Ask Mr. Smarty Plants

Since you live in either Northern Travis County or Williamson County, we are going to assume that you have a Quercus fusiformis (plateau oak), which is native to that area. Unfortunately, we cannot begin any discussion of problems with a live oak without talking about Oak Wilt. To give you more information about the appearance and symptoms of this disease, see this USDA website Identify, Prevent and Control Oak Wilt.  

There are two other possible reasons for the curling of the leaves, Oak Anthracnose and Oak Decline. Oak Anthracnose, while it causes curling and discoloration on lower leaves, seems to affect only white oaks, not live oaks. Ditto with Oak Decline, which is most often caused by insects or diseases that invade a tree already in trouble for some other reason.

It is almost impossible to diagnose a plant disease without seeing it. You would be advised to contact someone who is trained in the recognition of oak diseases and arrange to have the tree examined. Go to the Texas Oak Wilt Partnership webpage for some suggestions on how to get help. Another valuable source of information on tree diseases is the Texas A&M AgriLIFE Extension Office for Williamson County. There is always the possibility that some insect of which we are not aware is causing this type of symptom in your area. The website has contact information, and they possibly even can give you a source for diagnosis.