[header] How to control wild violets [title] Use a selective broadleaf killer. [step] For best results, select an herbicide containing either 2 , 4-d or dicamba. One containing quinclorac may also work well against wild violets. 
[substeps] These herbicides are formulated to kill broadleaf plants, like wild violets, while leaving most grasses unharmed. As such, they can be applied to the wild violets in your lawn without damaging the lawn itself.