Ask Mr. Smarty Plants

There are three species of the genus Quercus with the common name "Spanish Oak" in our Native Plant Database: Quercus buckleyi (Buckley oak), Quercus falcata (southern red oak) and Quercus texana (Texas red oak). You can follow the plant links to pages on the individual plants and determine which is growing in your area. It doesn't really matter in this context, however, as all are red oaks. Cause for concern? You bet! Species of red oak get Oak Wilt more frequently and succumb more readily than white oaks. The main period of infection is in the spring, with symptoms in red oaks occurring early in May. That is one ray of hope, at least, since the symptoms in your area were obviously appearing earlier than that. Please read this USDA Forest Service article on Oak Wilt by Charles O. Rexrode and Daniel Brown, which includes pictures of infected trees, ways the disease is transmitted and possible ways to prevent infection. There is no known cure for Oak Wilt.

There are other things, rapidly changing temperatures, insects, etc. that might be causing those symptoms, but it's out of our ability to diagnose or recommend from a distance. You should contact someone in your area who specializes in tree diseases and get them onsite to try to figure out what is going on. We would suggest you start by contacting the Texas A&M AgriLIFE Extension office for Hays County and asking for help. If this is as widespread as you say, they may already be aware of it and can give you information. At the very least, they can perhaps recommend a licensed arborist to come out and try to diagnose the problem. We very much hope that you find out that not only is it NOT Oak Wilt, but that the leaves are already starting to leaf out fresh and green.