Preemergence Options for Crabgrass Control in Louisiana Lawns

Daniel Gill  |  4/2/2015 7:36:23 PM

Crabgrass infesting Bermuda grass

Crabgrass

Crabgrass is a summer annual grass that is one of the most common weeds infesting Louisiana lawns. Soil temperatures are an important factor in determining when crabgrass germinates. Seed germination is initiated in the late winter when temperatures in the soil reach 55-60 F. This corresponds to middle to late February in Baton Rouge to early March in Shreveport and Monroe. Like most weeds, crabgrass is most likely to occur in poor lawns where the turf provides little competition for space. Crabgrass seeds need light for germination. Thin lawns allow light penetration to the soil surface and crabgrass seed germination is stimulated. This is just another reason to make lawns as thick and healthy as possible during the growing season through correct fertilization and mowing.

Lawns that are receiving proper care rarely have serious weed infestations. However, even "good" lawns can have some degree of crabgrass infestation. The good news about crabgrass is that the weed can be easily managed with preemergence herbicides. Preemergence herbicides suppress weed seeds and postemergence herbicides kill existing weeds. Preemergence herbicides prevent crabgrass emergence by killing the young grasses shortly after they germinate.

There are many preemergence herbicide options available for homeowners that can provide effective control of crabgrass. The following is a brief description of several preemergence herbicides that will help consumers make informed weed management decisions. Remember to read the label and follow the applications instructions exactly. Always apply these herbicides to established turf.

Crabgrass Characteristics:

·Pale green color
·Membranous ligule
·May root at nodes
·Germinates as early as mid-February in Louisiana
·Summer annual

Preemergence Crabgrass Herbicides:

Sta-Green Crab-EX
·Active ingredient: dithiopyr
·Rate = 3.4 lb /1,000
·1 bag covers up to 5,000
·Safe on all established southern turfgrass
·Preemergence and early postemergence activity on seedling crabgrass (1 to 2 weeks after germination)

Greenlight Crabgrass Preventer 2
·Active ingredient: dithiopyr
·Rate = 2.4 lb to 4.6 lb /1,000
·1 bag covers up to 5,000
·Safe on all established southern turfgrass
·Preemergence and early postemergence activity on seedling crabgrass (1 to 2 weeks after germination)

Hi-Yield Turf & Ornamental
·Active ingredient: dithiopyr
·Rate = 4.0 lb/ 1,000
·1 bag covers up to 5,000
·Safe on all established southern turfgrass
·Preemergence and early postemergence activity on seedling crabgrass (1 to 2 weeks after germination)

Greenlight Crabgrass Preventer
·Active ingredient: benefin + trifluralin
·Rate = 2.8 lb /1,000
·1 bag covers up to 5,700
·Safe on all established southern turfgrass
·Preemergence activity only

Scott’s Halts
·Active ingredient: pendimethalin
·Rate = 2.0 lb /1,000
·1 bag covers up to 5,000
·Safe on all established southern turfgrass
·Preemergence activity only

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