Does anyone know what this is? It's in neighbors yard and spreads like crazy. Is there some way to control it? - Wayne
The plant is a wild violet, and is a host plant for Fritillary butterflies.
Where violets are considered a weed, they are hard to control, as when they bloom in the spring, the plant ejects the seed so that it is widely dispersed. As with all unwanted plants in grass, a thick turf will impede the presence of weeds.
To control wild violets, you can use a weed killer containing triclopyr, which is more effective on violets than just 2,4-D + MCPP + dicamba. If you spot spray in the lawn, pick a cool, calm day, and protect any nearby foliage on desirable plants, as weed killers are easily carried on the wind, and they can become volatile and drift quite far at temps in the 80s. In a garden, it would be best to hand dig or cultivate them out.. Violets are at the end of their blooming cycle now. Here is the link to the KSU bulletin on weed control in turf grass: http://www.ksre.ksu.edu/bookstore/pubs/mf2385.pdf .
Carole-Johnson County Extension Master Gardener