Natural resource officials talk tree killers

Oak tree leaves that have been affected by oak wilt.

Two Parker County officials specializing in natural resources discussed two tree killers that have or will make their way into the area — oak wilt and the emerald ash borer beetle. 

Oak wilt is a fungus that invades and disables an oak trees’ water-conducting system and Texas A&M Forest Service Staff Forester II Rachel McGregor, who covers the Parker County area, said it’s important for residents to avoid pruning their oak trees from February through June each year.

“Since there is no cure for oak wilt at this time, prevention is important. If you don’t have oak wilt, you don’t want it. So, Feb. 1 through the end of June, don’t prune. Any other time of the year when you prune your oak trees, paint the wound immediately after,” McGregor said. “When planting, avoid injury to your tree and when mowing or weed eating, again, avoid injury to your trees. If an injury does occur on an oak tree, immediately paint the wound.”

Parker County AgriLife Extension Agent Jay Kingston said oak wilt not only spreads through wounds in trees, but also through beetles.

“The fungus will produce spores, which while not airborne, do attach to small sap-feeding beetles. There is a chance an open wound of a tree from pruning could attract one of these sap feeding beetles to your tree,” Kingston said. “The spores get dislodged from the beetle onto the tree, germinate and infect your tree. Wait until the coldest part of the winter, usually December/January, to prune any oaks in Parker County. The second recommendation for pruning would be in the hot part of the summer, July/August, when beetle activity is very low.”

McGregor said oak wilt can also be spread by moving unseasoned firewood.

“Transporting unseasoned firewood from diseased red oaks can spread oak wilt. Only buy seasoned firewood, this means wood that has been dried out for at least one full year,” McGregor said. “Oak wilt cannot be spread from burning — this is one of the biggest myths — however, fungal mats may form on unseasoned red oak wood that is being stored. To help prevent new oak wilt centers, oak wilt-infected red oaks that die in late summer, fall or early winter should be cut down and burned, buried and/or chipped to prevent new fungal mat formations the following spring.”

Kingston said trenching is a way to help prevent the spreading of oak wilt. 

“Trenching can be done that breaks the interconnected root systems between trees. A trench can be established at least 100 feet from the last symptomatic tree,” Kingston said. “For high-value trees, a homeowner can treat their trees with a fungicide called Alamo. It is most effective as a preventative treatment. Trees that are symptomatic have less of a chance to fully recover and it is not recommended to treat trees that have lost more than 30 percent of their canopy.”

McGregor said if residents suspect they may have oak wilt, visit for information or contact a local forester or certified arborist. 

Kingston said a diagnosis can be confirmed through the AgriLife office by calling 817-599-6591 or by contacting the Texas A&M Forest Service.

“Oak wilt is a devastating tree disease and some homeowners cannot afford the high cost of prevention or treatment,” Kingston said. “I recommend for homeowners to have a diverse tree population in their landscapes that do not include oaks. If you know you are within an oak wilt center or close to one, start preparation now. Oak wilt is coming.”

All oak trees are susceptible to oak wilt, but some species more than others, specifically red oak trees — Texas Red Oak or Spanish Oak, Shumard oak and Blackjack oak. 

Emerald ash borer beetle

The emerald ash borer was recently discovered in Tarrant County and the forest service united with the City of Fort Worth and ArborJet to protect two regional champion ash trees — the regional champion green ash and the regional champion Texas ash — from the deadly pest, according to a TFS release. 

Kingston and McGregor said they believe EAB will make its way to Parker County.

“I do believe EAB will make it here, it’s just a question of when. Remember, don’t move firewood,” McGregor said. “Tarrant County is under quarantine now, but unfortunately emerald ash borer had human assistance to make it to Tarrant.”

Kingston added, “There is no doubt that EAB will be in Parker County soon. I wouldn’t be surprised if we already have it considering how close we are to the identified area in Tarrant County.”

In Tarrant County, ArborJet’s Technical Manager Emmett Muennink injected the regional champion Texas ash trees at Pioneer’s Rest Cemetery with ArborJet’s TREE-age by drilling into the tree’s tap roots and setting an Arborplug, which functions much like an IV port and seals off the opening from any bacteria or fungi, according to the TFS. Muennink injected the pesticide with a needle.

“The adult beetle first feeds on an ash tree’s foliage in order to complete their maturation cycle,” Muennink said in the press release. “If EAB feeds on a treated tree, it will kill the adults. At the larval stage, it feeds on the vascular system. [The insecticide] is basically 99.99 percent effective at controlling both the adult beetles and the larval stage.”

McGregor said the forest service is already recommending injections for high-valued ash trees with systemic insecticide within a 15-mile radius of Eagle Mountain Lake, which is where a young boy discovered the beetle in December 2018. 

“Some cities within Parker County fall in that. Weatherford is just outside of that,” McGregor said. “Other options to be proactive include removing ash trees within your yard or property that are in poor condition to reduce risk.”

The Texas A&M Forest Service has 500 traps set up statewide to monitor the EAB population this summer, according to the TFS release. 

“The spread may be inevitable, but preventative methods will slow its spread,” TFS Entomologist Allen Smith said in the release. “This buys time for folks and municipalities to plan and mitigate any impacts from EAB. All it takes is one person to transport some infested firewood to new, ‘unprotected’ locale, and a new infestation can start.”

For more information about EAB visit

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