Young maple tree problem
Thank you for your question. Unfortunately, there are a number of diseases and insects that can cause defoliation, or failure to create foliage, and, without a closeup look at the remaining leaves and, perhaps, a soil test, it is impossible to diagnose with only one photo. I suggest you take the picture, along with some leaves from the tree, and visit your county Extension office so personnel there can diagnose and recommend solutions. I am sorry it has taken so long to respond to you; I'm certain the staff there will be immediately helpful. Good luck!