater, sustainable wine brands use practices that minimize their water use, optimize efficiency and reduce groundwater pumping.

Agriculture can feel like a battle against natural elements. Growers must learn to work with elements out of their control, including wind, frost, degree days or a family of ground squirrels that decides to call their vineyard home. Although the same can be said for precipitation, supplemental water application is one of the few inputs the grower has significant control over.

So, how does a vineyard manager know when to irrigate the vineyard and how much water to apply? As well as using visual cues from the vines themselves, sustainable winegrowers use hard data from plant and soil moisture monitoring devices to understand how their crops and the land respond to their practices. Using this data, they make informed irrigation decisions and only apply water when it is needed.

Low-volume irrigation systems are one of the most impactful water conservation tools in the grower’s toolbox. Drip irrigation is a sustainable winegrower’s go-to method. This type of irrigation system typically uses an impressive 20% to 50% less water per-acre than a sprinkler system (EPA 2017).

In a drip system, emitters are placed along an irrigation line that runs along a vine row a few inches above the soil. The emitters slowly drip water directly onto the planted areas at the base of the vine. This is a contrast to sprinkler systems, which spray high volumes of water over large areas, both planted and not. The slower, more targeted application of water delivered by drip means a greater percentage of what is applied is actually used by the crop, less water is lost through leeching and runoff, and water isn’t applied to areas that don’t need to be irrigated.

At the top of Shale Oak’s hill sit five 100,000-gallon water cisterns. This is where the rainwater from the wet season is pumped and held until the dry season to drip irrigate the 5-acre vineyard.

Responsible water management does not stop in the vineyard. It can take anywhere from 2 to 20 gallons of water to produce 1 gallon of wine (Wine Business Analytics 2014) depending on a winery’s water management practices. Between using water to clean and sanitize equipment, as a wine additive and as a processing aid, gallons can add up.
Sustainable winemakers don’t let the runoff water from tasks go to waste; they recycle it. Winery wastewater can be stored in an irrigation pond or aboveground or belowground holding tanks on the property. Wherever it is stored, wastewater must be treated before being reused.

After proper treatment, recycled water can be used for more cleaning and sanitizing of winery equipment, as an equipment coolant, for frost protection in the vineyard and even for irrigating grapevines and landscaping. If you’re concerned over whether the quality of grapes and composition of the soil could be harmed by recycled water, there’s no need to fret; several studies show that when managed correctly, winery wastewater has no negative effects on the health of grapevines or vineyard soils (Hirzel et. al. 2017; Buelow et al. 2015).

Sustainability in Action: Shale Oak Winery
It’s not just winery wastewater that is captured for later use. With proper architectural planning, rainwater that falls on roofs and driveways can also be collected and used for growing wine grapes. Some wineries are designed with rainwater capture in mind, like Shale Oak Winery in Paso Robles, Calif.

When rain falls on the roofs of Shale Oak’s winery and tasting room, it is directed through a water passage that flows to a water feature. While this water feature offers patio tasters a sense of serenity, it was designed to be more than a visual pleasantry. When it fills up, the overflow goes to a sump pump, where it begins its journey to the vines.

Shale Oak captures most of the rainwater that falls on their property through this roof collection system, and by utilizing the natural flow of the terrain. The water that falls on their grounds, driveway and parking lot are diverted to numerous waterways that lead to an underground cistern. All this water that would otherwise have run off their property will join the water collected from the roofs to deficit irrigate their vines.

At the top of Shale Oak’s hill sit five 100,000-gallon water cisterns. This is where the rainwater from the wet season is pumped and held until the dry season. During the hotter, drier months when the vines are in critical growing stages, all the rainwater they captured is carried out to drip irrigate their five acres of vines and hydrate their landscaping.
Since this water capture strategy was designed into every element of their layout, Shale Oak significantly reduces their pumping needs. In fact, Sean Walter, assistant winemaker, stated, “Our 500,000-gallon capacity, most of the time, can get us through the whole growing season if we have a significant rainfall throughout the wintertime.”

Learning how responsible producers like Shale Oak Winery go the extra mile to protect natural resources has a myriad of positive effects on the whole food system. It fosters deeper connections between agricultural producers and consumers, brings attention to sustainably minded growers and their good work, and helps consumers understand more about the agricultural systems we depend on every single day.

“Food disconnect” is a term used to describe the average consumer’s lack of knowledge about where their food comes from and how it’s made. When it comes to wine, most people only see the finished product: what’s in their glass.

If your wine brand practices sustainability, there’s yet another level to this disconnect with your customers. While consumers name food and beverage as one of the most important industries when it comes to sustainability, more than one in four U.S. adults said they don’t know what makes a product sustainable (Morning Consult 2022).

This highlights an opportunity to showcase the time and careful consideration that went into your wine’s production. By highlighting your dedication to sustainability, you create a deeper connection with your customers. Wine drinkers gain valuable (and engaging) insights into agriculture. Plus, it lets them know that when they support your brand, they also contribute to a more sustainable food system.

In the next issue of the Sustainable Story Series, we share the story of a San Luis Obispo, Calif. winegrower who unintentionally discovered a unique pest mitigation strategy while developing a vineyard planting method that significantly conserves water by using everyday hardware store materials.

New Bottle Bill Deadline is Approaching Fast, and Action is Required

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California Redemption Value labeling must be “clearly, prominently and indelibly marked,” according to CalRecycle.

Wineries have until Jan. 1, 2024 to sign up with CalRecycle to start reporting each month the number of wine bottles, cans and bag-in-box items they produce. It’s all part of the new bottle bill, SB 1013, passed in 2022.

The new law going into effect has two important deadlines for producers.
Part 1, due Jan. 1, 2024, is reporting and paying a small fee per container.
Part 2, due July 1, 2025, is labeling all containers with recycling redemption language, following specific CalRecycle mandated guidelines.

The overwhelming majority of wine and liquor containers sold are glass bottles: 87% by units and 99% by weight. PET plastic bottles make up 9% of wine and liquor units sold (less than 1% by weight). Aluminum cans make up only 2% by units and are negligible by weight, while 3% are cartons and foil pouches that are not eligible for California Redemption Value.

Part 1: Reporting and Paying 
Before this new law went into effect, consumers could turn in bottles and cans for non-alcoholic beverages for redemption and receive 5 or 10 cents back per item. The issue is that most did not visit a specific recycling center to get those nickels and dimes, but rather deposited their empties in municipal waste pickup programs.

The new law expands returnables to wine and spirits containers. It also requires retailers to do a better job of accepting returnables.

Then two months after the start of the Jan. 1, 2024 reporting deadline, producers will be required to pay fees based on the numbers in those reports.

The idea is to close the loop between producers and the potential waste they create. Redemption increases recycling rates, experts say. It also creates better-quality glass returns, researchers report, and that makes this recycled glass more attractive for reuse by glass manufacturers.

Examples of approved label samples.

According to CalRecycle, the bill will bring 4,200 California wineries into the fold and is expected to add 1.1 billion wine and spirits containers to recycling. That’s an overall increase of 4%, a department spokesperson said.

The CalRecycle registration page has details. The agency also has representatives available to assist in filling out registration forms.

Beginning in March 2024, producers will begin paying “processing fees.” The price is not fixed but is very low. Currently, the fee is $0.00452 per bottle, $0.00005 per plastic container and $0.00762 for a box or equivalent.

Tasting rooms in California do not need to report or pay processing fees, but any out-of-state wineries selling to Californians must report monthly and pay processing fees.

Examples of labels that were not approved.

Part Two: Labeling Changes
After completing the first phase of reporting and paying fees, the second big deadline takes place 18 months later on July 1, 2025. By then, wine and spirits containers sold in California must be labeled with the California Redemption Value (CRV) code.

Consumers will then begin paying CRV deposits of five cents for containers under 24 ounces, 10 cents for containers of 24 ounces or more and a flat rate of 25 cents for bag-in-box packaging (regardless of size).

CalRecycle offers wineries five options for the message to display on the container: California Redemption Value, CA Redemption Value, California Cash Refund, CA Cash Refund or CA CRV.

There’s more information available in the CalRecycle webinar, posted on its YouTube channel, and website instructions provide requirements and example how-to’s.

The labeling must be “clearly, prominently and indelibly marked,” according to the website.
For glass and plastic, the message needs to be on the container body label or secondary label. The text height should be 3/16 inches, or it can be 1/8 inches if it is in a contrasting color to the background and nearby text.

Examples of temporary label options.

For aluminum cans, the message must be on the top lid. If the top is more than two inches in diameter, the message must be 3/16 inches in height. If the top is 2 inches or less in diameter, the message must be 1/8 inches in height.

The agency is still working on details for box, bladder and pouch product labeling.
No monetary value appears in the messaging as that is subject to change in the future, CalRecycle said.

The CalRecycle website has do’s and don’ts examples posted on its website.

The End Goal: More Efficient Glass Reuse
According to Scott Defife of the Glass Packaging Institute, “California bottles have 40% recycled content. Oregon bottles have 70% recycled content. Washington bottles have 50% recycled content.”

CalRecycle hopes the redemption program will increase the recycling rate to 80% and increase glass reuse by glass manufacturers.

Industry researchers from the Container Recycling Institute say glass returned outside the consumer redemption system (where it is mixed in with other recycling items) is dirtier and costs $20 a ton to recycle. That’s in contrast to cleaner glass handled through redemption centers where it’s worth $20 a ton and is attractive to glass manufacturers.

Resources
CalRecycle online webinar: youtube.com/watch?v=x50d5FYvQdA
CalRecycle’s Beverage Distributors and Manufacturers: calrecycle.ca.gov/BevContainer/BevDistMan/
Bottle Bill resource page: wineinstitute.org/our-industry/bottle-bill/

Mechanical Leaf Removal is More Effective than Regulated Deficit Irrigation to Improve Fruit Quality While Maintaining Yield

Figure 1. Overly vigorous vine due to abundant winter precipitation and overirrigation (all photos courtesy G. Zhuang.)

Berry sugar and anthocyanin accumulation are key factors in determining the fruit quality of red wine grapes in the San Joaquin Valley (SJV), where >70% of California wine grapes are grown (California Grape Crush Report 2022). Hot climates are not ideal for red Bordeaux cultivars such as Cabernet Sauvignon and Merlot as anthocyanin accumulation is inhibited. However, fruit quality might be improved with certain management practices, including deficit irrigation and leafing. Previous research in the SJV demonstrated that moderate irrigation deficits can improve grape yield and quality in addition to saving water (Williams 2012). Mild or moderate irrigation deficits promote yield formation due to increased bud fruitfulness and decreased fungal disease pressure. Sustained deficit irrigation (SDI) of 70% to 80% evapotranspiration (ETc) was found to balance economically sustainable yield, fruit quality and water-savings goals (Williams 2010). Abundant winter precipitation and overirrigation cause grapevines to grow excessively, shading the fruit, directly reducing quality and favoring the development of fungal diseases (Mendez-Costabel et al. 2014) (Figure 1).

Figure 1. Overly vigorous vine due to abundant winter precipitation and overirrigation (all photos courtesy G. Zhuang.)

Years like 2023 might remind growers that managing water and canopy size to improve canopy microenvironment and enhance spray coverage will reduce fungal disease pressure (Figure 2). However, severe water deficits pre-veraison significantly impair grapevine vegetative and reproductive growth, photosynthesis and fruit maturity (Levin et al. 2020).

This year in Akif Eskalen’s powdery mildew trials, grape clusters in the untreated controls had 100% disease incidence.
Figure 2. Heavy powdery mildew infestation on Chenin Blanc (left) and botrytis bunch rot on Pinot Gris (right).

Figure 2. Heavy powdery mildew infestation on Chenin Blanc (left) and botrytis bunch rot on Pinot Gris (right).Removing leaves in the fruit zone is another beneficial practice growers may do to improve fruit quality. Leafing increases fruit exposure which may directly improve fruit quality, create a microenvironment that discourages powdery mildew and bunch rots, and improve spray coverage (Austin and Wilcox 2011) (Figure 3). Leaf removal is most practiced in cool climates as overexposure can easily reduce fruit quality in a hot climate. However, studies on leaf removal in a hot climate also showed similar benefits as reported in cooler climates (Cook et al. 2015). As with deficit irrigation, the timing and intensity of fruit zone leaf removal determines the potential impact on grapevine yield and fruit quality at harvest. In a cool climate, basal leaf removal prior to bloom may reduce berry set, thus lowering yield (Acimovic et al. 2016). Effects on berry set depend on the extent of leaf removal and the weather (Frioni et al. 2017). In hot climates, mechanical fruit zone leaf removal prior to bloom had no effect on berry set or yield (Cook et al. 2015). In addition to the potential to reduce set in cool climates, leaf removal prior to bloom can increase berry total soluble solids, anthocyanin content and berry aroma compounds (Ryona et al. 2008). Recently, mechanical fruit zone leaf removal has gained popularity due to labor shortage and increased labor cost in California (Kurtural and Fidelibus 2021). Years like 2023 which came with abundant winter precipitation, delayed harvest and cool temperatures might require additional fruit-zone leaf removal to open the canopy and increase spray coverage to help control fungal diseases.

Figure 3. Leaf removal around grape cluster (left). Spray coverage increases with leaf removal (right).

Three-Year Field Study
Aiming to find the “sweet spot” of water management and leaf removal on yield, sugar and anthocyanin accumulation of red wine grape in hot climates, we conducted a three-year field study on Cabernet Sauvignon grown in Madera as Cabernet Sauvignon is believed to be one of the most challenging varieties to be grown in the SJV due to lack of berry color at harvest.

Figure 4. Clemens roll-over leaf plucker with a sickle-bar sprawl clipper (left) and mechanical leaf removal at full bloom of Cabernet Sauvignon (right).

The experiment was conducted in a commercial vineyard located in Madera on fine sandy loam soil. 10-year-old Cabernet Sauvignon vines on Freedom rootstock with 4’x10’ spacing and Northeast-Southwest row orientation were used for the experiment. The grapevines were quadrilateral cordon trained with a 24-inch cross-arm to 48-inch height above vineyard floor with a pair of catch wires above the cordons. A two (deficit irrigation) × three (leaf removal) factorial split-plot design was applied for three seasons: 2018 through 2020. Two irrigation treatments were applied: 1) sustained deficit irrigation (SDI): water was maintained at 80% of weekly crop evapotranspiration (ETc) through the growing season; 2) regulated deficit irrigation (RDI): water was maintained at 50% ETc from berry set to veraison then switched back to 80% ETc until harvest. ETc was calculated using the equation of ETc = ETo × Kc (Williams 2010). On top of irrigation treatments, we applied three timings of mechanical leaf removal: 1) bloom, 2) berry set and 3) no leaf removal. Leaf removal was applied to both sides of the canopy using a roll-over leaf plucker with a sickle-bar sprawl clipper adapted for a sprawling-type canopy (Model EL-50, Clemens Vineyard Equipment, Woodland, Calif.) (Figure 4).

Results and Discussion
RDI reduced yield by 15% compared to SDI mainly due to smaller berries and clusters (Tables 1 and 2). Leaf removal did not significantly affect yield. Our result confirms that severe water deficit, like 50% ETc, pre-veraison, can result in significant yield loss. Contradictory to the previous field observation, bloom leaf removal had no effect on yield, and growers should be less worried about yield loss due to bloom leaf removal than severe deficit irrigation.

Berry soluble solids (Brix) were affected mainly by irrigation treatments in our study. RDI consistently reduced soluble solids each year (Table 2). Interestingly, we found that the effect on Brix depended on the interaction of leaf removal and water management (Table 3). Leaf removal increased Brix when vines were not water stressed or mildly stressed like when SDI was applied whereas leaf removal reduced Brix when vines were severely water stressed like when RDI was imposed. This implies to growers that if sugar is your biggest concern, you should water vines maintaining mild or moderate vine water stress and remove fruit-zone leaves.

Berry anthocyanin content is critically important for red wine grapes. RDI increased berry anthocyanins by 14% in comparison of SDI, and bloom and berry set leaf removal increased anthocyanins by 19% and 13%, respectively, compared to no leaf removal control (Table 2). This means the 14% increase in anthocyanin concentration from the RDI treatment is proportional to the decrease in berry weight and yield. So, there is no net gain of anthocyanins per berry associated with the RDI irrigation treatment. Bloom leaf removal increased anthocyanins by nearly 20% with no yield reduction and that means bloom leaf removal provides a net gain of anthocyanins per berry.

Bloom leaf removal was more effective than pre-veraison RDI at improving berry Brix and anthocyanins without adversely affecting yield. Given the significant reduction on yield from severe deficit irrigation and the low economic return per ton of fruit in the SJV, bloom mechanical leaf removal coupled with SDI of 80% ETc could be a useful practice for SJV growers.

References
Acimovic, D., Tozzini, L., Green, A., Sivilotti, P., and Sabbatini, P. (2016) Identification of a defoliation severity threshold for changing fruitset, bunch morphology and fruit composition in Pinot Noir. Australian Journal of Grape and Wine Research, 22: 399– 408. doi: 10.1111/ajgw.12235.
Austin, C and Wilcox, W. (2011) Effects of Fruit-Zone Leaf Removal, Training Systems, and Irrigation on the Development of Grapevine Powdery Mildew. Am J Enol Vitic. June 2011 62: 193-198.
Cook, M., Zhang, Y., Nelson, C., Gambetta, G., Kennedy, J., Kurtural, K. (2015) Anthocyanin Composition of Merlot is Ameliorated by Light Microclimate and Irrigation in Central California. Am J Enol Vitic. 66: 266-278.
California Sustainable Groundwater Management Act (SGMA) 2014 Sustainable Groundwater Management Act (SGMA) (ca.gov)
California Grape Crush Report 2022, USDA National Agricultural Statistics Service (NASS). USDA – National Agricultural Statistics Service – California – Grape Crush Reports
Frioni, T., Zhuang, S., Palliotti, A., Sivilotti, P., Falchi, R. and Sabbatini, P. (2017) Leaf Removal and Cluster Thinning Efficiencies Are Highly Modulated by Environmental Conditions in Cool Climate Viticulture. Am J Enol Vitic. 68: 325-335.
Kurtural, K and Fidelibus, M. (2021) Mechanization of Pruning, Canopy Management, and Harvest in Winegrape Vineyards. Catalyst: Discovery in Practice. 5: 29-44.
Levin, A., Matthews, M., and Williams, L. (2020) Effect of Preveraison Water Deficits on the Yield Components of 15 Winegrape Cultivars. Am J Enol Vitic. 71: 208-221.
Mendez-costabel, M., Wilkinson, K., Bastian, S., Jordans, C., Mccarthy, M., Ford, C., and Dokoozlian, N. (2014) Effect of increased irrigation and additional nitrogen fertilisation on the concentration of green aroma compounds in Vitis vinifera L. Merlot fruit and wine. Australian Journal of Grape and Wine Research. 20:80–90.
Ryona, I., Pan, B., Intrigliolo, D., Lakso, A., and Sacks G. (2008) Effects of Cluster Light Exposure on 3-Isobutyl-2-methoxypyrazine Accumulation and Degradation Patterns in Red Wine Grapes (Vitis vinifera L. Cv. Cabernet Franc). Journal of Agricultural and Food Chemistry 56 (22), 10838-10846.
Williams, L. (2010) Interaction of rootstock and applied water amounts at various fractions of estimated evapotranspiration (ETc) on productivity of Cabernet Sauvignon. Australian Journal of Grape and Wine Research. 16:434–444.04
Williams, L. (2012) Interaction of applied water amounts and leaf removal in the fruiting zone on grapevine water relations and productivity of Merlot. Irrig Sci. 30: 363-375.
Williams, L. (2014) Effect of Applied Water Amounts at Various Fractions of Evapotranspiration on Productivity and Water Footprint of Chardonnay Grapegrapevines. Am J Enol Vitic. 65: 215-221.

A Vintner from the Ground Up

Matt Trevisan and his daughter Gabrielle in the Linne Calodo tasting room (photo by C. Merlo.)

Back when Matt Trevisan was new to California’s wine industry, he received a piece of advice he’s never forgotten: “Wine is made in the vineyard.”

Those words stayed with him as he made his way, year by year, into viticulture and winemaking. Trevisan had no family background in the business, but he had fallen in love with all things wine while attending California Polytechnic State University, San Luis Obispo. He soon was apprenticing at wineries in the nearby Paso Robles area, picking grapes, driving forklifts, learning how varietals were grown, how wine was produced and bottled.
In 1998, Trevisan and his wife Maureen took a leap of faith and started their Linne Calodo winery. Two years later, they bought their first piece of land, located in the Willow Creek District just west of Paso Robles. It was the beginning of their estate vineyard, but it wasn’t until 2005 that they were able to plant its first five acres. In 2012, they bought 48 more acres nearby, calling it Stonethrower Vineyard and planting vines a year later.

Carefully maintained vineyards surround the entrance to Linne Calodo winery west of Paso Robles (photo by C. Merlo.)

Trevisan had already begun questioning the accepted belief that California blended wines were inferior to varietal wines. He set out to craft his own red blends and create wines with high-integrity growing and winemaking. Over the next few years, Trevisan and Linne Calodo would specialize in limited red blends, helping break new ground in Paso Robles winemaking.

Out of Linne Calodo’s passion-driven production came Rhone-variety blends with names like Rising Tides and Overthinker as well as Zinfandel-driven blends such as Cherry Red. Trevisan’s most popular wine, a blend of Zinfandel, Syrah, Grenache and Mourvédre, was created through a long, frustrating process he feared was a mistake. Instead, the result was a delicious blend, which he aptly named Problem Child.

But Trevisan never forgot that wine begins in the vineyard. The California native practices what he calls “nature positive” farming. It’s based on age-old ways of farming that work with the land’s limited resources. Linne Calodo vineyards rely on natural solutions and manual labor instead of chemicals and carbon-heavy activities.

Matt Trevisan, here in his winery cellar, plays a hands-on role in Linne Calodo’s operations (photo courtesy Linne Calodo.)

Over the past 25 years, Trevisan has made his mark. In July, he was named San Luis Obispo County’s 2023 Winemaker of the Year. The recognition came from the Paso Robles Wine Country Alliance in partnership with the San Luis Obispo Coast Wine Collective, the independent Grape Growers of the Paso Robles Area, The Vineyard Team and past award recipients. The annual award recognizes dedication, stewardship, innovation and leadership in the country’s wine community.

Just before this year’s grape harvest began, Trevisan shared more of his story with Grape & Wine.

Q. Where does your winery’s name, Linne Calodo, come from? What does it mean?
Linne Calodo is a series of calcium-based soils, mapped out by the U.S. Geological Survey, that predominate here on the west side of the Santa Lucia Mountains. When we chose our winery’s name, we looked for something unique that represented our neighborhood.

No-till farming is practiced at Linne Calodo’s vineyards (photo courtesy Linne Calodo.)

Q. How did your life’s path lead to winemaking?
I am a first-generation vineyard farmer and winemaker. I went to Cal Poly intending to major in aeronautical engineering. But then I switched to biochemistry. Along the way, I met multiple individuals involved in the wine industry, including people connected with Fetzer and Robert Mondavi. While at Cal Poly, I helped with harvest on the James Berry Vineyard. I really fell in love with this business. After I graduated in 1995, I went to work for Justin Winery, doing an apprenticeship there. The next seven years of my life were with Justin Winery and Wild Horse Winery and Vineyards, where I managed the warehouses and did any job I had to do.

Q. When did you buy your first vineyard property?
While I was working full-time at Wild Horse, my college roommate and I started making wine after hours. With the approval of Kenny Volk, who owned Wild Horse at the time, we used the facility every day from 10 p.m. to 7 a.m. When we started Linne Calodo in 1998, a lot of people, including other winemakers, helped out, both picking fruit for us and helping us process. I used the bottling line at Wild Horse to bottle the first vintages of Linne Calodo. That was a great time. In 2000, before the market really moved, my wife Maureen and I bought a property of 77 acres here in Paso Robles. It wasn’t until 2005 that I was able to plant my first estate vineyards; it was just five acres.

Carefully maintained vineyards surround the entrance to Linne Calodo winery west of Paso Robles (photo courtesy Linne Calodo.)

Q. You started that from the ground up?
Yes. In 2012, I bought another 48 acres across the road. Starting in 2012, we put vines in the ground on that and did full development. There was no power on that property, no wells, no roads or anything. I didn’t start with a chest full of money. It’s been a slow grind.

Q. What do you mean by “nature positive” in your vineyards?
It’s to let Nature take its course. I’m really just a steward of the land. We farm no-till, no herbicides. We spray only organics for mildew control. It really goes hand in hand with my winemaking style. When I pick grapes, it’s about letting them go through a natural process to become wine.

Q. Are you doing anything differently from five years ago?
No-till agriculture is something I had tried before and couldn’t figure out, using no herbicides out there. It’s a very labor-intensive process we’ve enacted, which is basically treating our vineyard like a home garden for our winemaking. We’re out there hand-weeding pretty much every square foot and trying to get invasive species out by hand.

Visitors enjoy both Rhone-variety blended wines and the exterior setting of Linne Calodo’s tasting room. (Photo courtesy of Linne Calodo)

Q. Do you irrigate your vineyards or dry farm?
I have both. My Zinfandel and Grenache vineyards are dry farmed. I’ve been experimenting over the last two decades how to create sustainability of grapevines. What’s the spacing of the grapevines? What are the irrigation or non-irrigation methods? I may irrigate when planting a vineyard but then pull back and end up on a vigorous enough root stock and clonal selections to where I’m really working backwards on the vine. It’s just a lot of fruit thinning and shoot thinning along the way to get the grapes to maturity.

Q. Why has Linne Calodo focused on limited red blends?
When I started making wine, people were still acidulating wines, changing tannin contents. It was fairly chemistry heavy. I understand chemistry and, yeah, I can manipulate things. I can do organic synthesis and create a pharmaceutical. But winemaking is not about that. It’s more like cooking. It’s more like putting different spices together to change the flavor characteristics. When you grow different grapes, you grow different flavors, with different acid and tannic levels. It really opens up the door to creating a composition that is exciting, artistic and enjoyable for everyone without just doing it through the use of chemistry manipulation.

“I’m really just a steward of the land,” says Matt Trevisan (photo courtesy Linne Calodo.)

Right now, I’m growing probably 11 different varieties, and they all have different flavors. And that’s not even talking about clonal selections or root stalks or soils and hilltop versus lower on the hill and south-facing versus east-facing versus north and so on. There are so many different qualities that exist in grapes. When you do blend them, it really makes them pop.

Q. Where do you think demand for wine is headed?
I think we’ve outpriced ourselves, in some ways, from getting the Gen Zs and the next generation to see wine as being approachable. I just recently woke up to the fact that even my own tasting fees were too high for the Paso Robles region. When I started, there were 26 wineries in Paso, and wine tasting was $5 or free. I raised my prices to $20 and $30 and $40. We all did that. I think I was wrong, and it’s time to re-think it.
We all rode a wave of thinking we needed to be more and more exclusive. Maybe we need to be more and more inclusive instead. I believe we are at a fork in the road with tasting fees. At Linne Calodo, we’ve lowered ours back down to $20. If we want to win over the younger generation, we have to make it easier for them to get in the door and fall in love with great wine.

Q. Today, the Paso Robles region is home to more than 40,000 vineyard acres and 200-plus wineries. Is there any doubt anymore that it’s a world-class viticultural area?
No, it is a world-class region. It’s just still growing. We’re still learning exactly what the best grapes and training methods are. It’s suffering all the same challenges of any fast-growing region. But there is a fine group of us trying to figure out better, more sustainable, more ecologically friendly ways to pass this on to our future generations.