Whats the call?
 

I have a game coming up and in the outfield there is overhanging trees. What’s the ruling on if the ball hits the tree in fair territory?

Depends on the ground rules, but normally (and in align with USA Rules) it is played as if it hit the ball. IOW, the ball cannot be caught for an out. If it leaves the park, it is a HR and counts toward the total. If it stops it from leaving the park, it is simply treated as a fair, uncaught batted ball.

But again, many places that have fields with such an issue have developed their ground rules which may vary from the rule book.(speaking USA)