I have heard it was your group that came up with the rule of thumb. I know nothing about it! And frankly, these black walnuts we have make fruit akin to small cannon balls so I would not care to be under one if someone was giving it a thump unless I had a helmet.
I had a Gum tree in my front yard. They look harmless but if they hit you in the head, they leave holes in your scale. Kind of like being hit with a nut mace !!
