Line a large baking sheet with foil, and coat with cooking spray. Insert 1 (6-inch) white dowel into stem end of each apple.
Combine sugar, corn syrup, water, and candies in a small heavy saucepan over medium heat. Cook until sugar dissolves, stirring occasionally. Cook, without stirring, until a candy thermometer registers 300° (about 8 minutes). Remove from heat.
Working with 1 apple at a time, holding apple by its dowel, dip in syrup, tilting pan to cover apple. Turn apple quickly to coat evenly with syrup; let excess syrup drip back into pan. Place apple, dowel side up, on prepared baking sheet to harden (about 5 minutes).