Oak Wilt is a contagious fungal disease that can kill many species within just a few months. While an outbreak often starts with sap-seeking beetles which carry fungal spores from an infected tree to an open wound or fresh cut of a healthy tree, the disease spreads to nearby oaks via interconnected root systems and can progress up to 100 ft annually.

 

Once an outbreak starts it's nearly impossible to contain. Timely application of fungicide can avert death of most oak species, but the mortality rate without proper treatment averages 90%. Fungicide is typically 4x less expensive than removing a dead tree, so WOHA encourgaes homeowners to be vigilant for encroaching risk. 

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Selecting an Arborist. ​When risk of disease is suspected, consulting a specially trained arborist is strongly recommended. While most licensed arborists posses the standard ISA certification, only a handful in Bexar County have also been certified by Texas A&M Forestry to properly administer Oak Wilt fungicide. Click to view a partial list of such firms.

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Fungicide Options. Fungicide is the only protocol scientifically verified by experts. ​Local arborists typically administer Propiconazole, often sold under the brand name Alamo, which is recommended by Texas A&M Forestry. It is a viscous liquid injected into the root flare via pressurized tanks. Some residents have experienced mixed results with this formulation in recent years, even when administered professionally and with sufficient lead time.

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When this occurs, some arborists may be willing to follow up with Tebuconazole which is a similar but less viscous alternative commonly used in other states. And while any regimen should ideally be timed a year apart, experts advise the risk of fungicide shock is low and may be necessary to save a symptomatic tree which is likely to die within months.

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Preparation and Planning. Timing is critical. The goal is to treat at-risk trees before they become symptomatic which indicates damage to the internal system needed to effectively circulate fungicide. More than one application may be necessary over a period of time depending upon the threat's surrounding longevity and the tree's response.

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Spring is the ideal time to administer because oaks "wake up" in warm weather but may then go dormant in a hot summer. Experts recommend slow steady root watering via soaker hoses well in advance of application to ensure the tree is hydrated and primed to circulate the fungicide.

 

Remember, the disease can travel in-ground a significant distance annually and kills healthy oaks quickly. So monitor nearby properties and consult an arborist promptly if a nearby tree is symptomatic.

 

Homeowner Responsibilities. ​​In 2025, most Units within Whispering Oaks ratified amendments to the Community Covenants establishing common sense mitigation policy:

 

• Non-emergency pruning is prohibited during the risk high period of February through June. Removal of the entire tree may be conducted at any time.

• All cuts must be sealed within 30 minutes. Homeowners are responsible to properly supervise their contractors.

• Homeowners must promptly alert adjoining properties if the disease is discovered.

• Dead or dying trees pose a safety risk and must be removed in a timely manner. Stumps visible from the street must be ground to soil level.