Q. What can I do for an old ash tree that has been losing yellow leaves for several weeks?
Thank you for your question. I know you are concerned about your 200 year old white ash tree (Fraxinus americana), so hopefully there will be a professional arborist to help. Below is the link I spoke of, just insert your zip code.
Also, I mentioned the arborist who teaches part-time here and works in the NYC area. His name is Bill Logan his number is 718 522-0612 email is urbanarborist.com.
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Hope this is helpful.