White cotton wool-like small scales presenting on bark of our acers. Please advise of causes if pest and best treatments.
Disease on Bark of Acers
Certified GKH Gardening Expert
This could be Mealybug, Wooly Aphid or a fungus.
Also sometime lichen can have a white appearance. Lichen is harmless to the tree.
I would treat with Neem Oil. It works as both an insecticide and fungicide so that you are treating both possible problems.
Here are some links for you.