Perhaps one of the most troublesome and common weeds to plague lawns across the globe, crabgrass is technically a type of grass. This undesirable grass makes lawns appear lumpy and unattractive and can quickly drive out desirable grasses if not managed.
Crabgrass grows in large clumps with outward pointing blades said to look like crabs. These clumps make lawns appear lumpy and produce light patches in lawns because the weed is lighter in color than most desirable grasses.
Crabgrass has many ways of infiltrating your lawn, from seeds deposited in bird droppings to sharing lawn mowers with a friend who has an infested lawn. Crabgrass can also enter a lawn in bags of grass seed which has not been thoroughly cleaned and sorted.
Crabgrass is easy to control by preventing the conditions that crabgrass seeds need to germinate. Crabgrass seeds need excessive light to germinate, so keep soil shaded with trees or cover exposed areas with straw or compost to prevent germination. You may also try pre-emergent herbicides on the lawn to hinder the germination process up to 30 days before germination begins, usually in April or early spring.