We have heavy deer and moose pressure; 20-30 deer in the area and 4-6 moose including a bull. The combination makes protecting trees a major challenge. Especially when you have neighbors who leave food out for them and have habitualized them to humans. Browse line for deer is 5-6 feet, browse line for moose is 8-9 feet. In autumn or spring in our area the Brix on tree tips and bark for a fruit tree is like crack to deer and especially moose. My recommendation is if you have serious deer or moose browse pressure to relocate your orchard.
We mistakenly planted a very large installation (3+ acres, maybe 1500 plants) of food forest in a tree friendly area of our farm, but it gets massive pressure from animals. Way more than we thought. I have tried all the passive solutions (dangly things, soaps, bone meal, predatory animal piss, my piss, running about yelling) and the work for about 2 weeks with deer and they adapt realizing there is no actual threat or risk. The moose don't care about any of these techniques. They only work if you are dealing with light pressure from deer.
Fishing line fence was a fail, it wasn't successful for more than 48 hours. Netting around individual trees was a fail, lasted until the moose came through, then once damaged the deer go in. Plus the moose damage the saplings when they take down the mesh around the larger saplings. Eventually the trees outgrow the mesh or grow through it and you get bonsai trees with no flowering. Tree tubes worked until plants poke out the top, then the moose and deer chew off the leader growth tips.
We trialed a number of 3D fencing options. The issue we run into is what stops a deer doesn't stop a moose, and what stops a moose doesn't stop a deer. A 6 foot fence, with high tensile lines every 16" from 8" off ground to top, running alternating hot/ground followed by a second fence 36" inset with standard 4 lines hot/ground alternating running at 5000v minimum would do it. Cost would be less than game fence, but not cheap. $5/linear foot for the big one, $3/linear foot for the short. (Canadian) $750-1000 for the energizer if you go solar (250w panel, marine battery, charge controller, 6 Joule energizer minimum). This is based on actual field trials of around a dozen 3D fencing systems over a 7 year period.
A traditional wildlife fence (12ft page wire, barbed line on top, post spacing every 15 ft) works too. But costs a fortune to install and maintain, and is ugly, and a harsh intervention.
If I total up the costs of time dealing with this stuff, and the fencing supplies and labour, I would have saved the cost of moving the whole orchard for sure. We put in a 3D fence around our new market garden and orchard area and are having success keeping the moose out and redirecting 90% of the deer pressure to other areas of the farm. It still needs some tweeks, as the spacing between the two fence lines is set too wide for deer in order to manage the moose, so a seasonal or short term third line on step ins might be needed until the deer are trained to the area. The key with electric fence and wildlife is diligence and persistence. You must keep that fence screaming hot, baited with scent traps on the hot lines, and on 24/7. Otherwise the animals start learning to get around the system and challenge it more. If you keep on it the system can retrain the entire wildlife pattern in your area, which is a far better long term solution than killing them all out or heavy handed fences.
Works okay for wapiti (elk) and bear too. As long as you can get it up past 7500v.