Answer: Sandburrs, aka sandspurrs or grassburrs, are difficult to control because the seeds remain viable for several years. So, even if you kill the tops of the plants, new ones will emerge as the seeds in the soil germinate. Therefore a two-pronged approach is best: treat the yard with Image or Momentum, Three Way, etc. to kill the existing weeds. (Sorry, there are no organic formulas effective against this weed.) You may have to make several applications (read and follow label directions). In conjunction with that, apply a pre-emergent herbicide to keep the seeds from germinating. Then, if you put your lawn on a regular feeding schedule, it will grow thick and lush enough to crowd out any weeds trying to emerge. Best wishes with your lawn!
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