Pest on maple?
Thank you for the question. Your maple has tar spot, a fungal disease that is rarely much of a problem for the tree unless it gets so bad that the tree loses all its leaves several years in a row. Management strategies focus on improving cultural conditions, rarely fungicides.
This publication reviews leaf spot diseases and if you scroll down to the bottom, there is a nice section on actions you can take now to minimize this problem and support your trees health: http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/management-of-leaf-spot-diseases/
Thank you for contacting Extension.