Herbicide That Kills Crabgrass

Identification

• Crabgrass is a light-green summer annual weed that grows throughout the United States. Several species of crabgrass exist, including smooth crabgrass and large crabgrass. Moreover, crabgrass is known by several names, including crowfoot grass, watergrass and summer grass. Crabgrass can be found growing in a broad range of areas, including lawns, ornamental landscapes, vegetable gardens, orchards and vineyards. Crabgrass can spread quickly if not controlled, as a single plant is capable of producing 150,000 seeds.

Pre-Emergent Herbicides

• Pre-emergent herbicides include bensulide, dithiopyr, oryzalin, oxadiazon, pendimethalin, prodiamine and trifluralin. Apply pre-emergent herbicides before crabgrass germinates. Generally, this occurs around March 1, though it can occur earlier in warmer climates.

Post-Emergent Herbicides

• Post-emergent herbicides include dithiopyr, fluazifop, quinclorac and sethoxydim plus oil. Apply post-emergent herbicides when crabgrass is small, between one and three leaves. If the crabgrass is larger, it will require more herbicide and the chance of injury to the turf grass increases. If you are attempting to control crabgrass in ornamental beds, you should use a selective herbicide, such as benefin, oryzalin or trifluralin. Alternatively, you can use a nonselective herbicide if you take care to make sure that the herbicide only comes into contact with the crabgrass.

Alternative Control Methods

• The way to prevent an invasion of crabgrass without using herbicides is to increase the vigor of your turf grass. A vigorous turf grass will prevent crabgrass from getting the water, sunlight and nutrients it needs to thrive. To ensure that your turf grass is vigorous, select the proper turf grass for your climate, mow to the desirable height of the specific turf grass, irrigate properly for the specific turf grass and apply fertilizer when the turf grass is actively growing. Additionally, you can control crabgrass by hoeing or hand pulling crabgrass when it is young and has not yet set seed.