It's a top tool of organic grapegrowers. But is copper sulfate truly safe for vineyards? A new push by European leaders to reduce—and eventually eliminate—copper compounds used by organic and biodynamic winegrowers is making the future of organic viticulture uncertain in some wine regions.
Vintners say that without effective alternatives to copper, crop loss in damp years will make organic vineyards economically unsustainable, forcing them to turn to synthetic chemicals or bankruptcy. But as the E.U. moves toward a vote on whether or not to reauthorize the use of copper compounds, leading winemakers argue that Europe's current approach to organic farming is too simplistic, and advocate a more nuanced strategy.
"Natural is good, synthetic is bad? It's too basic to reason that way," said Charles Philipponnat, CEO of Philipponnat Champagne. "The objective is to make fine wine in a way that doesn't leave a negative impact for our children."
Since the 1880s, copper compounds, typically copper sulfate mixed with lime, have been used by grapegrowers to fight fungus and bacteria threats to vines. For organic growers, who cannot use modern fungicide sprays, copper sulfate remains the most effective weapon against downy mildew. While wine grapes were the original target crop, copper compounds are also widely used for organic potato, tomato and apple farming.
But risk assessments by public authorities like the European Food Safety Authority (EFSA) show that copper compounds pose risks for farm workers, birds, mammals, ground water, soil organisms and earthworms. These risks make copper unpalatable to many vintners.
"Copper is a heavy metal and it stays in the topsoil. It's not natural; it's not clean," said Philipponnat. While his Champagne house has eliminated herbicides and chemical fertilizers and uses natural vine treatments, he doesn't rule out synthetic remedies. "I don't think it's bad to use synthetic molecules. Some synthetic molecules disappear much more rapidly. Some synthetic treatments are better than copper, but they aren't accepted for organic viticulture."
Can organic farming endure with less copper?
Nearly 17 percent of Italy's vineyards are certified organic. In France, 10 percent of the country's vineyards are certified organic or in the process of certification. In Italy, Hungary and Slovenia, roughly half of small and medium-size estates are organically farmed.
Under current E.U. rules, certified organic growers are allowed to spray about 5 pounds per acre per year. But there is also a so-called smoothing mechanism: Growers can spray more in wet years as long as they don't exceed 27 pounds per acre over a five-year period.
"In some areas they used [6 pounds per acre] this year," said Lorenza Romanese, policy advisor for the E.U. Confederation of Independent Growers.
Those days are numbered. E.U. lawmakers are currently leaning toward a 25 pound per acre limit over a seven-year period (3.5 pound per acre per year average) starting in January 2019. Initially, E.U. lawmakers did not include the "smoothing mechanism," but the French predicted more than half of the organic vineyards would return to conventional farming. Lawmakers acquiesced to a smoothing mechanism.
"At least we're not dead," said Romanese. "For all of Europe, with the smoothing mechanism, we can survive." But he says organic farming will shrink. "We lose Champagne and a few regions in the Loire. The Prosecco region and Trentino–Alto Adige, those two won't make it with [3.5 pounds]."
In Burgundy, Philippe Drouhin of the Beaune-based merchant house Joseph Drouhin, told Wine Spectator, "I think that will be a hard challenge for all of us, big and small estates."
Not all regions will be as impacted. "It depends where you grow the vineyard. If you are in Bordeaux or Alsace, it's different than if you are in Châteauneuf-du-Pape or Provence," said César Perrin, a fifth-generation grower in the Rhône whose family owns Château de Beaucastel and multiple other properties. "The last rainy vintage was 2008. This year we used [2.7 pounds per acre]."
While the concerns of organic farmers have not been ignored, E.U. Health Commissioner Vytenis Andriukaitis said, "The protection of health and the environment is my main priority."
With environmental and economic sustainability on the line, leading Spanish winemaker Miguel Torres told Wine Spectator, it's time to reconsider where we grow wine: "The most important challenge is climate change. Some organic vineyards have a higher carbon footprint than conventional vineyards. If we listen to nature more, ask ourselves, are we in the optimal place to grow wine grapes?"
What are the options for a greener future?
Some vintners believe they must look beyond copper. "We believe in organic viticulture, but I don't believe it's enough. It's the past. We have to look to the future," said Torres. "You have to listen to nature. If you have a warm, dry climate, then organic viticulture is fantastic. But if you try organic viticulture in places with high amounts of rain or humidity, the only recourse is fighting with copper, and you will pollute your vineyard with copper."
At the same time, Drouhin emphasized that vintners know the disease much better than they used to. And more precise weather forecasts—"To the millimeter is essential," said Drouhin—would allow growers to use sprays more effectively.
"I see a future for using essential oils and certain bacteria for fungicides," said Philipponnat, who said they had also had good results with a nettle-based spray.
In the Rhône, Perrin said, "We use an orange peel spray that helps a lot, and we use a 10 percent whey mixture spray that helps fight mildew. We are pleased with the results."
Both Perrin and Drouhin have also adopted the biodynamic philosophies. "With biodynamics, we help the vine be more resistant against those pathogens," said Drouhin. The frustration for biodynamic growers is the dearth of scientific research to back up their anecdotal claims. "Scientists say it's not a science," said Drouhin.
Scientists have, however, come up with promising innovations, some with ties to organic and biodynamic methods. For instance, in Bordeaux trials are underway using a spray made with Atlantic algae that has been successful in fighting mildew and has had mixed results in fighting botrytis. The product, created by engineer-enologist Laurent de Crasto and Lionel Navarro of the French National Center for Scientific Research, should be commercially available by 2022.
Meanwhile, the French National Institute for Agronomic Research, INRA, has been busy creating disease-resistant grape varieties. In October, they announced the sale of 400 cases of wine made from Artaban, one of the four new grape varieties recently approved for production that are more resistant to fungi. But many winegrowers are skeptical. "The ones we've tried, they've changed the taste of the grapes and the final wine," said Torres. "Will consumers accept the taste?"
The main lesson seems to be that organic farming cannot only look to past methods if it is to move into the future. "I'm convinced that if we invested [enough] financial means," said Drouhin, "we would find [an alternative] to copper."
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