Q: I have two crapemyrtles that have a sooty black color on the leaves and on the ground underneath each year. What do I do? I’ve sprayed with an insecticide and insecticidal soap.
A: When my mother saw cookie crumbs on the kitchen floor, she didn’t have to look in the cookie jar to know that one of her sons had paid an unauthorized visit. Likewise, you don’t have to examine every branch to know that crapemyrtle aphids caused the sooty color on your leaves. The aphids sucked sap from your plants and excreted sticky honeydew onto the leaves and nearby surfaces. Sooty mold then grew on the honeydew and that’s what you noticed. Aphids are easy to control with insecticidal soap if you spray thoroughly every few days. Honestly, you’ll get equally good control by blasting limbs with a water hose and won’t run the risk of harming insects that prey on aphids.