There is no treat-and-forget solution where it has been well-established in a lawn. It requires constant vigilence like being a lawn security guard. I've tried the oxalis-destroyer but fear it has made matters worse. The problem is that the chemical stresses out the lawn grass while it is attempting to control its targeted foe and a stressed lawn makes it that much easier for any weed to take hold. So you may need to just live with a slightly brown lawn until the violets have succumbed. Fall treatment followed by the following Spring is the best success and figure on a few years followed by close monitoring and more treatments when new eruptions occur. Use a surfactant to help break the wax (yes, the violet leaves have been preparing for our attack for thousands of years). And before you violet sympathizers begin to suffer the effrontery of eradicating this natural botanical... try to understand and sympathize with the lawn maintainers. Homeowners who spend years planting and caring for a lawn (in this context, "lawn" means grass!) resent any invader that seeks to undo all their efforts and expense which created the lawn in the first place. It's not the occasional tuft of violets that is at issue but rather an entire lawn covered to the point where the grass has been all but eliminated. If we wanted a field covered with violets we would have planted them in the first place. And trying to bag clippings is near impossible because violet leaves do not shear like grass and discharge through the chute. They create a slurry of green sludge that must be removed from the bag by hand or with a trowel. There is a difference between coexisting and invading. Wild violets are about as invasive a weed as there is and confounds lawn care all over the country. They have ceased to be "cute" additions to a cultured environment.

Hi! I notice most of this thread is 9 years old and i wonder if you folks are still here, reading this discussion makes me happy. I was researching if i could transplant iris, black eyed Susan, bergamot, and coneflowers into my damp sunny front yard violet patch and expect them to thrive, and I'm going to try it! @Hu of 5 months ago, that would be really pretty, columbine with violets. IDK if it would work but I will try it too after the hardy stuff establishes! My goal is to make a privacy screen so I feel less exposed in my front yard. I want it dense with always something blooming. Right now I have a big forsythia on one end, hollies on the other, and a 100yo rose bush in the middle. I want to be able to put a hammock between the apple trees without my neighbors leering at me. Zone 6 NE KY!

in fairness and in a more general sense of gardening (!) i have heard the soroia type violets can be a true weed in certain settings. the selective broad-leaf herbicides also used for clover and flat weeds in lawns is also good for violets as weeds. i tend to be very conservative using such sprays, but still think they have a place. i mix according to the instructions, measuring carefully, and only use a small hand sprayer. i then carefully spot spray the worst areas and put any hand weeding time into more 'sensitive' areas. timing is important, too. there will be several generations of plants due to delayed seed germination. this might give the impression no progress has been made! try to spray the worst areas before the masses of non-flowering seed pods mature. chose a day and time with no wind to avoid drift onto other plants. spot spraying (of all chemicals) is far friendlier to wild life than mass spraying. my fairly new garden is open invitation to weeds. a neglected vacant block over my back fence grew a huge crop of thistles last summer.....and now i'm pulling those out! i've also inherited tobaccum sylvestris and papaver somniferum as 'blow ins' to newly dug over areas. despite my activities my garden has frogs. i have a few bromeliads in the shade house and saw a little frog peering out of the collected water in one some months back. i can hear the frogs calling in the evenings and during rain. rob...

Those are wild violets. There are a couple different ways to kill them depending on how bad of an infestation you have. If you have a lot of them triclopyr is what you need to use. Ortho Weed-B-Gon Clover, Chickweed and Oxalis killer is the stuff to get. I prefer the concentrate which you mix up in a pump up sprayer. I use 2 ounces per gallon of water and be sure to mix in a non ionic surfactant to make it stick. You will need several applications about 10 to 14 days apart. Keep spraying them until they are brown and dead. This time of year you will have to be careful as you might get some turf damage if the temps are above 85 degrees. On another note, this is for cool season grasses only. This stuff will kill bermuda. Another method that probably works best if you don't have a lot of wild violets to deal with is Glyphosate (aka RoundUp). Pour a little straight glyphosate in a cup and add some non ionic surfactant (baby shampoo or liquid dish detergent will work too) and using a small hobby type paint brush paint each leaf with glyphosate. This method only takes one application to kill them plus it really doesn't matter how hot the temps are. Once they're gone you will still need to keep an eye out for new plants popping up. As soon as you see a new one hit it with the glyphosate. They are extremely hard to get rid of but with some vigilance you should be able to reach a point where they are easily manageable.