Crab grass, an annual warm season grass, can take over an entire lawn quickly if not properly cared for. Proper and constant maintenance of your lawn is necessary when fighting a crab grass infestation. Spread by seeds that have a three-year life span, this weed procreates rapidly and what was once a beautiful turf lawn quickly becomes a haven for crab grass and other weeds. Crab grass is also known as crowfoot grass, water grass and summer grass, according to the University of California.
Spread granular pre-emergent herbicides with active ingredients such as pendimethalin or dithiopyr in the late winter and again in the late spring. Use a broadcast spreader to evenly cover your entire lawn. Liquid pre-emergent herbicides with active ingredients such as bensulide or oryzalin are available to treat crab grass but with a higher difficulty application that can result in uneven lawn treatment.
Mow your lawn regularly using a mower with a sharp blade to reduce tearing of the grass blades. Tearing the grass blades can cause the lawn to weaken and thin, becoming more susceptible to disease and crab grass infestation. Keeping the grass at an appropriate height for your species of turf grass promotes a thicker lawn that can choke out crab grass.
Feed your grass with an appropriate fertilizer for your lawn by carefully reading the labels of the fertilizers available to you. Each lawn requires different fertilizers depending on the species of grass. Proper feeding of your grass promotes a healthier, thicker lawn.
Treat the crab grass with post-emergent nonselective herbicides whose active ingredient includes glyphosate. Nonselective herbicides cannot tell the difference between a good and bad plant. Spot treat by cutting the bottom from a gallon milk container, placing the container over the crab grass and spraying the herbicide through the opening at the top of the container.
Dig the crab grass from your lawn, making sure you dig up the root system. Discard the crab grass away from your lawn. The crab grass may contain seeds that could germinate in the spring. This might not kill the crab grass, but it will slow down the growth and spread of this pesky weed.