What Is Crabgrass and How Does It Get in My lawn?

Crabgrass is an annual grassy weed with broad blades, rough texture and a lighter green color. Germinating from seed each spring when soil temps reach 50° to 55°F, crabgrass plants mature and produce seeds.  The crabgrass plant is killed by frost in late autumn, leaving behind seed and a bare spot for the weeds to germinate the following spring.  The cycle continues, weed seeds carry in the wind, move by rainfall and settle into bare spots ready to multiply in warmer weather.

What Does Crabgrass Look Like?

Crabgrass is a low growing weed with lots of stems that form flat clumps. Clumps spread out and root along the stems at joints. The blades are coarse, pointed and short. As crabgrass matures, they send up branched seed heads that have thousands of crabgrass seeds. Looking out over your yard, crabgrass shows up as patches of much lighter green than the rest of your turf lawn.

Crabgrass in Fescue

How Do I Kill Crabgrass?

When you find crabgrass and foxtail in your lawn that has escaped the pre-emergence control from Prevent, control crabgrass and other annual grassy weeds with one of Uncle’s Q-Bomb products. Q-Bomb, post-emergent crabgrass herbicides containing quinclorac, will control a wide variety of grass weeds and broadleaf weeds, including crabgrass, foxtail, clover, dandelion, black medic, English daisy, morning glory, dollarweed, speedwell, torpedo grass, barnyard grass, bindweed, signal grass, and wild violet. Use a broadcast or spot treatments to actively growing weeds as a post-emergence. Do not broadcast apply these products when temperatures are above 90 degrees temporary turfgrass discoloration can also be expected with spot treatments when air temperatures exceed 90 degrees.

Always read and follow label directions for use before applying any pesticide.

Tips for Effective Post-Emergence Crabgrass Control

  • Uncle’s Q-Bomb products are most effective on crabgrass when applied to newly germinated crabgrass with one to six leaf while having no more than two tillers and after crabgrass has matured to five tillers or greater.
  • Do not mow 2 days before or after a Q-Bomb application. If soil is dry, irrigate turf grass in advance for best results. No rainfall or water for 24 hours after application. Apply ½ inch of water 2-7 days after application, if no rainfall has occurred during this time period.
  • Early summer treatments are generally more effective. Applications in mid-summer (July 15-August 15) to older, drought stressed grassy weeds are less effective. Late summer applications (after  August 15) to mature crabgrass can be very effective.

Crabgrass Life Cycle

Of all lawn weeds, crabgrass is the most common and bothersome. Crabgrass is probably the only weed that everyone hates! Even though it is a grass, crabgrass doesn’t blend in with lawn grasses in color, habit or texture and can be so aggressive that it out competes the good turf grass. Understanding the life cycle of crabgrass will help you deal with it more effectively.

What Is the Best Way to Prevent Crabgrass?

The best way to eliminate crabgrass in your lawn is to apply a pre-emergent barrier in spring. Prevent crabgrass germination with the two application formula of Prevent, a crabgrass preventer with fertilizer. The first application of Prevent goes down in early spring before crabgrass seeds can germinate and the second application of Prevent will go down 10-12 weeks later.


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