Oak Wilt

What is Oak Wilt?

Oak wilt is a lethal disease of oaks at epidemic levels in Central Texas. The disease is caused by the reaction of susceptible oaks to the fungus Ceratocystis fagacearum.

The fungus causes the water conducting system of the tree to become plugged so that the tree wilts and drops its leaves. Most infected oaks die within weeks or months.

Why should we care about oak wilt?

When one oak is infected with the oak wilt fungus, it transmits the fungus through the roots to surrounding trees. Oak wilt can keep spreading until the entire neighborhood is an "oak wilt disease center" with hundreds of dead and dying oaks.

Oak wilt has a high mortality rate (85 to 100%), it spreads rapidly (an average of 75 feet per year) and it is difficult to control (roots must be cut in a wide circle around the infected oaks). Oak wilt is considered by many scientists to be the most devastating tree disease in the south.

For more information go to:

Pruning Restrictions

You can prune your oaks anytime in the months of July through January regardless of temperature. You still need to paint all cuts immediately. Pruning oaks is still prohibited February through June.

Section 24.04.008 of the City of West Lake Hills Code of Ordinances states the following: 

The trimming or cutting of red oak and live oak species for purposes other than protecting public safety is permitted between July 1st and January 31st and prohibited between February 1st and June 30th. The resulting cut shall be treated immediately with commercial pruning paint to seal the exposed surface from contamination. Use of aerosol can is the preferred method of application for sealing cuts. Any wounds, whether made by trimming, construction or accident, shall be treated immediately with commercial pruning paint to seal the surface from contamination. The city inspector may conduct unannounced inspections to ensure compliance with all provisions of this article. (Ordinance 261 adopted September 12, 2012)

Get additional information regarding pruning guidelines.

Planting Recomendations

The following are trees that are not recommended for planting due to their high susceptibility to oak wilt: 

  1. Live oak (Quercus virginiana, Quercus fusiformis); 
  2. Texas red oak or Spanish oak (Quercus texana, Quercus buckleyi); 
  3. Shumard oak (Quercus shumardii);
  4. Southern red oak (Quercus falcata);
  5. Blackjack oak (Quercus marilandica); and
  6. Other members of the red or black oak group.

Trees that are usually oak wilt resistant are listed below: 

  1. Monterey or Mexican white oak (Quercus polymorpha);
  2. Lacey oak (Quercus laceyi, Quercus glaucoides); 
  3. Bur oak (Quercus macrocarpa);
  4. Chinkapin oak (Quercus muhlenberghii);
  5. Durand oak (Quercus durandii); and
  6. Other members of the white oak group. 

Required Removal for Diseased Trees

City of West Lake Hills Code of Ordinances Section 22.03.304 (b)(7) (7) 

When removing diseased, dying or dead trees under the following conditions:

  1. The property owner must submit a request for the permit to the city inspector specifying the affected species, location and trunk diameter.
  2. If the city inspector concurs with the property owner’s assessment of the condition of the tree, then the permit shall be issued.
  3. If the city inspector does not concur with the property owner’s assessment of the condition of the tree, then the property owner shall have the right to submit a signed letter from a certified arborist identifying the specific disease or condition from which the tree suffers and providing a professional justification for the tree’s removal. The city administrator shall then consider the arborist’s letter and determine if a permit is warranted. If the city administrator does not approve the permit, then the applicant may appeal the decision to the city council.
  4. In all cases, the permit for removal must be received prior to removal of the tree except as otherwise provided for in subsection (c) below.