Posted: 31/10/2014 at 11:58
Defintely do not rotavate. It will just make hundreds and thousands of cuttings as the roots are really persistent and grow again form the tiniest bit.
Do as advised and spray again in spring when any new growth starts but let it get a couple of inches high before spraying or there won't be enough green foliage to transport the active compounds back to the roots. Be patient, even if it takes a couple of months and several applications. It will be worth it.
When you do eventually dig, use a fork rather than a spade as this will produce fewer cut pieces and allow you to wrestle more or less whole roots out of the ground. Leave these aside on a plastic sheet so they can dry out and die over a week or two before putting them anywhere near a compost heap or trying to burn them.