Q: I have a clump of violets in my lawn that is beginning to spread all over. I have heard that there is a product on the market that will control them. Can you tell me what it is?
A: Welcome to the battlefront, soldier! Among all of the weeds you might encounter in your lawn, violets are among the hardest to control. Their fleshy roots help them to survive repeated herbicide attacks. Their numerous seeds insure that violet progeny will sprout in any lawn when just one plant is nearby. Fortunately, you have joined the fray when violets are at their weakest: in the fall. Their preparations for winter have rendered them susceptible to weed killers that wouldn’t have had much effect in the summer.
Spring is another good time to spray: when the leaves first appear.
The chemical you might be referring to is dicamba. This chemical is found in most of the broadleaf weed killer (click for sources) products. Read the labels of the various products labeled for broadleaf weed control to find the one that has the highest concentration of dicamba.
Managing your violets is more a matter of persistence and repeated spot spraying than expecting a miracle chemical to wipe out your weeds.