Fences or cages are a must. You can find liquid products to spray on the tree that contains blood meal and rotten egg/sulfur as those smells keep deer away. You can respray those each time it rains as they can wash away.
Fence them to keep.them out.
Deterrents can work for short times, but you have to switch them up. Try Irish spring soap, human hair, blood deterrents, etc.
Different tyoes of fence can keep them away, but ultimately, a big wildlife fence is best.