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Home and Landscape: Pesticide Active Ingredients Database

clopyralid

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Pesticide Type

Herbicide

See the Pesticide Terms page for definitions of terms used in this database.

How Does This Active Ingredient Work?

This active ingredient is a systemic, selective, preemergence or early postemergence herbicide and plant growth regulator (PGR) that is used mostly for broadleaf weeds and shrubs. Clopyralid mimics a plant growth hormone. It interferes with plant cell formation that results in abnormal growth.

Potential Hazards1

Environment People or other mammals
Water quality2
(aquatic wildlife)Footnote 1. Water quality ratings from Pesticide Choice: Best Management Practice (BMP) for Protecting Surface Water Quality in Agriculture, ANR Publication 8161, or the USDA-NRCS WIN-PST database—see Pesticides: Water-Related Toxicology of Active Ingredients. Information to be added. 		Natural enemies3
(beneficials) Information to be added. 		Honey bees4Footnote 3.Honey bee ratings are: (Very High) I-Do not apply to blooming plants; (High) II-Apply only during late evening; (Moderate) III-Apply only during late evening, night, or early morning; and (Low) IV-Apply at any time with reasonable safety to bees. For more information, see How to Reduce Bee Poisoning From Pesticides (PDF), Pacific Northwest Extension Publication PNW591. Information to be added. Acute5Footnote 4.Acute oral toxicity ratings for people and other mammals based on LD50 and US EPA Acute Toxicity Ratings system: H = Highly Toxic (LD50 < 50), M = Moderately Toxic (LD50: 50-500), L = Slightly Toxic (LD50: 500-5000), VL = Not Acutely Toxic (LD50 > 5000). Information to be added. Chronic6Footnote 4.Acute oral toxicity ratings for people and other mammals based on LD50 and US EPA Acute Toxicity Ratings system: H = Highly Toxic (LD50 < 50), M = Moderately Toxic (LD50: 50-500), L = Slightly Toxic (LD50: 500-5000), VL = Not Acutely Toxic (LD50 > 5000). Information to be added.
————NKR
Hazards Ratings: VL=Very low, L=Low, LM=Low to Moderate, M=Moderate, LH=Low to High, MH=Moderate to High, H=High, VH=Very High, N/A=Not Applicable, N=None, NKR=No Known Risk, — = No data
Honey Bee Ratings:
Do not apply or allow to drift to plants that are flowering including weeds. Do not allow pesticide to contaminate water accessible to bees including puddles.
Do not apply or allow to drift to plants that are flowering including weeds, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations. Do not allow pesticide to contaminate water accessible to bees including puddles.
No bee precaution, except when required by the pesticide label or regulations.

Safety Precautions

Read the product label for specific information on personal protective equipment (PPE) and safety requirements. Note that many consumer pesticide products do not include information about PPE on the label. You should still wear basic PPE to protect yourself from exposure, such as chemical resistant gloves, long sleeves, and goggles. Learn about safe use and disposal of pesticides.

Warning on the use of pesticides.

Pest Notes and Example Products

These products were registered for home and garden use in California in July 2013. Professional use products are not included. If no example products are listed, this active ingredient may be available only for professional use. Individual products are registered for specific uses on specific sites. Read the label to determine if the product is registered for your use. Note that some products may be formulated with additional pesticides. Information to be added

This active ingredient is mentioned in the following Pest Notes:

Example home, garden or landscape use products7:

    Monterey Star Thistle Killer

Example professional use products:

    Stinger, Transline
1 Potential hazard ratings may vary depending on the species, environmental conditions, application rate and type (i.e., bait vs spray), application location (i.e., indoors vs outdoors), and pesticide formulation (i.e., rodenticides are not applied in ways that would pose risks to water quality or honey bees). Ratings may not be available for all active ingredients due to these factors. Toxicity ratings may be averages of reported effects and should only be used as a general guide. Missing ratings will be added when data is available.
2 Water quality ratings are from the National Pesticide Information Center; U.S. Environmental Protection Agency; and USDA Natural Resources Conservation Services (NRCS) WIN-PST WaterTox database.
3 Impact on natural enemies ratings are from the UC IPM Pest Management Guidelines for Agriculture database and the USU Pollinator and Beneficials Toxicity Table.
4 Honey bee ratings are from the UC IPM Bee Precaution Pesticide Ratings.
5 Acute (short-term) oral toxicity ratings for people and other mammals are based on LD50 and US EPA Acute Toxicity Ratings system: H = Highly Toxic (LD50 < 50 mg/kg), M = Moderately Toxic (LD50: 50-500 mg/kg), L = Slightly Toxic (LD50: 500-5000 mg/kg), VL = Not Acutely Toxic (LD50 > 5000 mg/kg).
6 Chronic (long-term) toxicity information for people and other mammals is from the California Prop 65 list of chemicals known to cause cancer, birth defects, or other reproductive harm; and the U.S. Environmental Protection Agency list of chemicals evaluated for carcinogenic potential. If an active ingredient is listed on either list as a likely or confirmed carcinogen, it will be listed in the Potential Hazards table. If an active ingredient is not found on either list, is listed as an unlikely carcinogen, or has been determined to be noncarcinogenic, the rating will be indicated as NKR for No Known Risks.
7 Example consumer and professional products are derived from the California Department of Pesticide Regulation database and annual retail shelf survey by the UC Office of Pesticide Information and Coordination. Some of this information may become out of date as products and active ingredient restrictions change. No endorsements of named products are intended, nor is criticism implied of products not mentioned.