Page 2 of 47

TABLE OF CONTENTS

1. EXECUTIVE SUMMARY .................................................................................................... 3

2. INTRODUCTION .................................................................................................................. 4

3. USE CHARACTERIZATION................................................................................................ 5

4. CONCLUSIONS FROM PREVIOUS ASSESSMENTS..................................................... 11

4.1. Ecological Risk Assessments......................................................................................... 11

4.2. Drinking Water Exposure Assessments......................................................................... 12

4.3. Clean Water Act Programs............................................................................................. 13

5. ENVIRONMENTAL FATE AND TRANSPORT............................................................... 13

5.1. Transformation Products................................................................................................ 15

6. RECEPTORS........................................................................................................................ 16

6.1. Effects to Aquatic Organisms ........................................................................................ 17

6.2. Effects to Terrestrial Organisms .................................................................................... 17

6.3. Ecological Incidents....................................................................................................... 19

6.3.1. Ecological Incident Information System..................................................................... 19

6.3.2. Avian Monitoring System............................................................................................ 20

6.3.3. Aggregate Incident Database ..................................................................................... 20

7. EXPOSURE PATHWAYS OF CONCERN ........................................................................ 20

8. ANALYSIS PLAN ............................................................................................................... 21

8.1. Stressors of Concern....................................................................................................... 21

8.1.1. Ecological Risk Assessment........................................................................................ 21

8.1.2. Drinking Water Assessment........................................................................................ 21

8.2. Measures of Exposure .................................................................................................... 21

8.3. Measures of Effect ......................................................................................................... 22

8.4. Endangered Species Assessments.................................................................................. 22

8.5. Endocrine Disruptor Screening Program ....................................................................... 22

9. PRELIMINARY IDENTIFICATION OF DATA GAPS..................................................... 22

9.1. Environmental Fate ........................................................................................................ 22

9.2. Effects............................................................................................................................. 24

10. REFERENCES .................................................................................................................. 28

Appendix A. SIP and STIR Results.............................................................................................. 31

Appendix B. EIIS Incidents.......................................................................................................... 33
Page 3 of 47

1. EXECUTIVE SUMMARY

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

formulation for the ecological risk, environmental fate, endangered species, and drinking water 

assessments to be conducted as part of the registration review of clopyralid (PC code 117403; 

CAS Registry Number 1702-17-6). This document also covers three registered clopyralid salts 

(clopyralid monoethanolamine salt, PC code 117401, CAS #57754-85-5; clopyralid 

triethanolamine, PC code 117404, CAS #119308-91-7; clopyralid potassium, PC code 117423, 

CAS #58509-83-4). Unless otherwise specified, references to “clopyralid” throughout this 

document include clopyralid and its three registered salts.

The problem formulation describes the methods planned for the completion of drinking water

and ecological risk assessments and provides an overview of the environmental fate, ecological 

effects, and potential risks associated with the use of clopyralid. The problem formulation also 

addresses uncertainties unique to risk assessment of clopyralid. This document identifies 

additional studies that would be beneficial to the conduct of an ecological risk assessment. 

These studies are listed below; see Section 9 for additional details and explanation. Unless 

otherwise noted, studies are requested for clopyralid acid (PC code 117403). 

Environmental fate and transport data gaps:

• 835.4100 Aerobic soil metabolism (3 additional soils) 

• 835.4300 Aerobic aquatic metabolism (2 sediments)

• 850.6100 ECM and ILV studies in water, soil, and compost

• Non-guideline Dissipation study in compost

Ecotoxicology data gaps:

• Aquatic:1

o 850.1300 Chronic freshwater invertebrate 

o 850.1400 Freshwater fish early-life stage

o 850.4400 Aquatic vascular plant growth

o 850.4500 Aquatic non-vascular plant growth (2 additional species)

o 850.4550 Cyanobacteria toxicity

• Terrestrial

o 850.2100 Avian acute oral toxicity (passerine species)

o 850.2300 Avian reproduction (upland game species)

o 850.4100 Terrestrial plant: Tier II seedling emergence (clopyralid, clopyralid 

monoethanolamine salt, clopyralid triethanolamine, and clopyralid potassium)

o 850.4150 Terrestrial plant: Tier II vegetative vigor (clopyralid, clopyralid 

monoethanolamine salt, clopyralid triethanolamine, clopyralid potassium, and 

typical end use products that are co-formulated with other herbicides)

 1 Note that there are additional 40 CFR Part 158 aquatic ecotoxicology data gaps listed in Table 12 of this 

document that are not requested at this time because they are not expected to impact the risk assessment. These 

include 850.1025 Acute oyster shell deposition, 850.1035 Acute mysid, 850.1075 Acute saltwater fish, 850.1350 

Chronic saltwater invertebrate, and 850.1400 Saltwater fish early-life stage. See Table 12 in Section 9.2 for 

additional explanation.
Page 4 of 47

Major uncertainties in the assessment of clopyralid include (1) risk to non-target terrestrial plants 

from irrigation water contaminated with clopyralid and (2) potential synergism of herbicides in 

products that contain multiple active ingredients:

Data to better understand risk from residues in groundwater used as irrigation water: 

Clopyralid is mobile and persistent (see Section 5) and has been detected in groundwater. 

Incidents reported for other picolinic acid herbicides demonstrate the potential for groundwater

contaminated with these herbicides to damage non-target terrestrial plants when the groundwater 

is used for irrigation (USEPA, 2013). Screening level calculations comparing the highest 

concentration of clopyralid detected in groundwater to the most sensitive terrestrial plant 

NOAEC available show that less than one inch of irrigation water would be required to reach this 

endpoint. This estimate is expected to decrease (i.e., the NOAEC will be reached with even less 

irrigation water) when updated groundwater modeling exposure estimates and more refined 

terrestrial plant toxicity data become available.

Additional data are recommended to better understand the potential for risk due to residues of 

clopyralid in groundwater. Studies that would be useful include a prospective groundwater 

monitoring study or studies to refine groundwater modeling inputs for the Pesticide Root Zone 

Model for Groundwater (PRZM-GW) model. A prospective groundwater monitoring study 

could be used to determine where groundwater concerns are likely to occur and whether 

predictions based on laboratory data are observed in the field. Additionally, it could be used to 

determine vulnerability of different areas. Data to refine inputs to PRZM-GW may be used to 

refine modeling estimates of groundwater concentrations. Studies may involve understanding 

sorption or degradation in subsurface environments. It is recommended that a protocol be 

submitted, prior to conducting any of these studies. In the absence of more suitable inputs or 

scenarios, EECs generated from PRZM-GW in the same fashion as EDWCs for groundwater 

used as drinking water will be used to characterize risks to terrestrial plants from residues in 

irrigation water obtained from groundwater sources.

Terrestrial plant studies using co-formulated TEPs to identify synergistic effects: 

Clopyralid is co-formulated with many other herbicides, including 2,4-D, acetochlor, 

aminopyralid, benfluralin, dicamba, flumetsulam, fluroxypyr, MCPA, nicosulfuron, rimsulfuron, 

thifensulfuron, triclopyr, and trifluralin. Data on other picolinic acid herbicides suggest that 

chemicals in this class may exhibit synergistic terrestrial plant toxicity when co-formulated with 

other herbicides (USEPA, 2013). Data on representative typical end use products (TEPs) is 

needed to evaluate this potential risk. The registrant should justify the choice of TEPs used for 

these studies. The data can be limited to vegetative vigor studies, which are expected to be more 

sensitive than seedling emergence studies, and can include only the crops most sensitive to 

clopyralid. In the existing terrestrial plant studies, these include onion, snap bean, soybean, 

sunflower, tomato, and wheat.

2. INTRODUCTION

Clopyralid (3,6-dichloropyridine-2-carboxylic acid) is a picolinic acid herbicide. Picolinic acid 

herbicides are auxin growth regulators, which mimic naturally occurring plant hormones, thereby 

disrupting growth processes and causing abnormal growth patterns in plants. Registered uses 
Page 5 of 47

comprise many agricultural and non-agricultural use sites, including residential turf uses. 

Clopyralid is a persistent and mobile compound that is likely to leach to groundwater and may be 

transported to surface water by spray drift or runoff. NAWQA monitoring data confirm these 

transport routes. Clopyralid residues have also been found in compost.

EFED evaluated recent ecological risk assessments for clopyralid in association with the most 

recent toxicity, exposure, and usage information to determine if sufficient data are available to 

support registration review. The most recent EFED risk assessment for clopyralid is a 2012

Section 3 new use assessment for apple, leafy Brassica subgroup 5B, and rapeseed subgroup 

20A (USEPA, 2012b). In addition, EFED considered the latest Agency science policies and risk 

assessment methodologies. 

3. USE CHARACTERIZATION

Clopyralid was first registered in the United States in 1987 for use as an herbicide. 

Clopyralid is formulated as an emulsifiable, flowable, soluble concentrate, as water dispersible

granules, as granules, and as dust in multiple end-use products. Clopyralid is registered for use 

on a variety of agricultural, forest, commercial, and residential areas and may be applied via 

aircraft, ground sprayer, hand-held sprayer, and boom sprayer. Clopyralid may also be applied 

to forest plantings via broadcast, high volume spray, spot treatment, stump treatment, girdle 

treatment, frill treatment, tree wound treatment, and tree injection. There are 64 active Section 3 

registrations and 41 active Section 24(c) special local needs registrations in 20 states. 

Registered agricultural use sites now include alfalfa, apples, almonds, asparagus, barley, beans, 

brassica leafy greens, canola, chestnuts, cherries, cole crops, conservation resource program

(CRP), corn (field, pop, and sweet), cranberries, filberts, hickory nuts, lentils, macadamia nuts, 

mint, oats, pasture, rangeland, peas, peaches, pecans, pistachio nuts, potatoes, rapeseed, 

safflower, sorghum, soybeans, spinach, strawberries, sugar beets, sunflower, teff, wheat, and 

walnuts. Registered non-agricultural use sites now include cemeteries, farm buildings, 

fencerows, industrial sites, ornamental lawns and turf, ornamentals trees, athletic fields, golf 

fairways, parks, and rights-of-way. 

Based on private market usage data from 1998 to 2011, agricultural usage averaged 

approximately 880,000 pounds active ingredient (a.i.) applied annually on approximately 10 

million acres treated. The average a.i. rate over this time period was 0.085 pounds a.i./acre.

Between 2004 and 2011, 60,000 pounds of clopyralid were applied to sugar beets, covering an 

average of 45% and a maximum of 85% of the U.S. sugar beet crop. Other major uses include

barley (40,000 lbs, 15% of crop), corn (400,000 lbs, 5% of crop), and wheat (300,000 lbs, 5% of 

crop). Clopyralid is formulated as liquid concentrates that are mixed with water and applied as a 

spray. The maximum single application rate that has been previously assessed is 0.5 lb a.i./A.

Table 1 details the registered use patterns for clopyralid acid (PC code 117403; MW: 192), Table 

2 for clopyralid monoethanolamine salt (PC code 117401; MW: 252.07), Table 3 for clopyralid 

triethanolamine (PC code 117404; MW: 340.18), and Table 4 for clopyralid potassium (PC code 
Page 6 of 47

117423; MW: 230). Though these are four distinct chemical moieties, they will be assessed 

together using the acid equivalence (a.e.) method. That is, only the clopyralid acid component 

will be assessed and the application rates of the monoethanolamine, triethanolamine, and 

potassium salts will be adjusted to account for only clopyralid acid. EFED will use application 

scenarios that result in maximum exposure scenarios for a given use for the risk assessment. 

Some use patterns are not sufficiently characterized to permit ready calculation of a maximum 

application rate per acre, or else involve very broad use sites. More information on the following 

items would reduce uncertainty regarding such uses in the risk assessment:

• Some labels have instructions for applications to trees (cut surface, cut-stump treatment, tree 

injection, hack and squirt treatment, and frill and girdle method). The label should specify 

the maximum amount of clopyralid that may be applied per tree (e.g., as a function of trunk 

diameter), as well as the maximum number of trees that may be treated per acre. This is 

because maximum application rates (both single and total annual) in lbs a.i or a.e./A are 

needed in order to model exposures resulting from these types of uses. Additionally, the 

maximum number of applications per year and minimum retreatment interval should be 

specified for these uses.

• The labels have several nonspecific use sites. These broadly-categorized use sites will 

require EFED to employ the assumption that clopyralid can be used at a broad range of 

agricultural, commercial, residential, and forest sites. These use sites will also necessitate the 

assumption that application may occur to both aquatic and terrestrial environments. The 

following are examples of nonspecific use sites:

o non-irrigation ditch banks, seasonally dry wetlands (such as flood plains, deltas, 

marshes, swamps, or bogs), transitional areas between upland and lowland sites when 

dry, ditchbank weeds, shoreline weeds, non-cropland areas, and natural areas.

The Agency encourages that use site descriptions be made as specific as possible, so that 

potential use areas are not broader than necessary. Vague use site descriptions can impact 

assumptions made when doing proximity analysis for determinations on the potential risks to 

federally listed threatened/endangered (hereafter referred to as “listed”) species.

• Some restrictions are specified on a product basis rather than on an active ingredient basis.

• Some labels only include a maximum single application rate. They do not include a 

maximum annual or seasonal application rate, maximum number of applications, or 

minimum retreatment interval. Any absence of information will result in conservative 

assumptions as illustrated in the following examples:

o A maximum single application rate is specified with a re-application interval of 7 

days without specifying a maximum annual rate may result in an assumption of 52 

applications with 7-day intervals;

o A label that does not preclude aerial applications will likely result in an assumption of 

aerial pesticide applications;

o A label that does not specify an application interval may result in assumptions of 

short application intervals such as 1- or 3-day intervals.

• Some labels with multiple active ingredients, where acid equivalents are relevant, provide 

acid equivalent restrictions but do not specify to which active ingredient the limitations 

apply.
Page 7 of 47

Table 1. Uses Site and Application Information for Clopyralid Acid (PC 117403)

Use Site Formulation 

Type1

Max. Rate

(lbs a.e./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single Annual

Agricultural 

Fallow / 

Idleland 

Conservation 

Reserve

EC 0.5748

NS NS NS

Broadcast -

Aerial

Before seeding

Foliar

Established 

plantings

Weed 

postemergence

EC 0.5748 Broadcast -

Ground

Barley

EC 0.1289

NS NS NS

Broadcast -

Aerial Postemergence

EC 0.1316 Broadcast -

Ground

Corn, Field DF, EC 0.2252 NS NSNS

Broadcast - Ground 

Band treatment 

Burndown treatment

Soil incorporated 

treatment

Preplant, 

Preemergence 

Postemergence

Spike stage

Weed

postemergence

0.1193 0.2386 2 Broadcast - Aerial

Band treatment

Preplant, 

Postemergence

Corn, Sweet EC 0.1193 0.2386 2 NS

Broadcast - Aerial 

and Ground

Band treatment

Preplant, 

Postemergence

Flax EC 0.0922 0.0922 1 NS Broadcast - Aerial 

and Ground Postemergence

Golf Course 

Turf

EC, SC, 

Dust 0.1237 NS 2 NS Broadcast -

Ground Foliar

Grasses Grown 

for Seed EC 0.1844 0.1844 NS 21 Broadcast - Aerial 

and Ground

Preharvest 

Postemergence

0.1193 0.2386 Postharvest

Nonagricultural 

Right-of-Way / 

Fencerows / 

Hedgerows

EC, SC

0.6611

NS NS NS

Broadcast - Ground

Foliar

0.5748 Broadcast - Aerial

Nursery Stock EC 0.6611 0.6611 NS NS Broadcast - Ground Foliar

Oats EC 0.1289 0.1289 NS NS Broadcast - Aerial 

and Ground Postemergence

Ornamental 

and/or Shade 

Trees

EC 0.6611 NS NS NS Broadcast - Ground Foliar

Ornamental 

Grasses EC 0.6611 NS NS NS Broadcast - Ground Foliar

Ornamental 

Herbaceous 

Plants EC 0.6611 NS NS NS Broadcast - Ground Foliar

Ornamental 

Lawns and Turf

G, EC, SC, 

Dust 0.2895 NS NS NS Broadcast - Ground Foliar

Ornamental 

Sod Farm 

(Turf)

EC, SC 0.2895 NS NS NS Broadcast - Ground Foliar

Ornamental 

(unspecified) EC 0.3303 0.3303 NS NS Broadcast - Ground Foliar

Pastures EC 0.5748 NS NS NS Broadcast - Aerial 

and Ground Foliar

Paved Areas 

(Private Roads/ 

Sidewalks)

EC 0.0631 NS 2 NS Broadcast - Ground --

Rangelands EC 0.5748 0.5748 NS NS Broadcast - Aerial 

and Ground Foliar

Recreation 

Area Lawns

EC, SC, 

Dust 0.6611 NS NS NS Broadcast - Ground Foliar
Page 8 of 47

Wheat EC 0.1289 0.1289 NS NS Broadcast - Aerial 

and Ground Postemergence

NS - Not Specified 1 DF - Water Dispersable Granules (Dry Flowable); EC - Emulsifiable Concentrate; G - Granular; SC - Soluble 

Concentrate/Liquid

Table 2. Uses Site and Application Information for Clopyralid Monoethanolamine Salt (PC 

117401)

Use Site Formulation 

Type1

Max. Rate

(lbs a.e./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single Annual

Agricultural 

Fallow / 

Idleland 

Conservation 

Reserve

EC 0.5238 0.5238 NS

NS

Broadcast -

Aerial, Ground

(foliar, spot, stump, 

tree injection, girdle 

treatment)

Fallow, 

Foliar,

Established 

plantings, When 

needed, 

Postharvest

SC 0.3827 NS 2

Apple EC 0.2493 0.2493 NS NS Broadcast -

Ground

Bearing, 

Nonbearing

Asparagus EC 0.251 0.251 NS NS

Broadcast -

Ground, Band 

treatment, Spot 

treatment

Preharvest, During 

Harvest, Postharvest

Barley

EC 0.1330 0.1330

NS NS

Broadcast -

Aerial, Ground (Band 

treatment, Spot 

treatment)

Preharvest, Foliar

SC 0.127 0.190

Beets 

(unspecified) EC 0.1898 0.1898 NS NS Broadcast -

Ground Foliar

Blueberry EC 0.1251 0.2502 2 NS

Ground (Direct 

Spray, Soil 

Broadcast, Spot 

treatment, Wipeon/Wiper treatment

Post-bloom, 

Harvest, Pre-bloom 

Brassica (Head 

and Stem) 

Vegetables

EC 0.189 0.189 NS NS Ground (Broadcast, 

Spray) Foliar

Canola/Rape EC 0.1898 NS 1 NS Broadcast -

Aerial, Ground Foliar

Chard, Swiss EC 0.189 NS 1 NS Broadcast -

Ground Foliar

Christmas Tree 

Plantation EC 0.251 0.251 NS NS

Ground (Broadcast, 

Band, Spot 

treatment)

Foliar

Cole Crops EC 0.1898 0.2506 NS NS Ground (Broadcast, 

Spray treatment) Foliar

Commercial/ 

Industrail 

Lawns

G 0.1883 NS 2 NS Broadcast - Ground Foliar

Corn, Field EC

0.1316 0.2633 2

NS

Broadcast - Ground 

Band treatment 

Direct, Spot

treatment

Foliar,

Preplant, 

Postemergence

0.2492 0.2493 2 Broadcast - Aerial

treatment

Corn, Pop EC 0.1316 0.2633 NS NS

Ground (Broadcast, 

Direct Spray 

treatment)

Postemergence

Corn, Sweet EC 0.251 0.251 2 21

Broadcast – Aerial. 

Ground (Broadcast,

Band, Direct 

treatment

Foliar, Preplant, 

Postemergence

Cottonwoods 

(Forest/ EC 0.1316 0.2633 NS NS

Broadcast - Aerial 

Ground (Broadcast,

Band, Direct 

Preplant, 

Established 

planting, Foliar
Page 

9 of 47

Shelterbelt) treatment

Crambe EC 0.2493 0.24931 NS Broadcast

-

Aerial, Ground Foliar

Cranberry EC 0.251 0.5052 NS

Ground (Broadcast, 

Spot treatment, 

Wipe-on/Wiper 

treatment

After bud break, 

Dormant, Post-

bloom, Postharvest

Eucalyptus EC 0.1898 NS NS NS

Broadcast– Aerial. 

Ground (Broadcast,

Band, Direct, Spot 

treatment)

Preplant, 

Established 

planting, Foliar

Forest 

Plantings 

(Reforestation 

Program) (Tree 

Farms, Tree 

Plantation, etc)

EC 0.189 0.378 NS NS

Broadcast– Aerial. 

Ground (Broadcast,

Spot treatment)

Preplant, Postplant

Golf Course 

Turf

SC, G 0.2519 0.25192 NS Broadcast

-

Ground

Foliar, Weed 

Postemergence

Grasses Grown 

for Seed

EC 0.5024 0.5024 NS NS Broadcast

– Aerial.

Ground (Broadcast,

Band, Spot treatment 

Established planting

SC 0.505 NS2 21

Grass Forage / 

Fodder / Hay EC 0.1883 NS NS NS Broadcast

–

Ground Fall

HOPS EC 0.251 0.251 NS NS

Broadcast–

Ground, Spot 

treatment

Foliar

Meadowfoam EC 0.1913 0.1913 NS NS Broadcast

–

Ground Foliar

Mint / 

Peppermint / 

Spearmint

EC 0.5024 NS NS NS Broadcast

–

Ground Spring, Fall

Mustard EC 0.2493 0.2493 NS NS Ground (Broadcast,

Spray treatment) Foliar

Nonagricultural Right-of-Way / 

Fencerows / 

Hedgerows

EC 0.2493 0.5024 NS NS

Broadcast– Aerial.

Ground (Broadcast, 

Cut Stem, Foliar, 

Spot, Stump, Tree 

Injection, Girdle 

treatments)

Established 

Plantings, Spring, 

Postemergence, 

Fall, When needed, 

Foliar

Nonagricultural 

Uncultivated 

Areas / Soils

EC 0.3797 0.3797 NS

NS

Broadcast– Aerial.

Ground (Broadcast, 

Cut Stem, Foliar, 

Spot, Stump, Tree 

Injection, Tree 

Wound, Frill, Girdle 

treatments)

Weed 

Postemergence, 

Foliar, When 

SC 0.189 0.1891 needed

Oats EC 0.5238 0.5238 NS NS

Broadcast– Aerial. 

Ground (Broadcast, 

Band, Spot 

treatment)

Foliar

Ornamental 

Herbaceous 

Plants EC 0.5238 0.5238 NS NS Broadcast

– Ground, 

Spray Foliar

Ornamental 

Lawns and Turf G, EC, SC 0.3827 NS NS NS Broadcast

– Ground, 

Spray, Spot treatment

Foliar, Weed 

Postemergence

Ornamental 

Sod Farm 

(Turf)

EC 0.1330 0.5682 NS NS Broadcast

– Ground, 

Spray, Spot treatment Foliar

Ornamental 

(unspecified) EC 0.505 0.505 NS NS Broadcast

– Ground, 

Spray, Spot treatment Foliar

Ornamental 

Woody Shrubs 

and Vines

EC 0.505 0.505 NS NS Broadcast

– Ground, 

Spray, Spot treatment Foliar
Page 10 of 47

Pastures

EC 0.505 0.505 NS

NS

Broadcast – Aerial.

Ground (Broadcast, 

Cut Stem, Foliar, 

Spot, Stump, Tree 

Injection, Girdle 

treatments

Established 

Plantings, Spring, 

Weed 

Postemergence, 

Fall, When needed, 

Foliar

SC 0.505 0.505 1

Poplar (Forest / 

Shelterbelt) EC 0.505 0.505 NS NS

Broadcast – Aerial. 

Ground (Broadcast, 

Band, Spot 

treatment)

Established 

Plantings, Preplant, 

Foliar

Radish EC 0.5238 0.5238 NS NS Broadcast – Ground, Foliar

Rangelands

EC 0.3827 NS NS

NS

Broadcast – Aerial.

Ground (Broadcast, 

Cut Stem, Foliar, 

Spot, Stump, Tree

Injection, Girdle 

treatments

Foliar

SC 0.2493 0.5024 2

Recreation 

Areas EC 0.189 0.189 NS NS

Broadcast – Aerial.

Ground (Broadcast, 

Cut Stem, Foliar, 

Spot, Stump, Tree 

Injection, Girdle 

treatments

Established 

Plantings, Spring, 

Postemergence, 

Fall, When needed, 

Foliar

Recreation 

Area Lawns G 0.5238 0.5238 2 NS Broadcast - Ground Foliar

Southern Pine 

(Seed Orchard) EC 0.3827 NS NS NS Broadcast – Ground, 

Spot treatment

Weed 

Postemergence

Spearmint EC 0.5238 0.5238 NS NS Broadcast - Ground Spring, Fall

Spinach EC 0.1884 NS NS NS Broadcast - Ground Foliar

Stone Fruits EC 0.189 NS NS NS Broadcast - Ground Foliar

Strawberry EC 0.3777 0.3777 NS NS Broadcast – Ground, 

Band, Spot treatment

Established 

Plantings, Spring, 

Postharvest

Sugar Beet EC 0.189 0.189 NS NS

Broadcast – Aerial.

Ground (Band, 

Broadcast treatment

Foliar

Swamps / 

Marshes / 

Wetlands / 

Stagnant 

Water2

EC 0.251 0.251 NS NS

Broadcast – Aerial.

Ground (Broadcast, 

Cut Stem, Foliar, 

Spot, Stump, Tree 

Injection, Girdle 

treatments

Established 

Plantings, Spring, 

Postemergence, 

Fall, When needed, 

Foliar

Triticale EC 0.251 0.251 NS NS

Broadcast – Aerial.

Ground (Broadcast. 

Spot treatment

Foliar

Turnip 

(Greens) EC 0.251 0.251 1 NS Broadcast

Foliar

Turnip (Root) EC 0.5238 0.5238 1 NS Broadcast Foliar

Wheat

EC 0.1330 0.1330 NS NS Broadcast – Aerial.

Ground (Broadcast. 

Band, Spot treatment

Foliar

SC 0.1898 NS 1 NS

NS - Not Specified 1 EC - Emulsifiable Concentrate; G - Granular; SC - Soluble Concentrate/Liquid 2 Use is on non-irrigation ditch banks, seasonally dry wetlands (such as flood plains, deltas, marshes, swamps, or 

bogs) and transitional areas between upland and lowland sites. Use is permitted to the waters edge, but application 

directly to water is prohibited. Precautions to minimize spray drift onto water are recommended.
Page 11 of 47

Table 3. Uses Site and Application Information for Clopyralid Triethanolamine (PC 117404)

Use Site Formulatio

n Type1

Max. Rate

(lbs a.e./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single Annual

Agricultural 

Fallow / 

Idleland 

Conservation 

Reserve

EC 0.3244 NS NS NS Broadcast - Aerial 

and Ground

Weed 

postemergence

Commercial / 

Industrial 

Lawns

G 0.1593 NS NS NS Broadcast - Ground Foliar

Golf Course 

Turf G 0.1593 NS NS NS Broadcast - Ground Foliar

Nonagricultural 

Right-of-Way / 

Fencerows / 

Hedgerows

G 0.1593 NS NS NS Broadcast - Ground Foliar

Nonagricultural 

Uncultivated 

Areas / Soils

EC 0.3244

NS NS NS

Broadcast - Aerial Weed 

postemergence

G 0.1593 Broadcast - Ground Foliar

Ornamental 

Lawns and Turf

G 0.1593

NS NS NS Broadcast - Ground

Weed 

postemergence EC 0.1622 Foliar

Pastures EC 0.3244 NS NS NS Broadcast - Aerial 

and Ground

Weed 

postemergence

Rangelands EC 0.3244 NS NS NS Broadcast - Aerial 

and Ground

Weed 

postemergence

Recreation 

Area Lawns G 0.1593 NS NS NS Broadcast - Ground Foliar

NS - Not Specified 1 EC - Emulsifiable Concentrate; G - Granular

Table 4. Uses Site and Application Information for Clopyralid Potassium (PC 117423)

Use Site Formulation 

Type1

Max. Rate

(lbs a.e./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single Annual

Corn, Field DF 0.156 0.21 NS NS

Broadcast - Ground 

Band treatment 

Burndown treatment

Soil incorporated 

treatment

Preplant 

Preemergence 

Postemergence 

Spike stage 

Weed 

postemergence

Corn, Silage DF 0.156 0.21 NS NS

Broadcast – Ground

Band treatment 

Burndown treatment

Soil incorporated 

treatment

Preplant

Preemergence 

Postemergence 

Spike stage 

Weed 

postemergence

NS - Not Specified 1 DF - Water Dispersable Granules (Dry Flowable)

4. CONCLUSIONS FROM PREVIOUS ASSESSMENTS

4.1. Ecological Risk Assessments

The Agency has conducted multiple ecological risk assessments for clopyralid that serve as a 

basis for this problem formulation, most recently a Section 3 new use assessment for apple, leafy 
Page 12 of 47

Brassica subgroup 5B, and rapeseed subgroup 20A at maximum application rates of 0.25, 0.187, 

and 0.187 lb a.i./A, respectively (USEPA, 2012b). A 2009 Section 3 new use assessment

evaluated the use of clopyralid on annual strawberries at an application rate of 0.188 lb a.i./A,

cranberries and bushberries at 0.25 lb a.i./A with 2 applications, and Swiss chard at 0.25 lb a.i./A 

(USEPA 2009a). These assessments drew upon two 2001 clopyralid Section 3 new use 

assessments for use on (1) flax, perennial strawberries, and head/stem Brassica (USEPA, 2001a),

and (2) mustard greens, cranberries, garden beets, turnips, spinach, and stone fruit (USEPA, 

2001b). The maximum application rate in these two assessments is 0.5 lb a.i./A. A 24(c)

assessment in 2009 evaluated an application rate increase to 0.088 lb a.i./A for clopyralid use on

flax in North Dakota (U.S. EPA, 2009c). This assessment included a spray drift analysis using 

terrestrial and aquatic plant toxicity data from other picolinic acid herbicides.

Maximum estimated aquatic exposure concentrations modeled in PRZM-EXAMS in a 2009 

assessment for peak, 21-day, and 60-day exposures were 8.03, 7.56, and 6.80 μg/L, respectively

(USEPA, 2009a). Maximum estimated aquatic exposure concentrations modeled in GENEEC in 

a 2001 assessment for acute and chronic exposures were 29.2 and 28.6 μg/L, respectively, from

use on stone fruit at 0.5 lb a.i./A (USEPA, 2001b). The only identified direct risk concern in 

previous assessments was for terrestrial plants. The major ecological risk conclusions from these 

assessments are summarized in Table 5.

Table 5. Summary of Risk Concerns Identified for Clopyralid in Previous Assessments

Birds Mammals Terr.

Plants

Terr.

Inverts Fish Bioaccumulation

Aquatic 

Inverts

Aquatic 

Plants

Groundwater 

Contamination Persistence Degradates of Concern

No No Yes No No1 No No1 No Yes Yes No 1 No data were available for the assessment of risk to estuarine/marine invertebrates or fish.

4.2. Drinking Water Exposure Assessments

A drinking water exposure assessment for clopyralid was conducted in 2009 for the proposed 

new uses on Swiss chard, Bushberry subgroup 13-07B and annual strawberry (USEPA, 2009d) 

and updated in 2011 for the proposed new uses on apple, leafy Brassica subgroup 5B, and 

rapeseed subgroup 20A (USEPA, 2011). Maximum estimated drinking water concentrations 

(EDWCs) in surface water were generated by the FIRST model and were based on a single 

ground application of clopyralid at 0.5 lbs a.i./A for non-food crops. The maximum EDWCs in 

surface water for acute (1-in-10-year peak) and chronic (1-in-10-year average) exposure were 45 

and 11.9 μg/L, respectively. The EDWC in groundwater was generated by the SCI-GROW 

model and was based on two ground applications of clopyralid at 0.25 lbs a.i./A with a 14 day 

interval for bushberries.2 The maximum modeled EDWC in groundwater was 0.39 μg/L. 

Maximum application rates listed in Section 3 include rates up to 0.66 lb a.i./A, higher than those 

previously modeled in drinking water exposure assessments. Therefore, a new assessment will 

be needed for registration review.

 2 EDWCs in groundwater were previously modeled with SCI-GROW for a single application at 0.5 lbs a.i./A, 

however outdated input parameters resulted in a lower estimated groundwater concentration (USEPA, 2001a).
Page 13 of 47

A search of the NAWQA database (11/25/2013) returned maximum detection levels for 

clopyralid of 0.5288 ppb in surface water in Oregon and 0.42 ppb in groundwater in Washington. 

Data provided by the Montana Department of Agriculture include maximum detection levels for 

clopyralid of 0.800 ppb in surface water and 2.8 ppb in groundwater (Mulder, 2013). The 

measured concentrations in groundwater are higher than the previously modeled concentration.

The residues of concern included in the calculations were the parent compound only because the 

aerobic soil metabolism study did not identify any major degradates, i.e., no degradates were 

formed at >10% of the applied dose. No aerobic aquatic metabolism data were available.

4.3. Clean Water Act Programs

Clopyralid is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act.3

 No Total Maximum Daily Load (TMDL) criteria 

have been developed for clopyralid.

4

 Aquatic benchmarks have been established for clopyralid 

and are available at http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm. 

Any data submitted or otherwise located as part of the registration review process may be used to 

develop aquatic life benchmarks if applicable. 

5. ENVIRONMENTAL FATE AND TRANSPORT

Clopyralid acid and three salts, clopyralid monoethanolamine, clopyralid triethanolamine, and 

clopyralid potassium, are all registered with the Agency as active ingredients. The structures are 

depicted in Table 6 below. The clopyralid salts are expected to quickly dissociate to clopyralid 

acid in the environment. 

Table 6. Registered Active Ingredients Addressed in this Problem Formulation

Common Name PC Code CAS No. Molecular 

Weight Structure

Clopyralid 117403 1702-17-6 192.00 g/mol

Clopyralid 

monoethanolamine salt

117401 57754-85-5 252.07 g/mol

 3 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 4 http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant 

_group_name=PESTICIDES
Page 14 of 47

Clopyralid 

triethanolamine

117404 119308-91-7 340.18 g/mol

Clopyralid potassium 117423 58509-83-4 230.00 g/mol

Table 7 summarizes some chemical properties and environmental fate and transport

characteristics of clopyralid acid, the persistent form in the environment. Environmental fate 

data indicate that clopyralid is miscible in water (1 x 104 ppm) is stable to hydrolysis and 

photolysis, and is very mobile in soil (Kd <0.1 in four soils). Clopyralid may be transported to 

surface water via spray drift or by runoff occurring close to the time of application. Due to 

anaerobic metabolism stability and high mobility, clopyralid is likely to persist in groundwater. 

Aerobic metabolism is expected to be the primary pathway of degradation for clopyralid in the 

environment, although no aerobic aquatic metabolism data are currently available. Clopyralid is 

non-volatile, thereby limiting transport in air. The range of field dissipation half-lives included 

the single available aerobic soil metabolism half-life.

Table 7: Chemical Properties and Environmental Fate Characteristics of Clopyralid Acid

Parameter Value Description Source

(MRID)

Selected Physical/Chemical Parameters

Molecular Mass 

(Molecular Formula) 192 C6H3Cl2NO2 calculated

Vapor pressure 

(25°C) 1.26 x 10-6 mm Hg -- 46912208

Aqueous solubility 

(20°C) Miscible -- 46912208

Henry’s Law Constant 

(20°C) 3.81 x 10-11 atm-m3

/mole -- calculated

Log octanol-to-water partition 

coefficient (log KOW) -1.81 -- Senseman, 2007

Acid dissociation constant (pKa) 2.33 -- Senseman, 2007

Persistence

Hydrolysis half-life 

(25±1°C) Stable -- 42805701

Aqueous Photolysis half-life 

(25±1°C) Stable pH 7 43891401

Soil Photolysis half life

(25±1°C) Stable Silt loam 43891402
Page 15 of 47

Parameter Value Description Source

(MRID)

Aerobic Soil Metabolism DT50

(25±1°C) 12.8 days Silt loam 43891403

Anaerobic Aquatic Metabolism 

DT50

(25±1°C) Stable -- 43891405

Mobility

Organic carbon-normalized 

Freundlich coefficients (KFOC) 4.6 ml/g o.c. (mean)

12.90 (sand), 0.40 (clay 

loam), 2.12 (silt loam), 

and 3.15 (loam)

40095701

Field Dissipation

Terrestrial Field Dissipation DT50 10.7 – 25.2 days

10.7 days (NC, sand), 25.2 

days (IL, silt loam), and

16.5 days (WI, silt loam)

Quantifiable residues 

detected to depths of 46 cm 

(NC) and 30 cm (IL, WI)

43891406

Though aerobic aquatic metabolism is the anticipated primary route of degradation, it is currently 

a data gap for this chemical. Modeling guidance assumes aerobic aquatic metabolism half-life to 

be double that of aerobic soil metabolism in the absence of data (USEPA, 2009b). Although this 

is a conservative assumption, it should be noted that the primary route of degradation for this 

chemical is not well-characterized. 

Aerobic soil metabolism data are required for three additional soils. In the absence of these 

additional data, the single value will be multiplied by three for use as a modeling input, per the 

current input parameter guidance (USEPA, 2009b).

Clopyralid has been found to persist through the composting process when contaminated yard 

clippings are collected and composted (Washington State University, 2005). The chemical 

becomes concentrated in the final compost, which then may be toxic to plants to which it is 

applied. Clopyralid’s behavior in compost is a major uncertainty. Degradation and dissipation 

processes differ in compost as compared to guideline environmental fate studies. An 

environmental chemistry method and a compost dissipation study are needed to better 

characterize this pathway. The absence of information on the persistence of clopyralid residues 

in composted plant material or animal manure prohibits a quantitative assessment of the potential 

risk to non-target taxa posed by the application of composted material containing these residues. 

5.1. Transformation Products

Table 8 summarizes the transformation products of clopyralid and their maximum amounts 

formed by degradation pathway. There are no major degradates, the only identified degradate is 

carbon dioxide.
Page 16 of 47

Table 8: Clopyralid and Major Environmental Degradates

Chemical Name Chemical 

Structure

Study 

Type

Reference

(MRID)

Maximum

Percent Recovery 

(time period)

Study length

PARENT

Clopyralid (3,6-

dichloropyridine2-carboxylic 

acid)

TRANSFORMATION PRODUCTS

Carbon Dioxide O=C=O

Aerobic Soil

Metabolism 43891403 73.6%

(78 days) 78 days

Anaerobic Aquatic 

Metabolism 43891405 2.8%

(365 days) 365 days

Photodegradation

Soil 43891402 2.9%

(30 days) 30 days

Nonextractable 

or 

Uncharacterized 

Aerobic Soil

Metabolism 43891403 20.7% 

(43 days) 78 days

Anaerobic Aquatic 

Metabolism 43891405 4.0%

(181 days) 365 days

Photodegradation

Soil 43891402 4.5%(20 days) 30 days

6. RECEPTORS

Acute (short-term) and chronic (long-term) toxicity information is characterized based on 

registrant-submitted studies and a comprehensive review of the open literature on clopyralid. 

Reported ecological incidents associated with clopyralid are also summarized below.

Table 9 and Table 10 provide summaries of the aquatic and terrestrial taxonomic groups, 

respectively, and surrogate species tested to characterize the potential acute and chronic 

ecological effects of clopyralid acid. Based on the available ecotoxicity information, clopyralid 

is practically non-toxic to aquatic and terrestrial animals on an acute exposure basis. No chronic 

toxicity data are available for aquatic organisms. Some chronic toxicity was observed in 

mammals but no chronic effects were seen in birds. Aquatic and terrestrial plant studies 

demonstrate that clopyralid is toxic to plants, which is consistent with its use as an herbicide. No 

toxic effects were seen in honey bees via oral or contact routes of exposure.

Acute toxicity studies were conducted with an end use product containing 35% clopyralid 

monoethanolamine salt on freshwater fish (MRID 40151608), freshwater invertebrates (MRID 

40151608), birds (MRIDs 40151609, 40151610, 40151611), and honey bees (MRID 40151612). 

In all cases, the toxicity endpoints (adjusted for percent active ingredient) were equal to or higher 

than the toxicity endpoints from the studies with clopyralid acid technical grade active ingredient 
Page 17 of 47

(TGAI). Therefore, using clopyralid acid toxicity data to assess risk to terrestrial and aquatic 

animals is expected to be protective for uses of clopyralid salts as well. Toxicity differences 

between the different forms of clopyralid to plants have not been investigated.

6.1. Effects to Aquatic Organisms

Table 9. Summary of Aquatic Toxicity Studies for Clopyralid Acid

Taxonomic 

Group

Study 

Type

Surrogate Species Toxicity Value

(mg/L measured 

active ingredient)

Acute 

Toxicity 

Classification 

Source

(MRID)

Freshwater 

fish1 Acute

Rainbow trout

(Oncorhynchus 

mykiss)

LC50 = 103.5 Practically 

nontoxic 00139983

Bluegill sunfish

(Lepomis 

macrochirus)

LC50 = 125.4 Practically 

nontoxic 00059969

Freshwater 

invertebrates Acute Daphnia magna EC50 = 233 Practically nontoxic 00059972

Aquatic 

plants and 

algae

Nonvascular

Green algae 

(Pseudokirchneriella 

subcapitata)

EC50 = 6.9 Moderately 

toxic 40081402

1 Freshwater fish may be used as surrogates for aquatic-phase amphibians.

6.2. Effects to Terrestrial Organisms

Table 10. Summary of Terrestrial Toxicity Studies for Clopyralid Acid

Taxonomic 

Group

Study 

Type

Surrogate 

Species

Toxicity Value

(units in measured 

active ingredient)

Acute 

Toxicity 

Classification

Source

(MRID)

Birds1

Acute

Mallard duck

(Anas 

platyrhynchus)

LD50 = 1465 mg/kg Slightly toxic 00059970

Sub-acute 

dietary

Bobwhite 

quail (Colinus 

virginianus)

LC50 >4640 ppm Practically 

nontoxic 00073640

Mallard duck LC50 >4640 ppm Practically 

nontoxic 00073641

Chronic Mallard duck NOAEC / LOAEC = 

1000 / >1000 ppm -- 00156001

Mammals

Acute Oral

Laboratory rat 

(Rattus 

norvegicus)

LD50 >5000 mg/kg-bw 

(M&F)

Practically 

nontoxic 41641301

Acute 

Inhalation Laboratory rat LC50 > 1.0 mg/L Tox category 

III 41848301

Chronic 2-

gen Laboratory rat 

NOAEL / LOAEL = 

500 / 1500 mg/kg-bw/day 

Endpoints: reduced body

weights in F0 and F1

NA 00138155
Page 18 of 47

Taxonomic 

Group

Study 

Type

Surrogate 

Species

Toxicity Value

(units in measured 

active ingredient)

Acute 

Toxicity 

Classification

Source

(MRID)

Insects

Acute 

contact

Honey bee 

(Apis mellifera 

L.)

LD50 = >100 μg/bee Practically 

nontoxic 00081595

Acute oral Honey bee LD50 = >100 μg/bee NA 00059971

Terrestrial 

plants 2

Seedling 

Emergence

Monocot –

onion

NOAEC = 0.0037 lb ae/A

EC25 = 0.038 lb ae/A 

Endpoint: % emergence

NA 40081401

Dicot –

soybean

NOAEC = 0.0037 lb ae/A

EC25 = 0.0046 lb ae/A 

Endpoint: % emergence

NA 40081401

Vegetative 

Vigor

Monocot -

onion 

NOAEC = 0.0037 lb ae/A

EC25 = >0.37 lb ae/A 

Endpoint: 28-d height

NA 40081401

Dicot – snap 

bean

NOAEC = 0.000075 lb

ae/A

EC25 = 0.00038 lb ae/A 

Endpoint: 28-d height

NA 40081401

NA: Not Applicable

1 Birds may be used as surrogates for terrestrial-phase amphibians and reptiles. 2 The terrestrial plant study was conducted with an end use product containing 75% clopyralid potassium.

The tier II seedling emergence and vegetative vigor terrestrial plant studies (MRID 40081401)

were re-reviewed in 2012 (USEPA, 2012a). As noted in these reviews, the studies contain useful 

data but are lacking crucial elements including weight measurements in the vegetative vigor 

study and both weight and height measurements in the seedling emergence study. Because of 

these deficiencies, the studies are classified as supplemental and additional data are necessary to 

adequately assess the risk of clopyralid use to non-target terrestrial plants. Also, toxicity to 

terrestrial plants may vary for clopyralid acid and the three registered clopyralid salts. Data on 

formulations with each of these active ingredients would allow for this distinction. Terrestrial 

plant data using co-formulated TEPs would additionally allow for assessment of synergistic 

effects to plants, which have been observed for other picolinic acid herbicides (USEPA, 2013).

Results from the avian reproduction study with the mallard duck (MRID 00156001) included

statistically significant effects on normal hatchlings per eggs set and per eggs laid at the lowest 

treatment concentration (100 ppm) and statistically significant effects on 14-day old survivor 

weight at the lowest and middle treatment concentrations (100 and 330 ppm). No effects were 

seen at the highest treatment concentration (1000 ppm), and therefore these statistically 

significant effects were not considered to be treatment related. This study is scientifically sound 

and classified as acceptable. A low-dose effect (hormesis) is another possible explanation for the 

study results. Reproduction data for an additional avian species may help to illuminate the 

likelihood of this possibility.
Page 19 of 47

6.3. Ecological Incidents

Three databases were searched for ecological incidents possibly associated with clopyralid: the 

Ecological Incident Information System (EIIS), the aggregate incident database, and the Avian 

Monitoring System (AIMS). The EIIS is an OPP database that houses ecological incidents that 

have been reported to the Agency (USEPA, 2007a). When available, EIIS includes date and 

location of an incident, type and magnitude of effects observed in various species, use(s) of 

pesticides known or suspected of contributing to the incident, and results of any chemical residue 

analysis or other analyses conducted during incident investigation. EIIS incidents are 

categorized according to the certainty that the incident resulted from pesticide exposure. The 

AIMS database is administered by the American Bird Conservancy and contains publicly 

available data on reported avian incidents involving pesticides. Many of the incidents listed in 

this database are also in the EIIS. The aggregate incident reports provide counts of ecological 

incidents considered “minor.” These are reported to the Agency quarterly by registrants.

6.3.1. Ecological Incident Information System

EIIS returned 303 incidents, all of which involved damage to terrestrial plants, including 218

attributed to clopyralid use (PC 117403), 18 attributed to clopyralid monoethanolamine salt (PC 

117001), 1 attributed to clopyralid triethanolamine (PC 117404), and 66 attributed to clopyralid 

potassium (PC 117423). In sum, 236 of the 303 incidents involved registered uses, 12 were 

accidental misuses, 2 were intentional misuses, 7 were misuses with unknown intent, and 46 

were of unknown uses. Certainty of attributing the incidents to clopyralid use was “highly 

probable” for 8 incidents, “probable” for 132 incidents, “possible” for 155 incidents, and 

“unlikely” for 8 incidents. Many of the incidents were attributable either to direct application of 

a clopyralid product or to spray drift. See Appendix B. EIIS Incidents for a list of all incidents 

reported in EIIS through October 31, 2013. 

Three incidents provided information specific to use of compost with clopyralid residues:

1. Incident I010414-001: Two complaints were received from the Washington State 

Department of Agriculture regarding the damaging effects of compost from a regional 

compost facility in 2000. The problem was that grass clippings being composted had 

traces of clopyralid (Confront) which were not degraded during the 60-90 day 

composting period at the plant. When this compost material was used in the potting soil 

of greenhouses, it had a detrimental effect on plants. With tomato plants, for example, 

the symptoms were cupping of leaves, slight bending or twisting of stems, fiddleneck 

appearance of new growth, and sometimes even accelerated growth. There is a warning

on the label saying that compost containing grass clippings that had been treated with 

clopyralid should not be used in the growing season of application.

2. Incident I011897-002: Clopyralid was responsible for killing tomato plants that had been 

grown in compost prepared by Washington State University, as reported in incident 

I010414-001. A report in the September, 2000, issue of BioCycle described the 

persistence of clopyralid in compost containing clippings from lawns that had been 

treated with clopyralid. A product from the Washington State U. facility contained 100-
Page 20 of 47

1300 ppb clopyralid after the passage of a year. A compost product from Spokane, WA, 

had caused injury to tomato plants, and nine months later the residue ranged from 31 to 

75 ppb. A new composting method was instituted in the fall of 2000 but in the following 

March the concentration was measured at 57 to 67 ppb clopyralid. In May, analyses 

showed 73-80 ppb clopyralid.

3. Incident I012701-001: A Columbus, OH, Compost Facility conducted a bioassay to 

investigate the toxicity of their compost to tomato seedlings in 2002. The seedlings 

showed stunted growth and splitting of terminal leaves, which was attributed to 

clopyralid and triclopyr exposure with “probable” certainty. 

The number of documented incidents in EIIS is believed to be a very small fraction of total 

mortality caused by pesticides for a variety of reasons. Incident reports for non-target organisms 

typically provide information only on mortality events and plant damage. Sub-lethal effects in 

organisms such as abnormal behavior, reduced growth and/or impaired reproduction are rarely 

reported, except for phytotoxic effects in terrestrial plants. An absence of reports does not 

necessarily equate to an absence of incidents given the nature of the incident reporting.

6.3.2. Avian Monitoring System

AIMS identified one ecological incident involving clopyralid as of August 29, 2013. The 

incident was “highly likely” attributed to pesticide exposure, which included both triclopyr and 

clopyralid. Triclopyr and clopyralid have very similar acute and sub-acute avian toxicity 

endpoints. Three birds were killed, at least two of which were trumpeter swans. Chemical 

residues were found in the carcasses and circumstances were “clearly indicative of poisoning.”

6.3.3. Aggregate Incident Database

In addition to the incidents recorded in EIIS, registrants have reported minor clopyralid incidents 

to the Agency in aggregate reports. Registrants reported 263 minor plant incidents, five minor 

wildlife incidents and one other minor incident. These numbers include reports filed under PC 

codes 117401 (16 incidents), 117403 (150 incidents), 117404 (one incident), and 117423 (102

incidents). Unless additional information on these aggregated incidents becomes available, they 

will be assumed to be representative of registered uses of clopyralid in the risk assessment.

7. EXPOSURE PATHWAYS OF CONCERN

The environmental fate properties of clopyralid indicate that direct spray, spray drift, runoff, and 

leaching represent potential transport mechanisms of this chemical to aquatic and terrestrial 

organisms. Drinking water and inhalation exposure pathways were screened using the SIP 

(Screening Imbibition Program) and STIR (Screening Tool for Inhalation Risk) screening 

methods (see Appendix A. SIP and STIR Results for details). Potential exposure pathways of 

concern were found for clopyralid for drinking water but not for inhalation. SIP and STIR are 

described in detail at: http://www.epa.gov/oppefed1/models/terrestrial/index.htm.
Page 21 of 47

Because clopyralid can leach into groundwater, there is a potential for adverse effects on 

terrestrial plants when irrigated with a groundwater-derived source, particularly in areas where 

the soil is permeable and/or groundwater is shallow.

Clopyralid has been found to survive the composting process when yard clippings are collected 

and composted. The chemical becomes concentrated in the final compost, which then may be 

toxic to plants to which it is applied. 

8. ANALYSIS PLAN

8.1. Stressors of Concern

8.1.1. Ecological Risk Assessment

The stressor of ecological concern is the parent compound only. As described in Section 5.1, no 

major degradates are identified and among minor degradates only carbon dioxide (CO2) is 

identified. 

8.1.2. Drinking Water Assessment

Previous drinking water assessments are based on tier 1 models (FIRST and SCI-GROW) and no 

longer reflect the maximum application rates for clopyralid. The drinking water assessments will 

be re-evaluated with tier 2 models (PE5 and PRZM-GW) using the maximum application rates 

listed in Section 3 to better reflect the potential exposure. Available monitoring data will also be 

considered. The stressor of concern for drinking water is the parent compound only.

8.2. Measures of Exposure 

EFED will use standard available models to evaluate potential exposures to aquatic and 

terrestrial organisms as described at http://www.epa.gov/pesticides/science/models_db.htm. 

Available monitoring data will also be considered.

Screening level calculations have suggested that the drinking water exposure pathway may be 

significant for clopyralid for acute and chronic risk to terrestrial wildlife. This pathway may be 

further considered at the time of the risk assessment. 

Estimated concentrations of mobile and persistent herbicides, such as clopyralid, in irrigation 

water may be calculated to determine potential risk to irrigated crops. As detailed above, the 

persistence, mobility, and solubility of clopyralid indicate the potential for the chemical to reach 

ground and surface water. 

Clopyralid has been found to survive the composting process when yard clippings are collected 

and composted. The chemical becomes concentrated in the final compost, which then may be 

toxic to plants to which it is applied. Therefore, the exposure by this route will be addressed in 

the risk assessment.
Page 22 of 47

Applications to individual trees can result in absorption and translocation of clopyralid from the 

site of application throughout the tree. Birds, mammals, and terrestrial invertebrates may be 

exposed through ingestion of leaves, seeds, pollen, or other edible portions of the tree. Leaves 

containing clopyralid may fall onto the ground or into water resulting in movement of clopyralid 

to soil and water. Finally, trees treated with clopyralid may be used as compost. There is no 

currently approved model for estimating potential exposure to organisms from tree injection, cutstump treatment, hack and squirt method, and frill and girdle methods. A screening-level 

estimate of exposure will be completed for this assessment. 

8.3. Measures of Effect 

Toxicity data presented in Section 6 of this problem formulation will be used to calculate risk 

quotients. Any additional information submitted by the registrant or found in the open literature 

prior to conduct of the risk assessment will also be considered. The open literature studies are 

identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007b), which employs 

a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, 

and wildlife. The evaluation of both sources of data can also provide insight into the direct and 

indirect effects of pesticides on biotic communities from loss of species that are sensitive to the 

chemicals and from changes in structure and functional characteristics of the affected 

communities.

8.4. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to federally threatened and/or endangered (listed) species from 

registered uses of pesticides in registration review. The process for evaluating potential risks to 

listed species is further described at 

http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm.

8.5. Endocrine Disruptor Screening Program

Clopyralid was included in neither the first group of 67 chemicals issued an order to conduct Tier 

1 EDSP testing nor the second list of 109 chemicals. For additional information the EDSP 

program, visit http://www.epa.gov/endo/. 

9. PRELIMINARY IDENTIFICATION OF DATA GAPS

9.1. Environmental Fate

Table 11 identifies environmental fate studies by MRID that offer data for each guideline

requirement, as well as study classifications and whether or not further data are needed in order 

to support risk assessment. 
Page 23 of 47

Table 11. Submitted Environmental Fate Data for Clopyralid

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classification

Are additional 

data needed to 

conduct risk 

assessment?

Justification

835.2120 Hydrolysis 42805701 Acceptable No NA

835.2240 Aqueous 

Photolysis

43891401 Acceptable No NA

835.2410 Soil Photolysis 43891402 Acceptable No NA

835.4100 Aerobic Soil 

Metabolism

43891403 Supplemental Yes Only one soil tested; need a study of 

three additional soils.

835.4300

Aerobic 

Aquatic 

Metabolism

None NA Yes No data are available. Data are critical 

for aquatic assessments. A study of 

two water-sediment systems is needed.

835.4400

Anaerobic 

Aquatic 

Metabolism

43891405 Acceptable No NA

835.1230/

835.1240

Adsorption/ 

Desorption and 

Leaching

40095701 Acceptable No NA

835.6100 Terrestrial 

Field Dissipation

43891406 Acceptable No NA

NonguidelineDissipation in 

Compost

None NA Yes See justification below table.

850.6100

Analytical 

Method in 

Water

None NA Yes No analytical methods have been 

submitted for clopyralid. Methods and 

independent laboratory validations 

(ILV) for soil, water, and compost are 

needed. LOQs should be less than 

toxicological levels of concern.

Methods are requested that can be used 

with equipment found in state labs and 

that use standards that can be readily 

obtained.

Analytical 

Method in Soil

None NA Yes

Analytical 

Method in 

Compost

None NA Yes

Non-guideline Study: Dissipation in Compost. A study is requested to demonstrate the rates of 

degradation and leaching in vegetative and manure composts. The study will be used to 

characterize the risk from clopyralid residues in compost and may demonstrate potential 

mitigations such as compost holding times. The absence of information on the persistence of 

clopyralid residues in composted plant material or animal manure prohibits a quantitative 

assessment of the potential risk to non-target taxa posed by the application of composted material 

containing these residues. A protocol is requested for review before the study is conducted.

Through the SFIREG Pesticides Operations & Management committee on September 16, 2013, 

it was made known that Dow AgroSciences is developing a molecular imprinted polymer for 

solid phase extraction that could be used for detecting clopyralid in compost. It was expected 

that an analytical method could be released to state laboratories by April 2014.
Page 24 of 47

Guideline Number: N/A

Study Titles: Dissipation study in compost

Rationale for Requiring the Data

The application of clopyralid to vegetative matter that is subsequently used as compost or animal feed 

has been found to retain clopyralid residues and affect non-target plants. This route of exposure is 

common across the picolinic acid herbicides (aminopyralid, clopyralid, and picloram). A study is 

requested to demonstrate the rates of degradation and leaching in vegetative and manure composts. 

Practical Utility of the Data

How will the data be used? Through the SFIREG Pesticides Operations & Management committee 

on September 16, 2013, it was made known that Dow AgroSciences is developing a molecular 

imprinted polymer for solid phase extraction that could be used for detecting a picolinic acid in 

compost. It was expected that a method could be released to state laboratories by April 2014. A 

compost dissipation study would be instrumental in interpreting the monitoring data that will become 

available after this method is disseminated. 

How could the data impact the Agency’s future decision-making? The study will be used to 

characterize the risk from clopyralid residues in compost and may demonstrate potential mitigation

measures, such as compost holding times. 

9.2. Effects

Table 12 and Table 13 identify ecological effects studies by MRID that offer data for each

guideline requirement, as well as study classifications and whether or not further data are needed 

in order to support risk assessment. 

Table 12. Submitted Aquatic Ecological Effects Data for Clopyralid

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are additional

data needed to 

conduct risk 

assessment?

Justification 

850.1010 Freshwater 

invertebrate 

acute toxicity

00059972 Acceptable No NA

850.1025

850.1035

Saltwater 

invertebrate 

acute toxicity 

None NA No Freshwater invertebrate acute 

toxicity data indicate that 

clopyralid is practically non-toxic 

to aquatic invertebrates. The LC50

is 5 orders of magnitude higher 

than the highest EEC in previous 

assessments. Acute toxicity data 

for other picolinic acid herbicides 

shows endpoints for freshwater 

and saltwater invertebrates within 

one order of magnitude.

850.1075 Freshwater fish 

acute toxicity 

00139983 Acceptable No NA

00059969 Acceptable No NA
Page 25 of 47

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are additional

data needed to 

conduct risk 

assessment?

Justification 

850.1075 Saltwater fish 

acute toxicity 

None NA No Freshwater fish acute toxicity 

data indicate that clopyralid is 

practically non-toxic to aquatic 

invertebrates. The LC50 is 5 

orders of magnitude higher than 

the highest EEC in previous 

assessments. Acute toxicity data 

for other picolinic acid herbicides 

shows endpoints for freshwater 

and saltwater fish within one 

order of magnitude.

850.1300 Freshwater 

invertebrate 

life cycle 

None NA Yes No data are available with which 

to assess chronic risk to 

freshwater invertebrates. Due to 

clopyralid’s expected persistence 

in aquatic systems, these data are 

needed to determine if there is a 

risk concern.

850.1350 Saltwater 

invertebrates 

life cycle 

None NA No If chronic aquatic toxicity is 

determined to be a risk concern, 

freshwater species data will be 

used as a surrogate.

850.1400 Freshwater fish 

early-life stage

None NA Yes No data are available with which 

to assess chronic risk to 

freshwater fish. Due to 

clopyralid’s expected persistence 

in aquatic systems, these data are 

needed to determine if there is a 

risk concern.

850.1400 Saltwater fish 

early-life stage 

None NA No If chronic aquatic toxicity is 

determined to be a risk concern, 

freshwater species data will be 

used as a surrogate.

850.4400 Aquatic plant 

growth: Tier II 

vascular plants

None NA Yes No data are available with which 

to assess risk to vascular aquatic 

plants.

850.4500

(previously 

850.5400)

Aquatic Plant 

Growth: Tier II 

algae

40081402 Acceptable Yes Toxicity data on two additional 

species are needed. A, freshwater

diatom and marine diatom are 

recommended.

850.4550 Aquatic Plant 

Growth: 

Cyanobacteria

None NA Yes Toxicity data on blue green algae 

are needed as part of the aquatic 

plant growth toxicity data set.

NA: Not Applicable
Page 26 of 47

Table 13. Submitted Terrestrial Ecological Effects Data for Clopyralid

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment?

Justification and Assumptions 

EPA will Make in Absence of 

Data

850.2100 Avian oral 

toxicity

00059970 Acceptable Yes Acute oral toxicity data are needed 

for a passerine species. Clopyralid 

may be more acutely toxic to 

passerines than to the previously 

tested species. An LD50 only 10% 

lower than the mallard duck LD50

would result in a risk concern for 

listed species.

850.2200 Avian dietary 

toxicity 

00073640 Acceptable No NA

00073641 Acceptable

850.2300 Avian 

reproduction

00156001 Acceptable Yes Avian reproduction data are 

needed for an upland game species 

(e.g., bobwhite quail). Chronic 

exposure to clopyralid is a concern 

due to its persistence. Additional 

chronic toxicity data will help to 

minimize uncertainty in the results 

of the mallard duck study.

850.3020 Honey bee 

acute contact 

toxicity

00081595 Acceptable No NA

NonguidelineHoney bee 

acute oral 

toxicity

00059971 Supplemental No NA

850.3030 Honey bee 

residue on 

foliage

None NA No NA

850.3040 Field testing 

for pollinators

None NA No NA

850.4100 Terrestrial 

plant toxicity:

Seedling 

emergence

40081401 Supplemental Yes Guideline compliant Tier II 

seedling emergence data are 

needed for assessment of risk to 

non-target terrestrial plants. Data 

are requested for four typical end 

use products, one each containing 

clopyralid, clopyralid 

monoethanoloamine salt, 

clopyralid triethanolamine, and 

clopyralid potassium.
Page 27 of 47

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment?

Justification and Assumptions 

EPA will Make in Absence of 

Data

850.4150 Terrestrial 

plant toxicity:

Vegetative 

vigor

40081401 Supplemental Yes Guideline compliant Tier II 

vegetative vigor data are needed 

for assessment of risk to nontarget terrestrial plants. Data are 

requested for four typical end use 

products, one each containing 

clopyralid, clopyralid 

monoethanoloamine salt, 

clopyralid triethanolamine, and 

clopyralid potassium.

Additionally, data for 

representative TEPs co-formulated 

with other herbicides are 

requested for the purpose of 

evaluating synergism. Studies 

should provide justification for the 

selection of the TEP used. TEP 

studies can be limited to the most 

sensitive crops from prior 

clopyralid studies including onion, 

snap bean, soybean, sunflower, 

tomato, and wheat.
Page 28 of 47

10. REFERENCES

Mulder, R. Personal communication. Montana Department of Agriculture. Dec. 30, 2013.

Senseman, S. S., ed. 2007. Herbicide Handbook. 9th ed. Lawrence, KS: Weed Science Society of 

America.

U.S. EPA. 2013. Problem Formulation for the Environmental Fate and Ecological Risk, 

Endangered Species, and Drinking Water Assessments in Support of the Registration Review 

of Picloram. PC Code: 005101, 005102, 005104; DP Barcode: 416059. Dated December 3,

2013.

U.S. EPA. 2012a. Addendum to DERs for Seedling Emergence and Vegetative Vigor Studies 

with Clopyralid. PC Code: 117403; DP Barcode: 398834. Dated February 21, 2012.

U.S. EPA. 2012b. Ecological Risk Assessment for the Proposed Section 3 New Uses of 

Clopyralid on Apple, Leafy Brassica Subgroup 5B, and Rapeseed Subgroup 20A. PC Code: 

117403; DP Barcode: 394199, 391398. Dated March 26, 2012.

U.S. EPA. 2011. Tier I Drinking Water Assessment for Proposed New Use of Clopyralid on 

Apple, Leafy Brassica Greens Subgroup 5B, and Rapeseed Subgroup 20A, except Camelina 

(Gold of Pleasure). PC Code: 117403; DP Barcode: 391398. Dated December 19, 2011.

U.S. EPA. 2009a. Ecological Risk Assessment Addressing the Proposed Registration of 

Clopyralid for IR-4 New Uses on strawberries, Swiss chard, annual strawberry, blueberry, 

bushberry subgroup 13-07B. PC Code: 117403; DP Barcode: 364286, 361314. Dated 

October 30, 2009.

USEPA. 2009b. Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport of Pesticides. Version 2.1. U.S. Environmental Protection Agency, Office 

of Pesticide Programs, Environmental Fate and Effects Division, Oct. 22, 2009. Available

at: http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

U.S. EPA. 2009c. Review of North Dakota 24(c) Application Rate Increase for Clopyralid on 

Flax. PC Code: 117403; DP Barcode: 369950. Dated November 17, 2009.

U.S. EPA. 2009d. Tier I Drinking Water Assessment for Proposed New Use of Clopyralid on 

Swiss Chard, Bushberry Subgroup 13-07B and Annual Strawberry. PC Code: 117403; DP 

Barcode 361314. Dated September 9, 2009.

U.S. EPA. 2007a. Ecological Incident Information System. 

http://www.epa.gov/espp/consultation/ecorisk-overview.pdf

U.S. EPA. 2007b. ECOTOXicology Database. Office of Research and Development National 

Health and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent 

Ecology Division (MED). http://cfpub.epa.gov/ecotox/
Page 29 of 47

U.S. EPA. 2001a. IR-4 Request for the Use of Clopyralid in Flax, Perennial Strawberries, and 

Head/Stem Brassica. PC Code: 117403; DP Barcodes: 270512, 271509, 270505. Dated May 

3, 2001.

U.S. EPA. 2001b. IR-4 Registrations of Clopyralid in Mustard Greens, Cranberries, Garden 

Beets, Turnips, Spinach, and Stone fruit. PC Code: 117401/117403; DP Barcode: 278288, 

278292, 278295, 278297, 278301, 278307. Dated December 13, 2001.

Washington State University. 2005. Clopyralid in Compost. Accessed October 18, 2013. 

Available at: http://puyallup.wsu.edu/soilmgmt/Pubs/Paper_ClopyralidQandAv10.pdf

MRID Citation

Environmental Fate Studies

40095701 Woodbrun, K.B. and B.W. French. 1987. A Soil Sorption/Desoption Study of Clopyralid. Ag. 

Chemistry R and D Laboratories, Dow Chemical U.S.A., Midland, MI. 

42805701 Woodburn, K.B. 1987. Clopyralid - The Hydrolysis of Clopyralid in Sterile, Buffered Water. 

Laboratory Study ID: LEH060893. Study performed and submitted by Dow Chemical U.S.A., 

Midland, MI. 

43891401 Concha, M. and K. Shepler. 1994. Photodegradation of [14C]clopyralid in buffered aqueous 

solution at pH 7 by natural sunlight. Laboratory Project ID: 451W.

43891402 Concha, M., K. Shepler, and F. Batzer. 1994. Photodegradation of [14C]clopyralid in/on soil by 

natural sunlight. Laboratory Project ID: 454W. Unpublished study performed by PTRL West, 

Inc., Richmond, CA; and submitted by DowElanco, Indianapolis, IN.

43891403 Skinner, W., N. Jao, and J. Smith. 1995. Aerobic soil metabolism of [14C]clopyralid. Laboratory 

Study ID: PTRL Report No. 441W-1. DowElanco Protocol ENV 93125. 

43891404 Smith. J.K, S. Erhardt-Zabik, and K.D. Schnelle. 1985. Effects of temperature, moisture and soil 

on the soil metabolism and partitioning of [14C]clopyralid. Laboratory Study ID: ENV 93118.

Dow Chemical U.S.A., Midland, MI. 

43891405 Hawes, K. F. and S. Erhardt-Zabik. 1995. The anaerobic aquatic metabolism of clopyralid. 

Laboratory Study ID: ENV93076. Unpublished study performed and submitted by DowElanco, 

Indianapolis, IN.

43891406 Roberts, D. W., A. M. Phillips, B. A. Blakeslee, and M. E. Swanson. 1995. Terrestrial dissipation 

of clopyralid. Laboratory Study ID: ENV94020. 

46912208 Baker, S. (2006) Product Chemistry Data for Colt + Sword. Project Number: 06/6124/5323. 

Unpublished study prepared by Loveland Products, Inc. 15 p.

Ecological Effects Studies

00059969 Batchelder, T.L. (1974) Pollutional Evaluation of Dowco 290 (Picolinic acid: 3,6-Dichloro). 

(Unpublished study received Nov 12, 1980 under 464-563; submitted by Dow Chemical U.S.A., 

Midland, Mich.; CDL:099724-B)

00059970 Fink, R.; Beavers, J.B.; Brown, R.; et al. (1980) Final Report: Acute Oral LD50--Mallard Duck: 

Project No. 103-200. (Unpublished study received Nov 12, 1980 under 464-563; prepared by 

Wildlife International, Ltd. in cooperation with Washington College, submitted by Dow Chemical 

U.S.A., Midland, Mich.; CDL: 099724-E)

00059971 Cole, J.H. (1974) The Acute Contact and Oral Toxicity to Worker Honey Bees of Technical 

Dowco 290: DWC246/74726. (Unpublished study received Nov 12, 1980 under 464-563; 

prepared by Huntingdon Research Centre, England, submitted by Dow Chemical U.S.A., Midland, 

Mich.; CDL:099724-F)

00059972 Batchelder, T.L. (1980) Toxicity of Dowco 290, a Herbicide, to Freshwater Invertebrate 

Organisms: ES-392. (Unpublished study received Nov 12, 1980 under 464-563; submitted by Dow 

Chemical U.S.A., Midland, Mich.; CDL:099724-G)
Page 30 of 47

MRID Citation

00073640 Fink, R. (1973) Final Report: Eight-Day Dietary LC50--Bobwhite Quail: Dowco 290: Project No. 

103-103. (Unpublished study received Nov 12, 1980 under 464-563; prepared by Truslow Farms, 

Inc., submitted by Dow Chemical U.S.A., Midland, Mich.; CDL:099724-C)

00073641 Fink, R. (1973) Final Report: Eight-Day Dietary LC50--Mallard Ducks: Dowco 290: Project No. 

103-104. (Unpublished study received Nov 12, 1980 under 464-563; prepared by Truslow Farms, 

Inc., submitted by Dow Chemical U.S.A., Midland, Mich.; CDL:099724-D)

00081595 Cole, J.H. (1974) The Acute Contact and Oral Toxicity to Worker Honey Bees of Technical 

Dowco 290: DWC246/74726. (Unpublished study received Jul 30, 1979 under 464-EX-55; 

prepared by Hunt- ingdon Research Centre, England, submitted by Dow Chemical U.S.A., 

Midland, Mich.; CDL:098875-I)

00138155 Dietz, F.; Mensik, D.; Rachunek, B.; et al. (1983) Dowco 290: Two Generation Dietary 

Reproduction Study in Fischer-344 Rats. (Un- published study received Jan 11, 1984 under 464-

563; submitted by Dow Chemical U.S.A., Midland, MI; CDL:072287-A)

00139983 Batchelder, T. (1974) Pollutional Evaluation of Dowco 290 (Picolinic Acid: 3,6-Dichloro). 

(Unpublished study received Dec 21, 1978 under 464-EX-55; submitted by Dow Chemical 

U.S.A., Midland, MI; CDL:236656-G)

00156001 Beavers, J. (1985) Lontrel Herbicide: A One-generation Reproduction Study with the Mallard 

(Anas platyrhynchos): Final Report: Project No. 103-235. Unpublished study prepared by Wildlife 

Inter- national Ltd. 99 p.

40081401 Weseloh, J. (1987) A Summary of Three Greenhouse Trials To Deter- mine the Effects of 

Clopyralid, 3,6-Dichloro-2-pyridinecarboxylic Acid, on Seed Germination, Seedling Emergence, 

and Vegeta- tive Vigor of Six Dicotyledonae and Four Monocotyledonae Crop Cultivars. 

Unpublished study prepared by Dow Chemical U.S.A. 158 p.

40081402 Dill, D.; Milazzo, D. (1985) Evaluation of the Toxicity of Lontrel T Herbicide to the Green Alga, 

Selenastrum capricornutum Printz: ES-746. Unpublished study prepared by Dow Chemical U.S.A. 

16 p.

40151608 Dill, D.; Milazzo, D.; Bartlett, E. (1986) Evaluation of the Toxicity of Lontrel 35A Herbicide 

Concentrate to Representative Aquatic Organisms: ES-895. Unpublished study prepared by Dow 

Chemical Co. 16 p.

40151609 Hinken, C.; Grimes, J.; Jaber, M. (1986) Lontrel 35A Herbicide Concentrate: An Acute Oral 

Toxicity Study with the Mallard: Project No.: 103-252. Unpublished study prepared by Wildlife 

International Ltd. 18 p.

40151610 Grimes, J.; Jaber, M. (1986) Lontrel 35A Herbicide Concentrate: A Dietary LC50 Study with the 

Mallard: Project No.: 103-261. Un- published study prepared by Wildlife International Ltd. 17 p.

40151611 Hinken, C.; Grimes, J.; Jaber, M. (1986) Lontrel 35A Herbicide Concentrate: A Dietary LC50 

Study with the Bobwhite: Project No.: 103-260. Unpublished study prepared by Wildlife 

International Ltd. 17 p.

40151612 Hinken, C.; Dingledine, J.; Jaber, M. (1986) Lontrel 35A Herbicide Concentrate: An Acute 

Contact Toxicity Study with the Honey Bee: Project No.: 103-256. Unpublished study prepared by 

Wildlife International Ltd. 15 p.

41641301 Jeffrey, M.; Schuetz, D.; Johnson, K. (1987) Lontrel T Herbicidal Chemical (Penta Process): 

Acute Oral Toxicity Study in Fischer 344 Rats: Lab Project Number: K-038252-033A. 

Unpublished study prepared by The Dow Chemical Co. 15 p.

41848301 Nitscke, K.; Crissman, J. (1991) Lontrel T: Acute Inhalation Toxicity Study with Fischer 344 

Rats: Lab Project Number: K-0038252- 045. Unpublished study prepared by DowElanco. 33 p.
Page 31 of 47

Appendix A. SIP and STIR Results

SIP

The Screening Imbibition Program (SIP version 1.0; 6/15/2010) was used to calculate an upper 

bound estimate of exposure via drinking water using the solubility of clopyralid (143,000 mg/L, 

pesticide properties database). The most sensitive acute and chronic avian toxicity endpoints 

(mallard duck LD50 = 1465 mg/kg-bw and NOAEC = 1000 mg/kg-diet, respectively) and the 

most sensitive acute and chronic mammalian toxicity endpoints (rat, LD50 >5000 mg/kg-bw and 

NOAEL = 500 mg/kg-bw/day, respectively) for clopyralid were used. The non-definitive acute 

oral endpoint results in a conservative estimate of toxicity here. Drinking water exposure to 

clopyralid was determined to be a pathway of concern for both avian and mammalian species 

(LOC exceedances are expected). Results are presented in the tables below. 

SIP Avian Results for Clopyralid

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 115830 115830

Adjusted toxicity value (mg/kg-bw) 761 49.6

Ratio of exposure to toxicity 152 2335

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds

Exposure through drinking 

water alone is a potential 

concern for birds

SIP Mammalian Results for Clopyralid

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 24596 24596

Adjusted toxicity value (mg/kg-bw) 3846 385

Ratio of exposure to acute toxicity 6.40 64.0

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals

Exposure through drinking 

water alone is a potential 

concern for mammals

*Conclusions are for drinking water exposure alone. This does not combine all routes of exposure. Therefore, when 

aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through drinking water may 

contribute to a total exposure that has potential for effects to non-target animals.

STIR

The Screening Tool for Inhalation Risk (STIR version 1.0; 11/23/2010) was used to calculate 

upper bound estimates of clopyralid exposures via inhalation. The exposure pathways assessed 

include both droplet inhalation and vapor phase inhalation. Model inputs for clopyralid included 

molecular weight (192 g/mole), vapor pressure (1.26x10-6 mmHg), highest application rate (0.5 

lb a.i./A), most sensitive acute avian toxicity endpoint (mallard duck, LD50 = 1465 mg/kg-bw), 

and most sensitive acute oral and inhalation mammalian toxicity endpoints (rat, LD50 >5000 

mg/kg-bw and 4 hr inhalation LC50 >1 mg/L, respectively). The non-definitive acute oral and

inhalation endpoints result in conservative estimates of toxicity here. Neither droplet nor vapor 

inhalation were determined to be potential pathways of concern for avian or mammalian species.

STIR Avian (0.020 kg) Results for Clopyralid

Maximum Vapor Concentration in Air at Saturation (mg/m3) 1.30E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 1.64E-03
Page 32 of 47

Adjusted Inhalation LD50 1.18E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.39E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 4.80E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 4.08E-02 Exposure not Likely Significant

STIR Mammalian (0.15 kg) Results for Clopyralid

Maximum Vapor Concentration in Air at Saturation (mg/m3) 1.30E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.06E-03

Adjusted Inhalation LD50 5.95E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 3.46E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 6.04E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 1.01E-03 Exposure not Likely Significant
Page 33 of 47

Appendix B. EIIS Incidents

Table B-1. Incidents in the EIIS for PC 117401: Clopyralid monoethanolamine salt as of 10/31/13

Type Incident ID Use Site Date Legality1 Certainty2 State County Total Magnitude Appl. Rate Appl. Method Formulation3 Product

PLANTS I006199-001 Sugar beet RU 3 ND Unknown N/R Stinger

PLANTS I006199-002 Peppermint RU 3 OR Unknown N/R Stinger

PLANTS I006445-003 Corn RU 3 IA Unknown N/R N/R F Hornet

PLANTS I007739-001 Soybean 5/15/98 MA 3 MN Lyon 120 acres 5.66 oz/acre Broadcast, ground N/R Stinger

PLANTS I012726-001 Corn 5/15/01 RU 3 MN Carver 103.5 acres 3 oz/acre Broadcast, ground Hornet

PLANTS I012726-002 Corn, field 5/2/01 RU 3 IL Cass 141 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I012726-003 Corn, field 4/18/01 RU 3 IL Christian 60 acres of 120 3 oz/acre Broadcast, ground G Hornet

PLANTS I015748-016 Corn, field 5/29/04 RU 2 OH Defiance 132 acres 1 qt/acre Broadcast, ground EC Curtail

PLANTS I015748-017 Wheat 6/6/04 RU 3 MT Richland 36 acres Spray EC Stinger

PLANTS I015748-033 Corn, field 5/3/04 RU 2 IA Linn 520 acres affected 3.3 qts/acre N/R G Hornet

PLANTS I015748-040 Corn, field 6/1/04 RU 3 MO Carroll 62 acres 3 oz/acre dry N/R G Hornet

PLANTS I015748-048 Corn, field 5/5/04 RU 3 IN Marshall 406 acres 3.3 qts/acre G Hornet

PLANTS I015748-049 Corn, field 5/5/04 RU 3 IN Pulaski 146 acres 3.3 qts/acre Spray G Hornet

PLANTS I015748-051 Corn, field 5/16/04 RU 3 IN Porter 70 acres affected 2.65 qts/acre G Hornet

PLANTS I016312-001 Forest 4/1/05 UN 2 OR Benton 300 acres 8 oz/acre Spray, air EC Transline

PLANTS I016927-001 Corn, field 8/24/05 RU 1 MN Clay 179 acres field corn 15 oz/acre Spray, ground EC WideMatch

PLANTS I023574-025 Corn 6/8/10 UN 2 NE Chase 260 acre

1 pt/acre 

(product) Broadcast, ground WideMatch

PLANTS I023574-052

Agricultural 

area 5/25/10 UN 2 IN Putnam 100% of 28 acres 2 pt Broadcast, ground EC

Sure Start 

Herb

Abbreviations: Appl.=Application; N/R=Not Recorded

1 Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), UN=Unknown 2 Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. N/R=Not Reported 3 Formulation Code: DF=Dry Flowable; EC=Emulsifiable Concentrate; F=Flowable; G=Granular; WDG=Water Dispersable Granule; WP=Wettable Powder
Page 34 of 47

Table B-2. Incidents in the EIIS for PC 117403: Clopyralid as of 10/31/13

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I003104-001

Agricultural 

area 1/1/96 RU 4 ID All N/R N/R N/R Curtail

PLANTS I003138-001 Switch grass RU 3 MN Unknown Curtail

PLANTS I003151-001 Corn 1/1/96 RU 3 MN All N/R N/R N/R Scorpion III

PLANTS I004816-001 Soybean 1/1/97 RU 3 IA All N/R N/R N/R Stinger

PLANTS I004848-001

Agricultural 

area 1/1/96 RU 3 IL All N/R N/R N/R Scorpion III

PLANTS I006214-001 Corn 11/3/97 RU 3 MN Unknown N/R N/R N/R Scorpion

PLANTS I006214-002 Corn 11/3/97 RU 3 IA Unknown N/R N/R N/R Scorpion

PLANTS I006214-003 Corn 11/3/97 RU 3 IA Unknown N/R N/R N/R Scorpion

PLANTS I006214-004 Soybean 11/3/97 RU 3 IL Unknown N/R N/R N/R Scorpion

PLANTS I006214-005 Corn 11/3/97 RU 3 IA Unknown N/R N/R N/R Scorpion

PLANTS I006214-006 Corn 11/3/97 RU 3 IA Unknown N/R N/R N/R Scorpion

PLANTS I006214-007 Corn 11/3/97 RU 3 IL Unknown N/R N/R N/R Scorpion

PLANTS I006214-008 Corn 11/3/97 RU 3 IA Unknown N/R N/R N/R Scorpion

PLANTS I006214-009 Corn 11/3/97 RU 3 MN Unknown N/R N/R N/R Scorpion

PLANTS I006214-010 Corn 11/3/97 RU 3 MN Unknown N/R N/R N/R Scorpion

PLANTS I006214-011 Corn 11/3/97 RU 3 MN Unknown N/R N/R N/R Scorpion

PLANTS I006214-012 Soybean 11/3/97 RU 3 IL Unknown N/R N/R N/R Scorpion

PLANTS I006442-001 Corn 1/1/98 RU 3 WI All N/R N/R N/R Scorpion III

PLANTS I006442-002 Corn 1/1/98 RU 3 NE All N/R N/R N/R Scorpion III

PLANTS I006442-003 Corn 1/1/98 RU 3 IL All N/R N/R N/R Scorpion III

PLANTS I006445-001 Corn RU 3 NE Unknown N/R N/R F Hornet

PLANTS I006445-002 Corn RU 3 IL Unknown N/R N/R F Hornet

PLANTS I006445-004 Corn RU 3 IA Unknown N/R N/R F Hornet

PLANTS I006445-005 Corn RU 3 WI Unknown N/R N/R F Hornet
Page 35 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I006848-001

Agricultural 

area 1/1/98 RU 3 MI All N/R N/R N/R Hornet

PLANTS I006848-002

Agricultural 

area 1/1/98 RU 3 IA All N/R N/R N/R Hornet

PLANTS I006848-003

Agricultural 

area 1/1/98 RU 3 IA All N/R N/R N/R Hornet

PLANTS I007251-001

Agricultural 

area 1/1/98 RU 3 WI All N/R N/R N/R Scorpion III

PLANTS I007259-001 Corn 1/1/98 RU 2 WI Unknown Unknown N/R Hornet

PLANTS I007259-002 Corn 1/1/98 RU 2 WI Unknown N/R Unknown N/R Hornet

PLANTS I007259-003 Corn 1/1/98 RU 2 WI Unknown Unknown N/R Hornet

PLANTS I007259-004 Corn 1/1/98 RU 2 WI Unknown Unknown N/R Hornet

PLANTS I007702-001 Corn 8/9/98 UN 2 IN Henry

100 of 100 

acres 3.2 oz/acre Broadcast, ground Hornet

PLANTS I007702-002 Corn 8/9/98 UN 2 IN Delaware

All 100 

acres 2.40 oz/acre Broadcast, ground Hornet

PLANTS I007702-003 Corn 8/9/98 UN 2 IN Madison

All 40 

acres 4.0 oz/acre Broadcast, ground Hornet

PLANTS I007702-004 Corn 8/9/98 UN 2 IN Tipton

50 of 100

acres 2.80 oz/acre Broadcast, ground Hornet

PLANTS I007702-005 Corn 8/9/98 UN 2 IN Hamilton

30 of 60

acres 3.2 oz/acre Broadcast, ground Hornet

PLANTS I007702-006 Corn 8/5/98 UN 2 IL Iroquois

All 25 

acres 3.0 oz/acre Broadcast, ground Hornet

PLANTS I007702-007 Corn 8/4/98 UN 2 IL Ford

All 10 

acres 4.0 oz/acre Broadcast, ground Hornet

PLANTS I007702-008 Corn 8/4/98 UN 2 IL Ford

All 10 

acres 4.0 oz/acre Broadcast, ground Hornet

PLANTS I007702-009 Corn 8/10/98 UN 2 IN Madison

All 60 

acres 3.2 oz/acre Broadcast, ground Hornet

PLANTS I007702-010 Corn 8/18/98 UN 2 NE Pierce

All 70 

acres 3.2 oz/acre Broadcast, ground Hornet

PLANTS I007702-011 Corn 8/12/98 UN 2 IL Douglas

All 80 

acres 2.4 oz/acre Broadcast, ground Hornet

PLANTS I007702-012 Corn 8/25/98 UN 2 WI Chippewa All 3 acres 2.4 oz/acre Broadcast, ground Hornet
Page 36 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I007702-013 Corn 7/19/98 UN 2 IL Vermilion 18 rows 2.4 oz/acre Band Hornet

PLANTS I007702-014 Corn 7/20/98 UN 2 IL Vermilion Unknown 2.4 oz/acre Broadcast, ground Hornet

PLANTS I007714-001

Agricultural 

area 5/24/98 RU 3 IL Warren

20-30% of 

plants 4.0 oz/acre Broadcast, ground N/R Scorpion III

PLANTS I007750-001 Corn 5/1/98 RU 3 ND Richland 60 acres 2 pts/acre Broadcast, ground N/R Curtail

PLANTS I007754-001

Agricultural 

area

5/1 -

6/22/98 RU 3 IL Lee 56 plants 4.00 oz/acre Broadcast, ground N/R Scorpion III

PLANTS I007754-003

Agricultural 

area

4/28 -

6/10/98 RU 2 MN Goodhue 80 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-001 Corn 4/30/98 RU 2 WI Buffalo 67 acres 2.87 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-002 Corn

4/30 -

6/3/98 RU 1 MN Steele 155 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-003 Corn 5/1/98 RU 2 MN Steele 88 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-004 Corn 4/30/98 RU 2 WI Pierce 230 acres 3.20 oz/acre Soil incorporation N/R Hornet

PLANTS I007755-005 Corn

5/1 -

6/24/98 RU 2 MN 40 acres 3.20 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-006

Agricultural 

area 5/5/98 RU 2 WI Dunn 180 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-007 Corn 5/5/98 RU 2 IA Boone 200 acres 2.00 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-008 Corn 5/3/98 RU 2 IA Story 500 acres 2 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-009 Corn 5/2/98 RU 2 MN Renville 33 acres 2.4 oz/acre N/R N/R Hornet

PLANTS I007755-010 Corn 5/18/98 RU 2 IL Macoupin 5 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-011 Corn 4/23/98 RU 1 IL Macoupin 70 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007755-013 Corn 4/25/98 RU 2 IL Macoupin 90 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007867-001

Agricultural 

area 5/11/98 RU 3 IA Shelby All 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007867-002

Agricultural 

area 5/31/98 RU 2 MN Isanti 40 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I007867-003

Agricultural 

area 4/25/98 RU 2 IA Cass 40 Acres 4.00 oz/acre Broadcast, ground N/R Hornet

PLANTS I007867-004

Agricultural 

area 5/2/98 RU 2 IA Bremer 21 acres 2.00 oz/acre Broadcast, ground N/R Hornet
Page 37 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I007874-001 Alfalfa 4/4/98 RU 3 WA Grant 300 acres N/R Broadcast, ground N/R Stinger

PLANTS I008002-001 Corn 10/11/98 UN 2 IA Calhoun 80 acres 2.0 oz/acre Broadcast, ground Hornet

PLANTS I008002-002 Corn 10/12/98 RU 2 IA Carroll

All 330 

acres 2.0 oz/acre Broadcast, ground Hornet

PLANTS I008002-003 Corn 10/13/98 RU 2 IA Grundy

All 2400 

acres 2.0 oz/acre Broadcast, ground Hornet

PLANTS I008002-004 Corn 9/30/98 RU 2 WI Buffalo

All 655 

acres 2.4 oz/acre Broadcast, ground Hornet

PLANTS I008002-005 Corn 10/15/98 RU 2 IL Tazewell

All 37.8 

acres 2.4 oz/acre Broadcast, ground Hornet

PLANTS I008002-006 Corn 8/16/98 RU 2 IN Benton

All 160 

acres 2.4 oz/acre Broadcast, ground Hornet

PLANTS I008010-001 Corn 10/12/98 RU 2 IA Cerro Gordo

25 of 213 

acres 2.4 oz/acre Broadcast, ground Hornet

PLANTS I008010-002 Corn 10/14/98 RU 2 NE York

80 acres of 

1200 1.2 oz/acre Band Hornet

PLANTS I008079-001 Corn 5/7/98 RU 2 IA Dubuque 120 acres 2.00 oz/acre Broadcast, ground N/R Hornet

PLANTS I008079-002 Corn 4/30/98 RU 2 IA Jasper 300 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I008079-003 Corn 5/5/98 RU 2 IA Monona 160 acres 2.4 oz/acre Broadcast, air N/R Hornet

PLANTS I008079-004 Corn 4/27/98 RU 3 IA Pocahontas 395 acres 2 oz/acre Broadcast, ground N/R Hornet

PLANTS I008079-005 Corn 5/5/98 RU 2 IA Calhoun 938 acres 2 oz/acre Broadcast, ground N/R Hornet

PLANTS I008079-006 Corn 4/27/98 RU 3 IA Pocahontas 837 acres 2.00 oz/acre Broadcast, ground N/R Hornet

PLANTS I008079-007 Corn 4/28/98 RU 2 IA Pocahontas 392 acres 2 oz/acre Broadcast, ground F Hornet

PLANTS I008079-008 Corn 5/12/98 RU 2 IA Pocahontas 90 acres 2 oz/acre Broadcast, ground F Hornet

PLANTS I008079-009 Corn 4/26/98 RU 2 IA Pocahontas 898 acres 2 oz/acre Broadcast, ground F Hornet

PLANTS I008079-010 Corn 5/12/98 RU 2 WI Walworth 90 acres 3.20 oz/acre Broadcast, ground N/R Hornet

PLANTS I008079-011 Corn 4/26/98 RU 2 IA Pocahontas 911 acres 2.00 oz/acre Broadcast, ground N/R Hornet

PLANTS I008187-001 Corn 12/7/98 RU 2 IA Bremer 35 acres 2 oz/acre Broadcast, ground N/R Hornet

PLANTS I008187-002 Corn 12/6/98 RU 2 IL Peoria 69 acres 2 oz/acre Broadcast, ground N/R Hornet

PLANTS I008187-003 Corn 12/6/98 RU 2 IL Marshall

All 100 

acres 2.40 oz/acre Broadcast, ground N/R Hornet
Page 38 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I008187-004 Corn 12/15/98 RU 2 NE Boone

61 of 75

acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I008324-001

Agricultural 

area 5/15/98 RU 3 OH Huron 33 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I008324-002

Agricultural 

area 5/1/98 UN 1 MN Goodhue 90 acres 2.40 oz/acre Broadcast, ground N/R Hornet

PLANTS I008324-003

Agricultural 

area 5/15/98 MA 3 MN Dakota 100 acres 3.58 oz/acre Broadcast, ground N/R Hornet

PLANTS I008324-004

Agricultural 

area 5/6/98 RU 2 IA Pocahontas 259 acres 2.00 oz/acre Broadcast, ground N/R Hornet

PLANTS I008335-001

Agricultural 

area 6/9/98 RU 2 WY Fremont 124 acres 2 oz/acre N/R N/R Stinger

PLANTS I008455-001 Corn 2/5/99 RU 2 IN Parke 144 acres 2.4 oz/acre N/R Hornet

PLANTS I008455-002 Corn 2/24/99 RU 2 IA Sioux All 2.4 oz/acre N/R Hornet

PLANTS I009507-001 Soybean 7/22/99 RU 3 SD Roberts 10 acres 2.0 pts/acre Broadcast, ground N/R Curtail

PLANTS I009509-001 Asparagus 9/2/99 RU 3 WA Franklin 250 acres N/R N/R N/R Stinger

PLANTS I009512-001 Corn 6/13/98 RU 3 ND Cass

50% of 53 

acres 3.2 oz/acre Broadcast, ground G Hornet

PLANTS I009512-002 Corn 6/4/99 MA 3 IN Howard All 3.20 oz/acre Broadcast, ground G Hornet

PLANTS I009512-003 Corn 6/23/99 UN 3 WI Pepin All 2.40 oz/acre Broadcast, ground G Hornet

PLANTS I009512-004 Soybean 6/23/99 RU 2 MN Mower 50 plants 2.40 oz/acre Broadcast, ground G Hornet

PLANTS I009512-005 Alfalfa 6/23/99 RU 2 WI Pierce 20 acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-007 Corn 5/3/99 RU 1 WI Pierce 400 acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-008 Corn 5/1/99 RU 3 NE Thurston

30 of 60 

acres 3.5 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-009 Corn 5/10/99 RU 2 MN Rice 80 acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-010

Agricultural 

area 5/15/99 UN 1 MN Goodhue 200 acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-011 Corn 5/10/99 RU 2 SD Grant All 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-012

Agricultural 

area 5/15/99 MA 2 MN Le Sueur All 4.0 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-013 Corn 5/20/99 RU 2 MN Morrison 60 acres 2.4 oz/acre Broadcast, ground N/R Hornet
Page 39 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I009512-014 Corn 8/11/99 MA 2 MN Mower 214 acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-015 Corn 8/11/99 MA 2 MN Mower 216 acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-016 Corn 6/13/99 MA 2 MN Mower 600 acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-017 Corn 8/4/99 RU 2 MN Winona

75 of 126 

acres 3.2 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-018 Corn 8/16/99 RU 2 IL Carroll All 3.2 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-019 Corn 9/8/99 RU 2 WI Crawford All 3.2 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-020 Corn 9/15/99 RU 2 IN PIKE All 2.6 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-021 Corn 9/22/99 RU 2 OH Hardin

45 of 73 

acres 2.4 oz/acre Broadcast, ground Hornet

PLANTS I009512-022 Corn 9/25/99 RU 2 NE Red Willow All 1.2 oz/acre Band N/R Hornet

PLANTS I009512-023 Corn 9/23/99 MA 2 MN Dakota All 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-024 Corn 6/23/99 MA 2 MN Rock

37 of 76 

acres 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-025 Corn 7/15/99 MA 2 MN Lyon 40 acres 3.2 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-026 Corn 10/18/99 RU 3 IA Dubuque All 3.2 oz/acre Broadcast, ground N/R Hornet

PLANTS I009512-027 Corn 10/13/99 RU 3 MN Fillmore All 2.9 oz/acre Broadcast, ground N/R Hornet

PLANTS I009669-004 Corn 7/5/99 RU 1 IA Jasper All 2.4 oz/acre Broadcast, air N/R Hornet

PLANTS I009969-003 Corn 9/13/99 RU 3 NE Furnas All 2.4 oz/acre Broadcast, ground N/R Hornet

PLANTS I009969-005 Corn 6/16/99 RU 2 WI Crawford All 3.2 oz/acre Broadcast, ground N/R Hornet

PLANTS I010414-001 Turf 4/1/00 MA 3 WA Spokane N/R N/R Confront

PLANTS I010743-001 Taxus media 6/19/00 RU 3 MI Ottawa 18 acres 8 oz/ ? Spray, ground N/R Lontrel

PLANTS I010743-002 Yews 6/19/00 RU 3 MI Ottawa 35 acres 8 oz/ ? SPRAY N/R Lontrel

PLANTS I010837-016 Corn 6/2/00 UN 2 IL Lee All N/R N/R N/R Hornet

PLANTS I010927-001 Corn 5/5/00 RU 2 IA Dubuque All 7 lbs/acre Soil incorporation N/R Accent Gold

PLANTS I010927-015 Corn 5/2/99 RU 3 IA Franklin 132 acres 4 oz/acre Spray N/R Scorpion III

TERREST

RIAL I011897-002

Agricultural 

area 7/1/00 MI 3 WA Spokane Unknown N/R Compost

Comp

ost N/R

PLANTS I012357-002 Corn 5/3/01 UN 2 MN All N/R Broadcast, ground N/R Hornet
Page 40 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I012357-003 Corn 5/29/01 UN 2 MN All N/R Broadcast, ground N/R Hornet WDG

PLANTS I012363-002 Turf RU 4 PA 3 pint/acre

Broadcast, 

unincorporated

Coftront/

Millennium

PLANTS I012366-008 Corn, field 4/27/01 RU 3 IA Carroll 30 acres 4 oz/acre Broadcast, ground Scorpion III

PLANTS I012366-009 Corn, field 4/25/01 RU 2 IA Hardin 105 acres 4 oz/acre Broadcast, ground Scorpion III

PLANTS I012366-010 Corn, field 4/26/01 RU 2 IA Hardin 134 acres 4 oz/acre Broadcast, ground Scorpion III

PLANTS I012366-029 Corn, field 5/1/01 RU 3 WI Grant

20 of 23

acres 3.60 oz/acre Broadcast, ground G Hornet

PLANTS I012366-030 Corn, field 5/1/01 RU 3 MN Steele 80 acres 3.00 oz/acre Broadcast, ground G Hornet

PLANTS I012366-031 Corn, field 5/6/01 RU 3 IN Montgomery 203 acres 1.20 oz/acre Broadcast, ground G Hornet

PLANTS I012366-032 Corn, field 5/3/01 UN 3 MN 47.70 acres 4.00 oz/acre Broadcast, ground Hornet

PLANTS I012366-033 Corn, field 5/1/01 UN 3 MN 33.70 acres 4.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-034 Corn, field 4/14/01 RU 2 IN Cass 65.0 acres 3.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-035 Corn, field 5/9/01 RU 2 IA Dubuque

20 of 42 

acres 3.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-036 Corn, field 5/2/01 RU 3 WI Dane 40 acres 4.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-037 Corn, field 5/10/01 RU 3 IA Linn

99 of 139 

acres 4.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-038 Corn, field 4/19/01 RU 3 IL St Clair 90 acres 3.00 oz/acre G Hornet WDG

PLANTS I012366-039 Corn, field 4/24/01 RU 3 IN Tippecanoe

62 of 96 

acres 3.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-040 Corn, field 4/26/01 RU 3 MN Brown 21 acres 2.40 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-041 Corn, field 4/28/01 RU 3 WI Richland 294 acres 4.00 oz/acre Broadcast, ground DF Hornet WDG

PLANTS I012366-042 Corn, field 6/14/01 RU 3 IL Whiteside 174 acres 3.00 oz/acre Broadcast, ground DF Hornet WDG

PLANTS I012366-043 Corn, field 4/29/01 RU 3 IA Muscatine 94 acres 3.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-044 Corn, field 5/9/01 RU 3 WI Dane 31 acres 4.00 oz/acre Broadcast, ground G Hornet WDG

PLANTS I012366-055 Corn, field 5/9/01 RU 3 IA Dubuque

20 of 42 

acres 3.0 oz/acre Broadcast, ground G Hornet

PLANTS I012366-061 Corn, field 5/15/01 RU 3 WI Grant

20 of 23 

acres 3.60 oz/acre Broadcast, ground G Hornet
Page 41 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I012366-062 Corn, field 5/9/01 UN 2 IA Hardin 105 acres 4.00 oz/acre Broadcast, ground G Scorpion III

PLANTS I012366-063 Corn, field 4/26/01 UN 2 IA Hardin 134 acres 4.00 oz/acre Broadcast, ground Scorpion III

PLANTS I012366-066 Corn, field 6/2/00 RU 3 IL Bureau 20 acres 4.00 oz/acre Broadcast, ground Hornet

PLANTS I012366-067 Corn, field 5/10/00 M 3 KS Edwards 126 acres 2.4 oz/acre Broadcast, ground Hornet

PLANTS I012366-068 Corn, field 3/30/01 RU 2 IL 160 acres 2.40 oz/acre Broadcast, ground Hornet

PLANTS I012366-069 Corn, field 4/30/01 RU 3 OH Wood 7 acres 4.12 oz/acre Broadcast, ground Hornet

PLANTS I012366-070 Corn, field 5/2/01 RU 3 IA Dubuque 30 acres 2.40 0z/acre Broadcast, ground Hornet

PLANTS I012366-071 Corn, field 5/24/01 RU 3 WI Lafayette 60 acres 2.40 oz/acre Broadcast, ground Hornet

PLANTS I012366-072 Corn, field 5/2/00 RU 3 WI Columbia 60 acres 3.20 oz/acre Broadcast, ground Hornet

PLANTS I012366-073 Corn, field 4/9/01 RU 3 IL Pike 20 acres 2.40 oz/acre Broadcast, ground Hornet

PLANTS I012367-001

Turf, 

residential 

area 12/29/01 RU 4 CA Unknown N/R

Broadcast, soil 

incorporated N/R

PLANTS I012556-001 Corn 4/26/01 RU 3 MN Brown 21 acres 2.40 oz/acre Broadcast, ground G Hornet

PLANTS I012627-002

Turf, 

residential 

area 1/22/02 RU 3 WA Spokane Unknown

PLANTS I012628-002

Turf, 

residential 

area 3/7/02 RU 3 CA Los Angeles

PLANTS I012628-003

Turf, 

residential 

area RU 3 CA Los Angeles

PLANTS I013550-003 Corn 5/22/02 RU 2 IL Morgan

862 plants 

and trees 3.0 oz/acre Spray, air Hornet

PLANTS I013550-009 Corn, field 5/10/02 RU 1 MN Lacqui Parle 50 acres Spray, ground Hornet

PLANTS I013554-046 N/R 7/1/02 M 2 SD Douglas 68 acres Accent

PLANTS I013554-048 N/R 7/22/02 M 2 WI Chippewa 65 acres Accent

PLANTS I013636-001 Corn, field 4/15/02 RU 2 MO Pettis

72 of 149 

acres Broadcast Hornet

PLANTS I013636-004

Agricultural 

Area 5/1/02 RU 2 WI Pierce 373 acres Broadcast, ground Hornet
Page 42 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I013636-008 N/R RU 4 CANADA Curtail M

PLANTS I013636-025 Corn, field 4/23/01 RU 2 TN Dyer 80 acres Broadcast, ground Accent

PLANTS I013636-032 Corn, field 4/28/01 RU 2 IN White 313 acres 2.40 oz/acre Broadcast, ground Hornet

PLANTS I013883-028 Road 7/23/97 RU 2 WA Pierce N/R Spray, ground

PLANTS I013884-006 Pasture 6/11/98 RU 3 WA Chelan N/R Ground

PLANTS I014702-002 Potato 7/23/03 RU 2 ID Teton N/R N/R Ground N/R Curtail

PLANTS I014702-003 Wheat 5/15/03 RU 3 ND Stutsman 120 acres 1.75 pts/acre Broadcast, ground N/R Curtail M

PLANTS I014702-014 Corn, field 4/28/03 RU 2 IN Jasper 46 acres Broadcast, ground Hornet

PLANTS I014702-016 Corn, field 5/1/03 RU 3 NE Custer

1607.93 

acres 3.0 gal/acre Broadcast, ground WP Hornet

PLANTS I014806-001

Agricultural 

area 7/1/03 RU 2 ID Bannock 3020 acres N/R Ground N/R Curtail

PLANTS I015748-017 Wheat 6/6/04 RU 3 MT Richland 36 acres Spray EC WideMatch M

PLANTS I015748-019 Lettuce 6/25/04 M 2 AZ Yuma 15 acres N/R N/R EC Stinger

PLANTS I015748-022 Corn, field 5/20/03 RU 3 OH Seneca 36 acres 0.7 lbs/acre G Hornet

PLANTS I016962-030 Corn, field

4/15 -

7/21/05 RU 2 KS Franklin 857 acres 3 oz/acre Broadcast DF Hornet WDG

PLANTS I016962-032 Flax 6/12/05 RU 2 ND 180 acres Curtail M

PLANTS I016962-039 Corn, field 6/16/05 RU 3 IA Winneshiek 286 acres 3.5 oz/acre DF Hornet WDG

PLANTS I016962-040 Corn, field 6/15/05 RU 3 IA Shelby 265 acres 3 oz/acre DF Hornet WDG

PLANTS I016962-041 Corn, field 6/1/05 UN 3 MN Wabasha 342 acres 4 oz/acre Hornet

PLANTS I016962-045 Corn, field 4/29/05 RU 2 WI Lafayette 50 acres 3 oz/acre DF Hornet WDG

PLANTS I016962-046 Alfalfa 6/7/05 RU 2 WI Ozaukee 30 acres 3 oz/acre Hornet

PLANTS I016962-048 Corn, field 6/9/05 RU 2 NE Hall 22 acres 1.33 pts/acre WideMatch

PLANTS I017837-017 Grape MA 3 CA

San Luis 

Obispo 90 oz/acre Spray, ground N/R Transline

PLANTS I020627-031

Right-ofway, road 7/10/01 MI 2 WA Benton Unknown Ground

PLANTS I020998-029 Vineyard UN 3 WA Walla Walla Ground
Page 43 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I021276-010

Nursing 

home UN 3 WA Spokane Ground

PLANTS I022082-033 Corn, field 6/8/10 UN 2 IA Chickasaw

100% of 

138.2 acres

PLANTS I023302-021

Wheat, 

spring 7/1/11 UN 3 ND Pembina

100 % of 

423.2 acres 0.3 oz/acre Broadcast, ground N/R

Accent/

WideMatch

PLANTS I023302-025

Wheat, 

spring 6/27/11 RU 2 MN Kittson

100 % of 

560 acres Broadcast, ground N/R WideMatch

PLANTS I023302-040

Wheat, 

spring 7/13/11 RU 2 ND Pembina

100% of 

38.7 acres 0.3 oz/acre Broadcast, ground

Accent/

WideMatch

PLANTS I023574-002 Corn 4/21/11 UN 2 MN Lyon

2,1370 

acres of 

corn 1.78 pts/acre Pre-emerge, ground

Sure Start 

Herb GF2708

PLANTS I023574-006

Agricultural 

area 6/9/11 UN 2 NE Greeley 70 acres 2 pts/acre Broadcast, ground

Sure Start 

Herb GF2708

PLANTS I023574-053

Agricultural 

area 5/25/10 UN 2 KY Jefferson

100% of 

349 acres 2 pt Broadcast, ground EC

Sure Start 

Herb

PLANTS I023574-054 Corn 4/30/10 UN 2 IA Clinton

100% of 71 

acres Pre-emerge, ground WP Hornet

PLANTS I023574-054 Corn 4/30/10 UN 2 IA Clinton

100% of 71 

acres Pre-emerge, ground EC

Sure Start 

Herb

PLANTS I023574-055 Corn, field 5/3/10 UN 2 IA Jackson

100% of 

645 acres 2 pt Pre-emerge, ground WP Hornet

PLANTS I023574-055 Corn, field 5/3/10 UN 2 IA Jackson

100% of 

645 acres Pre-emerge, ground EC

Sure Start 

Herb

TERREST

RIAL I023574-061 Corn UN 2 IN 1,200 acres

Sure Start 

Herb

TERREST

RIAL I023574-062 UN 2 IA

Sure Start 

Herb

Abbreviations: Appl.=Application; N/R=Not Recorded

1 Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), UN=Unknown 2 Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. N/R=Not Reported 3 Formulation Code: DF=Dry Flowable; EC=Emulsifiable Concentrate; F=Flowable; G=Granular; WDG=Water Dispersable Granule; WP=Wettable Powder
Page 44 of 47

Table B-3. Incidents in the EIIS for PC 117404: Clopyralid triethanolamine as of 10/31/13

Type Incident ID Use Site Date Legality1 Certainty2 State County Total Magnitude Appl. Rate Appl. Method Formulation3 Product

PLANTS I012701-001 Greenhouse 2/13/02 UN 3 OH < 100 Confront

Abbreviations: Appl.=Application; N/R=Not Recorded 1 Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), UN=Unknown 2 Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. N/R=Not Reported

3 Formulation Code: DF=Dry Flowable; EC=Emulsifiable Concentrate; F=Flowable; G=Granular; WDG=Water Dispersable Granule; WP=Wettable Powder

Table B-4. Incidents in the EIIS for PC 117423: Clopyralid potassium as of 10/31/13

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I012525-004 Corn 5/5/01 RU 3 IN Cass All 4 oz/acre Broadcast, ground N/R Hornet WDG

PLANTS I012525-005 Corn 4/27/01 RU 3 IN Benton All 3.20 oz/acre Broadcast, ground N/R Hornet WDG

PLANTS I012525-006 Corn 5/10/01 RU 3 IA Linn All 4.00 oz/acre Broadcast, ground N/R Hornet WDG

PLANTS I012525-007 Corn 5/10/01 RU 3 IA Linn 99 ACRES 4.00 oz/acre Broadcast, ground N/R Hornet WDG

PLANTS I013636-003

Agricultural 

Area 4/15/01 RU 2 IL Mason

all 589.8 

acres Broadcast, ground Hornet WDG

PLANTS I013636-024 Corn, field 5/20/02 RU 2 NE Custer 155 acres Broadcast, ground Hornet WDG

PLANTS I013636-051 Corn, field 4/29/01 RU 3 WI Grant 99.10 acres 4 oz/acre Broadcast, ground Hornet

PLANTS I013636-052 Corn, field 5/1/02 RU 2 IL Montgomery 93 acres 3.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-053 Corn, field 4/29/02 RU 2 WI Waukesha 38 acres 3.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-054

Agricultural 

area 5/20/02 RU 2 IA Poweshiek 15 acres 3.0 oz/acre Hornet WDG

PLANTS I013636-055 Corn, field 4/20/02 RU 2 IN Marshall

500 out of 

950 acres 4.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-056 Corn, field 5/1/02 RU 2 WI 24 acres 3.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-057 Corn, field 5/10/02 RU 3 WI Sauk 99 acres 4.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-058 Corn, field 5/15/02 RU 2 MN Le Sueur

260 out of 

302 acres 2.5 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-059 Corn, field 5/14/02 RU 2 NE Phelps 120 acres 4.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-060 Corn, field 5/1/02 RU 2 NE Hall

802 out of 

896 acres 1.5 oz/acre Band Hornet WDG
Page 45 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I013636-061 Corn, field 4/28/02 RU 4 NE Custer 132 acres 2.40 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-062 Corn, field 5/2/02 RU 4 NE Buffalo 39 acres 3.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-063 Corn, field 5/8/02 RU 4 NE Knox

110 out of 

190 acres 3.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-064 Corn, field 4/28/02 RU 4 IA Lee 132 acres 2.40 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-065 Corn, field 5/2/02 RU 3 IA Buchanan 147 acres 4.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-066 Corn, field 6/1/02 RU 2 MN Rice 26 acres 3.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-067 Corn, field 4/20/02 RU 2 NE Dawson

390 out of 

425 acres 3.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-068 Corn, field 5/15/02 RU 2 MN Carver 3/0 oz/acre Broadcast, ground Hornet WDG

PLANTS I013636-069 Corn, field 5/3/02 RU 3 NE Knox 170 acres 4.0 oz/acre Broadcast, ground Hornet WDG

PLANTS I014702-021 Corn, field 6/27/03 RU 3 NE Hall 899 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-022 Corn, field 6/16/03 RU 2 WI Rock 6.5 acres 0.75 oz/acre Broadcast, ground G Hornet

PLANTS I014702-023 Corn, field 6/20/02 RU 2 IL Fulton

30 out of 36 

acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-024 Corn 5/13/03 RU 3 NE Franklin 35.85 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-025 Corn 5/13/03 RU 3 NE Franklin 35.35 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-026 Corn 5/10/03 RU 3 NE Franklin 39 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-027 Corn 5/10/03 RU 3 NE Franklin 39 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-028 Corn, field 6/23/03 RU 2 NE Hall 63 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-029 Corn, field 6/23/03 RU 2 NE Hall 185 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-030 Corn, field 5/14/03 RU 2 IA Cedar 385 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-031 Corn, field 6/23/03 RU 2 NE Hall 185 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-032 Corn, field 7/5/03 RU 2 ND Dickey 55 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-033 Corn, field 7/5/03 RU 2 ND Dickey 68 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-034 Corn, field 6/30/02 RU 3 IL Kankakee 12 acres 2.5 pts/acre Broadcast, ground G Hornet

PLANTS I014702-035 Corn, field 5/5/01 RU 2 IL Jasper 800 acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-036 Corn, field 5/1/02 RU 2 NE Dixon

257 of 277 

acres 4 oz/acre Broadcast, ground G Hornet
Page 46 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

PLANTS I014702-037 Corn, field 4/19/02 RU 2 IA Washington

16.5 of 36 

acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-038 Clover 4/11/03 RU 3 MN Olmsted 18 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-039 Corn, field 4/29/03 RU 3 WI Dodge 250 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-040 Corn, field 4/27/03 RU 2 WI Walworth 300 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-041 Corn, field 4/29/03 RU 2 WI Waukesha 110 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-042 Corn, field 5/27/03 RU 2 WI Brown

15 of 30 

acres 3 oz/acre Broadcast, ground G Hornet

PLANTS I014702-043 Corn, field 4/29/03 RU 2 WI Columbia 200 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-044 Soybean 5/9/03 M 3 WI Dane

14.5 of 29 

acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I014702-045

Agricultural 

area 5/2/03 UN 3 WI Rock 76 acres G Hornet

PLANTS I015748-015 Corn, field 5/22/03 RU 3 MI 100 acres 3 oz/acre N/R G Hornet

PLANTS I015748-024 Corn, field 4/15/04 RU 2 IL Lawrence 80 acres 3 oz/acre dry N/R G Hornet

PLANTS I015748-026 Corn, field 5/27/04 M 3 IN Marshall 500 acres 4 oz/acre Broadcast, ground G Hornet

PLANTS I015748-027 Corn 5/24/04 M 3 IN Pulaski 500 acres 2.8 oz/acre G Hornet

PLANTS I015748-034 Corn, field 6/11/04 RU 3 MO Nodaway 155 acres 3 oz/acre Spray, ground G Hornet

PLANTS I015748-036 Corn, field 6/2/04 RU 3 MO Linn 287 acres 3 oz/acre N/R G Hornet

PLANTS I015748-037 Corn, field 6/20/04 RU 3 MO Chariton 128 acres 3 oz/acre N/R G Hornet

PLANTS I015748-038 Corn, field 6/2/04 RU 3 MO Carroll 64 acres 3 oz/acre dry N/R G Hornet

PLANTS I015748-039 Corn, field 6/2/04 RU 3 MO Carroll 57 acres 3 oz/acre dry N/R G Hornet

PLANTS I015748-042 Soybean 5/10/03 UN 3 WI Pepin 607 acres 3.2 oz/acre Spray G Hornet

PLANTS I016962-002 Corn 5/22/04 RU 2 MI Jackson 140 acres Broadcast DF Hornet WDG

PLANTS I016962-033 Corn, field 5/3/05 RU 3 WI Pierce 260 acres 4 oz/acre DF Hornet

PLANTS I016962-035 Corn, field 5/5/05 RU 2 IA Ringgold 100 acres 2.7 qts/acre DF Hornet WDG

PLANTS I016962-036 Corn, field 4/24/05 RU 2 WI Columbia 411 acres 4 oz/acre DF Hornet WDG

PLANTS I016962-047 Corn, field 5/16/05 RU 3 WI Fond Du Lac 40 acres 4 oz/acre DF Hornet WDG

PLANTS I023574-051 Agricultural 5/28/10 UN 2 WI Juneau 100% corn 2 qt. Pre-emerge, ground WDG Hornet
Page 47 of 47

Type Incident ID Use Site Date Legality1 Certainty2 State County

Total 

Magnitude Appl. Rate Appl. Method

Formulation3 Product

area

Abbreviations: Appl.=Application; N/R=Not Recorded 1 Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), UN=Unknown 2 Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. N/R=Not Reported 3 Formulation Code: DF=Dry Flowable; EC=Emulsifiable Concentrate; F=Flowable; G=Granular; WDG=Water Dispersable Granule; WP=Wettable Powder