(Reuters) - Rain, cold and mold are threatening this year's California wine harvest prompting one vintner to call in a helicopter to fight Mother Nature. "We're about three weeks late. The whole state is late," said Chuck Wagner, the owner of Caymus Vineyards, the iconic Napa winery. "Cabernet Sauvignon was definitely affected," he said of the popular varietal. In neighboring Sonoma, Pinot Noir growers were finding botrytis - an unwelcome mold - on their grape bunches after recent rains. California produces about 90 percent of the wines made in the United States and the state's Department of Food and Agriculture is estimating that only 3.3 million tons will be produced, down about 9 percent from 2010.