Lawn Care · Grassy Weeds
Most weed killers people grab for crabgrass were never built to kill it.
No: 2,4-D, Trimec, dicamba, MCPP and ordinary weed and feed are broadleaf herbicides, and crabgrass is a grass, so it shrugs them off. Glyphosate Roundup does kill crabgrass, but it kills your lawn grass too. MSMA has been cancelled for home lawns since 2009, and atrazine is weak on summer grasses. What actually kills crabgrass in a lawn is a grass-selective herbicide such as quinclorac, fenoxaprop or mesotrione, matched to your turf and to how big the crabgrass is.
2,4-D / TRIMEC
Broadleaf only, no crabgrass
ROUNDUP (GLYPHOSATE)
Kills crabgrass and the lawn
MSMA ON HOME LAWNS
Cancelled by EPA in 2009
SELECTIVE CRABGRASS KILLERS
Quinclorac, fenoxaprop, mesotrione
Will it kill crabgrass? The quick answers
Crabgrass is a summer annual grass. A herbicide either has activity on grasses or it doesn’t, and most of the familiar lawn weed killers are designed to leave grasses alone. The table sums up each common product. The sections below explain the reasoning and the exceptions.
| Product or active ingredient | Kills crabgrass? | Why | Use instead |
|---|---|---|---|
| 2,4-D | No | Broadleaf herbicide; grasses tolerate it | Quinclorac or fenoxaprop |
| Trimec and other 3-way mixes (2,4-D + MCPP + dicamba) | No | All three ingredients target broadleaf weeds | Quinclorac, or a quinclorac combo like Q4 Plus |
| Dicamba or MCPP alone | No | Broadleaf activity only | Same as above |
| Weed and feed (broadleaf type) | No | Typically 2,4-D with dicamba or MCPP on fertilizer; crabgrass isn’t on the label | A crabgrass killer now, a pre-emergent next spring |
| Crabgrass preventer + fertilizer | No, it prevents | Pre-emergents stop seeds sprouting; they don’t kill grown plants | Apply before germination next year |
| Roundup Weed and Grass Killer (glyphosate) | Yes, and your lawn | Non-selective; kills any green plant it wets | Spot use or full renovation only |
| Roundup For Lawns | Partly | Different formula: contains quinclorac along with broadleaf ingredients | Read the label for your grass type |
| MSMA | Not an option | Residential lawn use cancelled by EPA in 2009 | Quinclorac, fenoxaprop or mesotrione |
| Atrazine | Poorly | A St. Augustine and centipede product aimed at winter weeds and broadleaves | Pre-emergent timing in those lawns |
| Vinegar | Only seedlings, briefly | Burns leaves on contact, not roots; browns grass too | A selective crabgrass killer |
Will 2,4-D kill crabgrass?
No. 2,4-D is the backbone of most lawn broadleaf sprays, and it is selective in the other direction: it kills dandelion, clover and plantain while lawn grasses tolerate it. Crabgrass is a grass, so it tolerates it too. Oklahoma State University Extension files 2,4-D combinations under summer broadleaf weed control and lists separate products for summer grassy weeds like crabgrass, goosegrass and foxtail.
If you sprayed 2,4-D on crabgrass and saw nothing happen, the product didn’t fail and you don’t need to wait longer. Our guide to how long 2,4-D takes to work covers what you should expect on the weeds it does control.
Does Trimec kill crabgrass?
No. Trimec is a brand of three-way broadleaf herbicide, built on 2,4-D, MCPP (mecoprop) and dicamba. Oklahoma State names Trimec as an example of a summer broadleaf product and says these combinations are safe on bermuda, Kentucky bluegrass, centipede, perennial ryegrass, tall fescue and zoysia. That turf safety is exactly why they leave crabgrass standing. The same goes for dicamba or MCPP sprayed alone, and for most other “3-way” and “4-way” lawn weed killers. We compare those products, and what each one is good for, in our roundup of the best weed killers for lawns.
Some newer combination products do include a grass-active ingredient. Q4 Plus, for example, pairs quinclorac with sulfentrazone, 2,4-D and dicamba, so it handles crabgrass and broadleaf weeds in one spray. The ingredient list on the label is what tells you, not the word “weed” on the front.
Will weed and feed kill crabgrass?
A standard weed and feed will not. Scotts Turf Builder Weed & Feed, a typical example, lists 2,4-D and dicamba as its active ingredients. Its long list of controlled weeds doesn’t include crabgrass, the product page says it won’t stop weed seeds from sprouting, and it is not for St. Augustine lawns.
The other kind of fertilizer combo is a crabgrass preventer with fertilizer. That one works on crabgrass, but only before it exists. Pre-emergent herbicides have to be in place and watered in before seeds germinate, per Oklahoma State. Spread one over July crabgrass and the plants already growing are unaffected. That is prevention for next year, covered in our crabgrass preventer timing guide.
Will Roundup kill crabgrass?
Classic Roundup (glyphosate) will kill crabgrass, along with everything else it touches. Oklahoma State groups Roundup with the non-selective herbicides, which kill whatever green, growing plant they land on. It has no way to tell crabgrass from your fescue or bermuda. The one lawn use the OSU sheet describes is a winter-weed spray on bermudagrass after it has gone fully dormant, usually January or early February. That timing doesn’t apply to summer crabgrass, because bermuda is green and growing then.
The brand name causes confusion. Purdue Extension points out that Roundup For Lawns is a different product: a selective mix of MCPA, quinclorac, dicamba and sulfentrazone rather than glyphosate. Its quinclorac gives it crabgrass activity, and Purdue notes a separate crabgrass product in that line uses topramezone instead. Same logo, very different result on your lawn, so check the active ingredients before you spray.
Will MSMA kill crabgrass?
MSMA, an organic arsenical, did control crabgrass, and older extension fact sheets still list it. Oklahoma State’s HLA-6420, for example, names the organic arsenicals as its summer grassy-weed option. But the EPA cancelled MSMA use on residential lawns, parks and athletic fields in 2009. What remains is limited to sod farms, golf courses, highway rights-of-way and cotton. A home lawn is not on any current label, so it is not a legal choice, whatever an old bag in the garage says. Our dallisgrass guide covers the MSMA history in more detail.
Does atrazine kill crabgrass?
Not reliably. Atrazine is mainly a St. Augustine and centipede herbicide. The University of Georgia turf weed control guide lists it for those grasses, zoysia and dormant bermuda, for annual bluegrass and broadleaf weeds, and rates its control of summer annual grasses as weak. In St. Augustine and centipede lawns, where the usual crabgrass killers aren’t labeled, crabgrass is mostly managed with a well-timed pre-emergent instead.
Vinegar and other home remedies
Household vinegar is a contact burner. It can scorch a tiny seedling, but it doesn’t reach the roots of an established clump, and it browns lawn grass as readily as weeds. Our homemade weed killer guide goes through why. For scattered plants, hand-pulling before they set seed beats any kitchen spray.
What actually kills crabgrass
The herbicides that kill crabgrass while sparing turf are grass-selective post-emergents. Penn State Extension lists the main home-lawn options and the growth stage each handles best. Crabgrass is counted in tillers, the side shoots that form around the base of the plant.
- Quinclorac (Drive XLR8, Quinclorac 75 DF, and in combination as Q4 Plus). Penn State says it controls newly emerged plants and mature plants past four tillers, but may fall short on plants in the two- to four-tiller range. Penn State says to add a methylated seed oil for best results. UGA’s guide says quinclorac is not for St. Augustine, centipede, bahia or carpetgrass. Our post on how long quinclorac takes to work covers what to watch for after spraying.
- Fenoxaprop (Acclaim Extra). Works on tillered crabgrass, with label rates rising as the plants get bigger. Penn State warns that it can injure some Kentucky bluegrass cultivars, particularly in hot weather, and that it loses strength when tank-mixed with 2,4-D or MCPP. UGA lists it for bluegrass, fescues, ryegrass and zoysia, not bermuda, centipede or St. Augustine.
- Mesotrione (Tenacity). Best on crabgrass with fewer than four tillers, and used mainly in new seedings of Kentucky bluegrass, perennial ryegrass and tall fescue. Treated crabgrass bleaches white, then dies. Penn State says not to use it in new fine fescue stands.
- Dithiopyr, early (Dimension 2EW). Mainly a pre-emergent, but it also kills very young crabgrass. LSU AgCenter puts that window at about one to two weeks after germination. It is a late-spring rescue, not a summer fix.
Penn State also lists topramezone (Pylex) for young crabgrass. Whatever you choose, take the rate, surfactant and turf list from the product label, which is the legal instruction for that product. For a side-by-side look at the products themselves, see our crabgrass killer comparison, and for a mid-season plan see how to get rid of crabgrass in the summer.
Don’t broadcast glyphosate over a crabgrass-filled lawn hoping to save the grass.
Glyphosate kills every actively growing plant it wets, so a whole-yard spray in summer is a renovation, not a weed treatment. If crabgrass has taken over most of the lawn, decide whether you are reseeding or resodding first, then plan the kill around that date. And don’t reach for quinclorac or a quinclorac combo in St. Augustine or centipede: those grasses aren’t on the label.
If you would rather hand the job off, our lawn weed control page connects you with a lawn care company serving your area.
Crabgrass killer FAQs
What herbicide kills crabgrass without killing grass?
Grass-selective post-emergents: quinclorac, fenoxaprop, mesotrione and topramezone are the main home-lawn options Penn State lists. Each has a turf list on its label, so match the product to your grass type before buying.
What chemical kills crabgrass the fastest?
Glyphosate and other non-selective products work on any plant, but they kill your lawn too. Among selective options, speed matters less than growth stage: spray young, actively growing crabgrass and follow the label’s repeat interval.
Does 24D kill crabgrass if I spray it twice?
No. A second application won’t change the result, because crabgrass, like your lawn grass, tolerates 2,4-D. Switch to a grass-active product.
Will weed and feed kill crabgrass if I apply it in spring?
Not a broadleaf weed and feed. A fertilizer that carries a crabgrass pre-emergent can prevent new plants if it goes down before germination, but it won’t kill crabgrass that has already come up.
Can I still buy MSMA for my lawn?
MSMA residential lawn use was cancelled by EPA in 2009. Remaining registrations cover sod farms, golf courses, highway rights-of-way and cotton, not home lawns.
Related guides
Sources: Oklahoma State University Extension HLA-6420: Lawn Management in Oklahoma · Penn State Extension: Postemergence Control of Crabgrass and Other Summer Annual Grasses in Lawns (updated 2025) · University of Georgia: Turfgrass Weed Control for Professional Managers (2024) · LSU AgCenter: Preemergence Options for Crabgrass Control · Purdue Extension: When Roundup Isn’t Roundup (2024) · EPA: MSMA (organic arsenical) status · Scotts: Turf Builder Weed & Feed product page
