When I began the orchyard I was most concerned with animal damage from mice or rabbits gnawing the bark and I fashioned tree guards from various materials, with ¼ inch hardware cloth being the most satisfactory. Deer came into the picture once they browsed some newly planted trees nearly to the ground (fortunately the tree guard for mice and rabbits interrupted their browsing), and raccoons announced their presence by decimating a cherry tree. Birds and squirrels have stopped by for a taste, and of course there is the world of insects to contend with.
I am, in general, happy to share my fruit with whatever desires to eat it – providing it is done in a non-damaging way. The occasional fox or coyote have meandered through, and they seem happy enough to suffice with windfalls. So far I have not had any significant issues with birds; they do enjoy the cherries but for whatever reason work their way from the top down, and as it is a full sized tree I can’t reach the top anyway so we are not in any competition. Unfortunately, deer and raccoons do not follow the same code of conduct.
My primary concern with deer is the damage they do to young trees by browsing on new growth. Unless they are quite hungry they will typically leave older growth alone. I have seen new shoots browsed to the trunk as effectively as if I had pruned them, and nearly as cleanly cut. They do seem to have taste preferences; apple trees are at the top of their list with Bramley’s Seedling seeming to be their favorite. It took years before it managed to grow high enough to clear the browsing danger, while the Claygate Pearmain and St. Edmund’s Pippin on either side were left pretty much alone.
Fencing the entire orchyard to keep the deer out was not a realistic option, so I opted to build deer guards around each tree instead. The initial version was made of wood lath and the plastic net sold as deer fencing, however that proved unsuitable as the trees grew into the netting and the device devolved into an annoying tangle. The second version was more successful. It is made of a length of 4 foot tall wire garden fence approximately 5 feet long, which is fastened together to make a cylindrical cage. Two stakes are driven into the ground either side of the tree, and the guard is attached to them with a piece of chicken wire placed over the top. When the tree grows tall enough that the top near the chicken wire cover, a similar cage is made of 2 feet wide chicken wire and attached to the top of the existing cage. When the tree grows out of the top of the extended guard, it is taller than deer can easily browse and the entire guard can be removed. Obviously the nature of the guard forces the tree to grow vertically rather than developing side branches, and those side branches which do grow need to be trimmed periodically as they will either grow upward along the edge of the cage or grow through the cage openings and become deer fodder. I have found it helpful to allow a few sacrificial branches to grow up along the side of the cage in order to keep the main trunk fairly central; this reduces the potential for damage to the main trunk from rubbing against the cage. These branches are pruned off when the guard is removed.
Raccoons are more troublesome than deer. Deer browse what they can reach and otherwise rely on windfalls, but raccoons will climb the tree and strip it bare if not checked. I have actually watched a raccoon climb into the cherry tree and eat it’s way out along a branch until it got so far out the branch could not support it anymore and it fell off, then climbed back up and repeated the process. The raccoon is a fruit tree destroying machine, leaving piles of leaves and broken branches under the tree and a few hours later piles of partially digested cherry pits wherever it happened to be. The year I moved in there were no raccoons and I harvested about 70 lbs of cherries. The next year the raccoons came and the only cherries I harvested were a couple of underripe ones from a branch that they had broken off but which got lodged too far out in the tips of other branches for them to get to. The next year the tree set very little fruit as many of the fruiting spurs had been broken off by the raccoons the year before, and the raccoons came back and once again got everything the tree did grow.
To make things less attractive for deer and raccoons I have tried a mixture of chemical and physical deterrents. The raccoon deterrents based on peppers (in either flake or liquid form) had no effect – the day I watched the raccoon climb the cherry tree was just after I had applied both types and it looked like the raccoon noticed something uncomfortable but the draw of the cherries was stronger. What has worked against the raccoons was hooking up an electric fence charger to two pieces of electrically isolated chicken wire surrounding the base of the tree or having a dog in the vicinity. For deer I have had some positive results with a deterrent spray made of eggs, Tabasco sauce, and garlic.