How to Kill Corn Speedwell in Kentucky Bluegrass Without Hurting Your Lawn
Direct Agronomic Answer
To selectively kill Corn Speedwell in Kentucky Bluegrass without damaging your turf, apply Drive XLR8 (Quinclorac 18.92%), Pylex Herbicide (Topramezone 29.7%) when air temperatures are between 60°F and 85°F.
Standard 2,4-D provides very poor control on Veronica species. SpeedZone with carfentrazone or Drive XLR8 burns down speedwell within days.
1. Labeled Safe Herbicides That Kill Corn Speedwell in Kentucky Bluegrass
| 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 |
| Pylex Herbicide EPA Reg. 7969-327 |
Topramezone 29.7% Group 27 (HPPD Inhibitor / Pyrazolone) |
55°F – 85°F Rainfast: 1h |
Must be applied with Methylated Seed Oil (MSO) at 1 to 1.5 tsp per gallon of water. Tank-mixing with Triclopyr Ester reduces white bleaching and speeds up Bermudagrass and Goosegrass mortality. | Check Price at DoMyOwn View on Amazon |
3. Optimal Seasonal Timing & Temperature Thresholds
Treat in late winter or early spring before heart-shaped seed pods develop.
Fall pre-emergent application of Isoxaben prevents seeds from sprouting in October.
4. Diagnostic Checklist: Confirm It Is Corn Speedwell Before Spraying
- Tiny, upright hairy stems (2 to 6 inches) growing in dense early spring patches
- Lower leaves rounded with scalloped margins; upper leaves narrow and stalkless
- Tiny, sky-blue four-petaled flowers followed by heart-shaped two-lobed seed capsules
Not 100% sure? Use our AI Photo Weed Scanner or review the full Corn Speedwell Botanical Profile.