Crape Myrtle Aphids and Sooty Mold: Timing Systemic Treatment

Sticky leaves on crape myrtles for three years running strongly suggest aphids or other sap-sucking insects, leading to sooty mold. A February soil drench failed because the tree wasn’t actively growing yet.

Why Timing Matters

Systemic insecticides like Bayer Advanced Tree & Shrub require active transpiration to move from roots to leaves. Applying in February (dormant season) means the product sits in soil, possibly leaching away before uptake.

Correct Approach

1. Wait until the tree is fully leafed out in spring (usually April–May in Alabama).
2. Apply the systemic drench then, following label rates for tree size.
3. Reapply annually if aphids persist.

Supplemental Control

For immediate relief, spray aphids on leaves with insecticidal soap or neem oil while waiting for the systemic to activate.