We have patches of what I believe is Selfheal. I have treated it with Resolva (can I say that? ) lawn wedd killer, this being done on the 16th April. So far, it doesn`t seem to have any effect, and there are no clues as to length of time for it to take effect, on the packaging. Can anyone tell me, have I used the right treatment, and if so, when will it start???. Thankyou in advance.