From the L.A. Times:

This sounds familiar: a national consumer group is fighting to maintain organic standards against industry people who want to weaken them. But when it comes to "organic wine," the well-meaning consumers may actually be discouraging more organic farming.

That's because of a quirk in the labeling laws. Currently for a wine to be labeled " USDA Organic" — a coveted seal of approval for most foods — it must have no added sulfites. However, most winemakers feel that sulfites are crucial in winemaking — they discourage spoilage and preserve fresh fruit flavors. Unlike most organic products, wine may sit for years before being opened. Furthermore, most wines contain some level of sulfites anyway since they are a naturally occurring byproduct of fermentation.

As a result, even though organic food is one of the fastest-growing categories in the supermarket, "organic wine" is an afterthought.

Why isn't more wine 'organic'?