COLLEGE STATION — More than $6 million has been spent since 1988 battling deadly oak wilt disease in Texas, but foresters estimate that $60 million worth of trees have been saved.
The Oak Wilt Suppression Project, handled by the Texas Forest Service, pits seven foresters full-time against googols of fungus spores that stick to the legs of sap-feeding beetles. The war rages in 54 Texas counties, according to Dr. Dave Appel, a Texas Agricultural Experiment Station plant pathologist who is researching the fungus.
Oak wilt, which spreads about 75 feet a year from injured trees infected by the beetles or through touching root systems, is deadly for red or live oaks. Though Texans first noted the problem in 1982, funds to help reduce losses on private land weren’t available until June 1988.
“The disease is here forever, and the more human activity there is out there, the more incidents of disease there will be,” said Ed Barron, Texas Forest Service resource development department head. “There’s no mystery as to the cause of the disease, but we’ll be able to do a better job of protecting trees as people learn more about it.”
Barron said since the suppression project began, teams of foresters, plant pathologists and landowners have worked in a “right now” mode trying to save infected trees. Those battles will continue, he said, but the forest service also plans to lead a strategic planning effort this year to project future goals for the project.
“We’ve been busy looking at stopping losses,” he said. “We need to look more at ways to stop the disease from spreading.”
The heaviest concentration of oak wilt disease is in 12 Central Texas counties where about 1,600 centers — groups of trees from which the disease has spread — have been counted in extensive aerial surveys. More than one-third of those have received treatment in a cost-share program using private landowner and federal funds.
Barron said the team plans to survey an additional five counties this year — Gillespie, Blanco, Kerr, Bandera and Comal — to establish a baseline for treatment efforts there.
“We’ve concentrated our service in the hardest hit counties,” Barron said. “We could do more counties, but that would take a lot more money.”
As it is, the forest service has eight full-time oak wilt suppression employees located throughout the affected region. Barron said each of those tries to service at least three counties. Of the 30 counties somewhat beyond that reach, Barron said, the incidence of oak wilt in minimal. In Brazos County, for example, a case of oak wilt has found years ago, but practically none has been reported since then.
Appel noted that the oak wilt identified last year in Houston “is not an impending epidemic.”
“There is a low level in Harris County, but we don’t anticipate any in the future,” Appel said.
People could be a first indication of where the disease is likely to crop up, and a key factor in controlling outbreaks, Barron added.
He said much of the suppression effort will focus on education — teaching people not to prune susceptible oaks when beetles are active, for example. Control efforts, he added, often hinge on neighborhood unity in urban settings because 100 percent participation — which can be extremely costly — is required to get control of an outbreak.
Removal of a 20-inch diameter tree, he said, can cost up to $1,000 in a city.
Yet the loss of trees not only scars the land but can decrease property values. Urban trees on average are valued at $2,000 apiece, according to the forest service, while rural trees are worth an estimated $50 each.
Barron said the oak trees also are a valued source of habitat and ecological balance for several endangered species. With that in mind, the forest service has begun environmental assessments of areas targeted for treatment which often involves digging trenches or injecting individual trees with fungicide, a chemical that kills fungus. They also are consulting with teams of archaeologists from Texas A&M to ensure that treatments don’t “recklessly damage cultural resources.”
He expects oak wilt to remain a major effort as people try to prevent or stop the disease.
“The demand for assistance in oak wilt suppression continues to increase as Central Texas landowners become more aware of the problem and the appropriate solutions,” Barron said.