GATESVILLE — It is spring time in Central Texas, but the leaves of some live oak and red oak trees are starting to turn yellow-orange and reddish brown.
These trees are dying of oak wilt, one of the most destructive tree diseases in the United States.
Oak wilt is “a fungus that clogs the xylem (the tree’s nutrient-transport system) and the tree starves to death,” said Renee Burks, a forester with the Texas A&M Forest Service.
The disease is a “significant problem” in Coryell County and much of Central Texas, Burks said.
While many oaks are susceptible to the disease, the live oak and red oak are the most seriously affected.
“Post oaks don’t get it,” Burks said. “Chinkapin and burr oaks are affected, but not as much.”
The symptoms of oak wilt are just starting to show, she said.
The veins of an infected live oak leaf will start to turn yellow-orange when the rest of the leaf is still green and the tips of the leaves may turn brown.
In red oaks, such as the Texas or Spanish oak and blackjack oak, the leaves turn red.
“The leaves turn red real fast,” Burks said. “In 10 days to two weeks, the (red oak) tree is deader than a doornail.”
Untreated, an infected red oak has a “100 percent chance of death,” Burks said.
The disease spreads in two ways — underground and by insects that carry the spores from tree to tree.
In a live oak mott, or group of trees sharing the same root system, the disease often moves underground.
In red oaks, the disease forms a spongy, smelly fungal mat under the bark. A small beetle feeds on the mat and spreads the infectious spores to other trees.
If treated in time, a tree can survive the disease, Burks said, but the fungicide injection is a “very invasive and time-consuming” procedure that should be done by a qualified professional.
James Briggs, a certified arborist in Lampasas, has been fighting oak wilt for more than two decades.
“Since 1992, this is all I have done,” Briggs said.
Briggs grew up in Lampasas and in 1980, he and his wife bought 18 acres there for their eventual retirement.
They bought the land for the beautiful live oaks, Briggs said. Then the trees started to die of oak wilt.
Briggs was one of the first to take the Texas A&M Forest Service Oak Wilt Certification course to learn how to apply the fungicide injection.
He treated 46 of the surviving trees on his land and saved all but one.
Now Briggs travels Central Texas from Austin to Stephenville, from Temple to Brownwood trying to save trees from oak wilt.
If your trees show symptoms of oak wilt, Briggs said, contact a certified arborist as soon as possible.
While the injection may take a pro, there are ways a homeowner can protect against the spread of oak wilt, Briggs said.
- Do not prune trees from February to June.
- Always seal any wound on the tree with pruning paint to prevent infection.
- Trim trees only in very hot or very cold weather — August or December.
For more information, go to texasoakwilt.org.
Contact Tim Orwig at firstname.lastname@example.org