This is an inexpensive, homemade remedy I found online. I haven't tried it, but thought I would pass it to you. I pray it will help your trees.
Deer Repellent
1 Separate the egg yolks from the egg whites. You will need enough egg yolks to fill a spray bottle with a mixture that is 20 percent egg and 80 percent water.
2 Stir the egg yolks into the water, mixing them thoroughly. Strain the liquid to remove the white stuff on the egg yolk, it will clog the sprayer. Fill the bottle with the solution.
3 Spray the homemade deer repellent around the trees that are being rubbed, as well as any others you want to safeguard. If you wish, you can also spray around the perimeter of your property.
4 Reapply the egg mixture after 30 days have passed. While the mixture is resistant to weather, it needs to be reapplied to maintain its effectiveness.