Welcome to the board taco's place!
I found after some discussion on the board that some green hardwoods still work well for smoking. I have used green fruit wood with good results. Go ahead and use your apple but I would suggest removing the bark first.
Here is some chatter on the topic that you may enjoy reading:
Green Wood or Dry Wood? Ginger or Mary Ann
Wood for Smoking
Wood for BBQing
Hope this helps.