Diagnosing a Single Ailing Crepe Myrtle Among Healthy Ones

One of 6-8 crepe myrtles in North Texas shows white powder on limbs, sticky coating, and drooping leaves despite regular watering. Extreme heat (70+ days over 100°F).

Differential Diagnosis

• White powder on limbs: Likely lichens (harmless, indicate thin canopy), not powdery mildew (which is on leaves).
• Sticky coating: Honeydew from aphids or scale. Inspect leaf undersides.
• Drooping: Combined heat/drought stress + insect feeding reducing water/nutrient transport.

Treatment

1. Spray strong water stream to dislodge insects.
2. Apply insecticidal soap or horticultural oil.
3. Verify deep watering: soil moist to 8+ inches (probe with stick).
4. Monitor other trees for early signs.

Genetic variation may make one tree more susceptible.