Peter Scott wrote:



sodium chlorate will work but contaminate the area for a long time.

It certainly works. To avoid contamination, drill a few downward sloping
holes in the side of the trunk with a flat bit. Spoon in some chlorate
then plug with a wine cork or similar. Or in the top of course if wide
enough.

I haven't used it for many years because it doesn't translocate like
glyphosate or ammonium sulphamate. We used to do just as you say and the
theory was it aided the burning of the stump later.

AJH