The label is the law. Rates and restrictions below are taken from the product labels listed under Sources. Your product's own label governs; read it before you mix or apply. Mixing calculator · Disclaimer
- Active ingredient
- Carfentrazone-ethyl
- Chemical class
- Aryl triazolinone herbicide; WSSA Group 14 protoporphyrinogen oxidase (PPO) inhibitor whose by-products disrupt plant cell membranes in light.[2][1]
- Mode of action
- WSSA Group 14: Protoporphyrinogen oxidase (PPO) inhibitors (triazolinones)[2][1]
- Signal word
- QuickSilver T&O Herbicide (F8426 Herbicide): Caution[1]
Why it shows up as a partner in weed mixes
Alone, carfentrazone controls young annual weeds. Mixed with phenoxy herbicides such as 2,4-D, dicamba or MCPA, the label says it speeds the kill and adds dandelion, white clover, wild violet, ground ivy, spotted spurge and plantains.[1]
It may also be tank mixed with clopyralid, metsulfuron, quinclorac, triclopyr and other turf herbicides; long-term control then depends on the partner product's label.[1]
Where not to use it
Don't apply it to carpetgrass, dichondra, or lawns where you want to keep clover. Avoid spraying warm-season grasses while they move into or out of dormancy, and keep drift off vegetables, flowers, shrubs and trees.[1]
Where it is used
It only injures the parts of a weed it touches, so coverage matters. Use 0.5 to 4 gallons of spray per 1,000 sq ft, more where weeds or turf are dense.[1]
Symptoms can show in 24 hours or less, with complete kill in 7 to 14 days. It is rainfast within one hour.[1]
Treated areas may be seeded or overseeded one day after application, and newly seeded or sprigged bermudagrass, St. Augustine, bentgrass, tall fescue, ryegrass and Kentucky bluegrass can be treated 7 days after emergence (zoysiagrass after 14).[1]
For spot spraying with a backpack or pump sprayer, mix 0.030 fl oz (0.9 mL) in 1 to 2 gallons of water to treat 1,000 sq ft.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| QuickSilver T&O Herbicide (F8426 Herbicide)[1] | Environmental Science U.S., LLC | 101563-270 | 21.3% | aqueous emulsion (1.9 lb carfentrazone-ethyl per gallon) | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| QuickSilver T&O Herbicide (F8426 Herbicide) | Ornamental lawns and turf at institutional, ornamental and residential sites, golf courses and stone-covered yards | Seedling annual broadleaf weeds such as henbit, speedwells, purslane, pigweeds, prostrate knotweed, mallow, bittercress and field violet | 0.023–0.048 fl oz product per 1,000 sq ft[1] Stand-alone rate of 1.0 to 2.1 fl oz per acre for weeds 4 inches tall or less. In mixes with 2,4-D, dicamba, MCPA or mecoprop, use 0.021 to 0.034 fl oz per 1,000 sq ft. |
| QuickSilver T&O Herbicide (F8426 Herbicide) | Bentgrass lawns, golf greens and tees | Silvery thread moss (Bryum argenteum) | 0.155 fl oz product per 1,000 sq ft[1] 6.7 fl oz per acre, repeated in 2 weeks, with a nonionic surfactant at 0.25% v/v and no tank-mix partners. Stay under 0.40 lb carfentrazone-ethyl per acre per year. |
Safety and environmental hazards
People
Signal word CAUTION: harmful if swallowed, absorbed through the skin or inhaled, and causes moderate eye irritation. Avoid breathing spray mist; wear long sleeves, long pants, waterproof gloves, shoes and socks.[1]
Pets
Keep people other than the applicator, and pets, off the treatment area during application, and don't enter until the spray has dried.[1]
Bees and pollinators
No bee-specific warning appears, but the label says it is toxic to plants and drift can harm forage and habitat for pollinators near the treated site.[1]
Fish and water
Very toxic to algae and moderately toxic to fish. It may be hazardous in clear, shallow water next to treated areas, so avoid runoff or drift to water.[1]
Common questions
- How fast does carfentrazone work?
- The QuickSilver T&O label says symptoms may appear in 24 hours or less, with complete desiccation and death in 7 to 14 days.[1]
- Does carfentrazone prevent weeds from coming back?
- No. The label calls it a contact herbicide with little or no residual activity, so it only affects weeds that are already up.[1]
- Can I overseed after using carfentrazone?
- Yes. The label allows seeding or overseeding one day after application.[1]
Sources
- U.S. EPA Pesticide Product Label System, “QuickSilver T&O Herbicide (F8426 Herbicide) label, EPA Reg. No. 101563-270 (EPA-stamped, Oct. 9, 2025).” www3.epa.gov/pesticides/chem_search/ppls/101563-00270-20251009.pdf (accessed 2026-10-06)
- Weed Science Society of America, “Summary of Herbicide Mechanism of Action According to the Weed Science Society of America.” wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf (accessed 2026-10-06)