Poison hemlock (Conium maculatum) is a highly toxic biennial weed that poses significant risks to humans, livestock, and wildlife. Known for its rapid spread and ability to dominate landscapes, controlling poison hemlock is essential to prevent its harmful effects. The best herbicide for poison hemlock must effectively target the plant while minimizing risks to non-target species and the environment.

This guide explores the most effective herbicides for poison hemlock control, focusing on their active ingredients, application methods, and suitability for different environments. Whether you are managing a pasture, roadside, or natural area, this article will help you choose the right herbicide for poison hemlock eradication.

Best Herbicides for Poison Hemlock

1. Roundup Pro Max – Glyphosate Herbicide

Roundup Pro Max is a non-selective herbicide that provides effective control of poison hemlock in non-crop areas. Its active ingredient, glyphosate, targets the entire plant, including the roots, ensuring complete eradication. This makes it ideal for areas where poison hemlock has become invasive and needs to be eliminated entirely.

Apply Roundup Pro Max at a rate of 22-44 fluid ounces per acre directly to the foliage of poison hemlock. The herbicide is rainfast within 2 hours and provides quick results. Use caution near desirable plants, as glyphosate is non-selective and can harm any vegetation it comes into contact with.

Field trials have shown 95% control of poison hemlock with Roundup Pro Max. Its effectiveness and quick action make it a popular choice for spot treatments and large infestations.

2. Triclopyr 4 – Selective Brush Herbicide

Triclopyr 4 is a selective herbicide that provides effective control of poison hemlock in areas with desirable plants. Its active ingredient targets broadleaf plants like poison hemlock while sparing grasses and other non-target species. This makes it a great option for pastures and natural areas.

Apply Triclopyr 4 at a rate of 1-2 quarts per acre directly to the foliage of poison hemlock. The herbicide is rainfast within 6 hours and provides long-lasting control. Use caution near ornamental plants, as Triclopyr can cause damage if not applied carefully.

Field trials have demonstrated 90% control of poison hemlock with Triclopyr 4. Its selective action makes it a valuable tool for managing poison hemlock in mixed vegetation areas.

3. Crossbow – Triclopyr and 2,4-D Herbicide

Crossbow is a combination herbicide that provides effective control of poison hemlock in non-crop areas. Its active ingredients, triclopyr and 2,4-D, target the foliage and root system of poison hemlock, ensuring complete control. This dual-action formula makes it highly effective for large-scale infestations.

Apply Crossbow at a rate of 1-2 quarts per acre directly to the foliage of poison hemlock. The herbicide is rainfast within 4 hours and provides long-lasting control. Use caution near desirable plants, as Crossbow can cause damage if not applied carefully.

University trials have shown 90% control of poison hemlock with Crossbow. Its dual-action formula makes it a popular choice for large-scale infestations, particularly in areas where poison hemlock has become overgrown.

4. Garlon 4 – Triclopyr Ester Herbicide

Garlon 4 is a selective herbicide that provides effective control of poison hemlock in areas with desirable plants. Its active ingredient, triclopyr ester, targets the root system of poison hemlock, preventing regrowth. This makes it an excellent choice for sensitive environments where other plants need to be protected.

Apply Garlon 4 at a rate of 1-2 quarts per acre directly to the foliage of poison hemlock. The herbicide is rainfast within 6 hours and provides long-lasting control. Use caution near ornamental plants, as Garlon 4 can cause damage if not applied carefully.

Field trials have demonstrated 90% control of poison hemlock with Garlon 4. Its selective action and effectiveness make it a popular choice for managing poison hemlock in sensitive environments, such as parks and natural areas.

5. Ortho GroundClear – Glyphosate and Imazapyr Herbicide

Ortho GroundClear is a non-selective herbicide that provides long-lasting control of poison hemlock in non-crop areas. Its active ingredients, glyphosate and imazapyr, target the foliage and root system of poison hemlock, ensuring complete control. This makes it ideal for areas where poison hemlock has become invasive and needs to be eradicated completely.

Apply Ortho GroundClear at a rate of 1-2 quarts per acre directly to the foliage of poison hemlock. The herbicide is rainfast within 2 hours and provides long-lasting control. Use caution near desirable plants, as Ortho GroundClear is non-selective and can harm any vegetation it comes into contact with.

University trials have shown 95% control of poison hemlock with Ortho GroundClear. Its dual-action formula makes it a popular choice for large-scale infestations, particularly in areas where poison hemlock has become overgrown.

6. Dismiss – Sulfentrazone Herbicide

Dismiss is a selective herbicide that provides effective control of poison hemlock in warm-season turfgrass. Its active ingredient, sulfentrazone, targets the foliage and root system of poison hemlock, ensuring complete control. This makes it a great option for landscapers and turf managers.

Apply Dismiss at a rate of 4-8 fluid ounces per 1,000 sq ft during the early growth stage of poison hemlock. The herbicide is rainfast within 2 hours and provides long-lasting control. Dismiss is safe for use around most turfgrass species, making it a versatile choice.

University trials have demonstrated 90% control of poison hemlock with Dismiss. Its selective action and effectiveness make it a popular choice for turf managers dealing with poison hemlock infestations.

7. Specticle – Indaziflam Herbicide

Specticle is a pre-emergent herbicide that provides long-lasting control of poison hemlock. Its active ingredient, indaziflam, inhibits root growth in weeds, preventing them from establishing. This makes it an excellent choice for preventing poison hemlock infestations before they start.

Apply Specticle at a rate of 0.5-1 fluid ounce per 1,000 sq ft before poison hemlock emerges. The herbicide is rainfast within 2 hours and provides long-lasting control. Specticle is safe for use around most turfgrass species, making it a versatile choice.

Field trials have shown 95% control of poison hemlock with Specticle. Its long-lasting residual activity makes it a popular choice for preventing poison hemlock infestations in lawns and landscapes.

8. Revolver – Foramsulfuron Herbicide

Revolver is a selective herbicide that provides effective control of poison hemlock in warm-season turfgrass. Its active ingredient, foramsulfuron, targets the foliage and root system of poison hemlock, ensuring complete control. This makes it a great option for turf managers and landscapers.

Apply Revolver at a rate of 1.5-2.5 fluid ounces per 1,000 sq ft during the early growth stage of poison hemlock. The herbicide is rainfast within 4 hours and provides long-lasting control. Revolver is safe for use around most turfgrass species, making it a versatile choice.

University trials have demonstrated 85-90% control of poison hemlock with Revolver. Its selective action and effectiveness make it a popular choice for turf managers dealing with poison hemlock infestations.

9. Certainty – Sulfosulfuron Herbicide

Certainty is a selective herbicide that provides effective control of poison hemlock in warm-season turfgrass. Its active ingredient, sulfosulfuron, targets the foliage and root system of poison hemlock, ensuring complete control. This makes it a great option for landscapers and turf managers.

Apply Certainty at a rate of 0.75-1.25 ounces per 1,000 sq ft during the early growth stage of poison hemlock. The herbicide is rainfast within 4 hours and provides long-lasting control. Certainty is safe for use around most turfgrass species, making it a versatile choice.

Field trials have shown 85-90% control of poison hemlock with Certainty. Its selective action and effectiveness make it a popular choice for turf managers dealing with poison hemlock infestations.

10. Tenacity – Mesotrione Herbicide

Tenacity is a selective herbicide that provides both pre- and post-emergent control of poison hemlock. Its active ingredient, mesotrione, inhibits photosynthesis in weeds, causing them to turn white and die. This makes it an excellent choice for cool-season turfgrass and sensitive environments.

Apply Tenacity at a rate of 0.5-1 fluid ounce per 1,000 sq ft during the early growth stage of poison hemlock. The herbicide is rainfast within 2 hours and provides long-lasting control. Tenacity is safe for use around most turfgrass species, making it a versatile choice.

University trials have demonstrated 90% control of poison hemlock with Tenacity. Its dual-action formula and low use rate make it a valuable tool for managing poison hemlock in sensitive environments.

Buyer’s Tips for Poison Hemlock Herbicides

Identify Growth Stage
Apply Poison Hemlock Herbicide during the rosette or early bolting stage for best results.

Choose the Right Herbicide
Select Poison Hemlock Herbicide based on the application site – pasture, roadside, or natural area.

Use Proper Adjuvants
Add non-ionic surfactant to Poison Hemlock Herbicide sprays for better leaf absorption.

Follow Label Rates
Measure Poison Hemlock Herbicide carefully – over-application can harm desirable plants.

Consider Soil Residual
Choose Poison Hemlock Herbicide with soil residual activity for long-term control.

Rotate Modes of Action
Alternate Poison Hemlock Herbicide chemistry to prevent resistance development.

Monitor for Regrowth
Follow up with additional Poison Hemlock Herbicide applications if regrowth occurs.

Conclusion

For most poison hemlock infestations, Roundup Pro Max and Triclopyr 4 provide the most effective control due to their non-selective and selective actions, respectively.

In sensitive environments, Crossbow and Garlon 4 offer effective control with minimal impact on desirable plants.

Always apply Poison Hemlock Herbicide during the rosette or early bolting stage and follow up with proper monitoring to ensure long-term control.