The answer to 'tree turning brown' is that there are several common causes, including drought, disease, pests, or damage to the tree. Symptoms may include leaves turning brown and dropping prematurely, or the entire tree appearing discolored and unhealthy.
If only a few leaves or branches are affected, it could be a minor issue that you can address with proper watering, mulching, or pest control. However, if the problem is widespread or the tree is in severe distress, it's best to call in a professional arborist to diagnose and treat the issue before it becomes too late to save the tree.