I have several large, beautiful Linden trees around the perimeter of my home. Last year I noticed many dead branches on one of them. Last fall I applied a "save a tree" type treatment as well as a treatment for aphids as advised by a lawn expert. This has not helped and an arborist has told me that aphids will not kill a tree. I am desperate to save this 20 year old tree. The leaves on the "sick" tree seem smaller and less green than my other Linden trees and as I said earlier many branches are dead. The tree gets ample water. We do use "weed and feed" one time per year on our lawn. Any advice?
Find somebody else there who can tell you what is going on, maybe at Idaho Cooperative Extension. The lawn herbicide might be involved, depending on what is in it and where you put it (relative to where the trees are). Weed 'n' Feed type products are a bad idea anyway. Don't purchase and apply anymore pesticides to the trees without knowing what, exactly the problem is.
I had an arborist from City of Boise come out today and look at it, but she didn't have any ideas yet. Seems like a mystery. Not to worry, I will not be touching the tree with anything until I get some conclusive information.