So probably why the peach trees on that end of the orchard that are very mature are starting to have more dead branches than live branches on them? They are probably 75ft away at their closest point. The walnut trees are not huge. If we got rid of the couple down near the orchard, would the dead roots in the soil continue to contaminate it? We have plans to add to the orchard down there, and fruit trumps black walnut in my book. It is also a perfect place for the garden and greenhouse.I think it is futile to think of planting anything anywhere near black walnut. It might look okay for a year or two but as the walnut tree grows taller and deeper it will eventually kill all competitors. I have two big ones on the property line and they killed a hemlock tree! What can kill a hemlock? Only thing that grows around them is grass, some scrubby juniper and goldenrod.