I was told by a game warden that if you put up a hot wire right about nose height, then put pieces of aluminum foil spread with peanut butter every few feet. After a while, the deer learn to give anything that smells like peanut butter a wide berth, so you just hang the foil with peanut butter on the trees. It sounds like a good idea, actually.
A single strand of hot wire around knee high to an average man will do the trick and you don't have to bait the line....they are curious enough to sniff it to gauge the height for jumping it and will get the zap. We kept them out of gardens like this for over 40 yrs, never had a deer cross the line.
For individual trees wherein it would be silly to try and run fencing, you can just build a wire cage for them or slit PVC pipe and place around the trunk.
I tried running an electic goat fence around a small stand of fruit trees. It does Not stop elk. Not even sure it slowed them down.
Everyone around here puts up a 6 to 8 foot fence. Same goes for gardens. I've given up on trying without fencing. Been setting up raised beds in the 25x50 silkie courtyard for next year. Silkies arent very destructive when let out except grass.