Crabgrass Killers for Centipede Lawns

Crab Grass

• Crab grass is a summer annual weed that frequently infests centipede grass lawns. The weed seeds starts to germinate at soil temperatures of 60 degrees Fahrenheit and starts to flower and produce seed during July. The hardy weed reproduces and spreads aggressively. Unless controlled in the early stages of growth, it can lead to heavy infestation in all turf grasses, including centipede grass.

Recommended Herbicides

• The Texas A&M University Extension suggests the use of pre-emergent herbicides as the best control option for crab grass in centipede grass. Pre-emergent herbicides are applied to soil before the germination of weed seeds. Products recommended for use include DCPA, bensulide, benefin or simazine. All herbicides are sold under different trade names.

Application Time

• The best time to apply pre-emergent herbicide to centipede grass is when the forsythia is blooming or very early in spring. According to research by the Purdue Cooperative Extension, pre-emergent herbicides applied as early as March 1 remain effective against crab grass all season. Do not apply herbicides on newly seeded or seedling centipede grass. The herbicide will retard the germination of grass seed as well.

Post Emergence Herbicides

• Crab grass also may be controlled after it has started to grow by applying post-emergent herbicides such as dithiopyr, MSMA, DSMA or fenoxaprop. The chemicals are most effective on younger weeds. Water the entire site well before treating to make sure that the grass is not under drought stress. Avoid mowing or watering the grass for up to 24 hours after treating. Apply the herbicides when the temperature is less than 85 degrees Fahrenheit for best results.