By Belle Nelson
Options on mitigating a fungus that targets specific types of oak trees in Central Texas was brought forth to the Buda City Council once again on Nov. 10.
Oak Wilt, a fungus that primarily targets Red and Live Oaks, has been a topic of discussion for quite some time in Central Texas. Buda City Council has visited the issue numerous times.
Erik Becker, one of seven Texas A&M Forest Service employees, is in charge of handling the issue in Hays County. He said on Nov. 10 the first reports of Oak Wilt in Hays County occurred in 1989.
“This is not something that’s going to go away quickly,” Becker said.
The disease spreads through either the roots of the trees, or through spores that beetles transfer from one tree to the next. Transmission of the fungus through the roots is the most common way for it to spread.
Oak trees can have roots that are almost 50 feet long creating a 100-foot diameter of potential infection.
Symptoms vary by tree species, but will most likely consist of leaf discoloration, wilt, defoliation, and eventually, death.
Some cities, including Austin, require immediate removal of infected trees. There’s a city ordinance to remove the tree within ten days of detecting Oak Wilt, and the city covers 40% of the cost.
On Nov. 10, a similar idea to assist the community with the cost of prevention and removal of affected trees was discussed briefly, but is still in its preliminary stages.
“Homeowners are probably the people this pertains to the most, at least financially,” Becker said. “Removing trees, digging trenches, or having dead trees in their yard can really affect the property value of their home.”
Buda City Council members also discussed the possibility of making citizens obtain a permit before pruning any oak trees. In addition, contracting with regional specialized arborists to monitor affected areas and help inform the community and update the city was also idealized.
According to Becker, there are a couple different methods of controlling Oak Wilt.The first is digging a trench around the infected tree in an effort to sever its roots and therefore combat the spread to the other trees in its vicinity.
This method can be disruptive, especially in residential areas, but it’s the most cost effective. The trench must be a minimum of 4 and a half feet deep.
A second method is injecting propiconazole, a fungicide.
For a large oak, as many as one injection a month may be required to immunize it from the disease.
“This is not only costly, but it can be hit and miss,” Becker said. “If a tree is injected, it doesn’t necessarily mean that Oak Wilt won’t simply jump that tree and move to the next, still infecting every other tree in the area.”
The third method of controlling Oak Wilt is removing the entire tree after it has died.
After removal, another costly procedure, the tree is burned in an effort to destroy the fungus. Limbs or logs from the tree shouldn’t be removed from the area, even for firewood.
“We’re doing our absolute best to control this, but there are things the community can do as well” Becker said. “Avoid wounds to oak trees especially in the spring, specifically from February to June, and always paint over a wound.”
He added that beetles that transport the spores are attracted to the sap, and without its presence, would be less attracted to the trees and therefore less likely to spread the fungus.
Beetles that carry the Oak Wilt fungus do not in fact have chewing mouthparts; they need something else to cause physical damage to the tree before they can access the sap.