Sum-frequency generation (SFG) of >16 W of 589 nm light has been achieved by a single pass through a 20 mm long, undoped, periodically poled, nearly stoichiometric lithium tantalate (PPSLT) crystal. This, to our knowledge, represents the highest reported average power in the visible produced by a single-pass SFG crystal and the highest visible average power produced by PPSLT. The stoichiometric lithium tantalate crystal was grown directly from the melt without magnesium doping.