AMINOPYRALID - The Dow Chemical Company

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V45-313-001 (01/05) BOD 

010-50433 

AMINOPYRALID 

TECHNICAL BULLETIN 

AMINOPYRALID IS NOT YET REGISTERED WITH THE U.S. EPA. FEDERAL REGISTRATION IS PENDING. 

THIS BULLETIN IS INTENDED TO PROVIDE TECHNICAL INFORMATION ONLY AND IS NOT AN OFFER FOR SALE OF PRODUCT.

Overview 

Aminopyralid (DE-750) is a new pyridine carboxylic acid herbicide intended for use in rangeland, 

permanent grass pastures, industrial vegetation management areas (including rights-of-way for roads, 

railroads and electric utility lines), natural areas (wildlife management areas, natural recreation areas, 

campgrounds, trailheads and trails), grazed areas in and around these sites, wheat, barley, sorghum 

and oil palm and rubber plantations. It is a new Dow AgroSciences compound designed and developed 

specifically for the control of noxious and invasive weed species in rangeland, pastures and industrial 

vegetation management sites. Aminopyralid is a new generation active ingredient that is effective at 

very low rates as compared to currently registered herbicides with the same mode of action, including 

2,4-D, clopyralid, triclopyr, picloram and dicamba. Aminopyralid is a broadleaf weed herbicide that 

provides systemic, postemergence control of noxious and invasive annual, biennial and perennial weed 

species, agronomically important weeds and certain semi-woody plants. Aminopyralid can provide 

residual control, thus reducing the need for re-treatment, depending on the rate applied and the target weeds. 

Once registered and commercialized, aminopyralid will be offered as a stand-alone treatment and in 

premixes with 2,4-D, fluroxypyr and triclopyr for use in rangeland, pastures, rights-of-way and natural 

areas. Dow AgroSciences intends to register aminopyralid globally. Applied as a stand-alone treatment, 

aminopyralid will control important invasive pasture weeds, including Acroptilon repens, Carduus 

nutans, Centaurea maculosa, Centaurea solstitialis, Cirsium arvense, Solanum viarum and Senecio 

jacobaea. Aminopyralid premixes, with other herbicides, will provide control of a broad spectrum of 

broadleaf weeds, including species in the genera Vernonia, Rumex, Urtica, Sida, Solidago, Vervain, 

Acacia and Mimosa. 

In wheat, aminopyralid can be applied for selective, postemergence control of key broadleaf weeds, 

including Polygonum convolvulus, Papaver rhoeas, Polygonum aviculare, Silybum marianum and 

Chrysanthemum segetum. Additional cereals concepts utilize fluroxypyr and florasulam as premix partners 

and metsulfuron in a co-pack. Product concepts for aminopyralid in wheat are being developed for use 

in Argentina, Australia, the United States, Europe, the middle East and Africa. 

Cirsium arvense Carduus nutans 

Additional product concepts being developed are for the use of aminopyralid + glyphosate in oil palm 

and rubber plantations; and aminopyralid + fluroxypyr for use in sorghum. Aminopyralid is selective 

in oilseed rape in Europe in concepts that will allow excellent control of a number of key dicot weeds, 

including species of Cirsium, Matricaria, Polygonum, Papaver, Galium and Geranium. Evaluations of the 

potential to develop aminopyralid alone or in co-formulation with other active ingredients in oilseed 

rape are ongoing. 

Noteworthy Features 

Aminopyralid was accepted for evaluation under the EPA’s Reduced Risk Pesticide program in October 

2004. Aminopyralid was accepted into this program based upon a combination of unique and improved 

features for the control of invasive weeds in rangeland, pastures, and non-cropland, compared to 

currently registered products. EPA’s decision to evaluate aminopyralid as part of its Reduced Risk initiative 

was based on data and risk assessments presented for toxicological, ecotoxicological and environmental 

fate effects. 

Aminopyralid applied alone and with other herbicides will provide the following attributes: 

Matricaria inodora 

1. Equivalent or superior postemergence and residual control of a broad spectrum of difficult-to-control 

noxious and invasive broadleaf or semi-woody plants compared to currently registered herbicides. 

2. Reduction in environmental herbicide loading in rangeland and pastures, industrial vegetation 

management areas, and natural areas by offering excellent control of many key species at rates 

substantially lower than labeled use rates for many currently registered herbicides. 

3. Residual weed control activity to reduce the need for re-treatment. 

4. An excellent fit into integrated weed management (IWM) programs. 

5. Efficacious control in cereals of Polygonum convolvulus, Polygonum aviculare, Papaver rhoeas 

(including ALS resistant and 2,4-D tolerant biotypes) and other broadleaf weeds 

6. Excellent tolerance and improved, weed free growth of perennial temperate and tropical forage 

grass species and grass crops such as wheat, barley and sorghum when used as recommended. 

7. A mode of action that provides an alternative to ALS-inhibitor herbicides for ALS herbicide resistant weeds. 

2 An Introduction to AMINOPYRALID An Introduction to AMINOPYRALID 3

The Aminopyralid Story 

Unmet Needs in Rangeland and Pastures, 

Rights-of-Way and Wildlife Management Areas 

One of the most serious problems facing landowners and 

land managers for rangeland and pastures, rights-of-way 

and natural areas is the rapid spread of noxious and 

invasive plants. Non-native invasive plants have been 

introduced into new habitats without the natural enemies 

that limited their reproduction and spread in their native 

habitats. These invasive plants are spreading rapidly in 

many areas. The infestation rate on Federal lands in the 

U.S. is now approximately 4,600 acres per day 1 . The U.S. 

Geological Survey reports that some $20 billion in 

damages can be linked to invasive plants. When left 

uncontrolled, invasive weed species are a form of biological 

pollution and produce many direct and secondary negative 

effects. These effects include the creation of plant monocultures that negatively impact endangered 

species, crowd out native species that are essential to properly functioning ecosystems, reduce production 

of forages used by game and livestock through competition and allelopathy, reduce rangeland carrying 

capacity, increase livestock production costs, increase soil erosion, increase rights-of-way maintenance needs 

and degrade the aesthetic qualities of desired plant communities. 

Dow AgroSciences has been a leader in providing effective herbicides for use in rangeland, pastures, 

rights-of-way and natural areas for many years. Continuing in this tradition, Dow AgroSciences is 

developing aminopyralid as a new active ingredient specifically designed for the management of noxious 

and invasive species and broad spectrum, broadleaf weed control in rangeland, pastures and rights-of-way. 

Aminopyralid is a new generation active ingredient of the pyridine carboxylic acid class that provides an 

effective tool for managing these difficult-to-control weeds using reduced application rates. Aminopyralid 

fits well into an integrated weed management program due to the low use rate. Overall, aminopyralid 

should prove to be a valuable tool in integrated systems approaches to managing rangeland, pasture, 

rights-of-way, non-cropland and natural area vegetation complexes. 

1 Asher and Harman, International J. of Wilderness 1(2) 1995. 35-37 

Formulations 

There are currently a wide range of aminopyralid formulation concepts in development to meet widely 

varying user needs in different geographic areas and crops around the world. Each of these concepts is 

designed to address specific weed management objectives. In some situations, aminopyralid will be 

sold in products in which it is a single active ingredient. To meet other specific needs, aminopyralid will 

be offered in mixtures or combinations with additional active ingredients. 

Registrations 

Dow AgroSciences will seek to register aminopyralid for use in more than 50 countries in North 

America, Central and South America, Europe, Asia, Australia and New Zealand. Initial aminopyralid 

registrations are anticipated from 2005 through 2008. 


Weed Control 

Vernonia baldwinii Solanum carolinense Mimosa pudica 

Aminopyralid products will provide selective, broad-spectrum control of annual, biennial and perennial 

broadleaf and semi-woody plants. Products are being developed for use in rangeland, pastures, industrial 

vegetation management areas, cereals, oil palm and rubber plantations. 

I. Range and Pasture, Rights-of-way and Natural Areas 

Aminopyralid controls a number of invasive plants and noxious weeds, woody and semi-woody plants 

including most of the species from the genera Acacia and Mimosa. Some woody and semi-woody 

species are treated on an individual plant basis. Aminopyralid will be recommended alone and or 

in pre-mixes with other herbicides. 

Long-term weed control is most effective where grass and other desirable vegetation form competitive 

stands after the aminopyralid application. The benefits of weed control achieved with aminopyralid may 

be optimized and extended when integrated with other vegetation management practices (i.e., prescribed 

fire, grazing management, fertilization, planting improved temperate and tropical grass and legume 

forages, mechanical controls, biological controls, etc.) that promote recovery of desirable vegetation 

and increase forage production. 

The following tables provide a listing of key economic weed species that are susceptible to aminopyralid 

and its mixtures with 2,4-D, fluroxypyr or triclopyr, when applied as a broadcast (Table 1) or directed 

spray (Table 2) in rangeland, pastures, rights-of-way, other non-cropland and certain crops. Examples 

of these weeds include Daucus carota, Solidago sp., Rumex sp., Vernonia sp., Vervain sp., Lespedeza sp., 

Ranunculus sp., Urtica sp., Taraxacum officinale, Symphoriocarpus occidentalis, Capsella bursa-pastoris 

and Lantana camara. 

Cirsium vulgare Lantana camara Sida rhombifolia 

Table 1. List of weeds controlled by aminopyralid and its mixtures in R&P as g ae/ha (broadcast)* 

Bayer Species Name Bayer Species Name Bayer Species Name Bayer Species Name 

Code Code Code Code 

Aminopyralid Aminopyralid + 2,4-D Aminopyralid + Fluroxypyr Aminopyralid + Triclopyr 

6 An Introduction to AMINOPYRALID An Introduction to AMINOPYRALID 7 

CENRE** 

AMASP 

AMBEL 

AMBPS 

AMBTR 

ARTAB 

CRUAC 

CRUNU 

CENDI** 

CENMA** 

CENSO 

CHYLE 

CIRAR 

CIRVU 

LACSE 

LAMAN 

MATIN 

RANBU 

RUMAC 

RUMCR 

RUMOB 

SENJA 

SOLVI 

VEEAT 

VENBA 

XANST 

Acroptilon repens 

Amaranthus spinosus 

Ambrosia artemisiifolia 

Ambrosia psilostachya 

Ambrosia trifida 

Artemisia absinthium 

Carduus acanthoides 

Carduus nutans 

Centaurea diffusa 

Centaurea maculosa 

Centaurea solstitialis 

Chrysanthemum leucantheum 

Cirsium arvense 

Cirsium vulgare 

Lactuca serriola 

Lamium amplexicaule 

Matricaria inodora 

Ranunculus bulbosus 

Rumex acetosa 

Rumex crispus 

Rumex obtusifolius 

Senecio jacobaea 

Solanum viarum 

Verbesina alternafolia 

Vernonia baldwinii 

Xanthium strumarium 

AMASP 

AMBEL 

AMBPS 

AMBPS 

ARTAB 

CENDI 

CENMA** 

CHYUV 

CHEAM 

CICIN 

CIRVU 

CVNCP 

DAUCA 

DEMIL 

EUPSQ 

GUEDR 

HENAM 

HPYSU 

IVAAN 

IVAXA 

SIDGZ 

SIDRH 

SIDSN 

SOLCA 

SOOMS 

SYPOC 

VEBST 

VENAL 

Amaranthus spinosus 

Ambrosia artemisiifolia 

Ambrosia psilostachya 

Ambrosia spilostachya 

Artemisia absinthium 

Centaurea diffusa 

Centaurea maculosa 

Tanacetum vulgare 

Chenopodium ambrosioides 

Cichorium intybus 


Croton capitatus 

Daucus carota 

Desmanthus illinoensis 

Eupatorium squalidum 

Gutierrezia dracunculoides 

Helenium amarum 

Hyptis suaveolens 

Iva annua 

Iva xanthifolia 

Sida glaziovii 

Sida rhombifolia 

Sida santaremnensis 

Solanum carolinense 

Solidago missouriensis 

Symphoricarpos occidentalis 

Verbena stricta 

Vernonia altissima 

CAPBP 

CHEAL 

CIRAR 

CIRVU 

EUPSQ 

HERSP 

IVAXA 

MATCH 

POLCO 

RANRE 

RANSA 

RUMAC 

RUMCR 

RUMOB 

CASOB 

SIDGZ 

SIDRH 

SIDSN 

STEME 

TAROF 

URTDI 

VENPO 

VENWE 

Capsella bursa-pastoris 

Chenopodium album 



Eupatorium squalidum 

Heracleum sphondylium 

Iva xanthifolia 

Matricaria chamomilla 

Polygonum convolvulus 

Ranunculus repens 

Ranunculus sardous 

Rumex acetosa 

Rumex crispus 


Senna obtusifolia 

Sida glaziovii 


Sida santaremnensis 

Stellaria media 

Taraxacum officianale 

Urtica dioica 

Vernonia polyanthes 

Vernonia westiniana 

Bayer Species Name Bayer Species Name Bayer Species Name 

Code Code Code 

Aminopyralid Aminopyralid + 2,4-D Aminopyralid + Fluroxypyr 

AROCA 

CRUNU 

CIRVU 

RUMOB 

SENJA 

SLYMA 

Arctotheca calendula 

Carduus nutans 



Senecio jacobaea 

Silybum marianum 

ACACO 

ACAFA 

ACAPT 

ASCCU 

BATRE 

BOICA 

LIPNO 

MEOPA 

MIMAL 

MIMPI 

MIMPU 

CASTO 

SIDAC 

SIDRH 

SOLJA 

WSSAM 

Acacia cornigera 

Acacia farnesiana 

Acacia pennatula 

Asclepias curassavica 

Baltimora recta 

Borreria capitata 

Lippia nodiflora 

Melochia parviflora 

Mimosa albida 

Mimosa pigra 

Mimosa pudica 

Senna obtusifolia 

Sida acuta 


Solanum jazminoide 

Wissadula amplissima 

ACADE 

ACAHA 

ACALE 

ACASC 

EUPAD 

EUPRI 

LANCA 

LANMV 

MACCO 

MALPA 

RUMSS 

Acacia decora 

Acacia harpophylla 

Acacia leiocalyx 

Acacia salicina 

Ageratina adenophora 

Ageratina riparia 

Lantana camara 

Lantana montevidensis 

Maclura chinensis 

Malva parviflora 

Rumex sp. 

CAPBP 

CHEAL 

CIRAR 

CIRVU 

HERSP 

MATCH 

RUMCR 

RUMOB 

TAROF 

URTDI 

Capsella bursa-pastoris 




Heracleum sphondylium 

Matricaria chamomilla 

Rumex crispus 


Taraxacum officinale 

Urtica dioica 

* Dow AgroSciences research 

** Rating base on control achieved one year after application of aminopyralid. 

For specific geographic and crop conditions, end-users should consult their local product labels and/or contact a Dow AgroSciences representative. 

Table 2. List of weeds controlled by aminopyralid and its mixtures in R&P as g ae/100L (directed) 

For specific geographic and crop conditions, end-users should consult their local product labels and/or contact a Dow AgroSciences representative.

II. Cereals – All Areas 

In wheat, aminopyralid has shown excellent postemergence 

control, as well as residual activity on key broadleaf weeds, 

including Polygonum convolvulus, Papaver rhoeas (including 

ALS resistant and 2,4-D tolerant biotypes), Polygonum aviculare, 

Silybum marianum and Chrysanthemum segetum. Dow 

AgroSciences will recommend aminopyralid + fluroxypyr in 

Australia and in the United States for the control of 

Polygonum convolvulus, Polygonum aviculare, Polygonum 

vaccinifolium and Kochia scoparia. In Europe, Asia and Africa, 

Dow AgroSciences will seek registration of aminopyralid in 

mixtures designed for specific weed management needs. 

Use rates for aminopyralid in wheat will vary from 4 g ae/ha 

to 10 g ae/ha. Table 3 lists cereal weeds that are susceptible 

to aminopyralid alone and in mixtures. 

Table 3. List of weeds controlled by aminopyralid and its mixtures in cereals as g ae/ha (broadcast) 

Bayer Species Name Bayer Species Name Bayer Species Name Bayer Species Name 

Code Code Code Code 

Aminopyralid Aminopyralid + Fluroxypyr Aminopyralid + Florasulam Aminopyralid + Metsulfuron 

AROCA 

CHYSE 

CIEAR 

EMEAU 

LACSE 

MATSS 

PAPRH 

PIBSA 

POLAV 

POLCO 

SLYMA 

VICFX 

VICSA 

Arctotheca calendula 

Chrysentemum segetum 

Cicer arietinum* 

Emex australis 


Matricaria spp. 

Papaver rhoeas 

Pisum sativum* 

Polygonum aviculare 


Silybum marianum 

Vicia faba* 

Vicia sativa* 

KCHSC 

LACSE 

PAPRH 

POLCO 

Kochia scoparia 




ANTAR 

BIFRA 

CIRAR 

GALAP 

MATSS 

PAPRH 

SINAR 

STEME 

Anthemis arvensis 

Bifora radians 


Galium aparine 

Matricaria spp. 


Sinapis arvensis 


Triticum aestivum 

CENSO 

CHEAL 

LAMAM 

LYCAR 

POLAV 

POLCO 

RAPRA 

RASRU 

STEME 

Centaurea solstitialis 


Lamium amplexicaule 

Lycopsis arvensis 

Polygonum aviculare 


Raphanus raphanistrum 

Rapistrum rugosum 


* volunteer plants 

For specific geographic and crop conditions, end-users should consult their local product labels and/or contact a Dow AgroSciences representative. 

III. Oil Palm and Rubber Plantations – Indonesia and Malaysia 

Dow AgroSciences is developing a premixture of aminopyralid + glyphosate for use in oil palm and rubber 

plantations as a postemergence treatment applied around the base of the trees for broad spectrum 

foliar control of key broadleaf and grass weeds including Ageratum conyzoides, Asystasia intrusa, 

Hedyotis verticillata, Mikania cordata and Paspalum conjugatum. 

Mode of Action 

Silybum marianum Polygonum convolvulus Polygonum aviculare 

Hedyotis verticillata Ageratum conizoides 

Plant growth is a complex process that is controlled, in part, by a variety of plant growth regulators, 

including auxin compounds. To ensure proper growth, plants produce very controlled amounts of these 

materials. Auxins bind to specific cell surface receptor proteins, turning on and off vital plant processes. 

Aminopyralid is a herbicide possessing auxin-like qualities. Aminopyralid moves systemically throughout 

the plant and deregulates plant growth metabolic pathways affecting the growth process of the plant. 

This disruption of plant growth processes, by binding of aminopyralid at receptor sites normally used 

by the plant’s natural growth hormones, results in control and death of susceptible plant species. 


Absorption/Translocation 

Aminopyralid is a systemic, phloem and xylem mobile herbicide that is rapidly absorbed by the leaves 

and roots. The compound translocates throughout the plant and accumulates in the meristematic tissue, 

resulting in uneven cell division and growth. 

Herbicidal Activity 

Symptoms are typical of those for the auxinic mode of action. Within hours or days of application 

depending on the weed species, aminopyralid causes symptoms such as thickened, curved and twisted 

stems and leaves, cupping and crinkling of leaves, stem cracking, narrow leaves with callus tissue, 

hardened growth on stems, enlarged roots and proliferated growth. Most annual susceptible weeds are 

controlled within 4 to 8 weeks after application. Complete kill of main stems and the root systems of 

woody and semi-woody plants may require 2 or more months after application. Plant growth will stop 

within 24-48 hours after treatment. 

Crop Tolerance 

Aminopyralid offers a high level of tolerance on a wide range of temperate and tropical forage grasses 

and on small grain cereals. More than 20 different forage grasses evaluated in field trials from 1999-2004, 

with aminopyralid applied at rates up to 2 times the maximum use rate, demonstrated tolerance to 

aminopyralid. The grasses evaluated included Agropyron sp., Andropogon gerardii, Andropogon 

saccharoides, Andropogon scoparius, Bouteloua curtipendula, Bouteloua gracilis, Brachiaria bryzantha, 

Brachiaria decumbens, Bromus inermis, Buchloe dactyloides, Cynodon dactylon, Cynodon nlemfuensis, 

Cynodon plectostachyus, Dactylis glomerata, Digitaria decumbens, Eragrostis ciliaris, Festuca sp., Lolium 

sp., Panicum maximum, Panicum virgatum, Paspalum notatum, Phleum pratense, Poa sp. and 

Sorghastrum nutans. 

Aminopyralid may be applied to small grain cereals from the 3-leaf crop growth stage up to the early 

joint stage. Field trial results confirm that aminopyralid offers crop selectivity that is equal or superior 

to that of standards on wheat, durum wheat, barley, rye and triticale. 

Crop Rotation 

Rangeland or permanent pasture areas treated with aminopyralid should generally not be rotated to broadleaf 

crops including cotton, soybeans, alfalfa, field peas, lentils and other leguminous crops within the same year 

of application. Exceptions might occur in tropical/subtropical regions with hot and humid conditions. 

Aminopyralid is primarily dissipated in the soil by aerobic microbial degradation and the rate of breakdown 

is dependent upon several factors including soil moisture and soil temperature. Specific local guidelines for 

planting of rotational crops will be contained on the label. In general, grass crops will be more tolerant as 

rotational crops. Rotational crop recommendations for broadleaf crops will vary among species. 

Resistance Management 

Aminopyralid has an auxinic growth regulator mode of action. Other growth regulator herbicides used 

on rangeland and pastures, rights-of-way and other non-cropland areas, natural areas and in cereals, 

include 2,4-D, clopyralid, dicamba, picloram and triclopyr. Despite extensive use, herbicides with this mode 

of action have demonstrated a low risk of resistance development compared to other herbicide 

mode of action classifications such as ALS-inhibitor herbicides, photosystem II inhibitor herbicides 

and ACCase-inhibitor herbicides. 

The International Survey of Resistant Weeds lists only six weed species in the United States and 24 species 

worldwide with resistance to the growth regulator mode of action. The risk of resistance development is 

less on rangeland, pasture and natural areas because herbicide applications are not typically made every 

year, thus slowing the increase in resistant genotypes in weed populations. Because of the low resistance 

risk, aminopyralid will be a useful herbicide tool to rotate with ALS-inhibitor herbicides and urea herbicides 

in range and pastures, non-cropland areas and natural areas. 

Worldwide, there currently are 82 weed species with confirmed ALS-inhibitor resistance and 20 with urea 

herbicide resistance. Many of these weed biotypes are encountered in rangeland, pastures, rights-of-way 

and cereals including Kochia scoparia, Salsola iberica, Papaver rhoeas, Ambrosia sp., Lactuca serriola, 

Helianthus annuus, Sinapis arvensis and Amaranthus sp. 

Chlorsufuron and sulfometuron are ALS-inhibiting herbicides that have been used repeatedly and extensively 

on rights-of-way. Metsulfuron, another ALS-inhibiting herbicide, has been used repeatedly and extensively 

on rights-of-way, rangeland and pastures. Triasulfuron, chlorsulfuron, metsulfuron, thifensulfuron and tribenuron 

are ALS-inhibiting herbicides that have been used repeatedly and extensively on wheat. 

There are only a limited number of herbicide modes-of-action available for rangeland, pasture and 

non-cropland areas. The existence of multiple known examples of ALS-inhibitor resistant weeds in these 

sites and in wheat, confirm the need for a sound weed resistance management strategy. Aminopyralid has 

a growth regulator mode of action and will control ALS-inhibitor herbicide and urea herbicide resistant 

biotypes for species within the aminopyralid weed spectrum. 


Description of Chemistry 

Chemical Name (IUPAC) 4-amino-3,6-dichloropyridine-2-carboxylic acid 

Chemical Name (CAS) 2-pyridinecarboxylic acid, 4-amino-3,6-dichloro- 

Common Name Aminopyralid (ISO proposed) 

Code Names DE-750, XDE-750, XR-750 

Chemical Class Pyridine carboxylic acid 

CAS Registry No. 150114-71-9 

Empirical formula C 6 H 4 Cl 2 N 2 O 2 

Structural formula 

Molecular Weight 207.026 g/mole 

Relative Density 1.72 at 20°C 

Appearance Off-white, odorless powder 

Melting Point 163.5°C 

Boiling Point Decomposes upon melting 

Vapor pressure At 20°C, 7.14e-11 mmHg 

Octanol/Water Partition Unbuffered water = 0.201 

Coefficient (log K ow ) at 19°C pH 5 = -1.76 

pH 7 = -2.87 

pH 9 = -2.96 

Dissociation Constant (pK a ) 2.56 

Hydrolytic Stability (DT 50 ) Stable 

Aqueous Photostability (DT 50 ) 0.6 Days 

Soil Photolysis (DT 50 ) 61 Days 

Solubility in water 2.48 

(g/L @ 18°C) 

Solvent solubility 

(g/L @ 20°C) 

Buffered water pH = 5 212 g/L 



Methanol 52 g/L 

Acetone 29 g/L 

Heptane Insoluble (< 10 µg/L) 


Mammalian Toxicity 

I. Short-Term (Acute) Toxicity 

Based on data generated for, or on behalf of Dow AgroSciences, the acute mammalian toxicity of 

aminopyralid is considered low for both technical and end-use formulations. The acute oral LD 50 and 

dermal LD 50 in rats were greater than 5000 mg/kg, respectively, while the acute inhalation LC 50 was 

greater than 5.5 mg/L. Dermal irritation was negative for the aminopyralid technical. Eye irritation ranged from 

a slight, transient irritation for formulated aminopyralid to irritating for aminopyralid technical. Aminopyralid 

was not a skin sensitizer. A summary of acute toxicology data for aminopyralid is provided below: 

Test Species Toxicity Parameters 

Acute Oral (technical ai) Rat LD 50 > 5000 mg/kg 

Acute Oral (GF-871, Rat LD 50 > 5000 mg/kg 

240 g ae/L formulation) 

Acute Dermal (technical ai) Rat LD 50 > 5000 mg/kg 

Acute Dermal (GF-871, Rat LD 50 > 5000 mg/kg 


Acute Inhalation (technical ai) Rat LC 50 male > 5.50 mg/L 

Acute Inhalation (GF-871, Rat LC 50 male > 5.79 mg/L 


Dermal irritation (technical ai) Rabbit Negative 

Dermal irritation (GF-871, Rabbit Slight irritation 


Eye Irritation (technical ai) Rabbit Irritating 

Eye Irritation (GF-871, Rabbit Slight irritation, 

240 g ae/L formulation) resolving within 24 hours 

Skin sensitization (technical ai) Guinea Pig No sensitization 

Skin sensitization (GF-871, Guinea Pig No sensitization 


Long-Term (Chronic) Toxicity 

Dow AgroSciences studies have shown that aminopyralid (technical) was not carcinogenic, 

teratogenic, mutagenic, neurotoxic or a reproductive hazard. Aminopyralid was tested 

for genotoxicity in both in vitro and in vivo systems. A summary of long-term (chronic) 

toxicity data is provided below: 

Test Species Toxicity Parameters 

2-year chronic feeding Rat Not carcinogenic 

NOAEL (mg/kg/day): 

Male = 50, Female = 500 

Teratogenicity Rat Not teratogenic 


Maternal = 1000 

Developmental = 1000 

Teratogenicity Rabbit Not teratogenic 


Maternal = 250 

Developmental = 500 

Reproductive toxicity Rat No adverse reproductive effects 


Parental = 1000 

Reproductive = 1000 

Acute and chronic neurotoxicity Rat No adverse neurological effects 

Mutagenicity Assay (in vitro) Ames test Negative 

Mutagenicity Assay (in vitro) CHO/HGPRT Negative 

Mutagenicity Assay (in vivo) Mouse micronucleus Negative 

NOAEL (mg/kg/day) = 1000 


Environmental Toxicology 

In Dow AgroSciences laboratory testing, aminopyralid has been shown to be practically non-toxic to 

birds, fish, honeybees, earthworms and aquatic invertebrates. While aminopyralid is slightly toxic to the 

eastern oyster, algae and aquatic vascular plants, the expected environmental concentration resulting 

from the use of this material for weed control is orders of magnitude below any level of concern established 

for these organisms by EPA. 

Study Species Value 

Birds 

Avian oral Bobwhite Quail LD 50 > 2250 mg ae/kg bw 

Avian dietary Bobwhite Quail LD 50 > 5620 mg ae/kg diet 

Avian dietary Mallard Duck LD 50 > 5620 mg ae/kg diet 

Fish 

Acute toxicity Rainbow Trout 96 hr LC 50 > 100 mg ae/L 

Acute toxicity Bluegill 96 hr LC 50 > 100 mg ae/L 

Acute toxicity Sheepshead Minnow 96 hr LC 50 > 120 mg ae/L 

Study Species Value 

Aquatic Invertebrates 

Acute toxicity Water flea 48 hr EC 50 > 100 mg ae/L 

(Daphnia magna) 

Acute toxicity Mysid shrimp 96 hr LC 50 > 100 mg ae/L 

Acute toxicity Eastern oyster Slightly toxic 

48 hr EC 50 > 89 mg ae/L 

Growth and Reproduction Water flea NOEC = 100 mg ae/L 

(Daphnia magna) 

Chronic Toxicity Midge NOEC = 130 mg ae/L 

16 An Introduction to AMINOPYRALID An Introduction to AMINOPYRALID 17 

Honey bees 

Acute Contact Honeybee 48 hr LD 50 > 100 ug ae/bee 

Acute Oral Honeybee 48 hr LD 50 > 120 ug ae/bee 

Earthworm 

Acute Toxicity Earthworm 14 d LC 50 > 1000 mg ae/kg soil 

Algae and Aquatic Plants 

Acute Toxicity Freshwater green algae Slightly toxic 

72 hr E r C 50 = 30 mg ae/L 

Acute Toxicity Freshwater Slightly toxic 

blue-green algae 120 hr EC 50 = 27 mg ae/L 

Acute Toxicity Saltwater diatom Slightly toxic 

72 hr E b C 50 = 77 mg ae/L 

Acute Toxicity Freshwater diatom Slightly toxic 

96 hr EC 50 = 14 mg ae/L 

Acute Toxicity Duckweed Slightly toxic 

(Lemna gibba) 14 d EC 50 > 88 mg ae/L

Environmental Fate 

Soil 

Aerobic microbial degradation is the primary route of breakdown of aminopyralid in soil. The rate of 

degradation in the field resulted in an average half-life of 34.5 days for 8 North American sites and 

25 days for four European sites. 

Laboratory experiments yielded an average K oc of 10.8 L/kg, indicating some potential for mobility. 

However, field experiments showed limited movement in the soil profile. No degradation metabolites 

of concern were produced in any studies. 

Water 

In water the primary route of degradation of aminopyralid is photolysis. The photolysis half-life under standard 

conditions is 0.6 days indicating rapid degradation in surface water. The material is stable to hydrolysis. 

Groundwater contamination potential for aminopyralid is considered to be low because of low use 

rates, the moderate field degradation rates and limited mobility observed in field studies. Using this 

information as inputs to EPA and European Union simulation models, aminopyralid demonstrated a low 

potential for groundwater contamination. 

Air 

The potential for transport of aminopyralid via 

volatilization of residues is extremely low, due to its 

low vapor pressure and small Henry’s Law constant. 

As with any herbicide, susceptible non-target 

plants may be injured via physical spray drift. 

Spray applications should be made such that 

spray drift cannot injure desirable, susceptible 

plant species. 

Disclaimer 

The Aminopyralid Technical Bulletin is provided for reference purposes only and is not a substitute for 

or an addition to the product label or MSDS. Always read and follow label directions for registered pesticides. 

The information and any recommendations in this bulletin (“Information”) are presented in good faith; 

however, Dow AgroSciences LLC makes no warranty as to the completeness or accuracy of the information. 

This information is supplied upon the condition that persons receiving it will make their own determinations 

as to its suitability for their purposes prior to use and consult with their advisors to ensure compliance 

with all federal, state and local regulations. In no event will Dow AgroSciences be responsible for damages 

of any nature whatsoever resulting from the use of or reliance on this information. 

AMINOPYRALID IS NOT YET REGISTERED WITH THE U.S. EPA. FEDERAL REGISTRATION IS 

PENDING. THIS BULLETIN IS INTENDED TO PROVIDE TECHNICAL INFORMATION ONLY AND 

IS NOT AN OFFER FOR SALE OF PRODUCT. 

NO REPRESENTATION OR WARRANTIES, EITHER EXPRESSED OR IMPLIED OF MERCHANTABILITY, 

FITNESS FOR A PARTICULAR PURPOSE OR OF ANY OTHER NATURE ARE MADE HERUNDER WITH 

RESPECT TO THE INFORMATION OR THE PRODUCTS TO WHICH THE INFORMATION REFERS. 

Notice to the State of New York: The conclusions which are contained with this Technical Bulletin 

relating to the toxicological and environmental properties and effects of aminopyralid are based on 

research and studies conducted by Dow AgroSciences. All such conclusions and findings are considered 

to be the opinions of Dow AgroSciences.

AMINOPYRALID - The Dow Chemical Company

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