Vine Maple White discoloration
The growth on your vine maple trees are lichen. There is no need for concern or for a solution. Lichens come in many colors, sizes, and forms, but none of them are considered to be parasitic or harmful the trees themselves. The read up on the rather remarkable, but ignored forms of life, see:
Hope this information eases your concerns.
You gotta love the Lichen!!!
Thank you for such great news Michael!!! We were worried about our sweet sweet tree that gives us so much joy!