Answer: I would dig the weeds out, If you simply whack off the tops of the weeds, the roots will remain alive and the weeds will resprout. If you can't dig the roots out, apply a vegetation killer or simply pour boiling water into the cracks to kill the weeds. If you use a vegetation killer such as Round Up, wait the prescribed amount of time (as listed on the label) and then apply a pre-emergent to keep weeds from growing there. Or, you might consider patching the cracks - that would permanently eliminate the problem.
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