Answer: Watering your tree once each week is really important so keep up the good work. Even with a deep soaking once each week, it sounds as though your tree is a little stressed - perhaps from dry air. In any event, I suspect that a population of aphids have arrived (insects seem to sense when plants are stressed). The sticky film is called honeydew and sucking insects such as aphids or scales excrete this substance as they feed. Curling and wilting leaves are symptoms of their feeding. The good news is that beneficial ladybugs will probably show up to feast on the aphids and eliminate the problem. Or, if the tree is small enough for you to comfortably spray it, use Insecticidal Soap to do the pesky aphids in. Be sure to spray both the tops and the undersides of all the leaves. Insecticidal soap will control soft-bodied pests such as aphids but will not harm beneficial insects, people or pets.
Best wishes with your crape myrtle!
Q&A Library Searching Tips