Oak Wilt is Killing Texas Trees in Epidemic Proportions: Stop the Spread

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Tony Maples Photography


If you’re a Texas Hill Country landowner, you may want to familiarize yourself with oak wilt. It’s an infectious tree disease that results from the fungus Ceratocystis fagacearum. The fungus works to disable the system in oak trees that conducts water. The most susceptible to date are red oaks, including Spanish oak, Shumard oak, and blackjack oak. Live oaks are considered less susceptible but have been the most drastically infected as a result of their grafted root systems. These allow the fungus to spread easily to their adjacent trees. The disease can be identified in red oaks by autumn colors appearing in summer months, in addition to the appearance of fungal mats. In live oaks, the disease can be witnessed in patterns of tree mortality as well as veinal necrosis.

sunlight through oak tree branches in morning

Photo: envato elements

Early review and detection for oak wilt and taking swift action are integral to successful management of the disease. Working with a certified arborist, who holds a certified applicator’s license in the diagnosis of such tree diseases, is one positive step in stopping the spread. Following their guidance and direction, the measures taken will rely on a number of circumstances. However, combinations of steps should help to prevent new infections and stop the spread of existing disease. One option is certified arborists from tree service rancho cucamonga to check the wellness of your trees.

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  • Red oaks that are identified to be diseased should be cut and disposed of immediately.
  • In order to break up any root connections, install a trench at a minimum of four feet in depth and approximately 100 feet outside of the perimeter of infected areas (meaning the last symptomatic tree).
  • Identify high-value oaks that are susceptible to oak wilt based on proximity to infection centers and inject fungicide into them. Consult an arborist with a certified applicator’s license for the possible use of propiconazole.
  • During the months of February through June, you should avoid pruning your oak trees.
  • Regardless of the time of year, pruning equipment should be sanitized and sterilized between trees, and any pruning points and fresh stumps should be painted with wound dressings.
  • Never store your unseasoned oak firewood near healthy oak trees, and burn all of your oak firewood before the springtime.
  • Plant additional trees on your property, in diverse types, which are oak wilt-resistant and can adapt well to the Hill Country growing zone. If you’re planting oaks, avoid wounding them during that process.

For those looking for more information, Texas A&M University features an eight-step program for oak-wilt management, which can be read at the link provided here.