There are several kinds of this weed...some are worse take a piece of it to the lawn & garden center to show them and ask which kind of spray you should use. When you cut the lawn use a lawn catcher and plastic bag that and trash it....do not mulch it. It spread seeds around and that is how it reproduces. Winter is the best time to control this while it is dormant. When you do chemical keep children & pets away from the area until it has rained. Use proper old long sleeved clothing, mask, hat, gloves and goggles. Don't spray if it is going to rain or if it is windy.