With only 1 to 2 percent of wine grapes picked on the North Coast, an extraordinarily late harvest is likely to turn hectic in October. “We have 1,500 tons to pick and we've picked five,” said Ned Hill, owner of La Prenda Vineyard Management, which oversees 420 acres in the Sonoma Valley. Many of the grape varietals are 10 to 14 days behind schedule due to the cooler summer, he said. Already this season growers have endured a cool summer's harvest delays, freakish sun damage and sluggish sales for the region's premier agricultural crop. Now they face the challenge of completing harvest before rain and autumn chill deprive them of a significant portion of tonnage.