Lawn Care
What Chemical Kills Stickers in the Grass? Identification & Control
Identifying the Culprit: Broadleaf vs. Grassy Stickers
When homeowners ask what chemical kills stickers in the grass, the answer depends entirely on the botanical classification of the weed. "Stickers" is a colloquial catch-all term for several distinct invasive species that produce sharp, spiny seed pods (burs). Applying a broadleaf herbicide to a grassy sticker weed will result in total failure, wasting time and money. Accurate identification is the mandatory first step in any chemical control protocol.
Lawn Burweed (Soliva sessilis)
Lawn burweed is a winter annual broadleaf weed. It germinates in the fall, grows low to the ground with feathery, carrot-like leaves, and produces hard, spiny burs that sit directly on the soil surface. Because it is a broadleaf plant, it is highly susceptible to synthetic auxin herbicides like 2,4-D and dicamba. According to NC State TurfFiles, lawn burweed thrives in compacted soils and thin turf canopies, making core aeration a vital cultural companion to chemical control.
Field Sandbur (Cenchrus spinifex)
Field sandbur is a summer annual grassy weed. It resembles crabgrass but produces distinct, spiky, burr-like seed heads that cling to clothing and pet fur. Because it is a grass, broadleaf herbicides (2,4-D, Dicamba, MCPP) will not kill it. Control requires grassy-weed specific post-emergents like quinclorac or MSMA, or strict pre-emergent barriers.
Puncturevine (Tribulus terrestris)
Also known as goatheads, puncturevine produces woody, caltrop-like seed pods capable of puncturing bicycle tires. This broadleaf weed is highly resilient and often requires specialized sulfonylurea herbicides like metsulfuron-methyl for complete eradication in warm-season lawns. The University of California IPM notes that puncturevine burs can remain viable in the soil seed bank for up to five years, necessitating multi-year chemical and cultural management.
The Pre-Emergent Strategy: Stopping Stickers Before They Sprout
The most cost-effective and turf-safe method to manage stickers is preventing germination. Pre-emergent herbicides create a chemical barrier in the top 0.5 to 1 inch of the soil profile, inhibiting cell division in germinating seeds. Timing is critical: apply pre-emergents when soil temperatures at a 2-inch depth consistently reach 52°F to 55°F for three consecutive days.
Timing Warning: Lawn burweed is a winter annual. You must apply pre-emergents in early fall (late August to September) before soil temperatures drop below 70°F. Field sandbur is a summer annual, requiring spring applications when soil temps hit 55°F.
| Active Ingredient | Brand Example | Application Rate (per 1,000 sq ft) | Target Sticker Weed |
|---|---|---|---|
| Prodiamine 65 WDG | Barricade | 0.23 oz - 0.46 oz | Sandbur, Burweed |
| Dithiopyr 40 WSB | Dimension | 0.33 oz - 0.55 oz | Sandbur, Burweed (early post) |
| Pendimethalin 3.3 EC | Pendulum | 1.0 oz - 1.5 oz | Sandbur, Burweed |
Post-Emergent Chemicals: What Kills Existing Stickers?
Once the burs have formed and the plant is actively growing, pre-emergents are useless. You must switch to post-emergent systemic herbicides. The specific chemical you choose is dictated by two factors: the weed species (broadleaf vs. grassy) and your turfgrass type. Applying the wrong post-emergent will chemically burn or permanently stunt your lawn.
Chemicals for Broadleaf Stickers (Burweed & Puncturevine)
- Three-Way Herbicides (2,4-D + MCPP + Dicamba): Products like Trimec Southern or SpeedZone Southern are the industry standard for lawn burweed in warm-season grasses (Bermuda, Zoysia, Centipede). Apply at 1.5 oz per gallon of water per 1,000 sq ft. Expect visible wilting within 48 hours and complete necrosis in 14-21 days.
- Metsulfuron-Methyl: Sold under brand names like Manor or MSM Turf. This sulfonylurea herbicide is exceptionally effective on stubborn puncturevine and burweed. It requires a micro-dose of just 0.5 oz per acre (roughly 0.01 oz per 1,000 sq ft). Warning: Metsulfuron-methyl will severely damage or kill St. Augustine and Centipede grass. Use only on Bermuda and Zoysia.
- Atrazine: The primary defense for St. Augustine and Centipede lawns. Atrazine (e.g., Image for St. Augustine) acts as both a pre-emergent and post-emergent broadleaf killer. Apply at 2.0 oz per 1,000 sq ft. Do not apply when temperatures exceed 85°F, as atrazine volatility will scorch St. Augustine turf.
Chemicals for Grassy Stickers (Field Sandbur)
- Quinclorac: Found in products like Drive XLR8. Quinclorac is one of the few post-emergents capable of killing grassy sandburs without harming cool-season fescue or warm-season Bermuda. Apply at 0.73 oz per 1,000 sq ft with a methylated seed oil (MSO) adjuvant.
- MSMA (Monosodium Methanearsonate): A highly effective, restricted-use arsenical herbicide for sandbur in commercial Bermuda and Zoysia turf. Due to EPA regulations, MSMA is generally unavailable to residential consumers and requires a licensed commercial applicator. Apply at 1.33 oz per 1,000 sq ft in multiple 10-day intervals.
Pro-Tip: The Surfactant Multiplier
Sticker weeds, particularly puncturevine and mature burweed, develop a thick, waxy cuticle on their leaves to retain moisture. If you spray post-emergent herbicides with plain water, the droplets will bead up and roll off. You must add a Non-Ionic Surfactant (NIS) at a rate of 0.25% v/v (roughly 1/2 teaspoon per gallon of spray solution) to break the surface tension and force the chemical into the plant's vascular system.
Sticker weeds, particularly puncturevine and mature burweed, develop a thick, waxy cuticle on their leaves to retain moisture. If you spray post-emergent herbicides with plain water, the droplets will bead up and roll off. You must add a Non-Ionic Surfactant (NIS) at a rate of 0.25% v/v (roughly 1/2 teaspoon per gallon of spray solution) to break the surface tension and force the chemical into the plant's vascular system.
Application Protocols and Calibration
Chemical efficacy is entirely dependent on accurate calibration. Guessing your spray volume leads to either herbicide resistance (under-dosing) or turf phytotoxicity (over-dosing).
- Calibrate the Sprayer: Mark a 1,000 sq ft area (e.g., 20x50 ft) on your driveway. Fill your backpack sprayer with a known volume of water (e.g., 2 gallons). Spray the marked area at your normal walking pace and pump pressure. Measure the water left in the tank. If you used 1.5 gallons to cover 1,000 sq ft, your carrier volume is 1.5 gallons per 1,000 sq ft.
- Mix the Tank: If the label requires 1.5 oz of herbicide per 1,000 sq ft, and your carrier volume is 1.5 gallons, you will mix 1.5 oz of herbicide into every 1.5 gallons of water in your tank.
- Nozzle Selection: Use an air-induction flat fan nozzle (such as the TeeJet AIXR11004). This nozzle produces coarse droplets that resist wind drift, ensuring the chemical lands on the sticker weed rather than drifting onto ornamental flower beds where it can cause severe damage.
- Mowing Restrictions: Do not mow for 48 hours before application (to maximize leaf surface area for chemical absorption) and wait 48 hours after application (to allow the herbicide to translocate to the root system).
Cost Analysis and Product Recommendations
Managing stickers requires an upfront investment, but bulk purchasing professional-grade concentrates drastically reduces the cost per square foot compared to ready-to-spray hardware store bottles.
- Pre-Emergent (Prodiamine 65 WDG): A 5 oz bottle costs approximately $45. At the 0.23 oz rate, this treats over 21,000 sq ft. Cost: $0.002 per sq ft.
- Post-Emergent Broadleaf (Trimec Southern): A 1-gallon jug costs around $38. At 1.5 oz per 1,000 sq ft, it treats 85,000 sq ft. Cost: $0.0004 per sq ft.
- Post-Emergent Grassy (Drive XLR8 / Quinclorac): A 32 oz bottle costs roughly $75. At 0.73 oz per 1,000 sq ft, it treats 43,000 sq ft. Cost: $0.0017 per sq ft.
By contrast, a standard 32 oz ready-to-spray hose-end bottle of consumer weed killer costs $12 and covers only 5,000 sq ft ($0.0024 per sq ft), while offering inferior active ingredient concentrations and lacking the necessary adjuvants for waxy sticker weeds.
Frequently Asked Questions
Will vinegar kill stickers in the grass?
Horticultural vinegar (20% acetic acid) acts as a non-selective contact desiccant. It will burn the top growth of the sticker weed, but it will not translocate to the roots, resulting in rapid regrowth. Furthermore, spraying vinegar on your lawn will acidify the soil and burn your desirable turfgrass. It is not a viable long-term solution for sticker control.
How do I get rid of stickers that are already on the ground?
Chemicals only kill living plant tissue. Once the sticker bur has detached from the plant and is resting on the soil, no herbicide will dissolve it. You must mechanically remove existing burs using a lawn sweeper, a heavy-duty leaf vacuum, or by dragging a piece of old carpet across the turf to snag the spines.
Can I apply pre-emergent and post-emergent at the same time?
Yes, this is known as a "split application" or "overlap" strategy and is highly recommended for severe infestations. Mixing a pre-emergent (like Prodiamine) with a post-emergent (like 2,4-D) in the same tank allows you to kill existing mature weeds while simultaneously laying down a chemical barrier to stop late-germinating seeds. Always check the specific product labels to ensure the tank-mix compatibility of your chosen chemicals.
