Oak wilt is a concern for homeowners across the San Antonio area, where live oaks and red oaks are a defining part of the landscape — and a major investment for property owners.
The disease is caused by a fungus that attacks a tree’s roots and water-conducting system. Once established, it can kill red oaks quickly and move through interconnected live oak roots, sometimes spreading from yard to yard.
The Texas A&M Forest Service says oak wilt has killed millions of trees across Texas and has been confirmed in dozens of counties, including Bexar and nearby Hill Country counties.
Local arborists and state forestry officials say the best defense is prevention. Homeowners should avoid pruning or wounding oak trees from February through June, when sap-feeding beetles are most active and can carry fungal spores to fresh cuts.
If pruning is necessary for safety, experts say every cut or wound should be painted immediately with wound paint, latex paint or spray paint.
That advice applies year-round. Storm damage, construction work, lawn equipment and even damaged surface roots can create openings for infection. Firewood also requires caution. Officials recommend using well-seasoned wood and avoiding fresh oak firewood from unknown sources, especially if the bark is tight and the cut ends do not appear dried or cracked.
The warning is especially important in neighborhoods with dense live oak canopies, where one infected tree can become a problem for an entire block. Symptoms may include leaf discoloration, rapid browning or leaf drop, but diagnosis can be difficult. Homeowners who suspect oak wilt should contact a certified arborist or the Texas A&M Forest Service before removing trees or cutting firewood.
Guests:
Ross Hosea is a manager with San Antonio Parks and Recreation where he oversees the Urban Forestry Division.
Elizabeth Nyawo is a forester with the Texas A&M Forest Service from the Kerrville office.
Mark C. Bird is city arborist with the Development Services Department where he manages the implementation of tree, landscape, and oak wilt ordinances.
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