Oak wilt causes ‘epidemic’ destruction in Central Texas, including on property values

CENTRAL TEXAS (KXAN) — Texas A&M Forest Service experts are forewarning Central Texas property owners about the dangers of oak wilt, a fungal tree disease that can substantially impact property values while costing thousands of dollars in treatment services.

What is oak wilt, and which oak species are most susceptible to the disease?

Oak wilt is caused by a fungus that affects every species of oak trees, said Kimberlee Peterson, a woodland ecologist with the Texas A&M Forest Service. Central Texas is home to the red, live and white oaks, which are all impacted differently by the disease.

Red oaks are the most vulnerable to the disease, with a 100% fatality rate once infected. For live oaks, those can be saved if the disease is caught early and the trees are treated with fungicide. However, without treatment, the live oaks only have a 15% survival rate and will die between three and six months post-infection.

White oaks are an outlier compared to other oak species and, while they can still get oak wilt, they’re not as susceptible to the disease.

How can oak wilt impact property values in Central Texas?

For property owners looking to sell their properties, they are legally required under the Deceptive Trade Practices Act to disclose whether or not any oak trees on their property have oak wilt, Peterson said.

“They are held liable to make sure that whoever’s buying that property is informed because treatment is not cheap,” she said.

And just how detrimental is oak wilt to a property’s value?

“It can decrease property value between 15% and 20%,” Peterson said.

How can you prevent oak wilt?

Communication is essential for property owners to alert others in their area about the presence of oak wilt, Peterson said. As part of preventative efforts, pruning is a critical practice that can help save your trees, but it needs to be done at the right time of year.

“We recommend to not prune from February through June, because that’s when the beetle that carries the oak wilt fungal spores is most active,” she said, adding: “Making sure that you’re also spraying the wounds whenever you prune it.”

Both a pruning spray as well as traditional spray paint will get the job done in covering any oak tree wounds post-pruning, Peterson said. The forest service recommends anything larger than the diameter of a pinky is sprayed after pruning to avoid an oak wilt infection, she added.

What treatment options are available for oak wilt?

The most common type of treatment for oak wilt is via a fungicide, which has to be applied following an initial infection as well as every few years following the initial treatment to prevent further damage to the infected tree. Fungicide also doesn’t prevent the spread of oak wilt to other trees, instead just treating the individual trees the fungicide is applied to, Peterson said.

Since red oaks have a 100% mortality rate once diagnosed with oak wilt, fungicide doesn’t work against those cases. Instead, fungicide can be used as a preventative treatment with red oaks, especially if there’s a particular red oak tree property owners are sentimental about, Peterson said.

With live oaks, those trees can be treated after symptoms emerge, but Peterson added homeowners need to weigh out the cost of treatment versus the extent of infection and the survivability of the tree.

“We generally recommend no more than 30% of the canopy being affected [receiving treatment] because once you get past that amount, the likelihood of the treatment doing any good goes way down,” she said. “Think of it like chemo: you’re putting a chemical in the tree and sometimes the tree is already stressed out. If you add a chemical on top of that, it can do more stress.”

An alternative treatment method is trenching, or essentially severing the root system. In those cases, Peterson recommended going at least 100 feet out past the last infected tree and four to six feet deep into the ground to encompass the whole center of the tree.

The Texas A&M Forest service also helps administer a federal cost-share program, known as the Texas Oak Wilt Suppression Program. That offers cost assistance with trenching or removing certain diseased red oaks, with more details on the program available online.

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