How to Kill Broadleaf Signalgrass in Tall Fescue Without Hurting Your Lawn
Direct Agronomic Answer
To selectively kill Broadleaf Signalgrass in Tall Fescue without damaging your turf, apply Drive XLR8 (Quinclorac 18.92%), Acclaim Extra (Fenoxaprop-p-ethyl 6.59%) when air temperatures are between 60°F and 85°F.
For Bermudagrass and Zoysia, Tribute Total or Celsius WG suppresses seedling infestations.
1. Labeled Safe Herbicides That Kill Broadleaf Signalgrass in Tall Fescue
| Recommended Product | Active Ingredient & Group | Application Temp (°F) | Surfactant & Mixing Protocol | Where to Buy |
|---|---|---|---|---|
| Drive XLR8 EPA Reg. 7969-272 |
Quinclorac 18.92% Group 4 (Synthetic Auxin / Quinoline Carboxylic Acid) |
60°F – 85°F Rainfast: 1h |
Requires Methylated Seed Oil (MSO) surfactant at 1.5 tbsp (0.75 fl oz) per gallon of water for effective cuticle penetration on multi-tiller crabgrass. | Check Price at DoMyOwn View on Amazon |
| Acclaim Extra EPA Reg. 432-950 |
Fenoxaprop-p-ethyl 6.59% Group 1 (ACCase Inhibitor) |
60°F – 85°F Rainfast: 1h |
Add Non-Ionic Surfactant (NIS) at 0.5 tsp per gallon only when targeting mature multi-tiller Goosegrass or Japanese Stiltgrass. Never tank-mix with 2,4-D (causes antagonism). | Check Price at DoMyOwn View on Amazon |
3. Optimal Seasonal Timing & Temperature Thresholds
Apply post-emergent sprays in early summer when plants have 2 to 4 leaves.
Apply pre-emergent Prodiamine in spring before soil reaches 65°F.
4. Diagnostic Checklist: Confirm It Is Broadleaf Signalgrass Before Spraying
- Short, wide, lance-shaped leaves with crinkled or wavy margins on one edge
- Creeping decumbent stems rooting at lower nodes forming dense mats
- Seedhead branches positioned like railroad signal flags at right angles
Not 100% sure? Use our AI Photo Weed Scanner or review the full Broadleaf Signalgrass Botanical Profile.