Home gardeners often face decisions about whether and how to use herbicides. While some gardeners prefer nonchemical approaches, there are situations where herbicides can be effective tools for managing difficult weeds. To use herbicides safely and effectively, it is important to understand how common active ingredients work, how they affect plants, and how to properly interpret herbicide labels.
Characteristics of Specific Herbicides | How Different Herbicides Work | More Information
Characteristics of Commonly Used Herbicides in the Home Garden
Herbicides are sold under many brand and trademark names, but the active ingredient is what determines how the product works. Knowing the characteristics of commonly used active ingredients helps gardeners select products that match their weed management goals and site conditions.
These characteristics influence where and how each herbicide should be used, how quickly results can be expected, and the potential risk to nearby plants.
| Active Ingredient | Sensitive Weeds | Type | Residual Activity in Soil | Associated Brand Names |
|---|---|---|---|---|
| 2,4-D | broadleaf | contact post-emergent | 2-4 weeks | WeedClear, Weed-B-Gon, Trimec |
| Acetic Acid (10-30%) | broadleaf, grasses | contact post-emergent | none | Green Gobbler, Weed Pharm |
| Citrus Oils, d-Limonene | broadleaf, grasses | contact post-emergent | none | Avenger |
| Dicamba | broadleaf, woody | systemic post-emergent | 2-12 weeks | Banvel, Clarity, WeedClear, Weed-B-Gon, Trimec |
| Diquat* | broadleaf, grasses, aquatic | contact post-emergent | none | Reward, Alligare, Aquacide, Tribune |
| Dithiopyr | broadleaf, grasses | pre-emergent, limited post-emergent | 12 weeks | Dimension |
| Fluazifop | grasses | systemic post-emergent | 2-8 weeks | Fusilade, Ornamec, Fusion, Tornado |
| Glufosinate | broadleaf, grasses | contact post-emergent | none | Finale XL, Cheetah Pro |
| Glyphosate | broadleaf, grasses, woody | systemic post-emergent | none | Roundup |
| Halosulfuron | sedges | systemic post-emergent | 6-8 weeks | Sedgehammer |
| Imazapic | broadleaf, grasses, sedges | systemic post-emergent | 6-24 months | Plateau, Panoramic |
| Imazapyr | broadleaf, grasses, woody, aquatic | systemic post-emergent | 2+ years | Habitat, Arsenal, Polaris |
| Indaziflam | broadleaf, grasses | pre-emergent | 4-6 months | Marengo, Specticle, Esplanade |
| Isoxaben | broadleaf | pre-emergent | 2-6 months | Gallery |
| MCPA | broadleaf | systemic post-emergent | 2-4 weeks | Chiptoz, Roundup for Lawns, Change Up, Triad Select |
| Mecoprop (MCPP) | broadleaf | systemic post-emergent | 1-3 weeks | Mecomec, Weed-B-Gon, Trimec |
| Oryzalin | broadleaf, grasses | pre-emergent | 4-6 months | Surflan |
| Pelargonic Acid | broadleaf, grasses | contact post-emergent | none | Scythe, Axxe, Slasher |
| Pendimethalin | grasses, some broadleaf | pre-emergent | 3-5 months | Pendulum, Aquacap, Corral |
| Picloram* | broadleaf, woody | systemic post-emergent | 1+ year | Tordon, Grazon |
| Prodiamine | grasses, some broadleaf | pre-emergent | 10-16 weeks | Barricade |
| Quinclorac | broadleaf, some grasses | systemic post-emergent | 20-30 days | Solitare, Q4 Plus, Triad QC, Weed-B-Gon Plus Crabgrass Control |
| Sulfentrazone | broadleaf, sedges | systemic post-emergent | 60 days | Dismiss |
| Triclopyr | broadleaf, woody | systemic post-emergent | 30-90 days | Brush-B-Gon |
| Trifluralin | grasses, broadleaf | pre-emergent | 4-8 months | Preen |
* While these herbicides are familiar to some home gardeners, they are restricted use pesticides (RUPs) and not available to individuals who do not have a certified applicator license.
| Active Ingredient | Time to Symptoms | Time to Death | Volatility Risk | Soil Mobility |
|---|---|---|---|---|
| 2,4-D | 1-4 days | 7-14 days | high | high |
| Acetic Acid (10-30%) | 0.5-2 hours | <24 hours | low | low |
| Citrus Oils, d-Limonene | 1-24 hours | 1-3 days | low | low |
| Dicamba | 1-3 weeks | 3-5 weeks | high | high |
| Diquat | 2-24 hours | 1-3 days | low | low |
| Dithiopyr | - | - | moderate | low |
| Fluazifop | 2-3 days | 3-4 weeks | low | low |
| Glufosinate | 2-4 days | 30 days | low | low |
| Glyphosate | 4-10 days | 2 weeks | low | low |
| Halosulfuron | 3-5 days | 14-30 days | low | moderate |
| Imazapic | 3-5 days | 2-4 weeks | low | high |
| Imazapyr | 2 weeks | 3-4 weeks | low | high |
| Indaziflam | - | - | low | low |
| Isoxaben | - | - | low | high |
| MCPA | 1-3 days | 3-5 weeks | high | high |
| Mecoprop (MCPP) | 1-2 weeks | 3-5 weeks | low | high |
| Oryzalin | - | - | low | low |
| Pelargonic Acid | 0.5-2 hours | <24 hours | moderate | low |
| Pendimethalin | - | - | low-moderate | low |
| Picloram | 1-3 days | 14+ days | moderate | high |
| Prodiamine | - | - | low-moderate | low |
| Quinclorac | 3-5 days | 1-2 weeks | low | high |
| Sulfentrazone | 1-2 days | 1-3 weeks | low | moderate |
| Triclopyr | 1-3 days | 3-5 weeks | low | moderate-high |
| Trifluralin | - | - | low-moderate | low |
How Herbicides Affect Plants
Herbicides control weeds by interfering with essential plant processes. Understanding the symptoms and mode of action helps gardeners recognize herbicide injury and better anticipate outcomes following application.
Those herbicides in the same WSSA Group work in a very similar fashion. If control is inadequate, consider an appropriate herbicide from a different group.
| Active Ingredient | Symptoms | Mode of Action | |
|---|---|---|---|
| 2,4-D | bending and twisting of stems, leaf cupping and curling | causes uncontrolled cell division and growth, destroying plant tissue | 4 |
| Acetic Acid (10-30%) | rapid browning and burning of foliage | ruptures plant cells, causing dehydration and death | 0 |
| Citrus Oils, d-Limonene | rapid browning and burning of foliage | strips leaf cuticle, causing dehydration and death | 0 |
| Dicamba | bending and twisting of stems, leaf cupping and curling | causes uncontrolled cell division and growth, destroying plant tissue | 4 |
| Diquat | quick wilting and browning of leaves | disrupts the process of photosynthesis | 22 |
| Dithiopyr | Seed distortion or failure to grow | disrupts mitosis in germinating seed, inhibiting root and shoot development | 3 |
| Fluazifop | yellowing and browning of young leaves starting at growing points, older leaves turn purple, orange, or red | prevents the building of new membranes required for cell growth | 1 |
| Glufosinate | leaf burning, yellowing, browning, leaf distortion, leaf crinkling, and death | disrupts nitrogen metabolism, causing a toxic buildup of ammonium destroying cells and disrupting photosynthesis | 10 |
| Glyphosate | yellowing and browning starting with new growth | prevents protein synthesis needed for growth | 9 |
| Halosulfuron | growth stops, Leaves turn yellow, eventually browning and dying | prevents the formation of certain amino acids, causing death | 2 |
| Imazapic | yellowing and browning starting at new growth, lower side of leaf and stem may turn purple | prevents the formation of certain amino acids, causing death | 2 |
| Imazapyr | yellowing and browning starting at new growth, lower side of leaf and stem may turn purple | prevents the formation of certain amino acids, causing death | 2 |
| Indaziflam | stunted growth of emerging seedlings, failure to emerge | prevents new cell walls from being formed, inhibiting cell division and growth of germinating seeds and early-stage growth | 29 |
| Isoxaben | stunted growth of emerging seedlings, failure to emerge | prevents new cell walls from being formed, inhibiting cell division and growth of germinating seeds and early-stage growth | 29 |
| MCPA | bending and twisting of stems, leaf cupping and curling | causes uncontrolled cell division and growth, destroying plant tissue | 4 |
| Mecoprop (MCPP) | bending and twisting of stems, leaf cupping and curling | causes uncontrolled cell division and growth, destroying plant tissue | 4 |
| Oryzalin | Seed distortion or failure to grow | disrupts mitosis in germinating seed, inhibiting root and shoot development | 3 |
| Pelargonic Acid | quickly develops dark, water-soaked appearance, followed by wilting and death | destroys cell walls, causing collapse and death | 0 |
| Pendimethalin | Seed distortion or failure to grow | disrupts mitosis in germinating seed, inhibiting root and shoot development | 3 |
| Picloram | bending and twisting of stems, leaf cupping and curling | causes uncontrolled cell division and growth, destroying plant tissue | 4 |
| Prodiamine | Seed distortion or failure to grow | disrupts mitosis in germinating seed, inhibiting root and shoot development | 3 |
| Quinclorac | Grasses: yellowing, wilting, browning starting at new growth Broadleaves: yellowing leaves, mild twisting of stems, and leaf cupping | causes uncontrolled cell division and growth, destroying plant tissue | 4 |
| Sulfentrazone | quick browning of leaves | destroys cell membranes causing cells to dry out | 14 |
| Triclopyr | bending and twisting of stems, leaf cupping and curling | causes uncontrolled cell division and growth, destroying plant tissue | 4 |
| Trifluralin | Seed distortion or failure to grow | disrupts mitosis in germinating seed, inhibiting root and shoot development | 3 |
More Information
- Using Pesticides Safely in the Home and Garden
- Understanding Herbicide Labels
- Herbicide Injury to Garden Plants
- Managing Weeds in Landscapes, Gardens, and Lawns
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