Stir apple, strawberries, blackberries, raspberries, and rhubarb together in a bowl. Pour lemon juice and sprinkle sugar over fruit mixture and toss to coat.
Line a 9-inch pie pan with prepared pie pastry. Turn apple mixture into pie pan. Cover with remaining pie pastry and pinch and crimp edges to seal the crusts. Cut several air holes into the top of the pastry.
Bake in the preheated oven until crust is golden and fruit is tender and bubbling, 30 to 40 minutes.
