In message , Janet Tweedy
writes
In article , Bob Hobden
writes

Roundup would and does work,

I've sprayed mine with roundup for the last three years but I have to
do it every year as there's always some degree of grow back......

There will be. There is a lot of mass and stored energy in the tuberous
roots. You have to dig most of it out after the glyphosate has taken
effect.

That way you don't get any regrowth from small bits that snap off.

If you insist on doing it all chemically it takes excessive amounts.

Regards,
--
Martin Brown