In the fall, deer will nibble the upcomming buds off the apple trees, ruining the tree and the new to be fruits. For tomato cages, I use a medium weight wire fence with approx. 3 inch openings, very flexible. The tomatoes are gone, the deer are browsing. I lay the cages on the ground in a circle around the apple trees.
On the list of ways to keep deer out of your garden is the use of objects that move in the wind or reflect light. This page is about how to frighten deer with plastic bags.