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For organic winegrapes, soil is ‘full of life’

Issue Date: September 8, 2021
By Kevin Hecteman
Ivo Jeramaz looks over cabernet sauvignon grapes in an organic vineyard near Yountville. Many of the cabernet sauvignon vines in this Grgich Hills Estate vineyard were planted in 1959. Jeramaz took the whole operation organic about 20 years ago.
Photo/Kevin Hecteman

For Ivo Jeramaz, it all starts with the soil. Not dirt. Soil.

"Dirt is a derogatory word for soil," said Jeramaz, vice president of vineyards and production at Grgich Hills Estate in Rutherford. "Dirt is devoid of life. Soil is full of life."

Jeramaz—whose uncle, Miljenko "Mike" Grgich, is responsible for the chardonnay that famously beat out French wines at a tasting competition in Paris in 1976—converted his family's vineyards from conventional to organic production about 20 years ago. His focus begins with building what he calls "disease-suppressive soil."

This includes use of cover crops and composting—and no tilling. He says that's because tilling adds oxygen to the soil, causing the microbe population to explode and then eat up organic matter responsible for soil structure. "You get the first-year flush of fertility," Jeramaz said. But after that, it's all downhill.

"Microbes are key ingredients in success of soil," Jeramaz said. "Not that we invented this—this is how nature intended."

Organic growers like the Jeramaz family combined to produce 3,777 acres of organic winegrapes harvested in Napa County in 2019, according to the California Department of Food and Agriculture's 2019 organic crop report. Only Mendocino County, with 3,993 acres, had more organic winegrape acreage harvested.

For comparison, Napa County winegrape growers had 43,365 acres in production in 2019, while Mendocino County was home to 16,506 bearing acres, according to the counties' 2019 crop reports.

Joseph Brinkley, who grows organic winegrapes near Hopland, said going organic requires a mindset change.

"On the organic and the biodynamic side, it's really like trying to create a healthy system and organism," Brinkley said. "You're really trying to prevent any issues, and preventing those issues often means farming in a more balanced way so you don't have a lack or an excess of, say, a nutrient or water or light."

To deal with mildew, an organic grape grower has to "make sure that your canopy management is timed properly," Brinkley said. "You've got good air and light flow through the canopy, protecting the fruit."

Like Jeramaz, Brinkley focuses on soil health, beginning with soil tests to check the pH balance. Brinkley said any compost added to the soil would be beneficial for organic matter and biological activity. He's also used fish emulsions and soy and seaweed products with nitrogen. Then there's manure from the sheep that graze the vineyards.

"Maybe 20, 30 years ago—or even 15 years ago—there weren't a whole lot of organic fertilizers out there," Brinkley said. "In the last 10, 15 years, the market has certainly shifted in that way towards organics. Consumers are wanting it, it seems, and there seems to be a growing awareness and need or demand for it."

Keeping disease and pest pressures in check involves a much different approach.

"We just don't have the broad toolbox of standard chemicals, like the conventional growers do," said Martha Barra, who farms in Redwood Valley.

Barra said she uses an organic-approved material containing chrysanthemum oil to keep leafhoppers in check, and stylet oil for mildew.

"We're just really limited to what we can use, but it seems to work for us," Barra said. "We've got our vineyards in balance. It has to do with timing in the application. We know how the cycles go, like in leafhoppers or mites."

Jeramaz said he found that conventional materials "go into plant sap and influence everything, and weaken plant immunity. While you might kill mildew for a couple of years, you weaken the plant." That, in turn, shortens the vine's life expectancy, he added.

"One generation ago, grapevines lasted at least 40 to 50 years," Jeramaz said. "Today, with all this new technology, we only get half. It's tremendously expensive."

Jeramaz's oldest vineyard, in Calistoga, contains 120-year-old zinfandel vines; some of his cabernet sauvignon vines in Yountville were planted in 1959.

Brinkley's thinking on life expectancy aligns with Jeramaz's.

"I feel like you get an increased longevity of that planted field," Brinkley said. "Instead of maybe 20- to 25-year replants, we're looking 35 to 40, or maybe even longer."

Brinkley said the difference between conventionally and organically grown winegrapes will depend largely on the varietal and the location of the vineyard.

"Often you'll find reduced yields in the organic system vs. the conventional system," Brinkley said, "but with those reduced yields, often you'll find a greater concentration, especially within the reds—some of the phenolics, the color profiles."

Jeramaz finds that in his neighborhood, sugar accumulation, measured as brix, can happen fast.

"Phenol, which we all need for great wine, is behind sometimes two weeks," Jeramaz said. That leads the grower to figure the grapes are not ripe yet.

"By the time they are happy with tannins in skins, we are talking 28 brix," Jeramaz said. "That's 17% alcohol. Nobody wants 17% alcohol." Boosting the number of grapes on the vine helps, he noted.

"We would like to slow down sugar accumulation in plants," Jeramaz said. "By putting a bit more grapes, that's what happens. Not only have we doubled our yield, we have quality better than ever."

Organic winegrape growers are sharing one sizable problem with their conventional cousins: California's punishing drought.

"It's pretty brutal," Brinkley said. "The North Coast, especially, we've certainly seen some serious curtailments of water use."

Brinkley said his vineyards' organic status may help them weather the dry years.

"Because of the years of cover cropping and composting, we're really trying to increase and grow the organic matter in the soil and allow the soil to be that bank, or that reservoir, that we're constantly adding to," he said. "The vines are able to withstand these extreme pressures better because we've been investing in them via compost and cover crops, and the root mass and the biology of the soil."

Barra said she'd already reduced the crop estimate to wineries by 30% at the outset, and "as we deliver, we're down another 20%," she added.

"It's happening across the board," Barra said. "The tonnage just isn't there." She said her vineyard foreman reported that "the rain is just not getting down to the roots and pushing the nutrition down."

Conventional farmers thinking of making the switch are in for a long commitment—the vineyard has to wait at least three years after the last application of any prohibited materials before it can be certified. Brinkley said the biggest barrier "is getting alignment from the top, the executive leadership, all the way down all the levels and into the field."

(Kevin Hecteman is an assistant editor of Ag Alert. He may be contacted at

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item.

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