How to Kill Annual Bluegrass (Poa Annua) in Zoysiagrass Without Hurting Your Lawn
Direct Agronomic Answer
To selectively kill Annual Bluegrass (Poa Annua) in Zoysiagrass without damaging your turf, apply Certainty Turf Herbicide (Sulfosulfuron 75%), Image Kills Nutsedge (Imazaquin 3.3%) when air temperatures are between 60°F and 90°F.
In cool-season lawns, Poa Annua is genetically related to Kentucky Bluegrass, making selective removal challenging. Pre-emergents (Prodiamine) in late summer prevent fall germination.
1. Labeled Safe Herbicides That Kill Annual Bluegrass (Poa Annua) in Zoysiagrass
| Recommended Product | Active Ingredient & Group | Application Temp (°F) | Surfactant & Mixing Protocol | Where to Buy |
|---|---|---|---|---|
| Certainty Turf Herbicide EPA Reg. 59639-138 |
Sulfosulfuron 75% Group 2 (ALS Inhibitor / Sulfonylurea) |
60°F – 90°F Rainfast: 3h |
Mandatory Non-Ionic Surfactant (NIS) at 1 tsp (0.25% v/v) per gallon of water. Frequently tank-mixed with Celsius WG for complete southern weed control. | Check Price at DoMyOwn View on Amazon |
| Image Kills Nutsedge EPA Reg. 228-719 |
Imazaquin 3.3% Group 2 (ALS Inhibitor / Imidazolinone) |
65°F – 90°F Rainfast: 6h |
Ready-to-mix liquid formulation contains surfactant; additional NIS is not required for standard broadcast or spot treatments. | Check Price at DoMyOwn View on Amazon |
| Hi-Yield Atrazine Weed Killer EPA Reg. 34911-15-7401 |
Atrazine 40.8% Group 5 (Photosystem II Inhibitor / Triazine) |
50°F – 85°F Rainfast: 6h |
Do NOT add surfactant when spraying actively growing St. Augustine or Centipede above 80°F to avoid foliar yellowing. Irrigate lightly within 48 hours for root uptake. | 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 |
3. Optimal Seasonal Timing & Temperature Thresholds
Apply pre-emergent Prodiamine in late summer (late August to September) when soil temperatures drop to 70°F.
Post-emergent sprays in warm-season turf work best on young seedlings in November or February.
4. Diagnostic Checklist: Confirm It Is Annual Bluegrass (Poa Annua) Before Spraying
- Bright apple-green to lime-green clumps contrasting sharply with darker turf
- Soft, crinkled leaf blades near the base with distinctive boat-shaped tips
- Abundant, prolific whitish seedheads produced even at mowing heights under 0.5 inches
Not 100% sure? Use our AI Photo Weed Scanner or review the full Annual Bluegrass (Poa Annua) Botanical Profile.