Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 4 ingredients in a large bowl. Cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Stir in oats. Add buttermilk to flour mixture, stirring just until moist. Gently fold in nectarines.
Turn dough out onto a lightly floured surface; knead lightly 3 or 4 times with floured hands. Pat dough into a 7-inch circle on a baking sheet coated with cooking spray. Cut dough into 10 wedges, cutting into but not through dough (do not separate wedges). Lightly coat tops of scones with cooking spray; sprinkle with turbinado sugar. Bake at 425° for 20 minutes or until lightly browned.