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Quackgrass isn’t just a weed — it’s a perennial invader that spreads through aggressive underground rhizomes, making hand-pulling a futile exercise that often makes the infestation worse. Any successful attack requires a selective herbicide that can translocate through those stems and kill the root nodes, or a non-selective option precise enough to avoid collateral damage.
I’m Mohammad Maruf — the founder and writer behind Gardening Beyond. I’ve studied hundreds of herbicide labels, compared active ingredient concentrations, and analyzed aggregated owner feedback to identify which products actually deliver on their promise of eliminating quackgrass from lawns and garden beds.
Whether you’re battling it in turfgrass or ornamental beds, finding the right best quackgrass killer means understanding how active ingredients like fluazifop-P-butyl, sethoxydim, and glyphosate interact with your specific grass type and landscape situation. Not every popular lawn herbicide actually lists quackgrass on its EPA label — we checked each product’s registered label before including it here.
How To Choose The Best Quackgrass Killer
Quackgrass is a cool-season perennial grass that spreads by seeds and white, underground rhizomes. Killing the top growth without killing those rhizomes guarantees re-infestation within weeks. Your choice depends on where the quackgrass is growing and what plants you want to protect.
Selective vs. Non-Selective Formulations
Selective grass herbicides built on fluazifop-P-butyl or sethoxydim target grassy weeds like quackgrass while sparing many broadleaf ornamentals — though they are not universally safe on every turfgrass, so check the label’s tolerance table before broadcasting over a lawn you want to keep. Note that not every “selective grass killer” on shelves is actually labeled for quackgrass — quinclorac and mesotrione, for example, are popular for crabgrass but do not list quackgrass as a controlled species. Non-selective options like glyphosate kill everything they touch, making them ideal for garden beds, pathways, or spot-treating before bare-soil renovation — but they require precise application to avoid drift onto ornamentals.
Active Ingredient Efficacy on Rhizomes
The most effective quackgrass killers contain active ingredients that translocate from leaf tissue down into the root and rhizome system. Fluazifop-P-butyl and sethoxydim are both ACCase-inhibitors that stop fatty acid synthesis in susceptible grasses, causing the whole plant — including rhizome tissue — to yellow and die over 1-4 weeks; both are labeled specifically for quackgrass control at defined growth stages. Glyphosate blocks the EPSPS enzyme but needs a surfactant to penetrate the waxy quackgrass leaf cuticle. Products with multiple actives (like glyphosate plus imazapyr) offer broader control but longer soil residual. Note that several widely sold turf herbicides — including mesotrione, quinclorac, and MSMA products — do not list quackgrass on their EPA labels at all, despite being marketed for “tough grassy weeds,” so it’s worth checking the label before buying one specifically for quackgrass.
Application Method and Coverage
Quackgrass grows in patches, so ready-to-use trigger sprayers work for small isolated clumps, while concentrated formulas mixed in a pump sprayer cover larger lawn areas. Concentrates offer better economics per square foot and let you dial in the right dose — critical because quackgrass often requires repeat applications 14-21 days apart to exhaust the rhizome energy reserves.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| Gordon’s Ornamec 170 Grass Herbicide | Selective | Cool-season turf & ornamental beds | 32 fl oz, 1.7% Fluazifop-P-butyl | Amazon |
| Syngenta Fusilade II Turf & Ornamental Herbicide | Selective | Professional-grade, large properties | 1 quart, 24.5% Fluazifop-P-butyl | Amazon |
| Martin’s Eraser Max Super Concentrate | Non-Selective | Garden beds & pathways | 32 oz, 43.68% Glyphosate + Imazapyr | Amazon |
| Fertilome Over The Top Grass Killer | Selective | Around shrubs & ornamentals | 8 oz concentrate, 8-gallon mix | Amazon |
| Ortho Grass B Gon Garden Grass Killer | Selective | Small garden beds (ready-to-use) | 24 fl oz spray, waterproof 1 hour | Amazon |
| Compare-N-Save Concentrate Grass & Weed Killer | Non-Selective | Large-scale bare-ground clearing | 1 Gal, 41% Glyphosate, makes ~85 gal | Amazon |
| Airmax Shoreline Defense | Non-Selective | Pond margins & shorelines | 1 Gal, Glyphosate aquatic formula | Amazon |
In‑Depth Reviews
1. Gordon’s Ornamec 170 Grass Herbicide
Ornamec 170’s active ingredient, fluazifop-P-butyl, is one of the few chemistries whose EPA label specifically names quackgrass as a controlled species — the label lists it under “Perennial Grasses” with a 6-10 inch growth-stage treatment window, alongside dallisgrass, rhizome johnsongrass, and bermudagrass. It works by inhibiting the ACCase enzyme grasses need for fatty acid synthesis, so treated foliage yellows and the whole plant, rhizomes included, dies back over one to several weeks.
The label calls for a broadcast rate of 9 fl oz per 1,000 sq ft per application for perennial grasses like quackgrass, with a maximum of 27 fl oz per 1,000 sq ft per year — in practice that’s roughly three applications spaced through the growing season for a mature stand. It’s also labeled for over-the-top spot use on a long list of ornamentals, trees, and shrubs, which makes it useful where quackgrass is creeping into a border rather than an open lawn.
The tradeoff is that fluazifop is a grass-killer, not a turf-safe blanket spray: the label itself notes temporary discoloration on tall fescue and warns some grasses are not tolerant. Treat it as a targeted tool for quackgrass patches in beds and rougher turf areas, spot-test on a small area of any lawn you want to keep, and always add the labeled nonionic surfactant — the active ingredient won’t penetrate quackgrass’s waxy cuticle without one.
What works
- Quackgrass explicitly named on the EPA label with a defined application rate
- Also labeled for spot use around a wide range of ornamentals
- Concentrate covers meaningful square footage per application
What doesn’t
- Not a blanket-safe lawn spray — can discolor some desirable turf
- Needs a nonionic surfactant and 2-3 applications for mature stands
2. Syngenta Fusilade II Turf and Ornamental Herbicide
Fusilade II is the professional-strength version of the same fluazifop-P-butyl chemistry in Ornamec, formulated at 24.5% active ingredient instead of 1.7%. Its EPA label is registered for “landscape areas, roadsides, nurseries, greenhouses, flower beds, groundcovers, interiorscapes, parks, sports fields, golf courses, commercial and residential areas,” and its perennial grass table names quackgrass at the same 6-10 inch growth-stage window, alongside torpedograss and rhizome johnsongrass.
Because it’s so concentrated, a single quart mixes into a large volume of finished spray — the ornamental-area rate is just 0.4-0.6 fl oz per 1,000 sq ft with a nonionic surfactant, so this bottle is built for larger properties, sports turf, or anyone treating quackgrass across a bigger footprint rather than a single lawn. The label calls for a 14-day wait before reseeding treated turf, and 30 days on bare ground.
The main drawback is price per bottle and the fact that this is a commercial-grade product: you’re paying for concentration and acreage coverage, not convenience. It also shares fluazifop’s core limitation — it’s a grass herbicide, so desirable turfgrasses that aren’t on the label’s tolerance list can be injured. Read the ornamental and turf tolerance tables before broadcast use.
What works
- Quackgrass named on the label at professional-strength concentration
- Registered for golf courses, sports fields, and large commercial sites
- One quart covers substantial acreage at labeled rates
What doesn’t
- Higher upfront cost than homeowner-sized concentrates
- Requires checking the turf/ornamental tolerance tables before broadcast use
3. Martin’s Eraser Max Super Concentrate
This non-selective super concentrate combines two potent active ingredients: glyphosate at 43.68% and imazapyr at 0.78%. Glyphosate works by blocking the EPSPS enzyme pathway, while imazapyr adds ALS-inhibitor activity for broader spectrum control and longer residual effect. This dual-action formula kills quackgrass down to the rhizomes, making it ideal for spot treatment in garden beds, pathways, and areas where complete vegetation removal is desired.
The 32-ounce bottle mixes at a rate of 1-2 oz per gallon of water, and a single application at labeled rates is generally enough to control most grassy and broadleaf weeds for weeks. The addition of imazapyr extends the window of control compared to straight glyphosate, though it also means treated soil will resist new plant growth for a longer period — plan on one or two bottles per season for routine bare-ground maintenance.
Because it is non-selective, extreme care is needed to prevent drift onto ornamentals, trees, or desirable lawn areas. The oil-based formulation can be difficult to clean from sprayer components if allowed to dry. This product is best suited for bare-ground applications, fence lines, and large-scale spot treatment where total vegetation knockdown is the goal.
What works
- Dual active ingredients kill roots and prevent regrowth
- High concentration means low cost per treated area
- Fast knockdown visible within days
What doesn’t
- Non-selective — kills any plant it touches
- Oil formula may clog sprayer nozzles if not flushed
4. Fertilome Over The Top Grass Killer – 10434
Fertilome’s Over The Top Grass Killer is a selective post-emergent herbicide that targets both annual and perennial grass weeds without harming broadleaf ornamentals, trees, shrubs, and vegetables. The 8-ounce concentrate makes 8 gallons of finished spray, covering roughly 2,000 square feet. Users commonly apply it over established flower beds to remove bermudagrass, quackgrass, and other invasive grasses without damaging iris, monkey grass, or shrubs.
Customer reports confirm that visible dieback begins within 2-3 days on short grass, but taller grass is only stunted and may require a second application. The product works more slowly than some non-selective alternatives, taking up to 3 weeks for complete kill on mature quackgrass clumps. Adding a few drops of dish soap as a surfactant reportedly improves adherence and results.
The main drawback is that effectiveness varies with grass height — clumps over 6 inches tall may only yellow and stall rather than die. Two applications are often necessary for heavy infestations. Some users report a strong odor during mixing. The product is best applied when quackgrass is actively growing and not stressed by drought or heat.
What works
- Safe to spray directly over ornamentals and shrubs
- 8 oz concentrate makes 8 gallons of spray
- Visible results start within 2-3 days
What doesn’t
- Less effective on grass over 6 inches tall
- May require two applications for mature quackgrass
5. Ortho Grass B Gon Garden Grass Killer Ready-to-Use Spray
Ortho Grass B Gon is a ready-to-use selective grass killer that targets crabgrass, fescues, bermudagrass, and quackgrass without harming ornamental flowers and shrubs. The spray requires no mixing, and the formula becomes waterproof in one hour, making it convenient for quick spot treatments. Each package contains two 24-ounce bottles for a total of 48 ounces — enough for small garden beds and targeted patches.
Users report that a single application kills grass but does not harm established Irises, daylilies, and other perennials. Dieback typically takes 2-4 days, and regrowth can occur after about a month, requiring reapplication. The product is most effective on young, actively growing grass and works well as a maintenance tool for keeping rock gardens and bed edges clean.
Several negative reviews note that the product failed to kill established grass even after emptying the entire bottle on a small area. This suggests that mature quackgrass with deep rhizomes may require a stronger concentrate formulation rather than a RTU spray. The product is labeled for non-edible garden areas only — avoid contact with vegetable plants.
What works
- Convenient ready-to-use spray — no mixing required
- Safe for use around flowers and ornamentals
- Waterproof in one hour after application
What doesn’t
- Inconsistent results on mature grass clumps
- Not for use in edible garden beds
6. Compare-N-Save Concentrate Grass & Weed Killer
This is a straight 41% glyphosate concentrate, and its EPA label explicitly lists quackgrass (Agropyron repens) for control — the label recommends applying in spring, late summer, or fall while quackgrass is actively growing for the best translocation into the rhizome system. Unlike the selective grass herbicides elsewhere in this guide, glyphosate is non-selective: it will kill any green plant it contacts, which is exactly what you want when clearing a heavily infested area down to bare soil.
One gallon mixes into roughly 85 gallons of finished spray at the standard rate (around 1.5 oz per gallon of water for general weeds, up to 2.5 oz per gallon for tough perennial stands like mature quackgrass), so this is sized for fence lines, large bare-ground renovations, or driveway and gravel-path edges rather than a small spot job. There’s no meaningful soil residual, so treated areas can typically be reseeded or replanted within a week or two once the dead growth is cleared — a real difference from products with longer soil activity.
The obvious tradeoff is that it’s non-selective: there is zero turf safety margin, so it’s the wrong tool if quackgrass is mixed into a lawn you want to keep. It also needs several days of dry weather after application and works best on actively growing (not drought-stressed) quackgrass.
What works
- Quackgrass explicitly named on the EPA label with application timing guidance
- One gallon concentrate covers large areas economically
- No lasting soil residual, so replanting can happen sooner
What doesn’t
- Non-selective — kills any desirable grass or plant it contacts
- Needs several dry days after application to work fully
7. Airmax Shoreline Defense Emergent Weed Control
Airmax Shoreline Defense is an aquatic-labeled glyphosate herbicide formulated specifically for emergent weeds like cattails, phragmites, and quackgrass growing along pond margins, lakeshores, and irrigation ditches. The product is safe for use in fresh and brackish water and will not harm fish, birds, pets, or other aquatic animals when applied according to label directions. It kills down to the root system, providing long-term control of shoreline grasses.
The concentrate mixes in a tank sprayer and is applied directly to the foliage. Results become visible in approximately two weeks, with complete dieback of target weeds. The 1-gallon container covers up to 10,000 square feet, making it a practical choice for large waterfront properties. For best results, users recommend applying in late summer with a surfactant for improved penetration.
The product is non-selective and will kill any desirable shoreline vegetation it contacts. Dead plant material must be physically removed after dieback to prevent nutrient recycling into the water. This product is overkill for standard lawn or garden quackgrass problems but is the best option when the infestation occurs in or near water bodies.
What works
- Approved for aquatic use — safe for fish and wildlife
- Kills quackgrass down to the root system
- Large 10,000 sq ft coverage per gallon
What doesn’t
- Non-selective — kills all shoreline vegetation
- Dead material requires physical removal
Hardware & Specs Guide
Active Ingredient Concentration
The primary determinant of efficacy against quackgrass is the percentage and type of active ingredient — but concentration only matters if the ingredient is actually labeled for quackgrass in the first place. Fluazifop-P-butyl products range from 1.7% (homeowner concentrates like Ornamec) to 24.5% (professional-grade Fusilade II); both list quackgrass at the same 6-10 inch growth-stage window, so the higher percentage mainly buys you coverage per dollar, not a different weed list. Sethoxydim works at 18% concentration. Glyphosate at 41-43.68% offers rapid non-selective control. Higher concentration does not always mean better — selectivity for your turf type and confirmed quackgrass labeling matter more than raw percentage.
Surfactant Compatibility
Quackgrass has a waxy leaf cuticle that repels water-based sprays. A non-ionic surfactant (NIS) or methylated seed oil (MSO) at 0.25-0.5% v/v dramatically improves droplet adherence and active ingredient absorption. Products that do not include surfactant in the bottle will underperform on mature quackgrass. Many experienced users add a few drops of dish soap as a low-cost alternative.
FAQ
Why does quackgrass keep coming back after I pull it?
Can I use a selective quackgrass killer on my St. Augustine lawn?
How many applications does it take to kill quackgrass completely?
Final Thoughts: The Verdict
For most homeowners fighting quackgrass around a lawn or ornamental bed, the best quackgrass killer winner is Gordon’s Ornamec 170 because it’s one of the few products whose EPA label names quackgrass directly, at a homeowner-friendly size and price. If your property is bigger — think sports turf, sod farms, or multiple large beds — the professional-strength Syngenta Fusilade II delivers the same verified chemistry at scale. If you need a non-selective heavy hitter for garden beds and pathways with long soil residual, grab the Martin’s Eraser Max Super Concentrate, and for large-scale bare-ground clearing without lingering soil activity, Compare-N-Save 41% Glyphosate is the most economical verified option.