(Sarah of the Clue Crew tests a beaker of wine in an aging cellar in Napa Valley, CA.) If this level in wine drops below about 3.0, the wine will be probably be a trifle sharp
(Sarah of the Clue Crew points out a grape vine in the vineyard in Napa Valley, CA.) Because American root stock and Europe vines resist different pests, growers combine them using this technique