It is recommended to sell a vineyard or winery in late spring as opposed to holiday times of year. It is recommended to sell a vineyard or winery in late spring as opposed to holiday times of year.
If you are planning to sell your vineyard or winery, the first thing to consider is the way it presents itself to a prospective buyer.
Appearance is “extremely important as you never get a second chance at a first impression,” said Joe Ramos, co-director of the Vineyard and Winery Division at Berkshire Hathaway HomeServices California Properties in Los Olivos, Calif. “Whether you’re selling a vineyard or winery, or a residential property, it’s ‘Salesmanship 101’ to have the property looking its very best.”
“Anytime you put a property up for sale, you want it to look sharp,” agreed Preston Smith, owner-broker at Prolacom Realty Advisors in Santa Rosa, Calif. “People are looking for cleanliness and sanitary conditions. You want your vineyard to be clean and well-manicured. The rows should look nice and clean.”
“At a bare minimum, the property should be cleaned up and any necessary maintenance attended to,” said Ramos. “We highly recommend our seller clients conduct presale inspections so issues regarding safety, health and permit violations are resolved prior to going on the market. Everything should be in working order.”
Smith noted when a prospective buyer sees something needing repair, “they automatically expect to pay twice what it actually costs to fix it.”
Water
Buyers need to know that the wells and pumps can adequately produce water for the property’s needs, said Smith.
Ramos said presale inspections should include a general well inspection that measures flow rate (GPM), depth of the well, water level and a drawdown test to determine the recharge rate. He recommends water quality tests, which include bacterial and chemical testing, be conducted.
“If the well is also supplying water to a dwelling, a potability test should be conducted to ensure the water is drinkable,” he said. “The results of these inspections should be readily available to all prospective buyers.”
Paperwork
“It’s very important that all your paperwork be in order and documentable,” said Smith. This includes weigh tags, “so you can prove to a buyer what the vineyard has been producing for the past five years.”
“Apart from local permits, the two major ones are obtaining permission from the Alcohol and Tobacco Tax and Trade Bureau (TTB), and [in California] a California Alcohol Beverage Control (ABC) Type 02 Winegrowers license,” said Ramos, who suggests that sellers understand everything they can about their property.
“Sellers should become experts on what they’re selling and really know the ins and outs of their property because if they don’t, buyers will become the experts and use the information they learn to drive the price of the property down in secondary negotiations,” he said.
If you are planning to sell your vineyard or winery, the first thing to consider is the way it presents itself to a prospective buyer (all photos courtesy J. Ramos.)
Equipment
“It is better to include the equipment and offer the property as ‘turn-key’ as possible,” said Ramos. “Many buyers are just beginning their path in the wine industry and may not know everything that is needed to produce wine. Having a farm and winery that includes all the equipment needed breaks down a big barrier to entry and allows them to step into a vineyard and winery with relative ease. The equipment is often more valuable to an incoming buyer than it is in the used equipment market.”
Including equipment in a sale depends on what the seller plans to do, according to Smith. If the seller is only selling one of several properties, he will probably not include the equipment. Often, a new vineyard manager will bring in their own equipment, lowering the value of the seller’s items in the sale.
It is good to include any winemaking or vineyard equipment in a sale to ease the buyer in.
Employees
There are different opinions on the importance of having experienced and competent employees. Ramos considers them “invaluable” to a sale.
“Working properties often have an existing human element that should stay in place,” he said. “This includes vineyard managers, ranch managers, tasting room staff, other employees and third parties who assist immensely in the day-to-day operations, know the properties and business intimately, and keep properties operating smoothly. It’s important to understand the full scope of the day-to-day operations and what it entails before diving into a working property. It’s also important to tread softly upon entry and not try to reinvent the wheel.”
However, Smith explained the importance of employees to a sale depends on the buyer. If a 300-acre vineyard is being sold to a supergrower, “they already have a staff and their own vineyard management.”
Brands and Bottom Line
The quality of a winery’s product “is paramount, especially when that product leads to the formation of a reputable brand and high demand,” said Ramos.
“If you have a high-end brand, a best-of-show, award-winning wine, you can command a higher price,” said Smith. “If you have Safeway and Costco buying your wines, you can command a higher price.
“Your bottom line is important in the evaluation of a winery,” he added. A prospective buyer wants to know “the net dollar amount they can depend on.”
“Recent profits are very important to the marketability of the property and operation as they provide a road map of what a buyer can expect when they take ownership,” said Ramos. “This allows incoming buyers an opportunity to plan better and manage expectations. However, a successful business often comes at a higher cost than businesses that are losing money. If the business has experienced losses, especially over a long period of time, it is often recommended the seller not include the business and simply focus on the real property component.”
However, the bottom line may not matter to the sale.
“Oftentimes, buyers are purchasing the property as a heritage property with the intent that the venture be multi-generational,” said Ramos. “Many buyers want to craft a business that is personal to their tastes and vision, including branding and the wine’s characteristics. In these instances, the business is less important because the buyer desires to form the business from the ground up.”
Tasting Rooms and Homes
“Wineries with a tasting room are often easier to sell because the buyer pool is larger,” said Ramos. “Many buyers enjoy the social aspect of the wine industry, and there’s no better way to interact and mingle with patrons than in a tasting room environment.”
“Homes are secondary,” said Smith, who added if the property has a home or two, they are generally for employees.
Ramos believes some attention should be given to any homes on the property but urges caution before making any improvements.
“We typically recommend being careful as many buyers have their own aesthetic preferences and may not like what the seller decides to do, oftentimes at considerable costs,” he said. “If improvements are going to be made, focus on items that will provide the biggest bang for your buck. These might be particular items that really date the house and scream that it’s due for a major overhaul. Often, these are features that were popular 10 or more years ago and have fallen out of favor. If you have purple carpet, that may be an item worthy of tackling. Remember to put your personal preferences aside and take a more neutral route. A quick Google search can help by providing trending materials, color schemes and ideas.”
When to Sell
“The holidays are horrible,” said Smith, explaining when definitely not to sell. “People are home with their families. If you put property for sale in November, you’re not going to get activity until January when people are back in business.”
He advises sellers, if possible, to put properties on the market in late spring. “May and June are always nice,” he said. “It’s always good after the vines leaf out.”
But spring brings another challenge.
“As spring begins, so do the costs,” said Smith, raising another major consideration in a sale. “Who’s going to get the crop?”
When selling a vineyard, it’s important to determine whether the buyer or seller gets the crop, and who pays the expenses to grow it.
Ramos recommends prospective buyers evaluate things such as acreage, size of the vineyard and winery, location, varietals, soil, water, weather, American Viticultural Areas, pedigree of neighboring vineyards, management, condition of the vines, entitlements granted under the permit and whether there is disease or a virus present.
One is a native son who grew up with California farming in his blood. The other is originally from the East Coast and has practiced law for decades in the Golden State.
On the surface, vineyard manager Dana Merrill and attorney Jeanne Malitz might seem like polar opposites. But their diverse lives converged earlier this year when they were honored with the two highest awards given by the California Association of Winegrape Growers.
Merrill received the Grower of the Year Award, CAWG’s top honor. The award recognizes excellence in viticulture and management as well as innovation and industry leadership.
Malitz was named CAWG’s Leader of Year for her efforts, extending to the national level, to help winegrape growers and agricultural employers with the federal H-2A guest-worker visa program.
CAWG recognized the two leaders at the Unified Wine & Grape Symposium Jan. 24 in Sacramento. CAWG President Natalie Collins singled out Merrill as “a pillar in the winegrape sector, from his dedication to sustainable farming to his innovation in developing new growing techniques.”
Collins acknowledged Malitz as “the industry’s go-to attorney on all H-2A matters. In a time when growers are continuing to look at diverse avenues to hire labor, Jeanne’s advice has been instrumental.”
Like winegrapes themselves, Merrill and Malitz have emerged from their own unique terroirs, with their diverse backgrounds and expertise producing big benefits for California agriculture.
Grower of the Year award winner Dana Merrill is “a pillar in the winegrape industry,” says the California Association of Winegrape Growers (photo courtesy Mesa Vineyard Management Co.)
From Federal Litigation to H-2A
Boston-born Malitz worked for a Wall Street law firm, then became a federal litigator before coming to California in the 1990s. She found her calling in employment and immigration law while working for a large law firm in San Diego.
“I loved it because it was people focused,” she said.
In 2002, the East Coast native established her own practice, Malitzlaw, Inc., in San Diego. Today, Malitz and her 12 employees work with clients in 11 states. The firm focuses on employment-based immigration matters, emphasizing permanent and temporary labor certification for agricultural employers. Her practice also counsels on employment verification, including e-Verify and I-9-related issues. It’s high-volume, fast-paced, often stressful work.
“We work with thousands of farmworkers and their employers,” she said. “We sometimes have 30 cases due on a single day.”
CAWG honored attorney Jeanne Malitz as Leader of the Year for helping ag employers with the H-2A program (photo courtesy Malitzlaw.)
The Good and Bad of H-2A
Malitz’s assistance in helping winegrape employers maneuver through H-2A’s legal and administrative paperwork and requirements has become more urgent as the need for foreign workers grows more acute.
Malitz cites a combination of factors for the labor shortage: domestic workers leaving the agricultural industry, the workforce aging out and greater enforcement of I-9 requirements and at the border, which reduces the pool of illegal immigrants who would go into agriculture.
“There aren’t even enough illegals to do agriculture,” said Malitz. “With all the enforcement, you don’t really want an illegal workforce, which is why people do H-2A. It’s reliable, consistent and dependable, versus a domestic workforce, which is very unstable.”
At the same time, Malitz acknowledged the H-2A program “is cumbersome and very expensive” for ag employers. To participate, they must work with multiple federal and state agencies. They’re required to offer free housing to their H-2A employees. Another problem is defining “the area of intended employment” and workers’ commuting distance.
Further challenging H-2A participation is the requirement that program workers must be paid $19.65 an hour for non-harvest work, $1 more than California’s regular H-2A rate. It’s a contentious issue.
The H-2A guest worker program is both necessary and cumbersome, say Malitz and Merrill (photo courtesy Paso Robles Wine Country Alliance.)
“I think we’re going to see litigation on this prevailing-wage issue in the winegrape industry,” said Malitz.
As a result of these hurdles, only a fairly low percentage of winegrape employers use H-2A, said Malitz. She advises those who do participate to apply well in advance of when they think they’ll need H-2A workers.
“Things can get delayed because of so many government agencies,” she said. “Employers need to be organized for us to be organized. They’ve got to set their expectations. They not only have to know the rules, they have to follow them.”
Malitz believes those who use the H-2A program “are the best employers who try to do everything right. They’re good players. That’s a message that never seems to get across to the public.”
Merrill’s positive outlook for California’s winegrape industry stems from the state’s ideal growing regions for high-quality wines. “Quality always sells,” he says (photo courtesy Paso Robles Wine Country Alliance.)
Central Coast Wine Industry Pillar
Some 330 miles to the north, at his headquarters in Templeton, Calif. near Paso Robles, Merrill focuses on developing and managing winegrape vineyards. His Mesa Vineyard Management Company oversees 12,000 acres of winegrapes. While his son, Matthew, has taken over as general manager, Merrill remains company president and deeply involved in strategic planning and problem-solving.
Merrill is a seventh-generation Californian whose ancestors came from Spain in the 1700s to help build the missions. He grew up on his grandfather’s ranch in Santa Ynez in Santa Barbara County. After earning a degree in agricultural business management from California Polytechnic University at San Luis Obispo, Merrill and his brother leased land to farm. That venture wasn’t financially successful. He was later hired by a large vineyard management and development company in Monterey County. That experience “really set in motion events that led to where we are today,” he said.
Dana Merrill accepts CAWG’s Grower of the Year Award from President Natalie Collins at the Unified Wine & Grape Symposium Jan. 24 (photo courtesy CAWG.)
When the company’s principals retired, Merrill again started his own firm, this time offering vineyard management services. It was 1989, and he called the new company Mesa Vineyard Management. Today, he and his team work with 25 major clients in Monterey, San Benito, San Luis Obispo and Santa Barbara counties as well as Oregon’s Willamette Valley. They include some of the wine industry’s most important brands, investment firms and coveted vineyards.
Mesa Vineyard Management has installed and redeveloped thousands of acres of vineyards. It provides daily production oversight, grape harvesting and winegrape sales for 30 different grape varieties each year.
Merrill, along with his wife Marsha and son Matthew, also launched Pomar Junction & Winery in 2008 to showcase estate wines from their own 120-acre Templeton vineyard in the Paso Robles appellation. Named for a nearby convergence of two old railroad lines, the winery features a Sante Fe caboose in its logo. The Merrills closed their winery when the pandemic hit but maintain a private tasting room at their main ranch.
At this year’s Wine & Grape Symposium, Jeanne Malitz (left) receives a proclamation from California State Assembly member Tasha Boerner Horvath (center). CAWG President Natalie Collins is at right (photo courtesy CAWG.)
A Good Vintage
All those moving parts take unique skills, and Merrill has them. He describes himself as someone with a “generally positive attitude and dry sense of humor,” who’s budget-oriented but with “instinctive grower skills.” He believes in collaborative problem-solving and finding areas of agreement to solve challenges.
Those traits were put to use when Merrill served as CAWG’s board chairman from 1999-2001 and as the first chairman of the California Department of Agriculture’s Pierce’s Disease and Glassy-Winged Sharpshooter Board. He was a charter board member of the Central Coast Vineyard Team. Merrill also was named 2012 Wine Industry Person of the Year by the Paso Robles Wine Country Alliance as well as the San Luis Obispo County Farm Bureau.
Business Challenges
Still, life returns to normal after the awards presentations. Like Malitz, Merrill wrestles with labor issues. His company relies on hundreds of seasonal people, but it’s difficult to find adequate labor. He has long used third-party labor contractors but recently began using the H-2A program too. That’s on top of Mesa Vineyard Management’s 85 full-time employees.
But the challenges don’t stop with labor. Merrill points to California’s chronic water shortages, the vine mealybug, fewer approved labels for chemical use, and inflation. This winter’s storms also caused flooding and erosion in some of the vineyards he manages.
Local water-well issues also challenge the Paso Robles area, which is all groundwater-supplied. Over the past 20-plus years, Merrill has watched the area expand to 40,000 vineyard acres and more than 200 wineries, creating a wine-centric mecca that draws tens of thousands of people each year. Further bolstered by hotels, restaurants and tasting rooms, Paso Robles has been transformed into a cultural center.
But that growth has created land- and water-use challenges for commercial winegrape producers, who often operate adjacent to rural residents living on one- or two-acre lots. In fact, groundwater shortages have led to a moratorium on new irrigated farmland in the Paso Robles area.
“I have spent significant time working with others to form the Estrella-El Pomar-Creston Water District in the west half of Paso Robles Basin,” said Merrill. “Trying to figure out how to comply with the Sustainable Groundwater Management Act and deal with less common cohesiveness everywhere makes a tough job even harder.”
Also high among his worries is the rising cost of wages. Mesa Vineyard Management has seen three state-mandated 8% increases over three consecutive years. On top of that are future wage increases tied to annual inflation. Those wage escalations “rippled through our company,” Merrill said. “When the lowest-paid people get a raise, everybody above them expects a raise too.”
Technology and Mechanization
Such labor problems have pushed Merrill and his team to use more mechanization and technology. Machines are doing more vineyard pruning, harvesting, tending of canopies and moving wires. Its grape harvesters are now programmed to calculate yields and unharvested blocks needed to fulfill grape contracts. Mesa Vineyard Management also has adopted more stringent irrigation management to comply with SGMA. The company has increased its precision application of chemicals. It further relies on electronic trackers placed on its trucks, grape harvesters and other equipment. That’s eliminated the need for employees to contact vineyards and wineries to locate vehicles.
“Who knows what’s ahead, but more tech is a given,” Merrill said.
Despite the challenges, Merrill’s outlook remains positive in part due to California’s ideal growing regions and their high-quality wines. “Quality always sells,” he said.
Merrill and Marsha, married for 48 years, just bought a vacation house in Costa Rica. He hopes to spend more time there, improving his Spanish-speaking skills and enjoying his favorite wine, a Merlot from his own Pomar Junction label. Seeing the next generation succeed also remains a goal for him. His advice to younger winegrape growers and managers?
“Learn all you can,” he said, “and figure there will be many twists and turns to your career.”
PET bottles, particularly the 187 ml size (center), have gained popularity in some market sectors because of their light weight, portability and cost (photo courtesy Amcor Rigid Packaging.)
Corey Manning, co-owner of Chateau Diana Winery in Healdsburg, Calif., knew he had to do something because he was paying nearly as much to ship 750 ml bottles of wine direct to consumers as he was to make the wine. He turned to the manufacturer Amcor Rigid Packaging, which produces polyethylene terephthalate, or PET, bottles.
Manning said he’s been able to reduce his shipping costs by replacing glass bottles with those made from PET, and he hasn’t received push back from customers. They won’t replace glass bottles entirely, as Château Diana continues to use glass for more premium wines. But Manning said 750 ml filled PET bottles, which weigh about one-third of comparable filled glass bottles, are a good fit for their value-priced lines and direct-to-consumer business.
Even with some wineries looking to alternative packaging for some markets, Scott DeFife, executive director of the Glass Packaging Institute, said his members haven’t seen a decrease in demand for glass bottles. In fact, DeFife said, just the opposite is true with domestic glass container plants shipping about 1.82 billion wine bottles through November 2022. That’s up 17 million bottles from the same period through November 2021. The vast majority of those were 750 ml.
“The industry is doing really well,” he said.
DeFife, who represents the North American glass container industry, said most of his members continue to address weight and shipping concerns by manufacturing lighter-weight bottles. Compared to 20 years ago, today’s bottles are 30% to 40% lighter, he said.
“Data shows the majority of the 750 ml bottles are actually lightweight and medium-weight bottles,” DeFife said. “So the production of lighter-weight glass bottles is up significantly from where it was, and in many cases, it’s the majority of bottles you can get.”
But freight costs are just one part of the sustainability equation, he said. One of glass’ attractions is its physical composition, which acts as a natural barrier to prevent oxidation, product interactions or external influences. For wines designed to age in the bottle, DeFife said this is a big draw.
“Anything that’s going to age, you’re going to want it in glass, and that goes to waste, food waste and shelf life, which are also important to sustainability,” he said.
Reduce, Reuse, Recycle
Glass also can be readily recycled and made into new bottles countless times without loss of quality or purity. DeFife said. Raw materials used to make glass include readily available sand, soda ash, limestone and cullet, an industry term for recycled glass. And up to 95% recycled glass can be used in place of raw materials to make new containers.
DeFife, who also serves as president of the non-profit Glass Recycling Foundation, admitted the California statewide consumer recycling rate for wine and spirits bottles could be better. But he pointed to Senate Bill 1013, which Gov. Gavin Newsom signed in September 2022, as a way to address that.
Beginning Jan. 1, 2024, the bill establishes a 10-cent California redemption value, or CRV, on most wine and spirits bottles. It also sets a 25-cent CRV on difficult-to-recycle wine packaging, such as boxes, bladders and pouches.
The legislation’s authors, President Pro Tempore Toni G. Atkins, D-San Diego, and Sen. Bill Dodd, D-Napa, said they wanted to enhance wine and spirits bottle recycling. Those containers currently are not covered by the California Beverage Container Recycling and Litter Reduction Act passed in 1986.
The lawmakers estimate that California generates more than 500 million wine and spirits bottles annually, with less than 30% being recycled and more than 300 million ending up in landfills.
DeFife, who was involved in bill negotiations on behalf of his members, said it can only help but enhance the industry’s sustainability efforts.
“We think that the West Coast and the wine regions of the country are going to see some of the most sustainable glass bottles in North America,” DeFife said. “The recycled content rate is high and growing, and the recovery rates and the recycling rates are going to go up to well above national average.”
A small but growing number of wineries are exploring 750 ml PET bottles for value-priced wines or because of their lighter weight and transportation advantages (photo courtesy Amcor Rigid Packaging.)
Similar Path to Screw Caps
Manning said he likes to compare the industry’s current packaging evolution to where it was in the 1990s when screw caps started making inroads. Back then, many people criticized the closures. But today, consumers widely accept them on many types of wines and in many price sectors.
“We were one of the first people to jump on screw caps because it made sense for what we were doing,” he said. “We were trying to develop an economical everyday wine that people could enjoy. Moving ahead into this, it’s the same premise, the same experiences. We saw potential pushback, but our position was we want to try it. We live in California, and we’re really lucky to benefit from the economics. But people in the rest of the U.S. don’t have the money to spend $25 for a bottle of chardonnay.”
For more than a decade, many wineries have slowly switched their single-serve offerings from glass bottles to containers made from alternate materials as a cost-cutting measure. PET bottles’ popularity has grown because they have the same shelf appeal as glass but with less weight, said Matt Shaieb, commercial sales director for Amcor Rigid Packaging.
By nature, PET is a porous material, which can potentially lead to oxidation and an off-flavor over time. To address that, he said Amcor applies the ultra-thin KHS Plasmax silicon oxide barrier coating to the inside of their containers. A glass-like material, Plasmax is Food and Drug Administration-compliant and fully recyclable.
Manning said he, too, had heard concerns about PET bottles imparting an off-taste to wine. But in taste tests where wine was stored for up to a year in the containers, he said they found no sensory issues. Manning said they haven’t gone past a year because most of their value-priced wines are consumed less than a year after bottling.
Because of their portability, the single-serve 187 ml size has become popular for use on airplanes, in the hospitality industry, in sports venues and for other activities where glass isn’t convenient. The bottles are about one-sixth the weight of comparable-sized glass containers, Shaieb said.
Senate Bill 1013, effective Jan. 1, 2024, would add a 10-cent deposit to most wine and spirits bottles, enhancing recycling and the glass industry’s sustainability efforts (photo by V. Boyd.)
In addition, larger sizes of PET bottles have made inroads into the spirits business. But 750 ml PET bottles are relatively new to the wine industry.
The potential for cost savings seen with 187 ml bottles was what attracted Chateau Diana to try PET for industry-standard 750 ml bottles.
Manning said a case of wine using 750 ml glass bottles weighs 36 pounds compared to 13 pounds for a case of filled PET bottles. He’s also able to put 70 cases of PET bottles on a pallet compared to 56 cases of filled glass bottles. Case dimensions have shrunk without the cardboard inserts needed to keep glass bottles from knocking against each other.
At the same time, a typical semi-truck can hold 2,000 cases of PET bottles compared to 1,230 cases of filled glass bottles bottles. Other factors constant, Manning said they’ve seen an 8% savings just by switching packaging.
Appealing to a New Generation
Much like early screw cap use, Manning said he’s heard industry concerns about potential customer pushback with PET bottles. But he really hasn’t experienced it in his business.
Based on customer demographics at the Chateau Diana tasting room, Manning said he’s seeing an influx of much younger drinkers aged 21 to 35 years old. This is the same generation that grew up with bottled water, so they’re comfortable with plastic containers.
“It’s a huge group that the wine industry has been trying to figure out for years,” Manning said. “They’re more apt to drink in non-traditional settings, and I also think that cost-wise, it makes sense for them.”
Sustainability also resonates strongly with Generation Z, as these newly minted adults are dubbed, and Shaieb said PET bottles have a good story. Compared to other alternative packaging such as aluminum cans, he said PET containers have a 30% lower carbon footprint.
And unlike bag-in-a-box containers where the bladder must first be removed and separated from the cardboard exterior, Shaieb said PET containers can be directly recycled into programs that accept the international recycling triangle symbol for Plastic No. 1.
Despite his adoption of PET bottles for some market sectors, Manning said he believed glass bottles won’t fade away.
“We’re still using glass bottles, and they’ll still be around,” he said. “But I do think there’s room in the wine business for lots of people to try different things.”
Figure 1. Images of wood necrosis retrieved in grapevine plants affected by the Esca complex of diseases.In the upper left image, brown wood streaking is shown; in the upper right, a mix of types of wood necrosis; and in the lower image, detail of the white rot syndrome is shown (top left and right photos by C. Bertsch, bottom photo by S. Moretti.)
There are historical sources describing at least one trunk disease in grapevine in ancient Roman and Greek civilizations as well as in the Mediterranean Middle Ages, with some authors suggesting that it may be as old as viticulture itself (Mugnai et al. 1999).
Nowadays, Grapevine trunk diseases (GTDs) are present in every grapevine-growing country. This designation refers to a group of wood diseases that affect the woody structures of grapevine plants, causing different symptoms in wood, leaves, twigs and berries, and eventually sudden or progressive decline of the affected plants, therefore reducing drastically the life of a vineyard (Bertsch et al. 2013; Kenfaoui et al. 2022). Their impacts are significant on many levels; they damage the viticultural landscape, cause reduction in grape yield, wine production and quality, and have a significant impact on the wine market and winegrowing economies generally. Particularly over the last two decades, GTDs’ incidence rose to alarming levels in most grapevine growing regions (especially in the Mediterranean basin), rendering a large percentage of affected vineyards unproductive (Guérin-Dubrana et al., 2019). In countries where the wine market is extremely important like France, loss in production is estimated at around a billion U.S. dollars per year, and numbers from California and Australia are on the order of millions and billions of dollars per year, respectively (Siebert 2001)(Fontaine et al. 2016). Learning to combat them more effectively is essential.
Figure 1. Images of wood necrosis retrieved in grapevine plants affected by the Esca complex of diseases.In the upper left image, brown wood streaking is shown; in the upper right, a mix of types of wood necrosis; and in the lower image, detail of the white rot syndrome is shown (top left and right photos by C. Bertsch, bottom photo by S. Moretti.)
Solutions for Combatting GTDs
Various curative and preventative solutions have been proposed over the course of time. Early strategies likely consisted of simply removing the affected plants. The twentieth century saw the widespread use of chemical pesticides like sodium arsenite against the Esca complex of diseases. While effective, over the last 30 years, most chemicals have been banned for environmental and toxicity concerns. Physical interventions, such as trunk renewal, trunk surgery (curettage) and good pruning techniques, are the most efficient, while the use of biocontrol agents has also proven effective to an extent (Mondello et al. 2018; Pacetti et al. 2021; SICAVAC 2022). However, for several reasons, some of these techniques are not always viable either financially or practically. There is a clear need for alternative sustainable and environmentally friendly strategies.
In the quest for alternative solutions, fundamental research on the pathogens and their mechanisms of action and interaction with grapevine plants is crucial. Indeed, these diseases are mostly associated with fungal pathogens, entering the plants mainly through pruning wounds, causing lesions and necrosis formation in wood as well as unique leaf symptom patterns.
The Esca Complex of Diseases
The Esca complex remains one of the most catastrophic GTDs, nowadays regrouping four different syndromes: Petri disease, brown wood streaking, grapevine leaf stripe disease (GLSD) and white rot (Surico 2009). The fungi behind each disease belong to two different groups: Ascomycetes and Basidiomycetes fungi (the two ascomycetes historically associated with the complex of diseases are Phaeomoniella chlamydospora (Pch) (Crows and Grams 2000) and Phaeoacremonium minimum (Pmin) (Gramaje et al. 2015.)) They cause multiple types of necrosis in the trunk of the vines while also often leading to “tiger stripe leaves”, the foliar manifestation of GLSD (Figures 1 and 2).
Figure 2. A series of foliar and canopy symptoms of grapevine plants affected by the Esca complex of diseases. On the upper left and right images, the typical “tiger stripe leaf” symptoms can be seen. In the lower image, plant apoplexy is shown (photos by C. Bertsch.)
The main fungus responsible for the white rot syndrome is usually a Basidiomycete fungus, most often a Fomitiporia species, that usually varies according to geographical region (Fischer 2006). In Europe, Fomitiporia mediterranea (Fmed) (Fischer 2002) is the main fungus responsible for white rot. The syndrome causes the complete degradation of the wood attacked, reducing it to a spongy-yellowish residue, therefore irreversibly compromising the physical structure of the plants and the water transport. In old vineyards, the situation in which both white rot and GLSD are present is more often observed, raising a series of question marks on possible links between Fomitiporia species and the tiger stripe leaf patterns, historically associated with Ascomycetes fungi species (these two diseases manifesting together are sometimes referred to as ‘Esca proper’ (Surico 2009.) Considering all these interactions, it is easy to understand the devastating impact caused by this complex of diseases.
Mechanisms of Action
Understanding the mechanisms behind the pathogens’ activity in the Esca complex is crucial for predicting their behavior, and preventing or counteracting the damage they can cause. Past research efforts in this context have mostly focused on two main fronts: firstly, attempts to identify compounds (either released by the fungi or by the degrading wood) possibly responsible for the typical foliar symptoms, potentially being transported to the vines’ leaves via the sap (never fully demonstrated); and secondly, the study of wood necrosis and lesions formation and wood degradation, the latter mainly attributed to enzymes secreted by the fungi to decompose lignin and cellulose, the main wood constituents (Sparapano et al. 2001; Claverie et al. 2020; Pacetti et al. 2022).
Moreover, most likely because of the historical conviction that Basidiomycetes species can only arrive once the terrain has been prepared by other fungi, research has mostly focused on Ascomycetes fungi, leaving the role of Basidiomycetes species quite unexplored in the Esca complex. However, a recent observation coming from trunk surgery confirmed what some researchers had suspected: the complete removal of white rot drastically reduced the foliar symptoms (Pacetti et al. 2021; Lecomte et al. 2022). This suggests that Basidiomycetes (such as Fmed) are not mere secondary pathogens degrading wood but might actually have a larger role in the Esca complex of diseases, fueling interest in studying their role in the disease, recently highlighted by other researchers (Brown et al. 2020).
Recent Research on Fomitiporia mediterranea
In our laboratory, we made Fmed a main research topic, taking innovative approaches to study the pathogenesis mechanisms of the fungus in collaboration with two other research groups, one led by Laura Mugnai (University of Florence, Italy) and the other led by Barry Goodell (University of Massachusetts, USA), world-renowned experts in Esca complex and wood decay mechanisms, respectively. Fungal wood degradation has always been theorized in the framework of a binary division between white rot in which the main process involves enzymes, and brown rot in which the main process involves chemical compounds and their interaction with iron present in the wood cells, generating free radicals (a non-enzymatic process) (Blanchette 1991; Goodell 2020).
Our approach was motivated in large part by recent genomic studies calling into question the white rot versus brown rot paradigm (Riley et al. 2014). We analyzed the possibility for Fmed, a white rot fungus, to adopt a series of chemical reactions of a non-enzymatic nature that ultimately produces free radicals (namely hydroxyl radicals) to start wood degradation. It is in fact well demonstrated that in intact wood cell walls, micropores are too small to allow enzymes to pass through and digest wood (Flournoy et al. 1991; Kleman-Leyer et al. 1992). These mechanisms have been recently proven possible for the other two Ascomycetes fungi involved in the Esca complex as well as for Eutypa lata, mainly involved in Eutypa dieback, another GTD (Perez-Gonzalez et al. 2022). Our in vitro research demonstrates that the non-enzymatic mechanisms producing free radicals are possible for Fmed too (Moretti et al. 2023), further confirming that decay mechanisms can be much more nuanced than a reductive binary classification while also offering new possibilities for disease control.
Future Perspectives
Indeed, what may seem a mere technical distinction does in fact have significant implications for real-world applications. Understanding that every main fungus involved in the Esca complex can employ some non-enzymatic mechanisms to produce free radicals immediately points to a possible new research approach to controlling and fighting the disease: antioxidants and chelators, which are substances that bind free radicals and iron, respectively. Targeted use of antioxidants and/or iron chelator could therefore in theory reduce this non-enzymatic degradation process, by rendering free radicals inactive or iron unavailable for the non-enzymatic processes. In vitro results on other GTD fungi are encouraging as it appears that free radical production is reduced or completely blocked in the presence of antioxidants/chelators (Sebestyen et al. 2022). Their impact on free radical production by Fmed needs to be tested with research conducted in plants and in the field that tests various application methods for any resulting reduction in wood necrosis and degradation. If antioxidants/chelators prove to be an effective potential way to control symptoms of the Esca complex, research should identify sustainable and environmentally friendly sources. This research approach could also be extended to other GTDs and respective pathogens.
References
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According to UCCE Wildlife Specialist Roger Baldwin, gopher mounds can kill vines, create weed seed beds and are a physical hazard in the vineyard (all photos by R. Baldwin.)
Pocket gophers stay active year-round wreaking havoc in vineyards and other irrigated land, but they can be particularly menacing in late winter or early spring when their breeding activity peaks. Thus, it’s crucial to think about management strategies now before it’s too late and populations are out of control.
Pocket gophers are rarely seen aboveground so calculating exact number of rodents in the vineyard can be difficult, but their burrow system is what gives them away. Under their obvious fan-shaped soil mounds over tunnel openings are typically hundreds of square feet of main tunnels with lateral branches.
In terms of damage, pocket gophers feed off vine taproots or belowground bark on vine trunks, killing young vines or reducing vigor on old ones if feeding is extensive enough. They also damage subsurface drip irrigation. According to UCCE Wildlife Specialist Roger Baldwin at the recent Grape and Wine meeting in November 2022, gopher mounds themselves can also kill vines, create weed seed beds and are a physical hazard in the vineyard.
Pocket gopher management, like most other forms of pest management, utilizes an integrated approach with different tools and strategies. “Mixing and matching these tools is generally going to give you a better result than if you were to rely on just one,” Baldwin said.
Currently available options for pocket gopher management include biocontrol, habitat modification, baiting, burrow fumigation and trapping. Repellent is one other option that may become more efficacious in the coming years.
Biocontrol with Barn Owls
Biocontrol is becoming more and more popular as an option for pest control today as chemical options continue to dwindle. In the case of pocket gophers, the barn owl, a predatory raptor species, will hunt them when present in the owl’s feeding territory; however, Baldwin said that barn owls are not a particularly territorial species.
While barn owls have been efficacious for control of other rodent types, results are inconclusive for pocket gophers. In vineyards, barn owl boxes can be erected to create a home for the owls to live in and breed.
“[Recent studies] have shown potential to reduce pocket gophers in a particular area, so that part is somewhat encouraging,” Baldwin said. “However, we do have to keep in mind that even if they provide some reduction in gophers, they’re certainly not going to eliminate gophers.
“That’s their food resource; if they eliminate it, they’ll have nothing to feed on.
“If you want to include them as part of an IPM program, I think that’s okay, that’s a good strategy, but I wouldn’t rely on them as your sole tool.”
Habitat Modification
Altering the desirable area for a particular species is the basis of habitat modification, Baldwin said, and pocket gophers utilize in-row cover and weeds as food sources.
In grape growing areas where gopher populations are high, it might be beneficial to remove cover crops and control weeds in order to reduce food for gophers. “It’s important to remember these nitrogen-fixing plants are good food sources for gophers and other rodents,” Baldwin said. “If you can shift away from some of these nitrogen-fixing plants to grasses that are less desirable, then that can potentially limit the densities of gophers that you get in a particular area.
Research conducted by Baldwin and others revealed that between 56% and 68% efficacy could be achieved for gophers across various soil conditions using carbon monoxide machines.
Many vineyards utilize nitrogen-fixing cover crops as they provide multiple benefits to plant and soil health in the long term, so removing them to control gophers could be a detriment in certain situations, thus Baldwin noted it can be a balancing act of which benefit outweighs which negative more in a given vineyard.
Important to note is not just modifying the food source but also the burrows themselves for gopher management. Once gophers are controlled, their burrows remain, and new populations can spring up fast if they are allowed to use existing burrows to establish. Baldwin recommended deep ripping to remove burrow systems.
Repellents
In general, according to Baldwin, repellants have not worked well for controlling rodents in field or orchard settings, noting that often repellents require periodic reapplication in order to maintain efficacy, which can be costly and laborious.
One possible application for rodent control using repellents is reducing damage to surface drip irrigation (SDI) from pocket gophers. SDI has become a popular irrigation option throughout the state, but Baldwin said that gopher damage is one of the biggest hurdles for greater implementation.
“The depth of the drip tape is usually at the perfect level for gophers, so they come through and chew quite extensively on this drip tape,” he said. “This creates situations like substantial flooding which leads to all kinds of issues.”
Baldwin said that he and researchers have begun to look at the potential of running a repellent through the water during an irrigation event to move gophers out of a particular area. A product called Protec-T (active ingredient is methyl mercaptan) became registered in California within the last two years.
“We’ve just begun to look at the efficacy of this. What we’ve seen so far is a 41% reduction in gopher numbers. It’s not getting rid of gophers, but it is reducing the number in the field.”
Baldwin said that they haven’t studied this method enough to determine whether damage is reduced on SDI, but he believes that the possibility of damage reduction is promising.
“We haven’t had a chance to do it yet, but we need to measure the number of strikes on drip tape. That’s the most important thing that we need to measure right now,” he said.
Burrow Fumigation and Trapping
In the last few years, California has legalized carbon monoxide machines, sometimes referred to as pressurized exhaust machines, according to Baldwin, for burrowing rodent control. The devices inject carbon monoxide through hoses into burrowing systems and kill rodents.
Currently available options for pocket gopher management include biocontrol, habitat modification, baiting, burrow fumigation and trapping. Repellent is one other option that may become more efficacious in the coming years.
Research conducted by Baldwin and others revealed that between 56% and 68% efficacy could be achieved for gophers across various soil conditions.
“The efficacy we observed with the PERC machine in dry soil conditions is much better than we would expect with more traditional burrow fumigants like gas cartridges or aluminum phosphide, and they seem to work as well or better than these same fumigants in ideal moist soil conditions,” Baldwin said. “So, I do think that these kinds of pressurized exhaust machines are probably very effective for ground squirrels and relatively effective for gophers.”
Trapping also appears to be highly efficacious in vineyards for pocket gophers. Traps are the most tried-and-true method of gopher control, Baldwin said.
“[In research], we saw 92% to 94% removal rates across two trapping sessions with the Gophinator trap,” Baldwin said, adding that trapping is also one of the most cost-effective control methods due to the high efficacy.
Maximizing nutrient uptake and energy conversion of vines begins at budbreak and leads to larger, higher-quality crops (all photos by S. Jacobs.)
Whether your grapes are destined for wine, raisins, juice or the table, the job of the grapevine is to capture energy from the sun and use it to convert CO2 and H2O to carbohydrates and O2. Maximizing this process begins at budbreak and leads to larger, higher-quality crops. To have the greatest influence, a wholistic understanding of plant nutrition and crop production need to be engaged to ensure that every dime of fertilizer applied best serves its intended purpose. This is where the Five Rs of Plant Nutrition enters the decision-making process.
By combining knowledge from plant physiology, soil science, microbiology and chemistry, core principles of plant nutrition arise that affect fertilizer use efficiency, yield and quality. The Five Rs provide this science-driven approach in a memorable way that helps to confirm or guide nutritional decisions. A series of checks, the Five Rs ensure that the applied nutrients get into the plant when and where they are needed with minimal unintended nutrient interactions or losses. When framed as a question, the Five Rs can be stated as:
For my application, is this the:
Right Nutrient?
Right Time/Crop Stage?
Right Form?
Right Nutrient Mix?
Right Place in the Plant?
The order of the Five Rs is easily re-organized to fit a given scenario, and when focusing on a specific growth period, considering the right time/crop stage first has the most value.
A combination of both foliar and soil-based applications for most nutrients will be necessary to meet the quantities and timing required for high-level production.
Right Time/Crop Stage
Early spring is a critical period for grapevine growth and development as the foundational support components of the plant and crop (xylem, phloem, initial leaves and new roots) are created. This timing is also very challenging because the ability of the plant to obtain and move the needed nutrients from the soil is hindered by low soil temperature and low atmospheric evaporative draw.
Cold soils inhibit microbial growth and function, preventing the cycling of nutrients from plant-unavailable to plant-available forms. Similarly, mineral solubility in the soil-water solution is also reduced as soil temperatures decline.
Evapotranspiration is the primary mechanism for the movement of nutrients between the soil and the plant. When air temperatures decrease, so does the amount of moisture a given volume of air can hold as does the rate that the air can cause evaporation. Coupled with the small surface area of new growth, very low levels of evapotranspiration result.
The classical thought that soil nutrient stores alone can support optimal plant growth and development early on is brought into doubt, and other fertility decisions need to be considered. Other non-evapotranspirational mechanisms exist within the plant to mobilize and move stored nutrients but should be viewed purely as supplemental.
Right Place in the Plant
Just as important as what nutrient to apply and when to apply it is identifying the most efficient or appropriate place in the plant for the application. As addressed above, early spring conditions result in the soil being a poor nutrient source with low delivery efficiency. Yet, nearly all nutrients found in or used by the plant over a growing season were sourced from the soil via the roots. So then why is “Right place in the plant” a core principle? When nutrient demand timing and nutrient delivery limitations meet, the end goal of maximizing economic yield focuses less on ‘where is the nutrient found?’ and more on ‘where are the nutrients needed and what is the best way to deliver them?’ Hint: The answer isn’t always via soil application.
Plant nutrient demands fluctuate over the season, and nutrient-to-nutrient ratios shift subsequently.
For most nutrients, what is found in or applied to the soil meets the volume requirements of the plant, but often soil conditions during the demand period or interactions with other nutrients limit their availability. Even in soils with perfect nutrient conditions, periods still exist where only foliar nutrient applications can meet the limited window of nutrient demand. Post-budbreak is such a time and pre-bloom, bud differentiation, set and berry development, post-veraison and postharvest periods all see benefits from timely foliar applications. During these periods, foliar nutrient applications can achieve results that the soil cannot deliver. And to go a step further, foliarly applied nutrients can uniquely alter nutrient ratios or balances within the plant in ways that cannot be achieved economically, or potentially at all, through the soil.
However, just as the soil cannot deliver all nutrients at the right time, the volume of macronutrients needed cannot be delivered solely through foliar feeding. In the end, some combination of both foliar and soil-based applications for most nutrients will be necessary to meet the quantities and timing required for high-level production.
Right Form(ulation)
The soil and leaf environments to which nutrients are applied are extremely harsh, albeit in almost opposite ways. This article will not go into specifics, but generally, foliar applications dry quickly, are exposed to comparatively high oxygen concentrations and wide-ranging temperatures, and are bombarded with solar radiation. The soil, on the other hand, is very chemically and physically active at the molecular scale and is teaming with life that needs many of the nutrients for its life cycle that our plants require.
Nutrient products are available as various compounds that can be organized roughly into four formulation groups: insoluble salts, soluble salts, chelates and complexes. Ideal use scenarios can generally be defined for each formulation group, and nutrient stability and uptake performance rely heavily upon where (right place) they are applied.
The main points to understand are 1.) there is no “magic bullet” formulation possessing very high performance as a nutrient delivery vehicle in both soil and foliar applications; and 2.) something else is always competing with the plant to acquire applied nutrients or acting against the formulation of the nutrient, decreasing its availability to the plant.
Insoluble salts: carbonates, oxides, hydroxides
Nearly or completely insoluble in aqueous solutions but micronize well. Foliarly, they coat tissues like paint and are highly effective reflectors/blockers of sunlight. As such, they are often used to prevent sunburn or sunscald of plant tissues. Foliar nutrient delivery performance is very poor. Slow conversion to plant-available forms in the soil results in poor performance.
Soluble salts: sulfates, nitrates, acetates, chlorides
Soil applications usually perform very poorly, but low cost can offset the inefficiency. Foliar performance is poor as uptake is slow, and excess accumulation of the companion anions (SO4, NO3, C2H3O2, Cl) elicit stress responses in the plant or are otherwise problematic.
Chelates: EDTA, EDDHA, EDDHSA, citric acid, amino acids
Synthetic, EDTA-type and similar are generally large, highly water-soluble materials that perform exceptionally well in soil applications. They are toxic to plants and soil organisms, however, and can solubilize heavy metals in the soil, causing accumulation in plant tissues. They are not great foliars.
Conversely, citric and amino acid based chelates perform well when applied foliarly and are less toxic. Stability is an issue in soil applications compared to EDTA-type chelates.
Complexes: dextrose-lactose, mannitol, glucoheptonate, lignosulfonate
Poor performers in soil applications, these naturally derived materials make average to exceptional foliar delivery vehicles. Molecular weight and size of the complex affects performance. The complexing compounds of some offer carbon skeletons that are easily assimilated by the plant once the nutrient is removed.
Right Nutrient/Nutrient Mix
While not always grouped together, the right nutrient and the right nutrient mix are closely related. Plant nutrient demands fluctuate over the season, and nutrient-to-nutrient ratios shift subsequently. Nutrient-to-nutrient inhibitions, synergies, antagonisms and stimulations exist and must be accounted for as not all nutrients work well together in the plant at the same time.
In our budbreak to pre-bloom vineyard, demand for all nutrients except potassium are high, and calcium and phosphorus are both needed early on. But Ca and P antagonize each other, decreasing application and assimilation efficiency. So, which do we apply? If we assess the right time and right place components, foliar application of Ca makes sense since it moves exclusively with the transpiration stream and as is needed in the leaves to initiate cell division and develop cell walls. P on the other hand provides the energy needed for cell division and other growth functions to occur. Under ideal circumstances, we could apply P foliarly today and Ca foliarly in three to seven days and see the greatest benefit. Practicality doesn’t often allow for this type of application situation, and in our attempts to reduce the number of passes through the field, we must apply both simultaneously.
Tie-ups and antagonisms in real-world agriculture are inevitable and will occur in the spray tank and in the plant. But synergies and gains in efficiency and yield will occur from a little time, effort and application of the Five Rs into your nutritional program.
One way the wine industry is meeting demand for more sustainable products is through certification (all photos courtesy B. Vukmanic.)
While “sustainable” is a common term in agriculture today, this was not the case in 1994 when a small group of vineyard growers got together on California’s Central Coast to talk about critical resource concerns like safe pest management, soil quality and farmworker training.
Nearly 30 years later, that small group of growers has expanded to include hundreds more, representing over 80,000 vineyard acres. They are members of the non-profit organization Vineyard Team. The organization continues to uphold the original growers’ mission: Bringing together experienced growers and researchers to educate the industry on sustainable winegrowing practices. Today, sustainability is accessible to growers across the globe through in-field meetings, digital resources and third-party certification.
Founders Dana Merrill of Mesa Vineyard Management, Steve McIntyre of Monterey Pacific and Don Ackerman of Constellation Brands reflect on three decades of sustainable research and education.
According to Don Ackerman, owner of Constellation Brands and co-founder of Vineyard Team, sustainability has become a guide for best practices within the industry and the world.
Evolution of Sustainability Concept
Consumers continue to prioritize their health and wellness as we enter the third year of the COVID-19 pandemic. But consumers’ health needs have evolved beyond the basics of physical wellbeing. With increasing concern for the future health of families, communities and the planet, many consumers are seeking brands and products that promise a better tomorrow. In a 2021 study conducted by Simon-Kucher & Partners, 85% of respondents indicated they have shifted towards purchasing sustainable products over the last five years.
One way the wine industry is meeting this demand is through certification. Programs like SIP Certified verify that the vineyard and winery are implementing practices that protect the people and planet. The process requires that growers and winemakers adhere to specific practices and complete audits with third-party inspectors to verify compliance.
“Within the industry and the world, sustainability has become a guide for best practices,” said Ackerman.
“Acceptance and participation have snowballed,” Merrill said. “Today, sustainability is a standard operating procedure. Most buyers expect a sustainability certification.”
Sustainability Just a Buzz Word?
Consumers today are growing increasingly environmentally conscious. WWF commissioned global research by Economist Intelligence Unit (EIU) in 2021 (An Eco Awakening) that found that searches for sustainable goods have increased globally by 71% since 2016.
Growers agree that certification is not just a marketing tactic. “We can do well by doing good,” Ackerman said.
Many certification programs began as an educational self-assessment tool. Today, certification enables winegrowers to better manage their practices. Regular peer reviews with university Extension programs and professors and industry experts ensure that the latest research and technology are incorporated into the SIP Certified program so participants implement new sustainable practices as they go through the certification process.
Steve McIntyre, owner of Monterey Pacific and co-founder of Vineyard Team, said that the goal of sustainability is to regularly improve at a farm level.
McIntyre reinforced that the goal of sustainability is to regularly improve at a farm level. “It is a competition with yourself.”
Wine consumer demand for sustainable products increases annually, and winegrowers should communicate their good work through certification to be visible to consumers who are looking for sustainable wines. Incorporating science-based best practices is good for the environment and communities and meets consumer demand.
Major Issues in Vineyard Sustainability Today
From integrated pest management (IPM) to irrigation efficiency to labor supply, farmers need to balance numerous issues that impact sustainability to bring a marketable product to consumers. At its core, sustainability is a holistic approach to the business of winegrowing. A single practice can have an impact on more than just one specific area of production. A generous employee benefits program will create labor stability for the vineyard and job stability for the employee. Decreasing irrigation reduces both water and electricity use.
When asked what they see as major issues in sustainability today, the founders mentioned the health and safety of workers, regenerative agriculture, technology and pest management. The resounding theme in all their responses was thinking about the cumulative impacts of a decision.
Sustainability encourages growers to consider multiple management options. Pest management is a great example of an area where the vineyard manager uses all the tools in the toolbox. IPM strategies begin with cultural practices like leafing to reduce mildew pressure. These kinds of practices in turn reduce the load of pesticides applied to the vineyard, which improves health and safety conditions for workers and often lowers costs to the vineyard.
“Farmers are continually looking for ways to do more with less,” McIntyre said. His company addresses weed control by using multipurpose equipment. This practice decreases tractor passes, thus burning less fuel and reducing pollution.
Merrill explained that good soil quality creates healthier plants so there is less need for chemical pest management. “Sustainability means farming the same ground hopefully forever because you have created a healthy system.”
Sustainability and the Ag/Urban Interface
In 2020, direct on-farm employment accounted for 2.6 million of the 19.7 million jobs related to the agricultural and food sectors, just 1.4% of total U.S. employment. Building relationships between agriculture and residential neighbors is very important because few people have direct experience with agriculture. Safe farming practices like night sprays that prevent drift and protect workers from heat stress can be misunderstood. When farmers proactively get to know their neighbors, they open the lines of communication. This builds trust that can mitigate conflict and misunderstandings.
“The more people understand sustainability, the better they feel about being a neighbor to a working farm,” Merrill said.
The requirements of being certified sustainable help to create good neighbors because sustainability necessitates consideration for the health and well-being of all members of the community. Ackerman believes that being considerate to neighbors is part of the ethos of sustainability.
At its core, sustainability is a holistic approach to the business of winegrowing.
“Sound farming practices protect the environment for neighbors and the community.”
Ultimately, sustainability helps farmers tell their story of stewardship.
The Future of Sustainability
In viticulture, sustainability is a grassroots movement. In three decades of promoting sustainable winegrowing, countless growers have told Vineyard Team that they continue their education, trial new practices, push the bar and get certified because, “It’s the right thing to do.” 30 years later, all three Vineyard Team founding members still see sustainability as the future because it is a doctrine that keeps evolving and improving so that winegrowers can have a positive impact on more acres, neighborhoods and communities for years to come.
California is the nation’s No. 1 wine producer, making 81% of U.S. wine (photo by C. Merlo.)
In Jeff Bitter’s view, California’s wine grape industry can no longer rely on market patterns that were considered normal even five years ago.
Market dynamics are changing, making it harder to forecast the coming year, said Bitter, president of Allied Grape Growers. The marketing cooperative represents some 500 California producers and sells more than $100 million worth of grapes each year.
Since 2019, Bitter pointed out, yearly harvests have consistently fallen below the once-normal crush of 4 million tons. California’s ongoing drought and escalating input costs are eroding producers’ margins. Wine shipments remain flat. The struggling economy adds another layer of uncertainty.
“There’s apprehension in some wineries about what’s going to happen on the demand side,” he added.
Bitter isn’t alone in trying to gain a clearer outlook as the wine grape industry evolves.
“There’s a lot of guessing about what’s going to happen in 2023,” said Craig Ledbetter, vice president and partner with Vino Farms. The company owns and manages over 15,000 acres of wine grapes throughout California.
California’s 5,900 wine grape growers produce on 621,000 acres (photo by C. Merlo.)
Supply Side Shift
The production drop that began with the 2019 wine grape crop “was a pivotal point in the California market in terms of supply, demand and balance,” Bitter said. “That drop had to do with one thing: oversupply. Many growers were unable to sell their grapes or excess tonnage and had to leave them on the vine to rot.”
The upshot was that many growers decided to pull out their vineyards or get out of the business. That reduced supply “a fair amount for the future,” Bitter added, because those acres were permanently removed.
Now, California’s 2022 wine grape harvest marks the state’s fourth consecutive crop to fall below 4 million tons. Both Ledbetter and Bitter estimate its volume at around 3.5 to 3.7 million tons, down 10% from an average crop. They attribute the decrease partly to the vineyard removals of the last couple of years. A late-spring frost in the Delta and Lodi growing regions and the statewide heat wave in late August and early September also hurt yields.
Yet the reductions in recent harvests can’t only be attributed to vineyard removals, according to Bitter. Longer term are questions about the effect of California’s drought on the size of future crops.
“Something else is going on that’s causing us to have shorter crops each year,” he noted. “So, you look at the drought and its lasting impact. Is the state’s capacity for 4 million tons over? Is the average crop size of 3.6 million tons the new normal? We’re in a flat market so we’re not looking for more supply. But it does point to the reality that farmers will have to become more productive in their vineyards if they’re going to continue dealing with issues outside of their control.”
While Cabernet Sauvignon accounts for California’s second-highest wine grape acreage, Pinot Noir has grown steadily in popularity (photo by C. Merlo.)
Demand Remains a Question
Underlying the effect of California’s smaller wine grape supply is, of course, the demand for wine.
“On the surface, after three short crops, you’d think the market should be stable, even strong if you’re looking at depleting inventories,” Bitter said.
But the wine market is still trying to find its bearings in the wake of COVID-19. Pandemic restrictions shifted demand for wine away from restaurants, bars, sporting events and other public venues to supermarkets. While that hurt many businesses, those changing market channels created opportunities for lower-priced wines to regain some health. That benefitted grapes grown in the state’s interior regions, which generally produce the wine sold in grocery stores.
The boost in sales at the $15-per-bottle level and higher is important, since 70% or more of the entire wine market sells at the $20-per-bottle price point, Ledbetter said.
The big question now is how wine consumers will react in the coming year as economic uncertainty and fears of a recession persist.
Wine sold in supermarkets has seen an upturn in sales since the pandemic began (photo by C. Merlo.)
“An economic decline won’t lead people to stop drinking wine, but they will trade down from their usual price points,” said Ledbetter. “If they typically drink a $35 bottle of wine, they’ll shift to a $20 bottle. That will help the lower end of the market.”
Among wineries, the flat wine market is leading to a greater focus on maintaining market share. It’s also driving more aggressive players “to try to steal someone else’s share of the pie,” Bitter said. “That’s where certain wineries and producers are growing. You don’t have a lot of strategy around growth or introducing new products or being the next greatest thing. It’s, ‘How do I maintain my portion in the market and operate my business without putting me at risk?’”
The industry also is grappling with how to market wine to different generations. The baby boomers, who helped drive market growth over the past few decades, have slowed their wine consumption.
“The biggest issue of our industry is trying to understand millennials [born from 1981 to 1996], who are the second largest segment of the U.S. population,” said Ledbetter. “They’ve been consistently inconsistent in their loyalty to wine.”
Export Optimism
Gino DiCaro, director of communications for Sacramento-based Wine Institute, said California wineries are optimistic about current and future demand for their unique and often sustainably grown and made wines.
“With a 10.6% increase in exports last year, we are seeing growing global demand, and domestically the direct-to-consumer (DTC) market has grown under expanded DTC channels,” he noted.
Wine Institute is the public policy advocacy group of 1,000 California wineries and affiliated businesses. It’s also the administrator of the USDA Market Access Program (MAP) for California vintners, representing 80% of U.S. wine production and 95% of U.S. wine exports. Under Wine Institute’s California Wine Export Program, more than 195 of the state’s wineries export to 142 countries.
“California’s wine-producing community is still growing,” DiCaro said, “which means we’ll be well suited to accommodate market demand for that coveted glass of Golden State wine.”
Grower-Side Pricing
Also coloring the 2023 wine grape outlook are growers’ high input costs. Soaring prices for fertilizer, labor, energy, parts and supplies as well as increased regulations have all raised producer expenses.
“The cost of putting in a vineyard in the Lodi area has increased 35% to 40% since COVID-19 arrived,” Ledbetter said. “The numbers no longer show a positive return on investment unless we see a dramatic increase in price. It’s very difficult to make money these days.”
Pricing needs to range from $800 to $850 a ton for Lodi area growers to be economically sustainable, Ledbetter added, versus the current $600 to $650 levels.
Chardonnay is California’s most-planted white-wine grape and the most popular wine in the U.S., according to Wine Institute (photo by Elizabeth Brewer.)
Bitter foresees pricing at the grower level remaining stable in 2023. But that’s not good news for growers. “Stable pricing means we’re going backward,” he said. “Input costs have been rising for the last 18 months and will continue to rise. The average grower today is less profitable than [they were] last year.”
Even so, growers like Ledbetter refuse to let their immediate challenges dim their outlook. They’re looking for opportunities to help them survive. To expand their options and sustain their farming future, for example, Ledbetter and his family have planted pistachio trees east of Galt and along Interstate 5 near Elk Grove between Stockton and Sacramento. But they aren’t leaving the wine grape business.
“I’m a farmer, so I’m optimistic,” Ledbetter said.
Figure 1. Pinot noir from the foliar Mg trial showing the canopies of the untreated control (top) and the high rate of Mg foliar treatment (bottom) taken in close proximity in one of the replicate plots on 9/30/22 (photos by P. Schreiner.)
Applying fertilizers or plant nutrients to foliage has a long history, and there is an extensive number of papers published on the subject. However, it may surprise some to learn that we still do not fully understand how nutrients applied to the foliage cross the leaf cuticle and enter the cytoplasm of plant cells where they can be used in metabolism. The cuticle is the main barrier to absorption of foliar applied nutrients.
Figure 1. Pinot noir from the foliar Mg trial showing the canopies of the untreated control (top) and the high rate of Mg foliar treatment (bottom) taken in close proximity in one of the replicate plots on 9/30/22 (photos by P. Schreiner.)
Many Factors at Play
All aerial plant parts, including leaves and berries, are covered by a complex structure (a little like our own skin) known as the cuticle. The plant cuticle limits or regulates the transport of water and other substances between the plant and the environment, in addition to protecting plant cells from UV light and discouraging or sensing pests or pathogens. The cuticle is a hydrophobic layer formed just outside the cellulose cell wall that is composed mainly of the cutin polymer (a polyester) with waxes both embedded in it and covering its surface. However, numerous other chemical constituents beyond the scope of this discussion are also present in the cuticle and alter its properties with respect to the transport of any compound across this barrier. While there is still much debate about how different compounds (including plant nutrients) cross the cuticle, two major pathways of transport are known: the non-polar pathway or waxy pathway, and the polar pathway or aqueous pathway.
Table 1. Hydrated radius of different foliar nutrients that may be applied to plants.
Compounds that are soluble in oil or an organic solvent, such as some herbicides or even smoke-related phenols, cross the cuticle easily through the waxy pathway because they are basically soluble in it. However, most plant nutrients are polar compounds or ions that are water-soluble, and transport of these substances relies on the aqueous pathway. This aqueous pathway exists because of ‘aqueous pores’ that occur within the waxy cuticle.
While these pores are known to exist based on indirect evidence, they have yet to be seen. Aqueous pores in the cuticle become more open or connected as the relative humidity in the air increases. Therefore, transport of foliar-applied nutrient ions is much greater at higher humidity, and spraying foliar nutrients early in the day when humidity is still high is more effective than at midday or in the afternoon when humidity drops. Higher humidity also translates to a longer time that the spray droplets remain wet, thus keeping ions in solution longer, which also facilitates greater transport across the cuticle. Humidity also affects what is known as the point of deliquescence (POD) for different ions, which is the level of humidity needed for a given ion to attract water vapor and remain in solution on a given surface. POD varies for different nutrients, but higher humidity levels increase the chance that POD will be exceeded.
Another property of nutrients or ions related to aqueous pores and transport through them is known as the hydrated ion radius, which is the molecular size of the given ion and those water molecules tightly adhered to it when dissolved in water (Table 1). Many macronutrient ions have a larger hydrated radius when compared to micronutrient ions. A smaller hydrated radius allows for greater transport through aqueous pores estimated from various studies to have a diameter of about 0.3 to 2.0 nanometers. This is one reason that foliar application of micronutrients is more effective than foliar application of macronutrients. However, one must also consider that micronutrients are needed in much, much lower quantities to be in a healthy range. Indeed, it would be difficult, if not impossible, to supply enough nutrients for most macronutrients like N through the foliage alone.
Table 1 shows that the hydrated radius for boric acid is actually on par with the macronutrients. Yet, we know that boric acid and other sources of boron (e.g., Solubor) are used very effectively to alleviate B deficiency in grapevines. This is because uncharged molecules cross the cuticle far easier than charged ions. While it is still not entirely clear, some foliar nutrition experts think that relatively small molecules that are uncharged, such as boric acid and urea, cross the cuticle via the waxy pathway. Indeed, water molecules appear to be transported to some extent via the waxy pathway, allowing some plants to take up significant water directly through their leaves.
Cuticles on the upper surface of leaves (known as the adaxial surface) are generally thicker than the corresponding cuticle on the leaf bottom surface (abaxial surface). When nutrients were applied separately to upper versus lower leaf surfaces, more transport occurred across the bottom side of the leaf, up to four times more. Another practical consideration to increase nutrient absorption is to ensure that sprays are well deposited on the underside of leaves by having good airflow during spraying. This could mean increasing fan speed.
Another consideration important for nutrient transfer is the contact angle of the spray droplets that land on plant surfaces. This property is mostly dictated by cuticle properties, particularly the waxes on the outer surface, and by the physio-chemical properties of the spray solution. Different plant species, different tissues (leaves vs fruits) and even different ages of the tissues along with the prevailing environmental conditions affect cuticle properties that alter contact angles. Spray adjuvants or surfactants can also reduce the contact angle (i.e., help spread out the droplets) and increase transport across the cuticle.
Numerous studies using isolated cuticles have shown the importance of spray adjuvants to increase foliar absorption of nutrients. In addition, adjuvants can delay the drying time of droplets and keep the nutrient in solution longer, allowing for greater uptake. It should be noted that there are also cases where the naked nutrients alone (without spray adjuvants) were absorbed just as effectively as when applied with an adjuvant.
What about chelates? This area gets a lot of marketing attention, but due to the proprietary nature of many chelates sold, it is often difficult to untangle advertising from evidence that specific chelates actually improve foliar uptake. While there are cases where chelates have proven more effective than nutrient ions alone, there are also cases where they have not.
Finally, another factor still unresolved regarding foliar uptake of nutrients is the role of stomates and other structures on the external surface of leaves, such as trichomes (leaf hairs) and specialized cells above veins.
Recent findings show that stomates can play a clear role in facilitating uptake of nutrients. For example, in a series of experiments with bean leaves where stomates were manipulated to be open or closed, uptake of nitrogen from urea, ammonium or nitrate was two times higher when the stomates were open. It should be noted that uptake via stomates does not just flow through the open stomatal pore; it is still a diffusion process along the edges of the stomatal guard cells that is more apparent when the pore is open. Additionally, recent studies using some new-age microscopic imaging methods showed that the base of trichomes was a key area for the uptake of foliar zinc in sunflower leaves, and other specific cell types directly above major veins was the primary uptake site of foliar phosphorus in barley leaves.
It is worth noting that much of what we know regarding cuticular transport of plant nutrients was derived from studies using isolated plant cuticles (enzymatically isolated from leaves.) Such a model system has its drawbacks, and artifacts can occur. For example, some studies comparing isolated cuticles to intact leaves did not yield consistent results for transport. This is why real-world studies with natural plant canopies under production conditions are needed to provide practical data on efficacy of foliar fertilizers. Numerous other factors not discussed here can also influence the success of foliar fertilization, which makes generalized recommendations difficult.
Foliar Nutrient Trials in Oregon Vineyards
My lab has conducted a number of foliar nutrient trials, and I will briefly share some of our findings. We have conducted three different trials using foliar urea-N for the specific purpose of boosting fruit or must YAN levels. Two experiments were conducted in Pinot noir and one in Chardonnay. These trials have shown that foliar urea is an effective tool to boost YAN (Table 2), and it has the advantage over soil-applied N in that canopy growth is not increased (a clear benefit for improving YAN in high-vigor sites.)
Table 2. Summary of foliar urea trials conducted in western Oregon vineyards.
We also conducted a P trial years ago at two Pinot noir vineyards in the Willamette Valley. P was applied in three foliar sprays at a moderate dose, and leaf blade and petiole P status was improved at only one of the two sites. The increase in leaf blade P concentration at one site at veraison was only about 12%, and I concluded there was little benefit to spraying vines with foliar P (data not shown).
Currently, as part of the High-Resolution Vineyard Nutrition Management (highresvineyardnutrition.com/project), we are testing a foliar potassium treatment along with two rates of soil-applied K to correct a low K Pinot noir vineyard, and we are assessing two rates of foliar magnesium to correct a low Mg Pinot noir vineyard.
In the K trial, we are comparing a foliar K product (K-Metalosate, Albion Labs, Layton, Utah) at the highest label rate using three sprays per year (total = 3.3 pounds K/acre) with fairly high doses of soil K (K2SO4) at either 188 or 369 pounds K/acre applied in spring. Results from year 1 of this trial showed no increase in leaf or petiole K status at bloom or veraison, nor any impacts of K on growth or yield as well as must sugars, pH or TA. However, K levels in dormant-season canes (pruning wood samples) were slightly improved by all three K treatments compared to the no-K control. In year 2, leaf and petiole K status at bloom was increased in the soil K treatments, more so by the high rate, but not in the foliar K vines. Veraison leaf and petiole nutrients and pruning wood nutrients have yet to be analyzed for year 2, but similar to last year, no effects on growth or yield as well as must sugars, pH or TA were apparent due to K treatments (data not shown).
In the Mg trial, we are testing foliar sprays using MgSO4 (Epsom salt) because an earlier trial my lab conducted in the Willamette Valley with soil-applied MgSO4 at a high rate was unsuccessful. We are comparing foliar sprays of MgSO4 at 10 or 20 pounds/acre using three sprays (supplying a total of 3 or 6 pounds Mg/acre). The high rate of Mg increased leaf blade Mg levels at veraison in year 1 but did not alter petiole Mg levels as we found before. Both the low and high rates of foliar Mg reduced the number of leaves with Mg deficiency symptoms by more than 75% around harvest time in both years (Figure 1, see page 24). However, Mg applications did not affect growth or yield as well as must sugars, pH or TA thus far.
In conclusion, foliar feeding of plant nutrients has its place in vineyard management, and certain foliar nutrients are effective in improving nutritional health of grapevines. This is especially true for micronutrients, notably B and zinc. Of the macronutrients, both Mg and urea-N have been effective in alleviating Mg deficiency or in boosting must YAN levels. Foliar applications of P and K have proven less effective so far. Caution is warranted when considering the myriad of foliar products that are being marketed to you as grape growers, and this is because we still have much to learn about how and when foliar-applied nutrients will be effective. A key question you should ask yourself when considering foliar nutrition is whether you have a deficiency or other problem that needs to be fixed. This is where money spent on tissue sampling for nutrients and tracking vine nutrient status over years will pay for itself in the long run. Prophylactic use of foliar fertilizers, except perhaps for B, is generally not a good idea.
Dialogue between winemakers and vineyard managers, both in the field and in the winery, is a crucial part of success for the modern winery, according to panelists at this year’s Unified Wine and Grape Symposium (photo by Cecilia Parsons.)
It can be agreed on by most that teamwork makes the dream work, especially when it comes to the business of winemaking.
At the Unified Wine and Grape Symposium in Sacramento, Calif. in January, winemakers and vineyard managers on a panel agreed that working together and communicating is key to achieving the best outcome when it comes to wine production. When those in the field are in sync with those in the tasting room, complications during the growing season and throughout the winemaking process can be reduced or eliminated.
The wine industry is naturally quite siloed, panelists said, due to the multiple different operations and departments that exist between growing grapes and making wine. Katie Madigan with St. Francis Winery and Vineyards said she’s seen a change over the last two decades with how teams in the industry work together, noting there’s been a shift away from the silo to being more integrated.
“Now you’re seeing much more collaboration,” she said. “You have to meet early [in the season] and often.”
Year-Round Communication
Winemakers and vineyard managers are starting to realize that the more each knows about each other’s happenings and commitments, the greater success the end product will see. The ideal level of communication is one that is year-round.
“It is just really important that it is a year-round relationship,” said Andy Erickson, winemaker at Favia Erickson Growers.
Communicating for the first time halfway through the season won’t do either side any good.
“Starting in May is tricky from a vineyard management perspective,” said Tim Rowe, vineyard manager at Domaine Carneros.
One common conflict the panelists see is how much fruit is wanted to be taken off the vine; the vineyard manager might have one idea about tonnage off the vine while the winemaker might have a different idea. Unmet expectations, Erickson said, are always a sticky point when one party expects a certain amount to be taken off and the other wants something else. This is where the ‘year-round’ aspect plays into communication. Starting the season off with a plan laying out specific numbers for specific blocks/fields is crucial.
“A farm plan helps to build trust off the bat between winemakers and winegrowers,” said Blake Wood, director of vineyard operations at Constellation Brands, Inc. “Discussions around the plan form the basis of trust.”
“Color-coating times and tonnages [on a plan] really helps,” said Chris Louton, winemaker at St. Francis Winery and Vineyards.
“We don’t know what Mother Nature is going to throw at us, so we have to be on the same page with our expectations all the time,” Madigan said.
Dialogue in the Field and the Winery
The notion echoed most often by the panelists was the importance of getting out in the field and facilitating the winemaker-vineyard manager relationship. This again goes back to separating from the wine industry silo, and while it can be a challenge at times, it’s an important part overcoming challenges on the road to being a successful winery with successful growers.
“When you’re on a ranch together, you know the problems are going to be taken care of,” said Tony Bugica, Atlas Vineyard Management’s director of farming and business development, noting team members should understand why a vine is being leafed or why a wine is being tasted. “Make sure everyone knows why things happen in the field and the winery.”
Rowe spends his time as a vineyard manager both in the field and the winery by choice, joining blending sessions for different wines to “dovetail” management strategies and techniques while also taking winemakers into the field so they can see what he’s doing. “Break that silo and help them understand opportunities and challenges to bridge any communication gaps.”
“It’s much better to go into June and July with things going as expected rather than having missed things,” Madigan said.
“It’s so critical for the winemakers to be out in the vineyard,” said Remi Cohen, CEO of Domaine Carneros. “If you go out in the end of the season and you don’t know what’s happening, that can cause tension. By the time you get to harvest, everyone is too stressed, and most of the work in the vineyard has already been done.”
Cohen started an internal mentorship program at Domaine Carneros to aid in winemaker-vineyard manager relations. Anyone can apply and will be paired up with an individual on the management team.
“We were trying to create these cross-department opportunities, especially for people who are just starting out in their career,” she said.
Domaine Carneros also holds monthly meetings that are bilingual to bring all vineyard management staff into the fold of winery culture.
Dialogue in the field even goes as far back as having the owner of a vineyard themselves out and being more involved in management decisions, according to Kirk Venge, owner of Venge Vineyards and Croix Estate. While a big challenge, he said, this is important because it ultimately affects the wineries the vineyard owners are growing for.
