My crepe myrtles have a white fungus all over their branches. What is it and how do I fix it?
White Fungus on Crepe Myrtle
Certified GKH Gardening Expert
If it's powdery in nature, then it is powdery mildew and can be treated with neem oil. Here is more info: https://www.gardeningknowhow.com/problems/get-the-cure-for-powdery-mildew.htm
If they are more spotty and raised or cottony looking, then your tree may have scale or mealy bugs. Again, neem oil will help with this. These articles will also help: https://www.gardeningknowhow.com/plant-problems/pests/scale-bug-how-to-control-plant-scale.htm