Sand spurs are summer annual weeds that germinate and mature each season. The fruits are felt in the fall, when it is too late to kill the plant using chemicals. Herbicides are not effective on sand spurs once they have bloomed in the fall. Apply a pre-emergent herbicide containing imazapic to the lawn in the spring, following the label directions, according to the University of Florida. Maintaining a healthy lawn will prevent sand spurs from forming.
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Christina Wheeler has been a professional freelance writer since 2007. She lends her expertise in animal care, gardening and home improvement to online publications such as Garden Guides and eHow. Wheeler studied business management at Ohio University.