No worries. The photo that you sent looks like yellow and gray lichen on the branches of your maple. The lichen will not harm the trees and shrubs that it grows upon. It is just a sign that the tree has been growing in a moist or shaded area. You can learn to "liken the lichen" by noticing the different types and colors that grow on trunks and branches. One of nature's great survivors as lichen needs so little to survive. Keep growing, Marianne Binetti