SAN ANTONIO – Oak trees are the backbone of South Central Texas. Hardy, evergreen and beautiful, oak trees can also provide plenty of shade.
But neighborhoods like Live Oak, Shavano Park, Hollywood Park and the Hill Country are threatened by oak wilt, a fungal disease that predominantly spreads underground through tree roots and can kill several trees at a time if not stopped or prevented.
Jessica Jones, an arborist with San Antonio Tree Surgeons, said the best way to identify oak wilt is by examining the leaves of a live oak.
Jones said the leaves are the last symptom and sometimes can’t be saved if they have veinal necrosis.
Veinal necrosis causes leaves’ veins to change color all over the tree. First, check the health of the live oak.
Jones said anyone can do this by checking if the leaves of a live oak are green and if the tips of the outer branches have leaves on them.
If the tips are bare or the leaves are brown, then the tree is signaling that it is sick. Live oaks usually remain evergreen, so the leaves don’t turn brown until after they fall on the ground.
It is best to call an arborist to determine if the tree is stressed from environmental factors, such as drought and heat, or if it’s oak wilt.
As for treating it, Jones said it’s always safest to call a professional.
“You basically use a vacuum, kind of pressurized system, where we drill into the base of the tree into a root flare like this,” Jones said. “And it’s a special antifungal specifically. It’s the one that most aggressively treats oak wilt.”
In the spring, some oaks — like red oaks — can develop open fungal mat wounds.
Jones said this is rare but can spread when sap-feeding beetles land on those fungal mats and then land on another oak with an open wound.
Jones stressed the importance to seal fresh cuts on the oaks.
“You can use something called wound sealant at Home Depot,” Jones said. “It’s super easy. You can use spray paint. It doesn’t matter. We just want a physical barrier.”
To be extra cautious, experts recommend trimming oak tree branches primarily during peak summer or winter, before mid-February.
And remember: always seal open cuts afterward.