Prevent the Spread of Oak Wilt in North Texas This Spring

Oak wilt is one of the deadliest tree diseases in the United States, and we can help prevent it from spreading, Texas A&M Forest Service said.

According to the Texas A&M Forest Service, the disease killing millions of trees in 76 counties of Central, North, and West Texas.

Prevention is key to stopping the spread of oak wilt, the Texas A&M Forest Service said. Any new wound on a tree can be an entry point for infection. Wounds can be created by pruning, construction activities, livestock, land or “cedar” clearing, lawnmowers, string trimmers, and storms.

“With wounds being the best entry point for the disease, landowners should avoid pruning or wounding trees from February through June,” said Demian Gomez, Texas A&M Forest Service Regional Forest Health Coordinator. “And no matter the time of year, to decrease the attractiveness of fresh wounds to insects, always paint oak tree wounds.”

Oak wilt is caused by the fungus Bretziella fagacearum.

According to the Texas A&M Forest Service, the fungus invades the xylem, or the water-conducting vessels of the trees.

The tree responds by plugging the tissues, resulting in a lack of water in the leaves, slowly killing the infected tree. the Texas A&M Forest Service said.

The Texas A&M Forest Service said all oaks are susceptible to oak wilt, but red oaks are the most susceptible and can die in as little as one month after being infected.

Live oaks show intermediate susceptibility but can spread the disease easily due to their interconnected root systems, and white oaks are the least susceptible, but they are not immune to infection.

According to the Texas A&M Forest Service, oak wilt can spread both above ground or underground. The disease is spread above ground more rapidly in late winter and spring because of high fungal mat production and high insect populations.

Texas A&M Forest Service said the disease spreads underground by traveling through interconnected root systems from tree to tree. Oak wilt spreads an average of 75 feet per year by the root system.

Oak wilt can be recognized in live oaks by yellow and brown veins showing in leaves of infected trees, known as venial necrosis, the Texas A&M Forest Service said.

The signs of oak wilt can be seen on a majority of leaves when a tree is fully infected, and landowners should contact a certified arborist if they are unsure if their tree is infected.

“For red oaks particularly, one of the first symptoms of oak wilt is leaves turning red or brown during the summer,” said Gomez. “While red oaks play a key role in the establishment of new disease centers, live oaks and white oaks move oak wilt through root grafts.”

According to the Texas A&M Forest Service, to stop the spread of oak wilt through the root system, trenches can be placed around a group of trees, at least 100 feet away from the dripline of infected trees and at least four feet deep to sever all root connections.

Oak wilt can also be prevented through fungicide injections, which only protect individual trees, the Texas A&M Forest Service said. This treatment is best for healthy oaks up to 100 feet away from symptomatic trees.

The Texas A&M Forest Service said other ways to help prevent oak wilt are to plant other tree species to create a variety in the area, to avoid moving oak firewood before it is seasoned, and to talk with neighbors about creating a community prevention plan for oak wilt.

The Texas A&M Forest Service said infected red oaks that died should be cut down and burned, buried, or chipped soon after discovery to prevent fungal mats that may form the following spring.

According to the Texas A&M Forest Service, oak wilt can reduce property values by 15-20%.

Some areas in Texas, including Austin, the City of Lakeway, Dallas, Fort Worth, Houston, San Antonio, and Round Rock, have oak wilt programs in place with municipal foresters dedicated to managing the disease.

Texans can also contact their local Texas A&M Forest Service representative with any questions about the disease.

For more information on oak wilt identification and management, visit https://texasoakwilt.org/ or Texas A&M Forest Service’s website.