🧪 Active Ingredient Profile

Triclopyr Brush and Woody Weed Killer

Pyridine Herbicide (Synthetic Auxin)

Triclopyr is the go-to herbicide for killing woody plants, brush, stumps, and vines that 2,4-D cannot handle. It excels at killing poison ivy, wild blackberry, kudzu, woody brush, and tree stumps. Available in both amine (Garlon 3A) and ester (Garlon 4 Ultra) formulations.

🧪
Classification
Pyridine Herbicide (Synthetic Auxin)
Signal Word
Caution to Danger (varies)
Mode of Action
Synthetic auxin: mimics growth hormone causing lethal uncontrolled growth in broadleaf and woody plants
Herbicide Auxin mechanism of action diagram

How herbicide auxin works — illustrated mechanism of action

⚖️ Educational use only. Always read and follow the full product label — the label is the law under FIFRA. Full disclaimer → | ⚗️ Mixing Calculator →

Target Pests

Woody brush, poison ivy and poison oak (excellent), wild blackberry, kudzu, multiflora rose, honeysuckle, buckthorn, privet, tree stumps (cut-stump treatment), woody vines. Also controls broadleaf weeds in lawns but 2,4-D is usually preferred for that purpose due to cost.

Products and Brand Names

Crossbow (Corteva - triclopyr + 2,4-D, the most popular brush killer), Garlon 3A (amine, professional), Garlon 4 Ultra (ester, professional), Ortho Brush-B-Gon, BioAdvanced Brush Killer Plus, Remedy Ultra (Corteva, rangeland). Cut-stump treatment formulations also available.

Safety and Precautions

Moderate toxicity. Ester formulations are more irritating than amine. Wear long sleeves, gloves, and eye protection during mixing and application. Toxic to fish - do not apply near water bodies. Observe buffer zones.

Ester formulations and drift: Triclopyr ester (Garlon 4 Ultra) is highly volatile in hot weather. Do not apply when temperatures exceed 85F. Vapor drift can damage or kill trees, gardens, and ornamentals hundreds of feet from application site. Use amine formulations (Garlon 3A) in summer.

Pro Tips

For poison ivy: Triclopyr is the most effective herbicide for poison ivy. Apply Crossbow or Garlon to actively growing leaves in late spring/early summer. Full coverage of leaf surfaces is critical. Expect die-back within 2-4 weeks. Large established patches may need a second application.

Cut-stump treatment: For killing tree stumps and preventing regrowth, cut the tree and immediately (within 5 minutes) paint the cut surface with undiluted triclopyr ester (Garlon 4 Ultra). The herbicide travels down through the vascular system to kill the roots. Wait too long and the cut surface seals over.

For brush clearing: Crossbow (triclopyr + 2,4-D) applied as a foliar spray to actively growing brush is the standard professional approach. Use a pump sprayer or backpack sprayer with a flat fan nozzle for even coverage. Apply until leaves are wet but not dripping.

Selective in lawns: Triclopyr controls broadleaf weeds that 2,4-D misses, particularly ground ivy (creeping charlie) and wild violets. Some lawn herbicide products include triclopyr for this reason.

🐛 Pests This Treats — Learn More

Click any pest to view its full identification guide, biology, and treatment options.

🐛 Ants → 🐛 Scales → 🐛 Ticks →

🌿 Environmental & Ecological Impact

🐝 Bees / PollinatorsLOW
🐟 Fish / Aquatic LifeMODERATE
🐦 BirdsLOW
🐕 Mammals / PetsLOW
🦐 Aquatic InvertebratesMODERATE
💡 Selective herbicide for woody plants. Moderate aquatic toxicity. Some formulations are aquatic-labeled.
Example
0.5 oz
per gallon
⚗️ Mixing Calculator
Enter your sprayer size and target rate — get the exact amount to pour. Backpack, hand sprayer, hose-end, or skid unit.
Open Calculator →

❓ Frequently Asked Questions

Q: Is triclopyr safe for pets?
Follow the product label. Keep pets out of treated areas until completely dried (2–4 hours for sprays). Once dry, treated surfaces pose minimal risk to dogs and cats.
Q: Can I use triclopyr indoors?
No — this is an outdoor-only herbicide.
Q: How long does triclopyr last after application?
Residual varies by formulation, surface type, weather, and UV exposure. Indoor applications last longer than outdoor. Check the product label for re-application intervals.
Q: What should I do if exposed?
Remove contaminated clothing, wash skin with soap and water. For eye contact, rinse 15–20 minutes. For ingestion or severe symptoms, call Poison Control (1-800-222-1222). Have the product label available.

📋 Safety Data Sheet (SDS)

📋

Triclopyr Brush and Woody Weed Killer — Safety Data Sheet

View the official SDS document for this product directly on the CDMS label database.

📄 View SDS on CDMS → 🏛 Search EPA Label Database →
Triclopyr Brush and Woody Weed Killer Safety Data Sheet page 1
📄 Triclopyr Brush and Woody Weed Killer — Safety Data Sheet · View the complete SDS document above or download below
📄 CDMS Label & SDS Database 📄 EPA Label Search
Did you know? Triclopyr was developed by Dow Chemical in the 1970s specifically to fill the gap that 2,4-D could not - woody plant control. The name Garlon comes from combining garland (wreath of plants) with on (against). It remains the most effective herbicide for woody invasive plant management in the US.
🔮
Reviewed by Derek GiordanoContent reviewed by a licensed pest management professional. Last reviewed: April 2026.
📚 Sources: EPA Pesticide Labels · NPIC Pesticide Info
Published: Jan 1, 2025 · Updated: Apr 7, 2026

Application equipment that improves consistency

Better application equipment improves results more than better product. A one-gallon pump sprayer with adjustable nozzle ($30-50) outperforms hose-end sprayers for residual product application because it delivers consistent dilution. A hand duster ($15-25) is the only effective way to apply dust to wall voids, cracks, and crevices — pre-bottled dust products typically deliver inconsistent coverage. A foam machine adapter is useful for treating wall voids where dust would be inappropriate. Measuring cups and a measuring syringe ensure correct dilution at the label rate. A respirator (organic vapor cartridge) is required for some products and reasonable insurance for others. Equipment investments pay back across many treatments and are usually the missing element when product application produces inconsistent results.

Common DIY mistakes that defeat otherwise correct treatments

Most DIY pest control failures aren't product failures — they're application failures. The recurring patterns we see across reader emails and field experience: treating only where pests are visible rather than where they live (the active surface is rarely the harborage), spraying repellents over residual products and breaking the residual film, applying baits in already-treated areas (the residual kills foragers before they return with bait), overdiluting product because 'less chemical is safer' (it's not — it accelerates resistance), expecting overnight results when the kill curve is two to four weeks for most products, and stopping treatment at the first sign of improvement rather than completing the protocol. Each of these failure modes is independently preventable with attention to the product label and the pest's biology, and avoiding them improves outcomes more than upgrading to a more expensive product.

Storing pesticides safely

Pesticide storage at home should follow specific practices for safety and product integrity. Original containers only — label information must remain attached. Locked storage cabinet or location inaccessible to children and pets. Cool, dry environment (not in unheated garages where temperature swings degrade product, and not in direct sun). Don't store with food, beverages, or personal care items. Don't store near ignition sources for flammable products. Keep an inventory and dispose of products that have exceeded shelf life (most pesticides retain efficacy for several years if stored properly, but separated emulsions, crystallized concentrates, or color-changed products should be discarded). Disposal: check with your local hazardous waste program; most municipalities have collection days or permanent drop-off sites for household pesticide disposal.

What's actually in the active ingredient column

Most pesticide products use a small number of active ingredients across many brand names. Pyrethroids (bifenthrin, cypermethrin, deltamethrin, lambda-cyhalothrin, permethrin) are the dominant household residual class — fast-acting, low mammalian toxicity, but increasingly affected by resistance in major pests. Neonicotinoids (imidacloprid, dinotefuran, thiamethoxam) are systemic-leaning and have specific uses for ant baits, termite treatment, and some flea products. Phenylpyrazoles (fipronil) underlie many termite, ant bait, and pet flea products. Insect growth regulators (pyriproxyfen, methoprene, hydroprene, novaluron) interrupt development rather than killing directly and pair well with adulticides. Botanicals (pyrethrum, spinosad) offer rapid knockdown but limited residual. Knowing the active ingredient class lets you rotate products properly and recognize when a 'new product' is really an old active in new packaging.

Why integrated pest management produces better outcomes

Integrated Pest Management (IPM) is the framework most pest management professionals follow and the framework the EPA recommends for residential and commercial settings. IPM is not anti-pesticide; it's a sequencing approach that uses cultural controls (sanitation, exclusion, moisture management) first, mechanical controls (traps, vacuuming, physical removal) second, biological controls (beneficial insects, microbial agents) where applicable, and chemical controls last and targeted. The benefit isn't ideological — it's empirical. IPM-treated sites have lower long-term pest pressure than chemical-only treated sites, because chemicals address the visible population without addressing why the population developed. Homeowners who adopt IPM principles see longer intervals between treatments, lower total pesticide use, and better outcomes during the times when chemicals are appropriate. The shift from 'spray when I see them' to 'fix the conditions, monitor, treat targeted' is the single highest-leverage change most DIY practitioners can make.

Pesticide rotation and the resistance management problem

Resistance management — using multiple active ingredients in sequence so that no single mode of action selects for resistant individuals — is standard practice in agricultural and commercial pest control but rarely makes it into residential treatment decisions. The underlying concern is real: chronic use of a single pyrethroid product against bed bugs has produced widespread pyrethroid resistance, with some populations now showing resistance factors of 1000x or more. The same pattern is documented in German cockroach resistance to chlorpyrifos and other historical actives, mosquito resistance to organophosphates in heavy-use regions, and house fly resistance across multiple compound classes. For residential treatment, the practical implication is to avoid using the same active ingredient repeatedly across multiple treatment cycles; rotating between products in different chemical families (e.g., pyrethroid → neonicotinoid → insect growth regulator → carbamate, or whatever subset is appropriate to the target pest) reduces selection pressure and preserves efficacy. The product label specifies the active ingredient family, allowing rotation choices to be made on actual chemistry rather than brand name.

Seasonal pest calendars: building one for your specific property

Generic seasonal pest calendars list typical activity windows by region, but every property has its own micro-calendar shaped by orientation, vegetation, drainage, neighbor properties, and structural features. After one or two years of observation, most homeowners can map their property's specific patterns: when wasps start scouting (typically early to mid spring as queens emerge), when ants first appear indoors (often after a specific rain pattern), when stored-product pests show up in pantries (often late spring through fall), when rodent activity increases (typically late fall as outdoor food declines and indoor warmth attracts them), when mosquito pressure peaks (varies enormously by local conditions), and when seasonal nuisances like cluster flies or boxelder bugs arrive (usually first hard cooling in fall). A personal calendar drives preventive timing — exterior perimeter treatment shortly before ant pressure builds is dramatically more effective than treatment after they're inside, exclusion work for rodents in early fall beats trapping in late fall, and wasp prevention in early spring beats removal in summer. Two years of observation produces a calendar more useful than any published guide for the specific property.

Application timing within the day and weather conditions

Pesticide applications produce significantly different results depending on application timing, and matching application to conditions improves outcomes substantially. For outdoor liquid applications, early morning (after dew has evaporated, before pollinators are active) and late evening (after pollinators have stopped foraging, before evening dew) produce best results: temperatures are moderate, wind is typically lower, and non-target exposure is reduced. Mid-day applications during high temperatures cause volatility losses and faster degradation. For interior treatments, timing depends on the pest: cockroach baiting works at any time but should follow rather than precede cleaning; bed bug treatments need to follow vacuuming and clutter reduction; ant baits work best when active trails are present, which often means specific times of day for specific species. Rain within 4 hours of outdoor liquid application washes off most surface residue except specifically rainfast formulations; checking the next 24-hour forecast before any outdoor treatment is the basic discipline that prevents this loss. Temperatures above 90°F or below 50°F outside the product label's recommended range produce reduced efficacy.

Reduced-risk pesticide selection: a category worth knowing

The EPA's reduced-risk pesticide program identifies active ingredients and formulations that meet specific criteria for lower toxicity to non-target organisms, reduced potential for groundwater contamination, lower likelihood of resistance development, or better compatibility with integrated pest management. Products in this category aren't free of toxicity — they're pesticides, and all pesticides have some toxic profile — but they represent the lower end of the risk distribution within their pest categories. For homeowners who want to use pesticides but are concerned about minimizing exposure and environmental impact, looking for products with reduced-risk actives is a defensible filter. Examples include some of the diamide insecticides, spinosyns, and certain microbial products. The catch is that retail availability lags behind the professional market for many reduced-risk products, and consumer pesticide aisles still skew heavily toward older pyrethroid and carbamate formulations. For homeowners willing to source products from agricultural supply channels or work with a pest control company that uses these products, the option exists; for those buying off the shelf at typical retail, the choices are narrower.

When neighborhood-level coordination matters for treatment

Some pests are house-scale problems and some are neighborhood-scale problems, and treating a neighborhood-scale problem as if it were house-scale leads to a familiar frustration: treatment works, then activity returns within weeks because the source was never inside your property. German cockroach problems in multi-unit buildings are the canonical example — treating one unit while the rest of the building is untreated produces temporary relief at best. Rodent infestations frequently span multiple adjacent properties, especially row houses, condo complexes, and dense suburban developments with shared boundary fencing or shared utility easements. Mosquito problems are obviously neighborhood-scale because adult mosquitoes don't respect property lines. The practical implication is that for these pests, isolated treatment is not just incomplete but in some cases economically wasteful. Coordinating with neighbors, talking to HOA or property management about whole-building or whole-block treatment, and identifying the actual sources rather than the symptom locations is what produces durable results. This is uncomfortable work in some neighborhoods, but no amount of treatment intensity in a single unit substitutes for it.

Pesticide drift and the neighbor dimension

Pesticide drift — the off-target movement of applied product through air, water, or runoff — is an under-discussed dimension of residential pesticide use, but it's an increasingly common source of conflict between neighbors and a real factor in the cumulative environmental load of pesticide use. Foliar sprays applied in even light wind drift further than most homeowners expect, particularly with finer droplet sizes. Granular products applied near property lines wash into adjacent properties in significant rainfall. Mosquito fogging can move across multiple properties depending on conditions. The implications are partly legal — drift onto neighboring property without consent has been the basis of successful nuisance claims in some jurisdictions — and partly ethical. Applying products only in low-wind conditions, choosing coarser droplet sizes when possible, using granulars rather than sprays near property lines, and timing applications to avoid imminent rainfall all reduce drift. For homeowners concerned about pesticide exposure from neighbors' applications, the productive conversation is usually about timing and product choice rather than about pesticide use in general, and approaching it that way tends to produce cooperation rather than escalation.