Your neighbor's tree looks like an elder
I had a sumac- it was the hardest thing to kill I ever saw!!! It was a Japanese or Chinese Sumac... I cut it down close to the ground and in a month is was sprouting. So I took an axe and chopped up the stump and poured kerosene and it sprouted again. I drilled holes about 6" deep and put gas in it and burned it... 2 months later it was sprouting again!
Wow! talk about tenacious!!! That is a great story!!
That thing just wouldn't die! I finally just gave up.