Question
Hi Jim...I live in central louisiana (a town called Mansura) I have very clay soil.(hard stuff) All my crepe myrtles have this black powdery like substance on them, they look wilty, I did find what I think was some sort of web on a few of them filled with many tiny insects. I sprayed a antifungus, but it did not seem to do too good. The trees are approx 3 years old and growing well so far, but I would hate to loose them.Please HELP! Thanks!

Answer
The black powder sounds like sooty mold. This fungus grows on honeydew from aphids. Aphids are small insects that suck the juice from leaves and excrete a substance called honeydew. Honeydew is high in sugar content and the fungus grows on it. Control the aphids and you will control the sootmold. Spray the leaves with an insecticide for aphids. A fungicide will do nothing for insects. Check with a local nursey/garden tyoe store for a systemic insecticide for aphids.