Resident brought in a sample of mountain ash showing marginal leaf necrosis. He thinks the tree did this last year also, but is not positive. He said it is sporadic throughout the crown with no pattern. If anything might be worse in the middle crown. He said there is no signs of insects, cankers, etc. Sounds like there is some lawn mower damage at the base of the tree. This issue that I worry about he that he damaged the roots this year trying to straighten the tree. It was established a minimum of 8 years when he did this.