En EspaŅol

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
rate this answer
Not Yet Rated

Friday - November 22, 2013

From: Dallas, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Is post oak resistant to oak wilt from Dallas TX
Answered by: Barbara Medford


I am confused. The NPIN website says that Post Oak IS susceptible to oak wilt, but all the other information I have been able to find says that it is resistant to oak wilt and rarely gets the diesase. Can you tell me where the information on the NPIN website originates from or if perhaps it is an error?


Don't feel alone. The facts on Oak Wilt are confusing to everyone. We did find the line on our wepage for Quercus stellata (Post oak) that you mentioned:

"Susceptible to oak wilt. Not often used in landscape situations. Slow-growing and long-lived." The Post Oak is a White Oak.

We will go to another source, texasoakwilt.org, for some clarification, if possible. We suggest you scan the whole site. From the Introduction to that site: "All oaks (Quercus spp.) are susceptible to oak wilt to some degree, but some species are affected more than others." Also from that website:

"Patterns of Tree Mortality

 Most live oaks defoliate and die over a 1- to 6-month period following initial appearance of symptoms. Some live oaks take longer to die, and a few untreated trees may survive many years in various stages of decline. Occasionally, a few live oaks in an oak wilt center may escape infection and remain unaffected by the disease.

Red oaks never survive oak wilt and often die within 3 to 4 weeks following the initial appearance of symptoms. During summer months, diseased red oaks often can be spotted from a distance because of their bright autumn-like coloration in contrast to the surrounding greenery."

From the Texas A&M Forest Service, here is a map of the counties in which oak wilt appears in Texas. Also from that site:

"Oak wilt has been found in over 73 counties and in almost every city in Central Texas, as well as, Abilene, Midland, Lubbock, Dallas, Ft. Worth, College Station, Houston, and San Antonio. It can be a problem wherever live oaks tend to be the predominate tree. It does not matter whether they are transplanted or naturally grown. An individual tree’s age, size or previous health status does not make it more

"Red oaks, particularly Spanish oak (Quercus buckleyi), are very susceptible to the fungus.  White oaks, like post oak (Q. stellata) and bur oak (Q. macrocarpa), are resistant to the fungus and rarely die from the disease."

Bottom line: If you want to add oaks to your landscape, a post oak is probably less  likely than the red oaks and live oaks to contract Oak Wilt. If you choose the post oak or have some on your property that you wish to protect, you should still follow the management policies from the Management section of texasoakwilt.org.


From the Image Gallery

Coastal live oak
Quercus virginiana

Coastal live oak
Quercus virginiana

Texas red oak
Quercus buckleyi

Texas red oak
Quercus buckleyi

Post oak
Quercus stellata

Post oak
Quercus stellata

More Trees Questions

How to Identify Male and Female Texas Persimmon Trees
October 07, 2014 - I have just learned that Texas persimmon trees are either male or female. Is it possible to tell which is which when buying one? I am planting on 50 acres near Blanco. Do I need one of each? I'd ...
view the full question and answer

Watering practices for live oaks in drought from New Braunfels TX
September 04, 2011 - We have conflicting info about watering live oaks. An arborist says to water now using soaker hoses or small sprinklers and a landscaper who spoke to our garden club said that after August is too late...
view the full question and answer

More trees to go with live oaks in Schertz TX
July 13, 2010 - We moved to a new house that has two recently planted live oak trees. Other than those two little trees there is nothing else on the property. Because of what I read about the oak wilt I would like ...
view the full question and answer

Tree roots in sewer from Paragould AR
September 30, 2012 - I have beautiful pecan trees, an apple in the back yard, a pine on the west side of the house and pecan trees in the front yard. Two trees are interrupting my sewer systems (at least one in the back y...
view the full question and answer

Safe branch length of oaks in Clayton NC
November 06, 2011 - I have 2 very large oak trees in my yard and I am concerned about the length of the branches over the house and driveway. Most seem larger than 4" in diameter. What is a safe length for these branc...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center