I live in Fort Worth, Texas and have three crepe myrtles that are losing their leaves. The leaves have a shiny, sticky surface on the top of them. I have not seen this before and do not know what to do to stop these trees from losing their leaves. I see no aphids on the leaves. I have watered the leaves to wash any insect off of them but this has not helped.
Crepe Myrtle Losing Its Leaves
Certified GKH Gardening Expert
While you may not see them, some type of insect pest has been affecting your tree. The shiny, sticky residue is honeydew secreted from the pests. This would also explain the leaf shedding since it's obviously stressed, which is the reason why most trees drop leaves. Try treating the tree with neem oil to get rid of whatever pest it may be--though it's most likely aphids. Here is more information: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm