How to Kill Yellow Woodsorrel (Oxalis) in Tall Fescue Without Hurting Your Lawn
Direct Agronomic Answer
To selectively kill Yellow Woodsorrel (Oxalis) 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.
Standard 2,4-D fails on Oxalis. Systemic Triclopyr or Mesotrione provides excellent foliar and crown kill.
1. Labeled Safe Herbicides That Kill Yellow Woodsorrel (Oxalis) 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 |
| TZone SE EPA Reg. 2217-920 |
Triclopyr 7.72%, 2,4-D 29.36%, Dicamba 2.22%, Sulfentrazone 0.66% Group 4 + Group 14 (Pyridine Auxin + Phenoxy + PPO Inhibitor) |
50°F – 80°F Rainfast: 3h |
Do NOT mix with surfactant when temperatures exceed 75°F. In cool spring or fall conditions (55°F–70°F), 0.5 tsp NIS per gallon improves waxy leaf penetration on Wild Violet. | Check Price at DoMyOwn View on Amazon |
2. What NOT to Spray on Tall Fescue When Treating Yellow Woodsorrel (Oxalis)
Warning: Common Yellow Woodsorrel (Oxalis) Killers That Damage Tall Fescue
Many retail herbicides advertised for Yellow Woodsorrel (Oxalis) 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 spring or early summer before the explosive cylindrical seed pods mature.
Once seed pods form, slightest contact shoots seeds up to 10 feet into surrounding turf.
4. Diagnostic Checklist: Confirm It Is Yellow Woodsorrel (Oxalis) Before Spraying
- Pale green trifoliate leaves with distinct heart-shaped, deeply notched leaflets
- Leaves fold downward along the center crease at night or in intense heat
- Bright yellow 5-petaled flowers followed by upright, okra-like explosive seed capsules
Not 100% sure? Use our AI Photo Weed Scanner or review the full Yellow Woodsorrel (Oxalis) Botanical Profile.