Heat oven to 325 degrees. Place roast on rack in shallow roasting pan. Do not cover. Roast to an internal temperature of 150 degrees.
Meanwhile, make sauce by heating applesauce, jelly and horseradish in small saucepan, only until blended.
When roast reaches 150 degrees. spread about 1/4 C. of sauce over roast. Continue roasting about 15 minutes to glaze roast and until internal temperature reaches 160 degrees. for medium doneness. Serve remaining sauce with roast.