Grape & Wine Magazine - March 2024

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2024 Grape and Wine Outlook Winery Feature: V. Sattui Winery LAMP as a New Tool for Testing Grapevine Red Blotch Virus Volume 2: Issue 2 TRUSTED PARTNER IN AG
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PUBLISHER: Jason Scott


EDITOR: Taylor Chalstrom



Phone: 559.352.4456

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Vicky Boyd Contributing Writer

Whitney Brownie Vineyard Team

Joseph B. DeShields Faculty Research Assistant, Oregon State University

Achala N. KC Assistant Professor, Oregon State University

Catherine Merlo Contributing Writer

Steve Pastis Contributing Writer

Pam Strayer Contributing Writer

Stephen Vasquez Chair, Western Region Certified Crop Adviser

Maria Zumkeller Technical Vineyard Manager, LangeTwins Family Winery and Vineyards


Surendra Dara Director, North Willamette Research and Extension Center

Kevin Day UCCE Pomology Farm Advisor, Tulare and Kings Counties

Elizabeth Fichtner UCCE Farm Advisor, Kings and Tulare Counties

Katherine Jarvis-Shean UCCE Orchard Systems Advisor, Sacramento, Solano and Yolo Counties

Steven Koike Tri-Cal Diagnostics

Jhalendra Rijal UCCE Integrated Pest Management Advisor, Stanislaus County

Mohammad Yaghmour UCCE Area Orchard Systems Advisor, Kern County

The articles, research, industry updates, company profiles, and advertisements in this publication are the professional opinions of writers and advertisers. Progressive Crop Consultant does not assume any responsibility for the opinions given in the publication.

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2024 Grape and Wine Outlook: Complex and Varied Industry Insiders Share Optimism and Concerns

KAs president and CEO of Sonoma County Winegrowers, she’s well aware of the industry’s challenges, from inflated input costs and worrisome labor challenges to slowing wine demand and increasing competition from ready-todrink alcoholic beverages.

Yet Kruse chooses to see the glass as half full.

“We’re coming into 2024 with one of the best vintages in the history of Sonoma

County,” she said. “The wineries are very excited, and the farmers are happy.”

Moreover, Kruse believes her association’s “Farm of the Future” efforts in sustainability and regenerative farming bode well for Sonoma County’s 1,800 winegrape growers and 60,000 acres of vineyards. And the organization’s new demand-building collaborations with the Houston Rockets basketball team and Landry’s, a major dining and hospitality company, also give Kruse reason to feel optimistic.

“Technology, innovation, mechanization and partnerships are all going to be

drivers for long-term viability for our farmers here and everywhere,” she said.

Kruse is not alone in her positive outlook. Other California wine and grape industry leaders are similarly upbeat about the future, although the overall forecast, like wine itself, is complex and varied.

“We are optimistic about 2024,” echoed Joel Peterson, executive director of the Paso Robles Wine Country Alliance, which counts 500 members, including wineries, winegrape growers and associated businesses.

4 Grape & Wine Magazine March 2024
arissa Kruse could easily adopt a bearish outlook for the grape and wine sector this year.
Vineyard mechanization and technology aim for long-term success for growers (photo courtesy Sonoma County Winegrowers.)
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“At a macro level, there are certainly some cloudy skies ahead,” he acknowledged. “You hear that people are drinking less. But we’ve got a lot of innovation here with wineries and producers.”

into underdeveloped


For example, Peterson said, Paso Robles producers are making progress in regenerative agriculture and reducing their carbon footprint. Some area wineries are moving beyond traditional glass bottles by putting more wines in alternative packaging, such as boxes or reusable vessels. Further, a new, more

youthful vibe is emerging in the region with the recent development of Tin City, a collection of tin buildings south of Paso Robles. The hub of 40 tasting rooms, breweries, wineries, distilleries and restaurants has become a popular attraction.

“The other thing that’s exciting is just the growth of our reputation and presence on a national level,” Peterson said. “If you go to any restaurant in America, you’re pretty much going to find a Paso Robles Cabernet by the glass.”

The October 2023 purchase of Daou Vineyards by Treasury Wine Estates for $1 billion, he added, reflects the growing prominence of the Paso Robles wine-producing region.

“That was a big deal for Paso Robles, a fortification of our reputation,” said Peterson. “There are exciting things happening here.”

Opportunities Beckon

Blaire Fraser, vice president of marketing for California-based O’Neill Vintners and Distillers, believes evolving consumer demands offer opportunity to expand sales for growers and wineries. A Certified B Corporation, O’Neill is a major player in the industry, annually producing nearly 7 million cases of wine for multiple brands.

Broad interest in sustainability is driving growth in organic wines, said Fraser. What’s more, consumers are expanding their taste horizons.

“We’re seeing uptake in the light, bright whites such as Sauvignon Blanc,” she added. “In fact, O’Neill is launching a new Line 39 Organic Sauvignon Blanc in 2024.”

Fraser also sees growth potential in the tried-and-true super premium Chardonnay category. “It’s one of the largest and fastest-growing segments of wine,” she said.

Tapping into underdeveloped audiences is another beckoning opportunity. “In California, 40% of consumers are Hispanic,” Fraser said. “There aren’t a

6 Grape & Wine Magazine March 2024
This Sonoma County vineyard will produce high-quality grapes for world-class wines (photo courtesy Sonoma County Winegrowers.) Karissa Kruse of Sonoma County Winegrowers says new initiatives and partnerships will boost viability “for farmers here and everywhere” (photo courtesy Sonoma County Winegrowers.) “Exciting things are happening here,” says Joel Peterson of Paso Robles Wine Country Alliance (photo courtesy PRWCA.) Tapping audiences holds opportunity” for wine, says O’Neill’s Blaire Fraser (photo courtesy O’Neill Vintners and Distillers.) In Sonoma County, 99% of vineyard acres are certified sustainable (photo courtesy Sonoma County Winegrowers.)

lot of brands that have tapped into that audience. That’s another huge opportunity for wine.”

Also voicing optimism is Tyler Thomas, president and winemaker at two Santa Barbara County vineyard-winery operations, Dierberg and Star Lane.

“There are a lot of great wines being made,” Thomas said. “There are still tons of people really interested in wine. And despite news about plateauing wine consumption, I don’t think it’s a slam dunk or that we should be panicking and abandoning the wine industry.”

Not Ignoring Challenges

At the same time, no one expects an easy year ahead. Vineyard pest and plant problems, including grapevine red blotch and Pierce’s Disease, persist. Labor availability and costs rank high among grower concerns. In many winegrowing areas, limited water availability remains an issue. Water shortages, for instance, have resulted in a moratorium on new plantings just east of Paso Robles.

“The general outlook from the grower, and even the winery side, is that 2024 is going to be a challenging year,” said Stuart Spencer, executive director of the Lodi Winegrape Commission. The organization represents 750 winegrowers in a region that accounts for some 20% of California’s winegrape production.

Supply and demand are out of balance, creating “a very competitive marketplace,” Spencer said. Lodi winegrape growers, for example, haven’t seen significant price growth over the last 20 to 30 years. The average per-ton price paid to the area’s growers is $600 to $650. Compare that to Napa’s growers, who produce far fewer grapes but can command $7,000 per ton.

“Napa has carved out a strong identity,” Spencer said. “But the large winegrape buyers don’t support the Lodi region in that way. They’re not branding Lodi or investing in it from a marketing perspective. They’ll purchase our grapes at a very low price. So, to maintain profitability, growers have responded by increasing production.”

A “COVID hangover” continues to be felt, not just domestically but globally, Spencer added. Another globally tied problem stems from the fact that some of California’s largest grape buyers are also the largest importers of bulk wine.

“If they can source a certain variety from another part of the world at a lower price, they’re going to do that,” said Spencer. “That’s keeping pressure on the industry here.”

Some see consolidation among wineries and distributors as another hurdle. While such unions can bring greater efficiencies and resources to smaller businesses, “it’s harder to get your brand recognized if you’re a small guy trying... to stand out against the big guys,” said Peterson.

A ‘Sputtering’ Market

March 2024 7
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Growers, expects market and grower pricing pressures to continue in 2024. His outlook is shaped by his daily responsibility of selling winegrapes for the cooperative’s 500 grower-members.

Bitter sees a market burdened by the slowdown in demand that began around 2016. Consumption has lagged with the shrinking number of baby boomers, who helped propel wine sales in recent decades. Younger generations haven’t adopted wine in the same way. On top of that, a growing anti-alcohol movement has emerged. The pullback in demand has caused the grape and wine industry to lose shipments and sales volume.

“For the last 18 months, the wine market has been sputtering,” Bitter said. The wine market, he said, is operating in reactive mode. Retailers aren’t seeing wine move off their shelves as quickly as before partly as consumers worry about rising grocery costs. Even wines below $15 to $18 a bottle have struggled to maintain shipments. That’s led to a slowdown in purchases from distributors. They don’t want to carry excess inventory in their warehouses since higher interest rates add to their storage costs. So, distributors have adopted more just-in-time, or only-when-needed, shipments. In turn, that backs up to the wineries, where tanks stay full. And that

diminishes the market for winegrape growers.

“In 2023, we saw the grape market kind of fail, particularly on red grapes,” said Bitter. “Anything that was available for sale was challenging to move at a decent price, particularly in the spot market.” In the Lodi area, he added, “tens of thousands of tons” of red grapes never found a buyer and remained on the vine after harvest.

As a result of the market imbalance, Bitter has been calling for an “acreage adjustment” of 50,000 net acres in vineyard removals. That would amount to about 10% of California’s 570,000 bearing acres of winegrapes.

“That’s the only way to match what we’re producing with what the market’s going to take off our hands,” he said.

Bitter recognizes achieving those acreage reductions won’t be easy. “Developing vineyards is a capital-intensive business,” he said. “Those who have developed vineyards are slow to remove them, particularly healthy, productive vineyards. There’s that mentality that if everybody else pulls out their vineyards, I’ll be the guy who still has my vineyard when the market turns around.”

Further, there aren’t always good alternatives or profitable crops to replace vineyards. A grower’s options depend on the region and the ground farmed.

8 Grape & Wine Magazine March 2024
An excellent vintage from last fall’s harvest has boosted spirits for many growers and vintners (photo by C. Merlo.) A postharvest vineyard in Northern California’s Lake County, another winegrape growing region with increasing potential (photo by C. Merlo.) The rising national reputation of Paso Robles wines, like this Austin Hope cabernet sauvignon, helps underpin the region’s confident outlook (photo by C. Merlo.) Stuart Spencer of the Lodi Winegrape Commission foresees another challenging year (photo courtesy Lodi Winegrape Commission.)

“If you’re going to pull out a vineyard in Napa, what are you going to plant instead?” Bitter asks.

That’s a dilemma Monterey County understands. Over the last five years, growers there have removed nearly 3,000 acres of the county’s total 40,000 acres of vineyards because “of a lack of clarity about what the market’s going to want,” said Kim Stemler, executive director of Monterey County Vintners and Growers Association. The majority of those pulled vineyards were chardonnay and pinot, the county’s top two varietals. While some of the ground was replaced with lemon trees, the question remains.

“What gets planted?” Stemler asked.

“That’s the big weight.”

“Survive to ’25”

Spencer said Lodi-area growers are hoping just to make it through the year as they wait for the market to rebalance. “One of our growers jokingly said his motto is ‘Survive to ’25,’ and there’s a lot of truth to that,” he said. “It’s a tough time right now, and there are not a lot of good answers at the moment.”

Still, Spencer believes the Lodi area and other wine regions must be more proactive in bolstering branding efforts, developing a sense of place and story in marketing and rising above the commodity image of their grapes and wine. A closer connection between farms and

the consumer would also benefit the industry, he added.

“People are not going to stop drinking wine,” he said. “It’s very much engrained in our community and our society. California and Lodi make incredible wines. We need to take ownership of that as growers and not rely on others to do it.”

Santa Barbara County’s Thomas agreed “brands need to find ways to take market share.” Digital marketing can be particularly useful.

“Even in the wholesale space, you can do direct marketing campaigns to buyers at restaurants or retail shops in Colorado or Florida, and you can do that from your office in California,” he said. “That could potentially help smaller producers maintain a toehold in the wholesale markets.”

All in all, Thomas believes the industry’s headwinds can bring fresh approaches to the grape and wine business. “It’s actually a great opportunity to shuffle the deck and for people to re-think their strategy,” he said. “It’s time to put the pandemic to bed and go forward. And this is the year to do that.”

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March 2024 9
Grape growers will continue to wrestle with high input costs and labor challenges (photo by C. Merlo.) “There’s a lot of opportunity out there,” says Tyler Thomas of Dierberg and Star Lane wineries in Santa Barbara County (photo courtesy Star Lane Vineyard and Winery,) Allied Grape Growers’ Jeff Bitter has been calling for the industry to remove 50,000 acres of winegrape vineyards (photo courtesy AGG.)


At first glance, V. Sattui Winery President Tom Davies and Owner and visionary Dario Sattui might have seemed like unlikely candidates for leading carbon reduction initiatives and farming organically at their two Napa estates. After 43 years in Napa, they were already quite successful in their two DTC wineries. So why change?

Their popular V. Sattui winery, with its cheese shop, gourmet takeout and picnicking, has been a hit with tourists for decades, and Dario’s inspired, authentic recreation, Castello di Amorosa, a medieval Tuscan castle, is a super popular tourist draw as well. Their estate farming operation, which provides 70% of their grapes, spans 350 acres growing 26 varieties in four counties. Everything is sold direct to consumer.

But lately, they’ve crossed a new business frontier, becoming evangelists for carbon footprint reduction and for organic farming. They’re now passionate about their greener path: starting a climate club, paying employees to carpool to work and converting all their estates to organic.

As Davies tells the story, the moves were inspired by two main events.

Inspiration #1: An Eye-Opening Climate Change Talk

One event was a talk on climate change

and fossil fuels by Andrew M. Isaacs, a senior lecturer at UC Berkeley’s Haas School of Business on climate change and business strategy who lives in Napa. The recipient of the Haas School of Business Sustainability Teaching Award, Isaacs consults for hundreds of companies on how businesses can take effective action on climate change.

“He gave a talk at Napa Valley Grapegrowers. That day changed me,” said Davies.

The take home message? “‘At the end of the day, it’s all about carbon.’”

Davies turned a new leaf.

“I went out and I put solar in my house, I bought an electric car. I eliminated all plastic here at the winery... And on and on.

“We started a climate club here at the winery. And we now pay people up to $10 per day to carpool, a program which has been very successful.”

Inspiration #2: Local Documentary on Roundup

The second event was when a mutual friend introduced Davies and Sattui to documentary filmmaker Brian Lilla, who has been showing his documentary on Roundup and health concerns in local community screenings.

Said Davies, “We had not yet seen his film Children of the Vine. But we just thought he’d be an interesting person to talk to.”

“So, Brian says, ‘Look, I’d love for you both to see the documentary.’ So he gave us a link. Dario watched it at home. I watched it here in my office. And I think we absolutely were both taken aback...”

The film details medical and community concerns from Roundup’s critics about the controversial product’s alleged carcinogenicity which have since forced its manufacturer, Bayer, to pay out $11 billion in legal claims in the U.S.

Davies had already made the decision in late 2022 to stop using Roundup (a systemic herbicide that contains glyphosate) on the estates, so he was exploring other options including Lifeline herbicide (a contact herbicide that contains glufosinate ammonium) but wasn’t finding much data. “It’s not been studied to death as much as Roundup; there wasn’t a lot of information out there regarding Lifeline,” he said.

At the same time, Davies had already been farming organically for over a decade on a few vineyards adjacent to main roads (which enabled the company to put up signage saying those vineyards were certified organic), but those were only a small fraction of overall production.

10 Grape & Wine Magazine March 2024

“In the spring of 2023, I sat down [with] the vineyard team and said, ‘Okay, let’s pencil out maybe another ranch or so that we could begin the process of converting to organic.’ But then both Dario and I saw the film. I had sent Dario an email early in the morning that said, ‘Look, the only way around this dilemma is just to go organic.’

“He didn’t see my email, but called me the next day and said, ‘Let’s go organic 100%.’ So, we both came at it at the same time, but somewhat independently.

“We were almost there, but that film just kind of coalesced in my mind what we needed to be to be better stewards of our land.

“And within a period of less than a week, we decided to go 100% organic on all our ranches. So, it was pretty much a very quickly made decision, but one that we’ve fully embraced and continue to embrace today.”

The Learning Curve

Putting the plan into action began in spring 2023.

“We certainly have had our challenges this year because of that, and it’s been a quick learning curve,” Davies said, with terrain playing a major role as well as

2023’s abundant rain.

“The whole idea about farming organically is about soil health, right? That is really the name of the game,” he said.

“It’s one thing to farm organically on flatland, especially with weed control, but once you get up in the hills and rocky soils, it’s another ballgame... but we made that commitment. And that’s what we’re doing.

“Fungicide has been a big deal this past year, which was a high-pressure year for powdery mildew.”

The team has made new discoveries as well, he said, discovering hotspots that conventional chemical farming had masked, shifting to a new schedule of weekly spraying instead of spraying every other week with chemicals which led to logistical adjustments.

March 2024 11
Dario Sattui, the owner and visionary behind V. Sattui Winery
Tom Davies is president of V. Sattui Winery in Napa County (all photos courtesy V. Sattui Winery.) V. Sattui President Tom Davies said it remains to be seen whether it’s profitable to farm organically on all varieties or just some varieties.


“We had to react quickly; that’s just the reality of farming, where you have so many tractors and so many crew members, and you need to get around in a very timely fashion. That’s just what it takes to farm.”

The Toolkit

The group implemented new techniques and new equipment to integrate organic practices and eliminate chemicals.

“For the first time this year, we brought sheep into our vineyards for grazing, and that was a great experience. We hope to expand that program,” he said.

Davies purchased some new equipment, namely two Monarch tractors and a Twister. The Twister can work well for weeding on hillsides, he said.

“We were able to take advantage of some of the rebates on these electric tractors, and we said, ‘Okay, let’s get a couple and see how they work.’ For doing sprays and stuff, they’re fantastic, even if they didn’t have quite the strengths of a traditional tractor.”

One unforeseen challenge of electric tractors: Wi-Fi connec-

tivity. “With those tractors, we needed to get Wi-Fi connections to ranches that are in the middle of nowhere. We finally just got our Wi-Fi connection because we didn’t even have phone lines at some of those locations.

“We had some success with the Twister. But it meant that we had to come back eventually with shovels, so certainly there was an increase of labor there.”

The Results

It’s too early for Davies to assess the impacts financially overall due to the cool weather, the rain, and the newness of the practices coupled with above-average yields. “It was the coolest vintage we’ve had in 20+ years,” he said, yet his yields on some varieties were up 20% over averages over the last five years.

It also remains to be seen whether it’s profitable to farm organically on all varieties or just some varieties, he said. “It will take us many years to measure, but what I’m proud of is that we took the bold step as a winery.”

While the wineries do not currently label the wines with organic certification, since they hand-sell everything, organic is a big talking point with consumers, he said. “We really do get to talk to virtually everyone that buys our wines... we like to shout from the rooftops that we are farming organically because we’re very proud of that.

“This is just one of the ways we demonstrate our dedication and stewardship of our environment. There’s many other things we do as well, but this is really important for the sustainability of our winegrowing economy and certainly to our community and to our laborers in the fields...”

Before the plans were put into place, employee reaction was uncertain, Davies said. The vineyard crew consists of 25 yearround employees.

“Some of the team members who were watching out for the fi-

12 Grape & Wine Magazine March 2024
Through the winery’s effort to implement new techniques and new equipment to integrate organic practices and eliminate chemicals, V. Sattui purchased two Monarch electric tractors. Sheep grazing is a new practice for V. Sattui Winery that it hopes to expand. V. Sattui Winery has organic and Napa Green certifications.

one was 100% on board, and our vineyard manager, David Bejar, said to me, ‘Thank you, Tom. Our crew thanks you. It just shows you really care, not only about the environment, but you care for our team members and their health.’

“And that, you know, that made me feel really good. It’s created more work for them... I think it was a real challenge for them, but even given that challenge, they stepped up and I think they feel really good about it.

“It’s certainly my hope down the road that with these healthier soils, healthier vines, we will see increased longevity. What if we were able to get another 5 to 10 years out of a Cabernet Sauvignon vineyard? That’s real money right there.”

ing day. I think it’s certainly a very doable dream.

“What a great thing we could do for our community because we are an ag-based community, we’re a tourism-based community. Both those things have to go hand-in-hand for us too. I want to be able to sustain what we have. And if we can’t continue to get buy-in from our community, for our community to embrace us, this whole thing can kind of collapse. And I just think this is how we can become a better part of our community. And continue with this for many more generations to come.

“You don’t want to be late to the game. We can be at the forefront of that. It just puts us in a much better position for us to have our continued success here.”

nancial health of the company were not sure,” he said. “I think there was some apprehension.

His dream goes further.

“What if the Napa Valley was the very first wine region to become 100% fully


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show their passion for decarbonization and a greener path, V. Sattui Winery is paying employees to carpool to work and converting all their estates to organic.

LAMP as a New Tool for Testing Grapevine Red Blotch Virus

| Faculty Research Assistant, Oregon State University and ACHALA N. KC | Assistant Professor, Oregon State University

Since its discovery in 2008, grapevine red blotch disease (GRBD) has negatively impacted the quality of wines due to reductions of sugar and color in the fruit. Its economic impact in the Western U.S. is estimated to range from $2,200 to $68,500 per vineyard depending on the growing region. Due to the presence of an insect vector capable of spreading the grapevine red blotch virus (GRBV), healthy grapevines can often become quickly infected during the growing season and symptoms can go unnoticed until the following season. Therefore, early detection of GRBV is even more crucial to preventing further transmission of the virus.

Symptoms of GRBD are often expressive in their characteristically red blotching patterns on leaves of red wine cultivars and likewise with yellow/yellow-white blotching on the leaves of white wine cultivars. However, symptoms on grapevines with established GRBV infections typically do not appear until after veraison. Consequently, molecular detection of GRBV can be critical for early determination of the infection status during early, non-symptomatic stages of infection.

Available GRBV Testing Strategies

There are multiple methods and strategies for diagnosing GRBD, includ-

14 Grape & Wine Magazine March 2024
(all photos courtesy J. DeShields.)
results from colorimetric GRBV LAMP reactions. Yellow indicates a GRBV-positive reaction
pink indicates a GRBV-negative reaction

ing foliar symptom observation and monitoring, hyperspectral imaging, conventional polymerase chain reaction (PCR), quantitative PCR (qPCR), loop-mediated isothermal amplification (LAMP), plasmonic CRISPR and recombinase polymerase amplification (RPA). Among all these methods, PCR has remained the standard since 2014 due to its reliability, specificity and sensitivity; however, the PCR method creates technical, financial and infrastructure barriers for laymen due to the requirement for clean spaces, expensive instrumentation, complex troubleshooting and interpretation of results.

Other DNA-based methods such as LAMP and RPA, which are conducted at a stable reaction temperature throughout the procedure, do not require the same expensive equipment that PCR requires. The results from these two methods can be achieved much faster with reaction times as short as 20 or 30 minutes. In addition, LAMP and RPA are typically considered more sensitive to the DNA they target and less sensitive to impurities in the sample.

What is LAMP?

LAMP is a molecular tool used to detect DNA, commonly used as a diagnostic method for infectious diseases of plants and animals. Since its initial discovery by Notomi et al. (2000), the LAMP method has received much interest from private, academic and government sectors as well as from growers due to the low barriers to entry. In the past two decades, new formats for LAMP have

been developed, making interpretation of results even more simplistic compared to the original method which had involved a gel electrophoresis system, additional chemicals and an advanced imaging system. These new formats allow the final interpretations to be done visually without any instrumentation. For example, the GRBV-positive reactions in some LAMP formats can create turbidity or cloudiness in the reaction tube, indicating GRBV was present in the sample, but more common is a change in color using pH indicators.

Recently, Romero Romero et al. (2019) published a LAMP method for the detection of GRBV along with a simplistic “pin-prick” DNA extraction method which consists of pricking leaf blades and petioles with a pipette tip and soaking them in water for 10 minutes to complete the extraction. Furthermore, these researchers paired this DNA extraction method with a colorimetric LAMP reagent that uses a pH indicator dye to determine whether the LAMP result was positive (yellow) or negative (pink) making interpretation faster and simpler.

We were interested in comparing its sensitivity and specificity to other more commonly used methods, such as PCR, qPCR and symptom monitoring.

The Experiment Design

We compared the four methods (LAMP, PCR, qPCR and visual symptom monitoring) at four different phenological time points per year for two years at a


commercial vineyard in southern Oregon. We compared these methods using fully expanded, mature leaves sampled between berry set and harvest and using dormant shoot tissue during the winter. Both tissue types were collected at three different heights in the grapevine’s canopy: low-canopy (basal), mid-canopy and upper-canopy (apical). A tissue sample consisted of four leaves (one leaf from four shoots) or four dormant shoot segments and were collected for each canopy height and for each of the 40 vines used in this study. Vines were recorded for GRBD symptoms at the time of sample collection. Tissues were either

March 2024 15
The pin-prick DNA extraction method being performed on grapevine leaves and dormant canes.

subjected to a standard lab-based DNA extraction method and tested using PCR or qPCR or were subject to a simple, no-equipment-needed pin-prick DNA extraction method paired with LAMP.

What Was Discovered

In leaf samples, the accuracy of all methods was reduced when samples were taken from higher positions within the canopy. Therefore, we will present the remaining results of this experiment from the data collected from basal sam-

ples only since this is already standard practice for most virus testing.

The sensitivity, or ability to detect a positive sample, of all four methods differed significantly at all time points and canopy heights. At berry set and veraison, both PCR and qPCR successfully detected GRBV in 98% GRBV-infected samples across both years whereas LAMP could only detect GRBV in 49% and 78%, respectively, of the same GRBV-infected vines. Only 31% of these same GRBV-positive grapevines expressed symptoms during veraison. At harvest, qPCR detected 100%, PCR

detected 98% and LAMP detected 96% of GRBV-infected samples. At this stage, 94% of grapevines were symptomatic. At dormancy, where there are no leaves to observe GRBD symptoms, 96% of the dormant shoots tested positive using PCR and LAMP, and 95% tested positive using qPCR. There was no statistically significant difference in false-positive rates (the percentage of samples incorrectly testing positive) between methods.

Due to the nature of this virus and its vector, some of our GRBV-negative vines became infected some time into the two-year experiment. Among the eight new infections observed, seven vines tested positive at our earliest sampling timepoint, berry set, by PCR and qPCR whereas LAMP only detected one of these vines at berry set and the other six thereafter. The eighth newly infected sample tested positive by all methods, but only at the harvest sampling.

The conclusion from this experiment was the accuracy of these three DNAbased methods very much depends on the location of the sample in the canopy. Use of lower-canopy leaf samples later into season increased the accuracy of GRBV diagnosis and reduced the variability in detectability. It is evidenced that testing with LAMP for GRBV later in the season (e.g., near commercial harvest) can yield comparable results to more standard methods such as PCR or qPCR.

More cost-effective and simple methods such as pin-prick DNA extraction and LAMP can offer a more accessible approach compared to external testing or the barriers and complexities of performing PCR in-house. While PCR and qPCR testing of GRBV remains the more accurate method when testing until veraison, this experiment suggests LAMP can serve as a useful tool for those who may be seeking alternatives to PCR testing. LAMP may be of interest for those wanting to test more routinely, closer to commercial maturity or during dormancy when foliar symptoms are absent.

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16 Grape & Wine Magazine March 2024
Sampling of lower-canopy leaves for GRBV testing.
Sensitivity to GRBV compared across detection methods, grapevine phenology and canopy location.
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What’s Old is New Growers look to wooly weed eaters to help economically and ecologically augment

An increasing number of winegrape growers are resurrecting an age-old practice of grazing sheep in vineyards to manage weeds, improve soil health, recycle nutrients and potentially reduce costs.

As with any new system, adding sheep comes with its own set of challenges. But many adopters say most issues are easily addressed and don’t discourage them from the practice.

Tommy Fenster, a UC Davis doctoral student, is trying to quantify how integrating sheep and other regenerative practices affect 45 selected vineyards from Lodi to the North Coast. Half are using livestock, while the other half are using conventional weed control and management.

At the end of his research, Fenster said he hoped to develop best management practices for grazing vineyards, incorporating what he found as well as knowledge from producers in Europe and New Zealand. Included will be an economic analysis related to hiring contract grazers.

Fenster’s project also is part of the much larger Ecdysis Foundation 1000 Farms Initiative, a two-year effort to research

regenerative farming systems nationwide.

Working with Nature

Since Paicines Ranch was founded in 1846 near Paicines, Calif., cattle and more recently sheep have grazed the hillsides. Beginning in 2001, ranch managers moved to a more holistic approach that used regenerative practices to try to return the exotic annual grasslands to native grasses.

When ranch owner Sallie Calhoun decided to plant a 25-acre vineyard beginning in 2017, she wanted to take a similar path.

“It’s flipping this whole idea of controlling nature and instead working with nature,” said Kelly Mulville, director of wine growing for Paicines Ranches. One of the operation’s goals is to increase biodiversity while remaining profitable.

Winegrapes are not new to the ranch, with it hosting what was at the time the world’s largest varietal vineyard in the 1960s through the 1990s.

Mulville described their latest vineyard endeavor as more of a large-scale experiment that includes 17 different va-

rietals. They looked globally for varieties that would thrive under similar hot, dry climatic conditions as those found near Paicines.

They planted the first 12.5 acres in 2017, hoping to take what they learned and apply it to the second planting of 12 acres in 2000. Mulville said he also sought a trellis design that would allow sheep to be grazed year-round in harmony with the vines.

Texas viticulturist Jerry Watson had developed a trellis system that improved

18 Grape & Wine Magazine March 2024
Frankie Arburua III, owner of F Ewe Sheep Co., conducts contract grazing for vineyard owners in the Lodi, Calif. area. In late fall through winter, the ewes give birth to lambs, which also feed on vegetation (photo courtesy F. Arburua III.) Some vineyardists, such as in the Lodi area, use sheep shortly after harvest to clean up vegetation in the vine rows (photo by V. Boyd.) vineyard management.

airflow to reduce mildew under humid Texas conditions. But it also elevated cordons to 66 inches, high enough off the vineyard floor to protect fruit from sheep grazing, Mulville said.

At the same time, the trellis design allows sheep to nibble on low-hanging parts of the canopy and provide shoot tipping and suckering. The drip lines are hung just below the cordons. A V-shaped split at the trellis top creates two fruiting walls, allowing leaves to catch more sunlight while partially shading fruit.

“You’re getting more fruit per vine this way, and the quality is very high,” Mulville said, noting a Grenache yield of 5 tons per acre in their third harvest. “We have a rather long wait list for our fruit.”

Mulville planted the vineyard using 6-by-12-foot spacing, about half the vines of a traditional VSP vineyard. The additional spacing not only reduced

planting costs but also made it easier for sheep and hand harvest crews to move between rows.

They chose hair sheep because they are hardier than wool breeds and have a wider pallete when it comes to vegetation. Of the 2,000- to 4,000-sheep flock on the ranch, Mulville said they run a portion in the vineyard for short periods based on the growth rate and recovery of the vegetation. By using sheep, they’ve significantly reduced tractor passes to just nine or 10 per season for fungicide sprays and applying and removing bird netting. The sheep also act as nutrient recyclers, eating vegetation and turning it into manure or urine.

“Sheep or any type of animal are not actually producing nutrients; they’re cycling them so they can only produce what they’re taking in off the ground,” Mulville said. “The really important thing with livestock in general is that they’re taking that material, that N, P

and K, and they’re making them more available through fermentation in the stomach.”

The urine, in particular, is a good source of nitrogen and potassium and was one reason why Mulville said they chose to set up the vineyard to allow year-round grazing.

Already, he has seen a 5-point Brix increase in their sap analysis, which is an indication of healthy vines. Mulville also noted soil carbon levels had risen by nearly 2%. That equates to about twice the soil moisture holding capacity as it was before they started. During last year’s record rains, he said they saw no runoff.

In addition, Mulville said they’ve documented more than 60 bird species and more than 100 species of plants, most of

March 2024 19
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which were not introduced to the vineyard. Before they planted, they had only found 11 plant species.

Grazing Benefits Organic, Conventional Alike

Vino Farms began looking at sheep for weed control when it began converting some of its vineyards to organic in 2018, said Daniel Meyers, Vino Farms viticulturist in Lodi, Calif.

“When you go organic, you essentially have very few options for weed control,” he said. “It’s just a great way when you go organic to graze everything.”

Their goal was to replace mowers used to reduce vegetation so drill-seeded cover crops would have an easier time getting established. In the process, Meyers said, they found sheep also were good for late-winter or early spring cleanup.

In vineyards with resident vegetation in the middles, the sheep help lower it to reduce frost risk, eliminating another mower pass.

The system worked so well that Vino Farms expanded sheep grazing to conventional vineyards, particularly those in the Delta where the high water table keeps grasses green year-round.

Grazing conventional vineyards also enhances preemergent herbicide activity by removing excess plant matter and improving soil contact.

Altogether, they’re currently using sheep on about 2,000 acres in the northern San Joaquin Valley and Delta because of its cost-effectiveness, Meyers said.

Vino Farms chose to contact for grazing services with Frankie Arburua III, owner of Lodi-based F Ewe Sheep Co. Based on his experience, Meyers said shepherds in the Lodi area charge between $20 and $60 per acre, depending on the acres growers can commit.

As part of the contract with F Ewe Sheep, someone cares for the animals, moves portable electrical fences and transports them among ranches. What makes the

arrangement successful is good communication between the parties, Meyers said.

A vineyard, for example, must have a fair amount of vegetation to make it worthwhile for the herder to bring in animals.

“It has to be pretty messy,” he said. If in doubt, Meyers will take a vineyard photo and send it to Arburua for his opinion.

In early spring when they’re applying fungicides, Meyers keeps Arburua in the loop so he can move animals “and he’s ahead of it.”

“It’s really important to have someone you can trust. It just makes it very easy,” Meyers said.

As older vineyards are removed and replanted, he said they likely will move to a single high-wire trellis system that allows for full mechanization of cultural practices. Having the cordons higher off the ground also lends itself to grazing for a much longer part of the season.

Because Vino Farms doesn’t have the facilities or space to maintain their own sheep, he said they plan to continue contracting for grazing services.

Sheep for Rent

And it’s for just that reason that Arburua, a fourth-generation sheep rancher, said he has seen his contract grazing business grow substantially the past few years. In 2021, he conducted a sheep grazing field with the Lodi Winegrape Commission on the 18-acre Schulenberg Vineyard. The vineyard is certified sustainable under Lodi Rules.

“Ever since then, it’s grown from doing 20 acres,” Arburua said.

This season, Arburua has 700 to 800 ewes, not counting lambs they produce, and estimates he’ll graze about 2,000 acres. Eventually, he’d like to build up to about 1,500 ewes.

His brother, Vince, has a separate contract grazing business, VA Livestock, with about 700 to 800 sheep.

Frankie Arburua uses hair sheep because they’re hardier, less prone to hoof rot, have lower nutritional requirements and don’t require sheering like wool sheep do.

How long the sheep are left in a vineyard depends on location, vegetation and the grower’s goals. Arburua said he also weighs the number of animals with the size of the fenced-off paddocks to minimize potential compaction.

The vineyard grazing season typically ends after budbreak in April. But Arburua is exploring how to extend the season and worked with a Linden-area walnut producer in 2023 to run sheep in orchards after grapes. He said the orchards could be grazed for much of the season were it not for food safety rules, which require animals be removed 120 days before harvest. Grapes destined for wine production don’t fall under those rules because fermentation with accompanying alcohol production is considered a pathogen kill step.

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20 Grape & Wine Magazine March 2024
UC Davis doctoral student Tommy Fenster is part of a study trying to quantify how integrating sheep and other regenerative practices affect 45 selected vineyards from Lodi to the North Coast (photo by T. Fenster.)

Protecting Your Vineyard From the Threat of Fungicide Resistance

Understanding Fungicide Resistance

Every grape grower understands the challenge of controlling fungal diseases. Although fungicide applications are the most e ective strategy for disease management, the rise of fungicide resistance poses a significant threat to e cacy. Growers are often unaware they have a fungicide resistance issue until devastating diseases like botrytis bunch rot and powdery mildew have caused substantial and irreversible damage to their crops. To protect grape health and maximize yield, grape growers should consider implementing proactive strategies to address fungicide resistance.

Fungicide resistance, as defined by the Fungicide Resistance Action Committee (FRAC), is an acquired reduction in sensitivity of fungi to specific fungicides. The key challenge is the genetic variability of fungal populations, which leads to fungicide resistance in certain fungi within the population. Without a proactive approach, those resistant fungi can rapidly reproduce, causing widespread fungicide resistance across the vineyard.

Best Management Practices

To avoid the development of fungicide resistance, consider these best management practices:

• Rotate fungicides with di erent FRAC groups to reduce the selection pressure on fungi population.

• Scout orchards daily for signs of disease development.

• Implement integrated disease management strategies.

• Apply the recommended label rates with adequate coverage.

• Apply fungicides preventively — prior to disease development.

• Select varieties with resistance to common grape diseases.

Protecting grape vineyards from the threat of fungicide resistance starts with informed decisions and proactive strategies. Visit or scan the QR code to learn more.

Spotting the Signs

Fungicide resistance is generally not found until there is an issue in the crop, but staying alert during the growing season can help grape growers spot signs of resistance. Avoid repeated use of fungicides from the same FRAC group, talk with neighbors about their treatment outcomes for di erent diseases and stay informed on resistant strains to avoid ine ective treatments.

E ects on Grape Growers

Fungicide resistance poses a serious threat to growers’ bottom lines.



With studies indicating potential preharvest losses ranging from 10% to 23% and postharvest losses of 10% to 20%, the stakes are high for growers across the industry.1 Implementing a proactive plan at the beginning of the growing season can give grape growers peace of mind when diseases, such as botrytis bunch rot and powdery mildew, occur in their vineyards.

March 2024
Trademark of Corteva Agriscience and its affiliated companies. ©2024 Corteva. 018695 BR (01/24) CAAG4ADVT062
1Steinberg, G., and S. J. Gurr. 2020. Fungi, fungicide discovery and global food security.


What does a typical day for you look like? If you’re reading this in the 21st century from the modern, industrialized U.S., nearly all your daily tasks require readily available energy in the form of electricity or fuel.

From industry, to transportation, to powering our homes and businesses, the U.S. produces and uses a considerable amount of energy. While energy comes from several sources, fossil fuels are the primary source for all sectors (U.S. Energy Consumption by Source And Sector 2022).

Atmospheric carbon dioxide levels have been on the rise since the Industrial

Revolution and have increased exponentially since the 1960s (Climate Change: Atmospheric Carbon Dioxide 2023). Burning fossil fuels for energy production is responsible for over 75% of global greenhouse gas emissions and nearly 90% of all carbon dioxide emissions (The Production Gap 2019).

Finding ways to improve energy efficiency is key to reducing greenhouse gas emissions and combatting climate change. Even small changes accumulate to make a significant impact.

Climate-smart companies make energy efficiency a key component of their sustainable business model. Sustainable

winegrowers and winemakers have several paths to greater energy efficiency.

Do you know how much energy goes into producing your favorite bottle of wine?

Making wine is an energy-intensive process powered by batteries, fuel and electricity. Energy is used at every step of the process, including field equipment that tends to the vines and harvests grapes; de-stemmers and rollers that turn the grapes to must; and the pumps, cooling systems, bottling lines and cold storage that bring the wine to completion.

22 Grape & Wine Magazine March 2024
Finding ways to improve energy efficiency is key to reducing greenhouse gas emissions and combatting climate change. Even small changes accumulate to make a significant impact.

With so many uses of energy, there are many places where efficiency improvements can be made.

Options in the Vineyard/Winery

In the vineyard, tractors and heavy equipment are the highest energy users. Greater efficiency can be achieved by using equipment that covers multiple rows or uses multiple attachments.

These equipment modifications reduce the number of times tractors need to drive up and down vineyard rows, cutting fuel use and emissions. Plus, this practice reduces compaction, helping to maintain healthy soils.

Using all-terrain vehicles instead of tractors and trucks for light-duty jobs, replacing older, less efficient motors and equipment, and ensuring all these are regularly maintained compound to make significant improvements to a vineyard’s energy efficiency.

Beyond vehicles and equipment, irrigation system improvements also make an impact on energy use. Variable frequency drive motors regulate and modify

pump speeds to ensure they are working at an optimal level. Many companies today even offer solar-powered irrigation pumps, so operations that cannot invest in a solar field can still access this renewable resource.

Since turning grapes into wine requires a lot of equipment and refrigeration, addressing electricity use is key to improving energy efficiency in the winery.

Conducting an energy use assessment is a great place to start. The assessment will reveal when and where energy is being used so informed optimization and conservation efforts can be made.

When the team at Center of Effort Estate in Arroyo Grande, Calif. decided to look at their energy use, they discovered several areas they could adjust to be more efficient. Over time, these changes have compounded tremendous energy savings.

Shifting their winery’s cooling system to run during off-peak hours was a simple yet powerful change. They programmed their chiller to turn off during the times

in the day when energy-demand is high. The thermal mass of their tank storage keeps everything cool until peak hours are over and the chillers can kick back on.

They saw the value in investing capital into improving their energy efficiency by replacing their 15-year-old chiller with a newer, more efficient one. This new chiller allows them to bring tank temperatures down on select tanks rather than the entire plant. The upfront financial investment started paying itself off immediately in the form of reduced energy use.

HVAC needs are high in a wine production facility. Center of Effort made two changes to minimize their use: cooling the barrel rooms and case goods storage rooms with nighttime air and installing a quick-draw door to address insulation losses in their production room.

Frequent forklift traffic meant their standard garage door was often left

March 2024 23
Center of Effort Estate in Arroyo Grande, Calif. decided to make energy efficiency a key component of their sustainable business model (all photos courtesy Center of Effort Estate.)

open. While convenient for the forklift operators, this allowed cool air to escape the production room.

Now, every forklift has a garage door opener that operates a quick-draw door. The door opens in two seconds and remains open for only seven seconds, plenty of time to get in the door and not so much time that dramatic temperature changes occur.

“A lot of the changes were pretty simple and had varying impact, but all together compounded into very meaningful dif-

ferences,” said Kevin Bargetto, associate winemaker.

Even before these smaller energy-efficiency changes were made, Center of Effort made a decision that would eventually turn their energy use to net-negative; they went solar.

Their solar plan went live in 2016 and was built to meet 95% of the energy needs of the winery at that time. It was a higher-than-average energy assessment for their first year being solar that compelled the team to look at how and when they were using energy and make all these improvements.

With the energy efficiency changes made over the past several years, the winery and hospitality areas are now fully powered by the sun. In fact, they are running net-negative, meaning they are even sending generated power back to the grid!

Nathan Carlson, winemaker and general manager, said the solar project “showed 100% return on investment over four years, no problem.”

Renewable energy sources play a significant role in reducing the amount of greenhouse gases released into the at-

mosphere. Producing energy from wind, sun and natural waterbody movement produces little to no greenhouse gases.

The amount of energy produced from renewable sources has increased over the past several decades. In 2023, the U.S. generated nearly 12 times as much solar power and 2.6 times as much wind power as it did in 2013 (Renewables On The Rise Dashboard 2023).

While he recognizes not every operation can go solar, Carlson suggested there are still plenty of areas where wineries can economize. “Question your process and make sure you are managing correctly,” he said. “Start by looking at energy set-points and asking, ‘Can we get by with less?’”

Businesses with sustainability goals know improving their energy efficiency is one of the easiest and most cost-effective ways to reduce their carbon footprint and increase their bottom-line.

They also know talking about these sustainable initiatives aligns with consumers’ shifting interests.

This alignment is so strong that some customers are even willing to pay more for wines produced sustainably, according to a 2021 study conducted by Kathy Kelley and her colleagues at Pennsylvania State University (Kelley et al. 2021).

“We’re seeing a consumer group that wants to be educated and wants to know exactly what is going on with sustainable wine production,” Kelley said.

It’s important to note the power is in describing specific sustainable practices, what they are and how they make an impact, something we like to call “telling a Sustainable Story.”

In the next Sustainable Story, learn from a Santa Barbara-based vineyard management company how working with an environment’s natural ecosystem can support a cultivated agricultural system.

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24 Grape & Wine Magazine March 2024
Center of Effort’s energy reduction changes have made the facility net-negative, meaning electricity is being sent back to the grid. Center of Effort’s solar plan went live in 2016 and was built to meet 95% of the energy needs of the winery at that time. Winemaker and General Manager Nathan Carlson said ROI on the project was 100% over four years.


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Wine Industry History Early California Winemaking Relied on Native Americans

Almost all California historians will tell you the state’s wine industry was started by Spanish missionaries in the late 18th century because they needed wine for their religious services. Eventually, they would establish 21 missions from San Diego to Sonoma. These Franciscan fathers were led by Father Junipero Serra, who would, amid controversy, be canonized as a saint by the Catholic Church in 2015.

“In 1777, Father Junipero Serra wrote to the viceroy of Mexico and asked that grapevines be sent to California,” said Frances Dinkelspiel, author of Tangled Vines: Greed, Murder, Obsession and an Arsonist in the Vineyards of California. She quoted Father Serra as writing, “The lack of wine for mass is becoming unbearable.”

“Grapes were brought in May 1778 on board the supply ship San Antonio and were unloaded in what would one day

be Orange County,” said Dinkelspiel. “They were planted at San Juan Capistrano. The first vintage from those grapes was probably 1782.”

The grapes were called mission grapes, and they flourished in the Orange County area. Even so, the Franciscans decided to concentrate their winemaking efforts at their missions across the state.

The area around the San Gabriel Mission soon produced the most wine in the state with about 170 acres planted and 35,000 gallons of wine a year produced. The next biggest wine producer was San Fernando, followed by Ventura and San Jose, according to Thomas Pinney, author of The City of Vines: A History of Wine in Los Angeles.

Working Conditions

“The Franciscan friars came to Califor-

nia with the intent of converting Native Americans to Christianity,” said Dinkelspiel, adding a lot of Native Americans agreed to be baptized not knowing what they were signing up for.

The Franciscans insulated the Native Americans and tightly controlled their daily lives. They separated the men and women and “made Natives work in the fields, regulated by a series of bells,” she said, explaining the church bells would signal when it was time to wake up, when it was time to start working in the fields, when it was time to eat and when it was time to sleep.

Many Native Americans became addicted to aguardiente, a type of brandy made from mission grapes that was 18% to 20% alcohol. They were not permitted to drink at the missions, so they would go to Calle de los Negros, a rough street in Los Angeles that was filled with

26 Grape & Wine Magazine March 2024
Father Junipero Serra (center) was instrumental in establishing the California wine industry.

brothels, saloons and gambling parlors, according to Dinkelspiel.

The Gold Rush caused a shortage of workers to plant and harvest grapes.

“When gold was discovered, most young men left for the gold fields, leaving very few people behind to grow food,” Dinkelspiel said. “So, vintners relied on the workforce that was available: Indians.”

The very first law passed by the new state of California in 1850 was intended to keep Native Americans in the vineyards.

“It was nicknamed the ‘Indian Indenture Act,’ and it was adopted to address the worker shortage caused by the Gold Rush,” said Dinkelspiel. “The law allowed any white man to identify a Native American as vagrant, lazy or drunk, which would permit a marshal or sheriff to arrest and fine him. Since most Native Americans could not pay the fines, a week’s worth of their labor would be auctioned off to the highest bidder, who would then pay the fines.”

There is no evidence from archaeological digs to suggest Native Americans in California learned winemaking techniques from tribes in other states (photo courtesy C. Dozier.)

Many of the businesses paid their workers in wine, she said. Since Native Americans had more difficulty processing alcohol, the sheriff would round them up. Most of them were put to work in the vineyards.

“They thought of them as savages,” she

said about the mindset of those running the state. “They’re ‘inferior to us.’ It was indentured servitude.”

Early Native American Winemaking

While almost all wine historians will say

March 2024 27 Contact us to see how we can help! (559)584-7695 or visit us as Serving California since 1983

California winemaking began with the missionaries’ need for wine, a recent discovery in Texas suggests the possibility Native Americans made wine before the European settlers arrived.

“I think it’s likely because wine is a highly soluble product,” said Crystal Dozier, Ph.D., assistant professor and archaeologist at Wichita State University.

The archaeological digs she conducted at three sites near Austin, Texas found ceramic remnants dating from 1300 to 1650 with the residue of two compounds, tartaric and succinic acids, which are both found in high concentrations in wine.

The area, which was inhabited by those believed to be ancestors of tribes such as the Lipan Apache, is known to have had grapes for many centuries.

“Texas is a great place to grow wild grapes,” said Dozier. “The early colonists were taken aback by how abundant the plants were.”

Historically, tribes in North America are known to have produced a variety of fermented drinks. Balché is a Mayan drink made from the bark of the balché tree and a small amount of honey. Pulque is a light agave wine produced by the Aztecs. Tribes in Southern Arizona and across the border in Northern Sonora produced saguaro cactus wine from the red fruit of the saguaro cactus. In Southern Mexico and Central America, Native Americans made coyol wine, an alcoholic beverage from the sap of coyol palms.

Virtually all tribes in North America had some fermented beverage that was reserved for special occasions when groups of people gathered, such as meetings of tribes for trade or other negotiations. Based on “the large ovens and big crockpot” and the amount of trash discovered during her dig, Dozier estimates “hundreds if not a thousand people” would often be at these events. After Dozier published her findings, a

similar study found what scientists believe is evidence of the earliest known wine drinking in the Americas on ceramic artifacts found on Isla de Mona, a small Caribbean island between the Dominican Republic and Puerto Rico. The findings were published in Archaeological and Anthropological Science: Reports

“It’s not the only study that found wine,” said Dozier, adding the likeliness of the discovery of a different fruit (causing the tartaric and succinic acids residue) is unlikely. “There are less varieties of fruit produced there.”

It seems it would be easy for tribes in California to make wine from grapes, which were abundant in the state.

“If you put grape juice in a container, it will start fermenting based on temperature,” said Dozier. “All the yeast needed for fermentation can be on the skin of grapes. You start seeing fermentation at 12 hours. Wine should be produced in three days whether it gets a high enough fermentation to be what you consider wine.”

Or Maybe Not

“While there is evidence native Californians harvested and used local wild grapes (Vitis californica), from our understanding, the production of grape wine in California did not take place until the Spanish Mission period,” according to an archivist at the Autry Museum in Los Angeles.

Vitis californica has been abundant in California for centuries, but it is considered too bitter for winemaking. Instead, it has been used for other purposes such as making jelly.

Since Native American tribes often interacted with surrounding tribes, perhaps any winemaking knowledge the tribes in Texas may have had eventually found its way to California.

“I haven’t seen any evidence of California artifacts in the sites in Central Texas, and no California sites have Texas artifacts,” Dozier said.

This suggests California tribes would probably not have learned any possible

winemaking techniques from the Native Americans in Texas, but that may never be known. No archaeological digs in the state have made this question a priority, according to Dozier.

“No one has looked for wine residue,” she said. “Also, some areas never produced ceramics.”

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28 Grape & Wine Magazine March 2024
Crystal Dozier, Ph.D., assistant professor and archaeologist at Wichita State University, said it’s likely Native Americans made wine before the European settlers arrived (photo courtesy C. Dozier.)
A piece of pottery from an archaeological dig analyzed for evidence of wine (photo courtesy C. Dozier.)

Diagnosing Vineyard Problems: Harnessing Data to Mitigate Damage and Yield Loss

In 2023, California grape growers faced a unique set of challenges that impacted production. A long, wet winter followed by a cooler-than-average spring resulted in delayed budbreak and high mildew pressure that persisted well into the summer. Unusual mid-season rain devastated some southern San Joaquin Valley table grape vineyards, resulting in millions of dollars in losses. Additionally, phenological delays complicated vineyard management decisions and harvest logistics. Despite these challenges, growers and viticulturists remained diligent in quickly identifying issues throughout the season and making decisions to mitigate losses in both yield and quality. Recognizing issues early is the foundation of an effective crop protection program, especially when a problem can be managed before impacting adjacent vineyards. However, when a quick diagnosis cannot be made, it is important to survey the vineyard to collect and record as much data as possible, using available technology when applicable, so damage can be mitigated.

Biotic vs Abiotic

Vineyard issues impacting vine health and fruit production fall into two distinct categories: biotic and abiotic. Problems caused by insects, fungi, bacteria, viruses,

rodents, birds and other living organisms are biotic. Abiotic issues include non-living factors like climate, soil compaction, water pH, nutrition, etc. While biotic factors tend to be the most common reason for poor grapevine health, they may not always be the primary cause. Distinguishing between symptoms of biotic and abiotic vine health issues can take time to sort through since symptoms can have multiple causes. For example, a vineyard may show signs of decline due to root rot infections. However, the real cause may be the presence of hardpan not allowing water to drain. Water accumulating around vine trunks often leads to fungal infection, decline and vine death. Both fungal infections and inadequate water penetration can manifest similar symptoms such as weak vine growth with chlorotic foliage. Identifying the primary cause is important so a solution can be developed and implemented.

Prompt Data Collection and Record Keeping

When diagnosing abnormal plant growth, it is important to collect and record as much data as possible near the time the issue was first observed. The dates of observation(s), symptoms (e.g., abnormal growth), signs (e.g., insects), records,

etc. are important for all parties (e.g., grower, PCA, etc.) working on determining the cause of poor growth. Table 1 highlights important information to collect for proper diagnosis. The most basic information focused on vineyard characteristics, such as variety/rootstock, weather, soil, irrigation type, grape tissue analysis, etc., is typical data needed to solve vineyard problems. Sometimes it can take days or weeks of consideration to determine what has affected grapevine health. However, there are times when a problem remains unsolved, even after data have been collected and reviewed by multiple experts.

After collecting basic vineyard information, reports (Table 1) of varying types are important pieces of information for deciphering vineyard issues. Reports that include phenological stage and calendar date, yield and quality, fertilizer and pesticides used, irrigation timings, etc. may give clues about what has happened throughout the season and past years and could help identify a particular issue. The more reports available for review will make solving the problem easier.

Photos are also a great tool because they provide important context and can easily

30 Grape & Wine Magazine March 2024
Figure 1. Aerial vineyard view taken in 1980 showing weaker vines caused by soil pests infecting their roots. Aerial imagery taken today can be taken with specialized sensors that provide additional data for assessing a vineyards condition (photo by L. Peter Christensen, UCCE Emeritus.) Figure 2. Aerial vineyard view taken in 2022 showing a patch of collapsed vines using a drone equipped with a standard RGB camera. Successive photos may help better understand the pattern and cause of the problem (photo by M. Zumkeller.)


- Variety

- Rootstock

- Vineyard age

- Soil type

- Irrigation type

- Surrounding vegetation (crops and native)

- Yield and quality

- Pesticide use

- Fertilizer use

- Irrigation timings

- Soil maps

- Soil and water amendments

- Establishment

- Production practices

- Previous crops grown

- Source of plant material


- Leaves

- Canopy

- Fruit

- Roots

- Cross section of canes, cordons, trunk

- Pests

- Surroundings

- Aerial images


and quickly be shared via email or text. However, there is a difference between a snapshot and a useful photo that can help identify the cause of symptoms. Useful photos show details that can aid in determining a symptom’s cause. For example, a picture of a single leaf on the truck bed probably won’t help identify a problem. A more useful photo would highlight symptomatic foliage showing leaf location on the grapevine, which may highlight the root cause of a problem.


Down the vine row Irrigation

Gopher damage

Spray damage/injury

Mechanical injury

Irregular, related to soil type

Irregular, related to abiotic causes

Nutrient deficiencies

Salinity or alkali

Soil compaction

Recording the location in the vineyard where symptoms are observed can be helpful if the problem persists across multiple seasons. Doing so can be as simple as drawing on a vineyard map printed via Google Earth which is freely accessible from both the desktop and mobile application. Alternatively, other mobile applications, such as GPS coordinates, Google Maps or Avenza Maps, can provide the exact location to be included with other records of the problem. There are numerous scouting applications avail-

Moisture: deficiencies or excess

Rootstock differences

Nematodes or phylloxera

Plant diseases

Inadequate irrigation

Leveled ground; topsoil moved

Chemical drift

Mechanical injury; i e tractor blight

Girdling; i e grafting tape

Seasonal impacts

Temperature related

Frost or freeze events

Cool weather post budbreak

Hot weather


- Water

- Soil

- Tissue

- Leaves

- Stems

- Roots

- Sap

- Insects

- Diseases


Poor growth, yellowing leaves

Weak or dead vines

able to collect data, capture photos and record locations in a single platform. The MyEV tool from the Efficient Vineyard Project ( offers these features along with other precision viticulture tools free of charge.

Necrotic spotting/burned foliage/fruit

Weak or dead vines, poor growth, leaf color

Various leaf colors and foliar patterns

Water, soil and tissue laboratory analyses, when taken annually, help identify trends over seasons. The best approach is to pull samples at specific times (i.e., growth

Marginal leaf burn, chlorosis

Weak vine growth, chlorosis



Varying vine growth & foliar patterns

Weak vine growth, chlorosis

Weak vine growth, varying foliar patterns

Poor growth, chlorosis or reddening

Weak vines, poor canopy growth

Spotting on leaves and fruit, dead vines

Weak or dead vines, poor growth, color

Weak, poor growth, dead vine

Dead leaves, shoots, or vines

Spring fever symptoms

Burnt leaves, dead vines

31 Garton Tractor, Inc. 4780 South K Street Tulare, CA 93724 (559)686-0054 |
T5.120 with
Table 1 Table 2 Table 1. Data collected to help identify vineyard problems.


Down the vine row


Gopher damage

Spray damage/injury

Mechanical injury

Irregular, related to soil type Nutrient deficiencies

Salinity or alkali

Soil compaction

Moisture: deficiencies or excess

Rootstock differences

Nematodes or phylloxera

Plant diseases

Irregular, related to abiotic causes

Seasonal impacts


Inadequate irrigation

Leveled ground; topsoil moved

Chemical drift

Mechanical injury; i e tractor blight

Girdling; i e grafting tape

Temperature related Frost or freeze events

Cool weather post budbreak

Hot weather

stages) each year so the information is available when decisions need to be made. For example, taking water samples at the beginning of the growing season will help determine how much nitrogen is coming from irrigation water sources. Once known, planned fertilization rates can be adjusted depending on the amounts in the water. Excess N applied during the season without knowing what is in well water is an unnecessary expense, can contribute to poor fruit quality and may further contaminate the aquifer.

Understanding Patterns

Patterns of symptomatic vines are an important piece of information needed to solve the cause of poor vineyard growth. An easy way to identify patterns is the use of aerial imagery (Figure 1) to survey your vineyard. Aerial imagery has improved tremendously and can help detect differences in vine growth,


Poor growth, yellowing leaves

Weak or dead vines

Necrotic spotting/burned foliage/fruit

Weak or dead vines, poor growth, leaf color

Various leaf colors and foliar patterns

Marginal leaf burn, chlorosis

Weak vine growth, chlorosis


Varying vine growth & foliar patterns

Weak vine growth, chlorosis

Weak vine growth, varying foliar patterns

Poor growth, chlorosis or reddening

Weak vines, poor canopy growth

Spotting on leaves and fruit, dead vines

Weak or dead vines, poor growth, color

Weak, poor growth, dead vine

Dead leaves, shoots, or vines

Spring fever symptoms

Burnt leaves, dead vines

soil and irrigation issues, pest or disease problems and more. Accessing aerial imagery can be as easy as using your own drone to capture footage or hiring a licensed pilot or company to take photos and video for you, of which there is a spectrum of resolutions offered. While an image captured with a standard RGB camera may be useful to visualize obvious patterns within a vineyard (Figure 2), data from aerial imagery captured with a multispectral camera can be transformed into helpful indices of vegetation such as NDVI, which provide a greater degree of insight and help direct scouting in the vineyard. Other specialized sensors can provide additional data for assessing vineyard conditions such as thermal or hyperspectral images.

In instances where patterns of symptoms have been observed over multiple seasons, freely available public satellite data sources such as Sentinel-2 and Landsat 8 may help visualize the spread of the pattern over time. This data is captured at

low resolution (10 or 30 meters) at more frequent intervals in comparison to contracted aircraft services which offer very high resolution (< 1 m) but often at fewer time points due to cost. While this data can be downloaded from the web, a GIS mapping software (e.g., qGIS or ArcGIS) is required to process the data and create a map.

Driving and walking vine rows with a soil, vigor (NDVI) or elevation map in hand can be very helpful for assessing problem areas. Surveying the vineyard on foot or with an ATV allows for a closer look at problematic areas. Direct observation may provide additional clues that can complement aerial imagery. Patterns of poor growth found on vineyard edges, down rows or in small patches are sometimes easily solved when those areas are directly observed. For example, Figure 3 shows a young planting with dead grapevines in multiple rows. At first glance, overirrigation or a fungal disease might be the suggested cause

32 Grape & Wine Magazine March 2024
Table 2. Some likely causes and symptoms of certain patterns found in vineyards. Note: Specific pest, disease and nutrient deficiency symptoms have not been included in this table.

of poor growth and/or death. But after further investigation, data that included irrigation scheduling and amounts, soil and plant pathology lab reports and discussions with the grower, it was found an over application of N fertilizer killed the young vines. Once the problem was identified, the vineyard was replanted, and no additional fertilizer was applied during establishment.

Symptom Diagnosis

Diagnosing abnormal growth symptoms is somewhat of an art and a science. When called to identify the cause of poor or unusual growth, a vineyard diagnostician must consider all the scenarios that might be causing symptoms. A methodical approach that results in an accurate diagnosis is important since time is of the essence when considering management strategies to minimize yield and quality losses. Variety, rootstock, vineyard age, soil type(s) and depths, irrigation methods and timings, nutrition, common pests, diseases, climate and many other factors must be considered. A systematic approach must be taken to identify the primary cause that includes symptoms found in the vineyard, including related reports, photos and laboratory analyses. Diagnosing grape pests or diseases can be easier than abiotic causes since three factors need to be present: the pest or disease, grape (i.e., host) and favorable environmental conditions. Often, lack of optimal climatic conditions does not allow for pest or disease outbreaks. In contrast, the cause of abiotic symptoms is more difficult to identify and costs time and resources. Once pests or diseases have been eliminated as causes, a diagnostician must spend time reviewing reports and lab analyses and walking the vineyard looking for patterns and additional clues. A shovel, shears, soil probe and a lot of time will be needed to narrow down the cause.

Finding a Trusted Advisor

Solving vineyard problems that are negatively impacting yield and quality can be daunting, especially when you are working alone. At some point, you may need to consult with an expert. Finding a trusted advisor can also be daunting because there’s often a cost associated with hiring someone. Here are some considerations for finding and hiring a CCA, PCA,

private consultant or agricultural forensic consultant.

Before hiring someone, clear goals need to be identified so they can be shared with a prospective consultant. First, what are the yield and quality goals for the vineyard and are they being impacted by the problem? Are you trying to determine what had reduced vineyard performance or what has killed vines? Second, do you want solutions to end the loss of vines and stop the yield decline? Finally, do they have the experience needed to help you solve your vineyard problem? Are they focused on your success or are they just interested in selling you something that will “correct” the problem? If it is a challenging problem, do you feel confident they will tell you the truth if they don’t know what the cause of poor growth is in your vineyard? If you don’t already have a trusted CCA or PCA, it may take some time to interview a consultant you feel confident will help you and have your success in mind.

There are many useful resources available to help figure out the cause of peculiar vineyard symptoms. Books, websites, blogs and webinars are great sources of information for starting your investigation. However, be mindful these types of resources may be specific to a location, climate, variety, production system, etc., which may be different from your situation. If your vineyard health issue needs immediate attention, consider contacting a UC farm advisor, extension specialist, CCA or PCA that specializes in grape production. If your grapevine health issue is caused by a pest or disease, experts can help develop a management program that minimizes crop damage.


Internet and App

UC Integrated Pest Management: http://

Vineyard Advisor app

Android: apps/details?id=edu.tamu.agrilife.VineyardAdvisorApp

Apple: vineyard-advisor/id1187381601?mt=8

SoilWeb app: store/apps/details?id=com.casoilresourcelab.soilweb

Acres land management app with interactive GIS layers (soil, historical imagery, annual Sentinel-2 NDVI, and elevation):

Efficient Vineyard MyEV tool: https://


Grape Pest Management, 3rd Ed. University of California Publication-ANR 3343

Raisin Production Manual, University of California Publication-ANR 3393

Harvesting and handling California

Table Grapes for Market, University of California Bulletin 1913

Compendium of Grape Diseases, Disorders, and Pests, 2nd Ed. APS Press

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March 2024 33
Figure 3. Newly established vineyard displaying dead grapevines thought to be caused by overirrigation or a fungal disease. However, an overapplication of fertilizer was determined to be the primary cause of death (photo by L. Peter Christensen, UCCE Emeritus.)

Napa Green announced it is becoming “the first sustainable winegrowing certification globally to require the phaseout of Roundup and ultimately synthetic herbicides” (all photos courtesy Napa Green.)

In Napa, the country’s highest-priced wine region, the sustainability group Napa Green announced it is becoming “the first sustainable winegrowing certification globally to require the phaseout of Roundup and ultimately synthetic herbicides,” the group said in a press release

The move comes as a result of soil health, community health and consumer concerns, its leaders said.

On the soil health front, Anna Britain, Napa Green’s executive director, said synthetic herbicides ran counter to promoting terroir-driven wines. “...[soil] diversity increases resilience, and [synthetic] herbicides reduce diversity. So, the herbicides are reducing the health of the fungal and microbial networks that are deeply tied to the functioning and the health of the plants above ground.”

Napa Green’s Vineyard Program Manager Ben Mackie and Britain pointed to scientific findings that herbicides reduce the fungal and microbial networks in the soil and that soil diversity increases resilience.

The group created a Weed Management Toolkit to help growers transition and is also offering financial and technical assistance to members for transitioning to synthetic herbicide-free farming.

Public Influence

In addition to soil health, other factors played a part in the decision. These included consumer opinions, media inquiries and community health issues.

On its website, Napa Green wrote, “Roundup has dramatically risen in


public awareness and concern due to IARC’s carcinogen finding, lawsuits against Bayer (the manufacturer of Roundup), tests showing glyphosate residues in food and beverages... and concerns about Monarch butterfly and honeybee decline.” IARC stands for the International Agency for Research on Cancer and is part of the World Health Organization of the United Nations.

The group went on to say, “Regionally, we’ve seen increased concern about wine industry Roundup use with the release of the documentary, ‘Children of the Vine.’”

The film was made by a local documentarian, Brian Lila, and has been seen in dozens of community screenings in northern California and elsewhere. It focuses primarily on the widespread use of glyphosate-based herbicides on commodity crops and the health issues associated with that.

In wine, the film features two local wine producers with certified-organic vineyards who don’t use synthetic herbicides, Ted Lemon of Littorai in Sonoma and Frank Leeds of Frog’s Leap in Napa, who say opting out of Roundup is not hard.

In a public talk, Lilla shared a group of teenagers in St. Helena found out their high school grounds were being sprayed with Roundup. “They went to the school board, and long story short, they now ban it throughout the entire school district,” he said.

According to Napa Green’s website, this is not an isolated occurrence.

The website’s FAQs section says, “More than 45 cities and counties in California have banned the use of Roundup on city-/county-owned property and/or school campuses.”

Focus on Sustainability

Britain stressed Napa Green’s sustainability program is about evolving. “Sustainability is a path, not a destination. We always have to continuously grow and evolve. And I think this is a critical next step in our leadership.”

“About 64% of our members and transitioning members don’t use synthetic herbicides already,” she said.

Meanwhile, Napa Valley Grape Growers has also taken an interest in weed control and glyphosate alternatives. Its latest Rootstock conference released data

Consumer opinions, media inquiries and community health issues also played a part in Napa Green’s decision to phase out Roundup.

34 Grape & Wine Magazine March 2024

The main reason for the phaseout comes from scientific findings that herbicides reduce the fungal and microbial networks in the soil and that soil diversity increases resilience. Improving soil health is part of Napa Green’s sustainability vision.

in November showing Roundup use had halved since 2018, and public data shows glufosinate ammonium acreage rose 28% from 2017 to 2021, increasing from 7,596 acres in 2017 to 9,731 acres in 2021 as growers tried to avoid saying they used Roundup.

“The only cons are that we do anticipate we’re going to lose some members, probably some of the members that are in transition but haven’t finished the certification process yet,” Britain said. “But, on the other hand, it is a phaseout. We did intentionally create a realistic timeline to work with growers to make this transition.”

While it will appeal to certain segments of the grower community and the wine market, the move will alienate some, Britain said.

“Sadly, the sword a lot of people are willing to die on is, ‘You are not taking my tools out of my toolkit. You are not taking my herbicides out of my toolkit.’ I don’t want to speak for them. But I think there’s various approaches.

“We’re trying to work with members on any number of issues.”

Said Britain, “It’s hard to keep talking about leading regenerative soil health practices and terroir, this idea that grapes are an expression of place, if we’re undermining the soils that those vines and grapes are coming from,” Brittain said. “There’s been more consumer demand and media demand putting

growing attention on this issue, and we recognized that allowing Roundup and other synthetic herbicides go against our focus on soil health.”

Members must phase out Roundup and glyphosate-based herbicides by Jan. 1, 2026 and other synthetic herbicides including Lifelink (which contains glufosinate ammonium) by Jan. 1, 2028.

In the press release, Andy Erickson, board chair of the Napa Valley Vintners,

said, “I see this as an important step for Napa Valley. It makes perfect sense that our valley and community should be on the forefront of eliminating these herbicides and moving in a more sustainable direction.”

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