Disease/Pest on Purple Beech/Birch
Thank you for your question. I hesitate to give you a diagnosis without seeing the leaves under a microscope, as well as a photo of the entire tree. I suggest you take some of the leaves, and a full picture, to the Clackamas County Extension office at 200 Warner-Milne Road, Oregon City, any work day between 9:00 a.m. and noon, or 1:00 pm to 5:00 pm. so one of the Master Gardeners there can assist. Good luck!