Trumpet vine doesn’t just grow — it invades. That relentless root system can travel dozens of feet from the original plant, sending up suckers through your lawn, under your foundation, and into your prized flower beds. A general-purpose weed killer mostly annoys it. To truly eliminate trumpet vine, you need a systemic brush herbicide that penetrates the woody tissue and moves deep into the rhizomes.
I’m Rikta — the co-founder and writer behind Lawn Gear Lab. I’ve spent weeks comparing the chemical profiles, reviewing application methods, and analyzing owner experiences to find which herbicides actually stop trumpet vine’s aggressive regrowth cycle.
This guide breaks down the top chemical solutions to help you find the best herbicide to kill trumpet vine permanently.
How To Choose The Best Herbicide To Kill Trumpet Vine
Trumpet vine’s root system stores massive energy reserves. The wrong herbicide merely burns back the leaves, and the plant bounces back in weeks. The right choice must be systemic, woody-plant specific, and applied to the vascular tissue.
Active Ingredient: Triclopyr vs. Glyphosate
Triclopyr is the gold standard for woody brush and vines. It is formulated to penetrate bark and travel through the phloem directly to the roots. Glyphosate works but is weaker on woody species — it often requires higher concentrations and multiple applications to fully kill a mature trumpet vine.
Application Method: Foliar Spray vs. Cut-Stump
For trumpet vine, the cut-stump method is dramatically more effective. You sever the main stem near the ground and immediately paint or spray the herbicide onto the fresh cut. This delivers a lethal dose directly into the root system without harming surrounding plants. Foliar spraying works on young, accessible growth but risks overspray drift onto desirable plants.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| ALLIGARE Triclopyr 4E | Concentrate | Heavy-duty, large infestations | 61.6% Triclopyr | Amazon |
| Southern Ag Crossbow | Concentrate | Broad brush and bramble control | Triclopyr + 2,4-D | Amazon |
| Roundup Promax | Concentrate | Non-selective, large area | 50.2% Glyphosate | Amazon |
| Roundup Poison Ivy Plus | Concentrate | Foliar spray on vines | Triclopyr + Diquat | Amazon |
| Bonide Poison Ivy & Brush Killer | Concentrate | Lawn-safe brush control | Triclopyr | Amazon |
| Southern AG 01113 Brush Killer | Concentrate | Budget-friendly small areas | Triclopyr | Amazon |
| TORDON RTU Brush Killer | Ready-to-Use | Spot-treating stumps | Triclopyr | Amazon |
In‑Depth Reviews
1. ALLIGARE Agri Star Triclopyr 4E
This is the professional-grade triclopyr concentrate that serious land managers reach for. At 61.6% active ingredient — the same formula as the branded Garlon 4 — this 1-gallon jug provides enough chemical to treat acres of woody brush for a fraction of the retail price of ready-to-use bottles. For trumpet vine specifically, users report that a single cut-stump application using this concentrate fully kills the root mass with no regrowth observed after one season.
The ester formulation has an advantage: it penetrates bark and waxy leaf cuticles more aggressively than the amine salt versions found in most box-store brands. This makes it ideal for the hack-and-squirt method on thicker trumpet vine stems. Mix it at a 2% ratio for foliar sprays with a non-ionic surfactant, or apply it full-strength to fresh cuts. The strong petroleum odor confirms the ester base is working, but it demands careful handling with nitrile gloves and a respirator.
User feedback highlights its cost efficiency for large-scale invasions. Several owners comparing this directly to smaller bottles of Ortho or BioAdvanced found the per-ounce savings substantial, while noting identical or superior results on difficult woody weeds like black locust and multiflora rose. The main criticism involves the smell and the need for a separate surfactant, which adds a small step for casual users.
What works
- Highest triclopyr concentration on this list
- Excellent for cut-stump application on thick stems
- Cost-effective compared to ready-to-use alternatives
What doesn’t
- Strong petroleum odor requires ventilation
- Requires separate surfactant purchase
2. Southern Ag Crossbow Specialty Herbicide
Crossbow combines triclopyr with 2,4-D, giving it a broader spectrum against broadleaf weeds while retaining the woody-vine-killing power needed for trumpet vine. This one-gallon jug makes up to 96 gallons of spray solution, covering up to 2.23 acres. Users consistently praise it for annihilating overgrown ivy, brambles, and trumpet vine within a week when applied as a foliar spray at a 1-2% dilution.
The 2,4-D component accelerates knockdown on the leafy canopy, while the triclopyr does the deep root work. For the cut-stump method, applying it undiluted to the cambium layer stops the trumpet vine from resprouting. The formulation has a 3-day soil half-life, which makes it a safer choice around livestock and wells compared to some persistent herbicides, though overspray on desirable plants still causes damage.
Owner experiences show consistent success on creeping Charlie, jewelweed, and pokeweed in addition to trumpet vine. A few users noted that very rainy conditions or rich soil with high organic matter reduced its efficacy, requiring a second application. The product smells strongly of chemicals during mixing — a proper respirator is non-negotiable.
What works
- Broad-spectrum formula handles multiple weed types
- Excellent cost-per-acre value
- Short soil half-life reduces environmental persistence
What doesn’t
- Strong odor during mixing and spraying
- Heavy rain within 3 days can reduce effectiveness
3. Roundup Promax 1.67 Gallon
If you prefer glyphosate for its broad-spectrum non-selectivity, the Promax formulation is the highest concentration available in a consumer-size container. At 50.2% glyphosate acid equivalent, this is significantly more potent than the standard 41% concentrate found in many retail jugs. For trumpet vine, it is viable — but only at higher mix ratios (around 2 ounces per gallon) and with thorough leaf saturation.
Users report that this concentration kills kudzu, ivy, and heavy brush within 7 to 10 days when sprayed during active growth. The rainfast window of 30 minutes is a practical advantage if you are working around unpredictable weather. The sheer volume — 1.67 gallons — provides excellent coverage for large areas of vines or food plot preparation.
The limitation is that glyphosate is weaker than triclopyr on the woody root system of trumpet vine. Many users noted that regrowth occurred faster than expected from a single glyphosate-only application, especially on well-established roots. Multiple reviews recommend using the cut-stump method at full strength to get the best kill rate on trumpet vine, rather than relying on foliar spray alone.
What works
- Highest glyphosate concentration available
- Rainfast in just 30 minutes
- Large volume for covering extensive vine infestations
What doesn’t
- Requires higher concentration for woody trumpet vine
- Weaker on deep rhizomes than triclopyr-based options
4. Roundup Poison Ivy Plus Tough Brush Killer₂
This Roundup formulation combines triclopyr with diquat dibromide and fluazifop-P-butyl, creating a tri-active stack that kills the trumpet vine canopy quickly while the triclopyr translocates to the roots. The diquat provides the “visible results in hours” claim — it burns the leaf tissue rapidly — but the triclopyr does the real systemic work over the following days. This concentrate treats 1,500 square feet per gallon of mixed solution.
Users report excellent results on poison ivy, kudzu, and woody brush. The hack-and-squirt method with a 50% dilution applied to multiple stems is the most common successful approach for trumpet vine. Several owners with acre-plus properties combined this with a surfactant and cooking oil mixture to improve adhesion on the waxy vine leaves. The rainproof window of 30 minutes is identical to Promax and very forgiving.
The main downside is that the diquat can make the user think the plant is dead too quickly, leading them to stop treatment early. The canopy wilts fast, but the roots may still be alive if the triclopyr did not fully translocate. A second application 14 days later is often necessary for larger trumpet vine root systems. The concentrate size also runs out quickly for extensive infestations — buying multiple bottles gets expensive compared to a gallon jug of pure triclopyr.
What works
- Triple-active formula for fast visual results
- Rainfast in 30 minutes
- Good for hack-and-squirt on stems
What doesn’t
- Fast burn can mask incomplete root kill
- Small bottle size is costly for big jobs
5. Bonide Poison Ivy & Brush Killer BK-32
Bonide’s BK-32 is one of the most frequently recommended herbicides for trumpet vine in online gardening communities. The 32-ounce concentrate is formulated with triclopyr and is explicitly labeled for use on poison ivy, oak, sumac, and trumpet vine. Users consistently report that it kills the entire root system permanently when applied on a hot, sunny day with 48 hours of no rain. The product is designed to spare lawn grasses, making it a safer bet for spot treatments in turf.
This concentrate covers 1,000 square feet per bottle. For the cut-stump method, users apply it undiluted directly to freshly cut stems. The product also works well as a foliar spray on younger trumpet vine shoots that have not yet developed thick bark. Several verified buyers noted that the chemical completely eradicated trumpet vine that had been choking fences and trees for years after just one correct application.
The main drawback is that on some established ground ivy and very mature trumpet vine, it can take two or three treatments to finish the job. A few users reported overspray damage to their lawn and adjacent plants because the chemical is potent even at the recommended dilution. Strict adherence to the label instructions and careful nozzle control is necessary to avoid collateral damage.
What works
- Explicitly labeled for trumpet vine control
- Sparks lawn grasses when used as directed
- Affordable price point for small to medium areas
What doesn’t
- May require multiple treatments on old vines
- Overspray easily damages surrounding plants
6. Southern AG 01113 Brush Weed Killer
Southern Ag’s 01113 is a straight triclopyr concentrate at a very accessible price point. The 32-ounce bottle covers 512 to 1,024 square feet per gallon of mixed solution, making it suitable for smaller trumpet vine outbreaks along fences, roadsides, and pastures. Users coming from big-box store products found that this concentrate killed brush and vines that previously refused to die, citing the high triclopyr concentration as the game-changer.
The liquid form mixes easily with water and a surfactant. For trumpet vine, the recommended approach is to cut the vine at the base and immediately apply the undiluted concentrate to the stump. The product is also effective at preventing sprouting on clean-cut stumps of other woody species. Several reviewers noted that it worked on tough invasive species like Chinese privet and multiflora rose, which are comparable to trumpet vine in resilience.
The only complaint from users is that the 32-ounce size runs out quickly if you are covering a large area of thick brush. For a single trumpet vine infestation or a few dozen stumps, the bottle is enough. For multiple acres of woody growth, the cost-per-ounce is higher than the gallon options, so you may want to step up to the ALLIGARE or Crossbow sizes.
What works
- Effective triclopyr concentrate at a low entry cost
- Good for small to medium infestations
- Prevents stump sprouting effectively
What doesn’t
- Small bottle is not economical for large areas
- Weaker than higher-concentration professional formulations
7. TORDON RTU Brush Killer
TORDON RTU is a ready-to-use formulation that requires no mixing — you simply open the bottle and apply it directly to the target. This makes it the most convenient option for a quick stump treatment on a single trumpet vine. The triclopyr base is the same active found in the concentrates, but it is pre-diluted, so you pay a premium for convenience. For a small infestation of one or two vines, this is a very low-friction solution.
Users report excellent results on fresh-cut stumps of weed trees like mulberry and on invasive buckthorn and honeysuckle. For trumpet vine, the recommended method is to cut the main stem and apply the liquid directly to the cambium layer within minutes using the built-in squeeze bottle or a foam brush. Several reviews emphasized that the product kills the entire root system without the need for repeated applications, saving time and labor.
The obvious limitation is the price per ounce. For anyone dealing with a large patch of trumpet vine that has spread across the yard, the TORDON RTU runs out too fast and becomes expensive. It is best viewed as a surgical tool for spot-treating a few resistant stems, not for area-wide spraying.
What works
- No mixing required — use straight from bottle
- Excellent for precise stump application
- Reliable root kill on a variety of woody species
What doesn’t
- Higher cost per ounce than concentrates
- Small bottle volume limits large-scale use
Hardware & Specs Guide
Triclopyr Concentration
Triclopyr is the active ingredient proven to kill woody vines like trumpet vine by moving systemically through the phloem. Higher percentages (60%+) in professional products like ALLIGARE Triclopyr 4E deliver more active chemical per ounce, allowing lower dilution rates and stronger cut-stump applications. Consumer-grade concentrates like Bonide or Southern Ag 01113 typically contain 8-12% triclopyr and require larger volumes for the same result.
Cut-Stump Application
This is the most effective technique for trumpet vine. Cut the main stem 2-4 inches above the soil line and immediately apply herbicide to the fresh-cut surface within 30 minutes. The xylem and phloem are still open and will pull the chemical directly down into the root system. Use undiluted concentrate for the strongest effect. A foam brush or squeeze bottle gives better control than a sprayer for this method.
FAQ
Will glyphosate-only herbicide kill trumpet vine roots?
How long does it take for triclopyr to kill trumpet vine?
Final Thoughts: The Verdict
For most gardeners, the herbicide to kill trumpet vine winner is the ALLIGARE Agri Star Triclopyr 4E because the 61.6% triclopyr concentration provides the deepest, most reliable root kill per dollar. If you want a balanced formula that also knocks down broadleaf weeds, grab the Southern Ag Crossbow. And for a quick, convenient spot treatment on a single vine, nothing beats the TORDON RTU.