What conditions is it in? Pot? Ground? full sun?

I MOVE IT FROM GROUND TO GROUND, IN FULL SUN.

It is probably in shock. You probably cut off some roots... keep watering it, see if it comes back. Trees sometims are best moved during dormant season, if you have one.

Enrico, a good sign that a tree a coping well with stress is if the dying leaves defoliates and drops easily off the branches. I think its usually a bad sign if the leaves dry and wilt but can't be remove easily from the tree. How large is your tree? Do you have any pictures?