The new labeling comes with stricter rules, including a reduction in the permitted levels of sulfur dioxide, which can cause allergic reactions in asthma sufferers. (Some critics say sulfur dioxide, low levels of which are naturally present in many wines, also causes headaches, though I have yet to see conclusive evidence on this.)

The new rules have not resolved debates over what “organic” means, or should mean, when it comes to wine. For producers, merchants and consumers, trans-Atlantic differences on this issue have caused a different kind of headache.

In the United States, there are several “organic” categories, including “organic wine” and “wine made from organic grapes.” The former label is so restrictive, barring the addition of sulfur dioxide, that only a handful of producers qualify. The “made from” category is more inclusive, permitting winemakers to add sulfur dioxide and even a small percentage of conventionally grown grapes.

Wine was excluded from a recent pact under which the European Union and the United States agreed to recognize each other’s organic regulations for a variety of other agricultural products, allowing either label to be used in each market.

Negotiators are set to meet this autumn to try to come up with a solution for wine, but in the meantime, E.U. wine sold in the United States will have to meet the U.S. requirements. That means most wine sold as “organic” in Europe will need to be re-labeled as “made with organic grapes” in the United States.

Paolo Bonetti, president of Organic Vintners, an importer in Boulder, Colorado, says the ban on added sulfur dioxide in organic wines in the United States has held back the growth of the category because it is almost impossible to meet the regulations.