Growing Things: Lawn fertilizer can hamper apple tree production

Q: We would appreciate your advice regarding an apple tree. We have one apple tree that is a several years old, which we have fertilized with all-purpose fertilizer, and it has never borne fruit. Would the fertilizing regime described in one of your recent columns — alternating general and high phosphorous fertilizers — be appropriate for this tree? We have some haskap berry bushes nearby which we also fertilize with all-purpose fertilizer, and they bear lots of berries, so we