I tested 5 herbicides on wild violets in my neighbors lawn with his OK, (Thank you). Week was dry; high temps about 85. In order of effectiveness at 48 hours, Quicksilver was most effective, Followed by T-Zone, Speedzone, Confront and Drive. I will try to check the results again in about 10 days to better understand which products work best long-term. Since Quicksilver is supposed to have mainly contact action--I am not sure if the roots or underground stems would be affected.