Answer: It is probably experiencing transplant shock and suffering from roots lost during the digging process. The best thing to do is to keep the soil evenly moist, do not let the soil dry out. Using several inches of organic mulch over the root area will help to keep it naturally moist.
Use your finger to dig into the soil and feel it. If it begins to dry then you need to water. Water slowly and deeply so it soaks down deep to the deepest roots. After watering, wait a few hours and then dig down to see how far the water went; sometimes it can be surprising. Be sure you are watering deeply, not just giving a light sprinkling.
If it lost some roots when you moved it, consider trimming the branches somewhat, maybe shorten the branches by a third. This will help reduce the stress on the plant.
If your tree was moved in an open vehicle, it may have suffered foliage damage due to the wind during travelling. The old foliage may drop as a result, but hopefully it will releaf in a few weeks. If the roots were allowed to dry out during the move, there would be some root damage which would also lead to leaf drop. Again, hopefully it will recover and releaf in time.
To give your tree a little special care, you could top dress with some good quality compost. Do not fertilize it as the increased pressure to grow will add to the stress. The most important thing is to keep the soil damp and be patient.
Good luck with your tree.
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