The oldest black walnut trees in my part of the world are in old yards, where a house used to be, and may be chock full of nails and other things saw blades don't like. It seems to have been almost a given that a tenant house, or sharecropper's house, would have a walnut tree on the yard. They have the characteristic of emitting some odor or substance that drives fleas away. Maybe that is part of the reason for their popularity in yards of old. I have been told you could throw some walnut limbs, with green leaves, in a dog pen that is infested with fleas, and they would be gone overnight.

SRH

May God bless America and those who defend her.