Strange death on my leaves
Portions of almost all the leaves on my tree in the backyard have died. What's going on here and should I be worried? What are the treatment options? Is this because it needs water? I've never watered in the past four years and it's been fine. Unfortunately I do not know what type of tree I have other than that it's very tall. Thanks.
Multnomah County Oregon ash trees
You have an ash (Fraxinus) tree. There are many leaf problems, at first glance yours looks most like Anthracnose. Some years are worse than others. Generally keep the leaves that drop disposed of, rather than mulching or composting with them to limit the disease.
If this is a problem again next year, you may want to hire a certified arborist to diagnose and make a treatment plan. I will include a link to the PNW Pest Management Handbook for Ash Anthracnose. It does include some homeowner available treatments. https://pnwhandbooks.org/plantdisease/host-disease/ash-fraxinus-spp-anthracnose