How to Kill Carpetweed in Tall Fescue Without Hurting Your Lawn
Direct Agronomic Answer
To selectively kill Carpetweed in Tall Fescue without damaging your turf, apply Tenacity (Mesotrione 40%), SpeedZone Lawn Weed Killer (2,4-D 28.57%, Mecoprop-p 5.88%, Dicamba 1.71%, Carfentrazone-ethyl 0.62%) when air temperatures are between 55°F and 85°F.
Carpetweed has shallow roots and thin cuticles, making it susceptible to nearly all common selective broadleaf killers.
1. Labeled Safe Herbicides That Kill Carpetweed in Tall Fescue
| Recommended Product | Active Ingredient & Group | Application Temp (°F) | Surfactant & Mixing Protocol | Where to Buy |
|---|---|---|---|---|
| Tenacity EPA Reg. 100-1267 |
Mesotrione 40% Group 27 (HPPD Inhibitor) |
55°F – 85°F Rainfast: 6h |
Always apply with Non-Ionic Surfactant (NIS) at 1 tsp (5 mL) per gallon of water for post-emergent applications. Causes temporary white bleaching on susceptible weeds and turf tips. | Check Price at DoMyOwn View on Amazon |
| SpeedZone Lawn Weed Killer EPA Reg. 2217-833 |
2,4-D 28.57%, Mecoprop-p 5.88%, Dicamba 1.71%, Carfentrazone-ethyl 0.62% Group 4 + Group 14 (Synthetic Auxins + PPO Inhibitor) |
50°F – 85°F Rainfast: 3h |
Do NOT add surfactant. Adding NIS or MSO increases ester volatility and causes severe contact burn on desirable cool-season turf. | Check Price at DoMyOwn View on Amazon |
| Barricade 4FL (Prodiamine 65 WDG) EPA Reg. 100-1139 |
Prodiamine 40.7% (or 65% WDG) Group 3 (Microtubule Assembly Inhibitor / Dinitroaniline) |
45°F – 90°F Rainfast: 0h |
Pre-emergent soil barrier: do NOT use foliar surfactant. Must be watered in with 0.5 inches of irrigation or rainfall within 14 days of application to activate. | Check Price at DoMyOwn View on Amazon |
2. What NOT to Spray on Tall Fescue When Treating Carpetweed
Warning: Common Carpetweed Killers That Damage Tall Fescue
Many retail herbicides advertised for Carpetweed are formulated for different turf zones and will severely injure Tall Fescue:
- AVOID Celsius WG (Thiencarbazone-methyl 8.7%, Iodosulfuron-methyl-sodium 1.9%, Dicamba 57.4%): Rated 'avoid' on Tall Fescue — high risk of turf phytotoxicity or stunting.
- AVOID Hi-Yield Atrazine Weed Killer (Atrazine 40.8%): Rated 'avoid' on Tall Fescue — high risk of turf phytotoxicity or stunting.
3. Optimal Seasonal Timing & Temperature Thresholds
Spray in early summer when mats first appear in thin turf areas.
It germinates later in spring when soils warm above 70°F. Pre-emergents (Prodiamine) prevent seedling emergence.
4. Diagnostic Checklist: Confirm It Is Carpetweed Before Spraying
- Whorls of 3 to 8 smooth, spoon-shaped leaves at each stem node
- Prostrate, flat circular mats radiating up to 2 feet from a central taproot
- Tiny, white, five-petaled star-shaped flowers on slender stalks in leaf whorls
Not 100% sure? Use our AI Photo Weed Scanner or review the full Carpetweed Botanical Profile.