My CM-trees leaves are falling - leaves are brown with black spots (dots) on both sides. The underneath of the leaves seem to be a shade lighter than the top. We have had ample enough rain. I have two other trees in the yard and they are OK. Can you advise?
Crepe Myrtle Diseases
Certified GKH Gardening Expert
It sounds like you may have a pest like scale or aphids. Treat with a pesticide. I like neem oil as it is safe for people and pets and also treats the fungus that commonly accompanies these pests. Here is more info: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm If you find no evidence of these pests, then it is likely Cercospora leaf spot (http://edis.ifas.ufl.edu/lh082) or black spot (common on roses but can affect other plants https://www.gardeningknowhow.com/ornamental/flowers/roses/black-spot-roses.htm, both of which are caused by fungus.