I need diagnosis and treatment of a disease of my mature oak tree. A large section of its foliage contains leaves that get brown at the edges in early summer. This is the second summer I have noticed it. I have researched the leaves online ,and it looks like they might be symptoms of several possible conditions—some mild and some serious. I only want to work with an excellent arborist and Hope you can refer me. This is a large, mature and treasured tree in my landscape. It otherwise appears healthy and strong. Can you advise?