Preheat oven to 375°.
Combine plums and next 5 ingredients in an 11 x 7-inch baking dish coated with cooking spray.
Combine oats and next 3 ingredients in a medium bowl. Cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Add turbinado sugar, stirring well.
Sprinkle oat mixture over fruit mixture. Bake at 375° for 45 minutes or until topping is lightly browned and fruit mixture is bubbly. Let stand 15 minutes before serving.