Q: I have an obnoxious, unkillable, unpreventable WEED in my lawn. It is low growing and the leaves look a little bit like parsley. In summer it has almost-invisible stickers that make going barefoot impossible. I never had this weed until three years ago. HELP!
A: I feel sure you have lawn burweed. Spread a pre-emergent (click for sources) in early September to prevent the seed from germinating. Check the label to be sure the product prevents broadleafed weeds and that it can be used on your specific lawn grass
If you can see the green plants, spray them with a product that contains triclopyr (click for sources)
Be sure to read the pesticide label for full directions.