Products, Vendors, CAD Files, Spec Sheets and More...
Sign up for LAWeekly newsletter
Postemergent herbicide is a fancy phrase for killing/controlling unwanted grasses and broadleaf weeds. The ?EUR??,,????'?????< Postemergent herbicides can be selective or nonselective. A selective herbicide is designed to kill specific grasses or broad leaf weeds. Ornamec, for example, is a turf herbicide to control grass-type weeds. A nonselective herbicide, e.g., Roundup, will affect any vegetation to which it is applied. Postemergent herbicides target visible weeds. They are used primarily against broadleaf weeds, perennial grasses, and sedges. The chemicals 2,4-D, dicamba, carfentrazone, triclopyr, clorpyralid, MCPP and MCPA are broadleaf herbicides. They have been combined in many products that control broadleaf weeds, such as Weed-B-Gon Weed Killer for Lawns, Trimec Southern, Bayer Advanced Southern Weed Killer for Lawns and many others.
Postemergent herbicides can be selective or nonselective. A selective herbicide is designed to kill specific grasses or broad leaf weeds. Ornamec, for example, is a turf herbicide to control grass-type weeds. A nonselective herbicide, e.g., Roundup, will affect any vegetation to which it is applied.
Postemergent herbicides target visible weeds. They are used primarily against broadleaf weeds, perennial grasses, and sedges. The chemicals 2,4-D, dicamba, carfentrazone, triclopyr, clorpyralid, MCPP and MCPA are broadleaf herbicides. They have been combined in many products that control broadleaf weeds, such as Weed-B-Gon Weed Killer for Lawns, Trimec Southern, Bayer Advanced Southern Weed Killer for Lawns and many others.
Most broadleaf weeds are best treated in the spring or fall when air temperatures are between 65 and 85???????(R)? F. In hotter temperatures, turf damage is more likely. Weather conditions are a factor. Treat weeds when no rain is expected for at least 24 hours, for the obvious reason that watering will dilute the herbicide and perhaps spread the herbicide where you don?EUR??,,????'?????<
Best treatment results occur when weeds are young. Repeat applications, 10 to 14 days apart, may be required to get the control you need. You should not mow immediately prior to or after postemergent application, as it lessens the surface area contacting the herbicide.
Postemergent herbicides can be applied to newly seeded lawns, but at only half the recommended rate and only after the lawn has been mowed four times. If overseeding after a postemergent herbicide treatment, you must wait one to four weeks, depending on the product.
Coverage is easier with spray applications and herbicides that you can spray are generally less expensive. One drawback is that some herbicides (whether liquid or granular) are volatile, i.e., the tendency of the herbicide molecule to become a vapor, which may result in the movement of herbicide to unwanted areas or loss of effectiveness at the application site. Barricade and Ronstar are essentially nonvolatile. If you spray a volatile herbicide, you will need to water it in.
Granulars coverage is generally not as uniform as spraying. Mixing granulars with fertilizer defeats the volatility of herbicides. Regardless, the granular herbicides must be watered in to activate them.
(Feb.-March) Before turfgrasses begin to green up for summer growth, apply a postemergent herbicide to control the emerging winter broadleaf weeds or summer broadleaf weeds. With any pesticide, read the label to make sure that it is appropriate for your situation.
(May-June) If annual grasses (e.g., crabgrass) or perennial grasses (e.g., dallisgrass) have emerged, apply 2-3 applications (14 to 21 days apart) of a postemergent grass herbicide. For broadleaf weeds, apply a three-way mixture.
(Aug.-Oct.) Continue to treat grassy weeds and watch for wild onions and wild garlic.
(Nov.-Jan.) On mild days treat winter broadleaf weeds. Nonselective herbicides, such as Roundup, can be used safely on turf that is completely dormant.
Trimec Lawn Weed Killer?EUR??,,????'?????<dandelions, clovers, thistles and bindweed.
Manor?EUR??,,????'?????<three perennial and annual weedy grasses (Bahiagrass, foxtail and ryegrass) and broadleaf weeds.
Corsair Herbicide?EUR??,,????'?????<Virginia buttonweed, wild violets, chickweed, purslane, wild onion, wild garlic and many other weeds. Can be applied on all turfgrass species except tall fesuce, ryegrass and dichondra. Some discoloration or delayed green-up may occur on St. Augustinegrass, buffalograss, centipedegrass, zoysiagrass or bahiagrass.
Manage Herbicide?EUR??,,????'?????<nutsedge; suppresses Kyllinga, spp. Both cool-season and warm-season grasses tolerate this herbicide.
Momentum?EUR??,,????'?????<wide variety of broadleaf weeds, particularly good for buttonweed and spurge.
Vantage Herbicide?EUR??,,????'?????<annual and perennial grasses in centipede turf.
Image Herbicide?EUR??,,????'?????<broadleaf, sedges and grassy weeds in turf (and ornamentals).
Fusilade Herbicide?EUR??,,????'?????<grassy weeds; for zoysiagrass turf, ornamentals and some ground cover.
Dimension?EUR??,,????'?????<crabgrass.
Sources: 1. Managing Weeds In Warm Season Lawns. Clemson University Extension. 2. North Carolina Turfgrass. Turfgrass Council of North Carolina. 3. www.pestproducts.com
60: Degrees, the ground temperature at the point the crabgrass germinates. Source: Lowe?EUR??,,????'?????<
85: Degrees, the maximum outside temperature recommended for the application of postemergents. Source: www.lawnfertilizer.com
Francisco Uviña, University of New Mexico
Hardscape Oasis in Litchfield Park
Ash Nochian, Ph.D. Landscape Architect
November 12th, 2025
Sign up to receive Landscape Architect and Specifier News Magazine, LA Weekly and More...
Invalid Verification Code
Please enter the Verification Code below
You are now subcribed to LASN. You can also search and download CAD files and spec sheets from LADetails.