Oak wilt is a serious problem in Austin. If not managed properly, the oak wilt fungus can wipe out an entire neighborhood’s population of oak trees in a few years. Our ancient native oaks are a living link to our past and every effort should be made to salvage them. So, what do you need to know? And, how should oak wilt be managed?

This first thing you need to know is that there is an enormous amount of mystery that surrounds oak wilt. Many of our questions do not have answers. Oak wilt is very difficult to diagnose, its rate of spread is highly variable and oak wilt treatments are inconsistently effective. There are a few
symptoms that are associated with the fungus, but you need to understand that symptom and diagnosis do not have the same meaning. There are other tree disorders that cause the same symptoms as oak wilt. The best way to identify oak wilt is by identifying a pattern of spread. We know that it

spreads from tree to tree through interconnect roots at a rate somewhere between 50 and 100 feet per year. Oak wilt is theoretically capable of spreading above ground, but 95% of oak wilt in the central Texas area passes under ground. The above ground spread is very complicated; what you need to know is that above ground spread is primarily a problem in more northern
areas where the forest composition is different.

If you suspect you might have oak wilt on or near your property you’ll need to know the best way to manage it. The two most important aspects of a good management plan are the two most often overlooked aspects. You need a good diagnostic process and you need regular follow up inspections. A good diagnostic process is a series of property inspections, since a
pattern of spread is the best way to identify oak wilt. We’ve already discussed that leaf symptoms are not diagnostic, and laboratory isolation tests are usually inconclusive. You should spend at least one full year with 3 or more inspection visits prior to engaging any treatments because treatments mask the visual symptoms of oak wilt and make identifying the pattern of spread impossible. Even after treatments, the follow up inspections are equally important to ensure the management plan is working. I
recommend a tree health care program in conjunction with the follow up inspections to help ensure that no other problems show up. If you are able to reasonably diagnose (through pattern of spread) that you do have oak wilt, the two treatments available are trenching to break underground root connections and injections with fungicides.

There are many, many more details that are critically important to managing oak wilt in the Austin, Texas area. This article is intended serve as an introduction to oak wilt. Visit my series on oak wilt for more specific details.