In article , John Carruthers
writes
six inches to a foot above
ground level, dowse it with stump killer,

Thanks, I'll give it a go.

Hmm ... in your original post you said it was near to a pond and you
were worried about the effects on other creatures. I would check first
whether stump killer or glyphosate is least likely to cause problems.
--
Kay
"Do not insult the crocodile until you have crossed the river"