Vintners currently incur large costs fighting diseases like powdery mildew, mainly by using an array of chemical sprays. If a disease-resistant grape could be engineered without diminishing its quality, some vintners would welcome it.

"We spend a fair amount of dollars ... [and] time fighting powdery mildew in the vineyard through a spray schedule," says Stephen Reustle, owner and wine maker at Reustle Prayer Rock Vineyards, in Oregon, a region known for its pinot noir. "From a general point of view, a disease-resistant pinot noir grape would be a real economic benefit to the vineyard owner."

Still, there is reluctance among many wine farmers to use genetically modified organisms. In 2005, a proposed ban on planting or cultivating genetically altered crops divided Sonoma County, CA. Ultimately, voters rejected the ban, but similar prohibitions have been passed in Marin and Mendocino, CA.

"It'll be a long time before we can use this," says Steve Smit, head of vineyard operations for Constellation Wines, the purveyor of the Robert Mondavi label. "There are a lot of good arguments on both sides: you no longer have to use chemicals, but maybe you're changing something that's important elsewhere in the ecosystem."