Oak wilt is one of the most destructive tree diseases in the United States, and unfortunately, it thrives right here in Texas and many places throughout America. Caused by the fungus Bretziella fagacearum, this disease can move faster than homeowners realize, killing red oaks in weeks and slowly choking out live oaks over months. If you’ve ever seen a stand of dead oaks in a neighborhood seemingly overnight, there’s a good chance oak wilt was behind it.

• Root Grafts: In live oaks, interconnected root systems allow the disease to spread underground like wildfire.
• Insects: Sap beetles carry spores from fungal mats (spore pads) on infected red oaks to fresh wounds on healthy oaks.
• Pruning Wounds: Improper timing of pruning, especially in spring, leaves trees vulnerable to infection.

• Red Oaks: Rapid wilting, bronze/brown discoloration starting at leaf tips. Dead within weeks.
• Live Oaks: Veinal necrosis (leaves turning brown along the veins while tissue between veins remains green). Often spreads in patches or “disease centers.”

1. Prevention First – Avoid pruning between February and June when beetle activity is high. Always seal pruning cuts immediately with a wound dressing.
2. Root Disruption – Trenching around disease centers can break up root grafts and slow spread.
3. Fungicide Injections – Propiconazole injections by a trained professional can protect high-value trees if applied preventatively.
4. Sanitation – Dead red oaks with fungal mats should be promptly removed and destroyed (burned, buried, or chipped).