Posted: 01/10/2015 at 08:25
I have had some success by using Roundup at the highest recommended dosage. I worked by pulling all I could see out and then waiting until new growth was a few inches tall. Then walked all over it to bruise the stems and finally sprayed Roundup. Stems turned black within a few days and didn't have any major regrowth for a couple of years.
Unfortunately I was then unable to do much due to knee problems and it did reappear, so it was a battle won, not the war!. This time I have dug over the area and removed all I can of the root by hand. I know it won't stop regrowth but I'll be better placed to treat any that does appear.