But the weekend salons I attended bore witness that these wines are more than just a splash in the glass; they attest to a movement that has been growing for years in France and elsewhere to produce quality wine that is as pure as it can be.

There is broad agreement that France, the European Union’s largest agricultural producer, uses too many pesticides on all kinds of produce. The nation is the third-largest consumer of pesticides in the world, after the United States and Japan. Apples grown in southern France, for example, are subjected to about three dozen pesticides.

The pesticide and big-agriculture lobbies are strong, resisting any initiative that could affect farm yields, so there is little political will to take risks. In late January, the French agriculture minister, Stéphane Le Foll, announced that a government pledge to cut pesticide use in half by 2018 would be delayed until 2025. “We set a goal that was too ambitious without giving the means to change the production model,” he said in a newspaper interview.

And the pesticide controversy is only part of a larger debate about the deployment of chemicals in vineyards. A 2013 report by a team of scientists near Bordeaux examined more than 300 French wines from the 2007 and 2008 vintages of the Rhône and the wider Aquitaine region. It found that 90 percent contained traces of chemicals commonly used to treat vines. Even some organic wines were tainted with pesticide residues, most likely a result of contamination from neighboring vines.

One challenge facing wine producers is that there is neither a definition nor regulation of what constitutes a “pure” or “natural” wine in France. Wines defined as organic by the European Union are produced from organically grown grapes that can be chemically manipulated, with limitations on the use of sulfites, in the winemaking process. Many producers call their wines natural, which connotes a further step: Nothing can be added or removed during winemaking. Some natural winemakers add a small quantity of sulfites at bottling; others do nothing more than bottle fermented grape juice, call it wine and hope that it’s fit to drink. Biodynamic methods involve a holistic, almost spiritual approach to the ecosystem that treats the soil as an organism in its own right.