The looks like it needs water,leaf have some brown spot and trunk has a film(funus) of some what.
Will this kill the tree or can i put some a power or spray tree with? or to much water?
Washington County Maryland
Please send us photos of the whole tree, around the base of the tree, and affected foliage so we can see what you are dealing with.
Sounds like the tree may have symptoms of powdery mildew and spot anthracnose, fungal diseases on the foliage. This is fairly common on flowering dogwood trees in Maryland and tends to be more severe in years when we have very wet spring weather. Refer to our webpage for additional information on care for dogwood trees, https://extension.umd.edu/hgic/topics/flowering-dogwood-trees-selection-care-and-management-disease-problems
The growth on the trunk sounds like lichens. This can be common on mature trees and not a cause for decline. https://extension.umd.edu/hgic/topics/lichens