PERU SUGAR HARVEST SEEN LOWER -- USDA Sugar production in Peru for the 1986/87 season has been revised to 593,000 tonnes (raw value), down 10 pct from the previous forecast and 21 pct below the 1985/86 harvest, the U.S. Agriculture Department said in its World Production and Trade Report. It said while rains in the northern mountain region are improving the supply of irrigation water, the major benefits will not occur until the 1987/88 season.