Q.Best way to eradicate or control spread of old fashion violets
Other than just ripping out the vining stems, but with the underground vining, I never get all of them. And, with the (violets) prolific reseeding, their advancing spread is almost unimaginable. Could I spray them with a broadleaf weed killer to wipe them out? I don’t really want to kill any other plants in the area, or sterilize the soil. Can you provide me with any info, please? It would be most appreciated!

Certified GKH Gardening Expert
Here's an article that will help:
https://www.gardeningknowhow.com/ornamental/bulbs/violet/kill-wild-violets.htm
For the best substances to use on them, you'll need to talk with your local nursery experts or contact an extension service for help.