Now that many chemical insecticides are banned , what can I use to spray on my apple trees to prevent rot and insects?
Certified GKH Gardening Expert
This is a great link that will help you.
Your best bet is to keep up with proper maintenance of your tree and its surroundings. Proper pruning, weeding, and watering are your first defense. If all else fails here is a link on a multitude of possible pests and their control;