I have 5 crepe myrtle trees, which have a white powdery substance on them. After a short time, a black substance appears on the leaves. I have had this problem for a couple of years and have sprayed them with several different things, but nothing seems to get rid of it. Any suggestions?
Crepe Myrtle Problem
Certified GKH Gardening Expert
The white powdery substance is powdery mildew and can be treated with neem oil. Here is more info: https://www.gardeningknowhow.com/plant-problems/disease/get-the-cure-for-powdery-mildew.htm, https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm The black substance sounds like a sooty mold issue, most often brought on by pests. Neem oil can also be used to get rid of the pests as well as the fungus This article will help: https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm