DuPont Response to the EPA’s “Proposed Registration of Aminocyclopyrachlor on 

Non-Crop Areas, Sod Farms, Turf, and Residential Lawns” 

Compiled by Rebecca M. Ashley 

July 16, 2010 

DuPont has applied for the initial registration of the active ingredient 

aminocyclopyrachlor, and associated end-use products, for use in the non-crop, 

vegetation management (VM) market. As part of the review process for this registration 

action, the Agency has posted a number of documents to the public docket (EPA-HQOPP-2009-0789-0011) for review and comment. Presented here are DuPont’s initial 

comments to the Agency document titled “Proposed Registration of 

Aminocyclopyrachlor on Non-Crop Areas, Sod Farms, Turf, and Residential Lawns”. 

That document includes the following proposed label language for the vegetation 

management end-use products: 

In order to mitigate risk to non-target plants and keep the pesticide on the 

intended treatment area, the following spray drift language must be placed on all 

aminocyclopyrachlor end-use product labels 

Products Primarily Intended for Commercial Use on Non-Crop Areas

 Aerial Application Restriction 

“When applying by air, maintain a 50-foot buffer around non-target aquatic 

areas and between the point of direct application and the closest downwind edge 

of non-target terrestrial areas. Apply only using nozzles which will deliver coarse 

or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. 

Do not release spray at a height greater than 10 feet above the ground or crop 

canopy unless a greater height is required for aircraft safety. Do not apply when 

wind speed is greater than 10 mph. Do not apply during a temperature 

inversion.” 

Ground Application Restriction 

“When applying by ground, maintain a 50-foot buffer around non-target aquatic 

areas and between the point of direct application and the closest downwind edge 

of non-target terrestrial areas. Apply only using nozzles which will deliver coarse 

or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. 

Do not apply with a nozzle height greater than 4 feet above the ground or crop 

canopy. Do not apply when wind speed is greater than 10 mph. Do not apply 

during a temperature inversion.” 

For several reasons discussed below, DuPont believes that the stated buffers to non-target 

aquatic areas and non-target terrestrial areas are not necessary to mitigate off-target 

1
movement of aminocyclopyrachlor end-use products used in vegetation management 

programs. Specifically: 

1. The Agency’s estimate of possible off-target movement of 

aminocylopyrachlor applications is based on laboratory data from the 

terrestrial plant studies combined with extrapolations from models including 

Terrplant and AgDrift. DuPont believes that the use of these laboratory data 

and the models results in gross overestimates of possible off-target movement, 

and calculated or recommended buffers. 

 

2. Applications of aminocyclopyrachlor end-use products will be made by 

applicators using modern spray equipment under application conditions 

designed to reduce off-target movement. In addition, these applicators are 

typically required to undergo training that includes instructions on reducing 

possible off-target movement of herbicides during their application. 

3. Addition of buffers to aminocyclopyrachlor end-use products will result in 

lessened utilization of the products, and will force land use managers to 

continue to use older, more problematic products to attempt to control weeds. 

 

4. Aminocyclopyrachlor offers unprecedented control of a large number of 

weeds - including many invasive and noxious weed species that are currently 

not being optimally controlled. The addition of the buffer for 

aminocyclopyrachlor end-use products will consequently result in reduced 

control of these important weed species. 

DuPont understands and supports the Agency’s effort to minimize any potential off-target 

movement of aminocyclopyrachlor containing end-use products which, in turn, will 

mitigate possible effects on non-target plant species. DuPont believes that this can be 

accomplished through the best management practices that are currently in place in the 

vegetation management industry. Therefore, as an alternative to EPA’s suggested buffers 

to non-target terrestrial and aquatic areas, DuPont is herein proposing label language, 

similar to that found on current vegetation management products, for the relevant 

Aminocyclopyrachlor end-use products. DuPont believes that this language, combined 

with other recommended restrictions, will provide adequate margins of safety to 

terrestrial and semi-aquatic plants for Aminocyclopyrachlor uses. 

Current Modeling and Risk Assessment Results– Overestimation of Risk

Terrplant and AgDrift Modeling 

Comments on Terrplant: 

The EECs calculated from Terrplant modeling and the subsequent inputs into the AgDrift 

model result in a large overestimate for the need for buffers for aminocyclopyrachlor 

2
end-use products. Refined modeling using appropriate vegetation management use 

scenarios for aminocyclopyrachlor end-use products demonstrate a much lower 

likelihood of spray drift from both ground and aerial application than that demonstrated 

by using the AgDrift model (which is more appropriate to agricultural crop applications). 

Extrapolation from existing data also demonstrates that the likelihood of 

aminocylopyrachlor residues being found in waters that might be used for irrigation, 

which could result in risk to non-target plants, is low. 

The EPA has assessed the potential risk from applications of aminocyclopyrachlor to 

non-target plants growing in semi-aquatic habitats by utilizing the risk assessment 

strategy developed and implemented through the model Terrplant version 1.2.2. This 

model assessed an application to bare soil at a rate of 0.284 lb ai/acre by ground and 

aerial spray equipment for non-crop use. The model assumes a runoff value of 10% of 

the applied product based on the solubility of aminocyclopyrachlor. The model scenario 

also assumes channelized flow and eventual deposition of the runoff from a 10 acre 

application area to a 1 acre low lying semi-aquatic area. It further assumes an additional 

environmental loading of 1% of the applied rate for ground application and 5% for aerial 

application as a result of spray drift. The resulting total estimated environmental 

concentrations (EEC) for aminocyclopyrachlor applied at the maximum use rate for noncrop uses (0.284 lb ai/acre) was 0.14484 lb ai/acre and 0.1562 lb ai./acre for ground and 

aerial applications, respectively. 

The Terrplant assessment endpoints were derived from the pre-emergent terrestrial nontarget plant studies (soil emergence and vegetative growth). The ER25 and NOAER for 

the most sensitive monocot and dicot species are the most appropriate endpoints for 

assessment. In semi-aquatic areas, the Terrplant risk quotients (RQs) calculated by the 

Agency for monocot species for non-listed and listed species are 3.7 and 3.0 respectively. 

The Terrplant RQs for dicot species are 273 for non-listed species, and 295 for listed 

species. (Table 5.2 of the EFED assessment dated January 22, 2010.) These values are 

derived from ground application. Aerial RQs are proportionally higher, based on the 

higher drift level of 5%. 

We believe, however, that the Terrplant scenario used to evaluate risk to semi-aquatic 

plant species is not appropriate for non-crop vegetation management applications since 

that model is based primarily on conditions typical of crop use. Aminocyclopyrachlor at 

the maximum labeled rate will be used for more localized application, and for linear 

applications along railroad, highway, and other types of rights-of-ways, as proposed for 

registration. Unlike applications to cropland, vegetation management applications are 

characterized by narrow swath applications over considerable linear distance. For 

example, a linear application with a swath width 25 feet would require over three miles of 

linear distance to treat the equivalent of 10 acres of right-of-way. Any runoff from that 

25 foot x 3 mile treated area would not be expected to flow into a single 1 acre pond or 

semi-aquatic area. Further, these applications are made by highly trained operators with 

equipment specifically designed to eliminate off-site movement through spray drift. In 

addition to the spatial considerations, heavily vegetated zones typically border the 

3
application areas and would serve to reduce runoff and channelized flow from the treated 

areas, thus further reducing the exposure to off-target semi-aquatic habitats. 

For these reasons, we would propose that the runoff scenario/assessment to dry areas is 

more appropriate to assess the proposed vegetation management uses of 

aminocyclopyrachlor – recognizing that it may still overestimate actual exposure at 

distance due to the narrow swath width and the degree of vegetative cover found in 

vegetation management applications. Such an assessment resulted in RQ values for 

monocot species for non-listed and listed species of 0.43 and 0.36 respectively. The 

Terrplant RQs for dicot species are 32 for non-listed species, and 35 for listed species. 

These values are derived from ground application. Aerial RQs, as noted above, are 

proportionally higher based on the higher drift level of 5%. 

Therefore, based on the above considerations, we believe that a buffer to non-target 

aquatic areas for VM applications of aminocyclopyrachlor is not warranted. 

 

Comments on AgDRIFT: 

The proposed label statements regarding nozzles, release height, wind speed and 

temperature inversions are consistent with practices that are commonly used in vegetative 

management applications and are generally accepted best practices for aerial applications. 

The buffer requirement, however, is impractical since many of the use sites will be along 

rights-of-way, and the proposed 50-foot buffer would have the effect of prohibiting some 

key uses for this product. For example, rights-of-way may be only 50 feet wide along 

railroads or power lines, and applications to roadsides may be restricted to 20 feet on 

either side of the roadway. Rights-of-way could not be treated effectively since the nontarget areas would be immediately adjacent to the site, and would require an on-site 

buffer that is actually greater than or equal to the width of the treated area. 

Aerial Application 

To minimize drift from applications to rights-of-way, many aerial applicators have 

adopted spray technologies that deliver ultra coarse droplet size distributions (VMD > 

1000) using high volumes of spray solutions. Using slow speed helicopters in light 

winds, these applications would require no buffers to minimize the potential for off-target 

effects on terrestrial plants. The drift modeling conducted by EPA provides a useful 

starting point for further analysis which illustrates the low risk to non-target areas from 

VM applications with the low drift nozzles. 

The default AgDRIFT model input parameters were designed to simulate deposition from 

typical agricultural applications and, consequently, assume a larger number of flight lines 

(or swaths) and droplet size distributions that are not typical of applications to rights-ofway (ROW). Modeling inputs typical of ROW are shown in Table 1 and compared to 

EPA model inputs. While the AgDRIFT model is not overly robust to assess VM 

applications, we have forced alternative inputs for typical vegetation management use 

4
scenarios with coarse droplet size using a single flight line into that model to simulate an 

application to a right-of-way with a swath width of 60 feet. [Note, however, that swath 

widths in VM applications are generally less than 60 feet.] Typical application 

conditions in vegetation management reduce the need for buffers, and the following 

assessment adjusts the modeling inputs to simulate the different vegetation management 

application scenario. 

Table 1. Inputs for AgDRIFT - Aerial VM applications 

Original EPA 

inputs used by 

EFED 

EPA proposal - 

requirement for 

coarse droplet size 

ROW fixed wing 

VM scenario 

ROW rotary 

wing VM 

scenario 

AgDRIFT Tier II or III III III III 

Aircraft Slow fixed wing Slow fixed wing Slow fixed wing Slow rotary 

Droplet size 

distribution 

Very fine to fine Coarse Coarse Coarse 

Application rate 

(lb ai/acre): 

0.284 0.284 0.284 0.284 

Non-volatile 

application rate 

(lb ai/acre): 

0.568 0.568 0.568 0.568 

Application volume 

(gals/acre): 

10 10 10 10 

Swath displacement 

fraction 

0.6505 0.2489 0.2489 0.2489 

Flight lines (number of 

application swaths) 

20 20 1 1 

Wind speed (mph) 10 10 10 10 

The buffers calculated by AgDRIFT using the EPA inputs for very fine to fine droplet 

size ranged from about 108 feet (monocot seedling emergence endpoint) to >2640 feet 

(dicot vegetative vigor endpoint). However, as shown in Table 2 below, using the 

proposed requirement for a coarse droplet size distribution and simulating a ROW 

application with a single flight line (or swath), the calculated buffers are significantly 

reduced as compared to the results from the EPA modeling (ranging from 13 feet for 

monocot seedling emergence to 846 feet for dicot vegetative vigor). 

Table 2. Comparison of Calculated Buffer Distances to Attain a Risk Quotient at the EPA 

LOC

Endpoint Fraction 

of applied 

EPA 

Modeling 

(very fine to 

fine droplets) 

EPA proposal 

– requirement 

for coarse 

droplet size 

ROW 

Fixed wing, 1 

swath, coarse 

droplet 

ROW 

Rotary wing, 1 

swath, coarse 

droplet 

Seedling emergence, 

monocots 

0.169 108 ft. 23 ft. 16.4 ft. 13 ft. 

Seedling emergence, 

dicots 

0.00187 >2640 ft. 1644 ft. 305 ft. 262 ft. 

Vegetative vigor, 

monocots 

0.0204 1749 ft. 180 ft. 108 ft. 95 ft. 

Vegetative vigor, 

dicots 

0.000264 >2640 ft. >2600 ft. 846 ft. 807 ft. 

5
Further modeling to simulate low drift alternatives typically used in aerial application for 

vegetation management, i.e., using extremely coarse droplet size distributions, shows 

dramatic reductions in modeled drift compared to coarse droplet size distributions. For 

example, the droplet size distribution for the Accuflo 028 nozzle is representative of 

similar extremely coarse droplet technologies, and was obtained from the SDTF library. 

For this modeling scenario the swath displacement fraction was set to 0, which forces a 

higher deposition fraction at 0 feet than for simulations using the swath displacement 

fractions in AgDRIFT. The modeling inputs and resultant calculated buffers are shown in 

Tables 3 and 4, respectively. 

Table 3. Alternative Low Drift Modeling Inputs for ROW applications 

ROW fixed wing – 

extremely coarse droplet 

scenario 

ROW rotary wing - 

extremely coarse droplet 

scenario 

ROW rotary wing, low 

wind speed - extremely 

coarse droplet scenario 

AgDRIFT Tier III III III 

Aircraft Slow fixed wing Slow rotary Slow rotary 

Nozzle Accuflo 028 (VMD 

1212 μm, relative span 

0.6915) 

Accuflo 028 (VMD 

1212 μm, relative span 

0.6915) 

Accuflo 028 (VMD 

1212 μm, relative span 

0.6915) 

Droplet size distribution Extremely coarse Extremely coarse Extremely coarse 

Application rate: 0.284 lb ai/ac 0.284 lb ai/ac 0.284 lb ai/ac 

Non-volatile application 

rate: 

0.568 lb ai/ac 0.568 lb ai/ac 0.568 lb ai/ac 

Application volume: 10 gals/acre 10 gals/acre 10 gals/acre 

Swath displacement 

fraction 

0.0 0.0 0.0 

Flight lines (number of 

application swaths) 

1 1 1 

Wind speed (mph) 10 10 5 

Table 4. Comparison of Calculated Buffer Distances to Attain a Risk Quotient at the EPA 

LOC 

Endpoint Fraction of 

applied 

ROW fixed 

wing – 

extremely coarse 

droplet 

ROW rotary wing - 

extremely coarse 

droplet 

ROW rotary wing, 

low wind speed - 

extremely coarse 

droplet 

Seedling emergence, 

monocots 

0.169 13 ft. 6.6 ft. 0 ft. 

Seedling emergence, 

dicots 

0.00187 56 ft. 29.5 ft. 26 ft. 

Vegetative vigor, 

monocots 

0.0204 33 ft. 13 ft. 6.6 ft. 

Vegetative vigor, dicots 0.000264 135 ft. 111 ft. 82 ft. 

As noted above, the buffers calculated by AgDRIFT using the EPA inputs for very fine to 

fine droplet size ranged from about 108 feet (monocot seedling emergence endpoint) to 

>2640 feet (dicot vegetative vigor endpoint). However, as shown in Table 4, modeling 

the typical extremely coarse droplet size distribution and simulating a ROW application 

6
with a single flight line (or swath), results in calculated buffers that are significantly 

reduced (ranging from 0 feet for monocot seedling emergence to 135 feet for dicot 

vegetative vigor) as compared to the results from the EPA modeling. 

Based on modeling for aerial applications using more realistic inputs simulating typical 

vegetation management use scenarios, there are significant reductions in the calculation 

of buffers, which demonstrate that buffers should not be required for applications of 

aminocyclopyrachlor end-use products - especially when using low drift equipment and 

best management practices as proposed on the label. 

Ground Application 

Drift modeling for ground applications using AgDRIFT is limited by the data for the 

empirical relationships that the model is based on. Of particular concern is that the 

deposition data only allow separation into two drop size categories and two application 

heights - which precludes the simulation of the coarse to extremely coarse drop size 

distributions that are common in ground ROW applications. However, within the 

framework of the AgDRIFT model, two forced changes to the EPA modeling scenario 

are possible to simulate ROW applications: 1) reduce swaths from 20 to 1, and 2) select 

fine to medium/coarse drop size category. Table 5 summarizes the base modeling 

scenarios and the ROW application alternative scenarios. 

Table 5. Inputs for AgDRIFT ground applications. 

EPA inputs EPA proposal for 

use of coarse 

droplets 

ROW Scenario I ROW Scenario II 

AgDRIFT Tier I I I I 

Application height high high high high 

Droplet size 

distribution 

Very fine to fine Fine to 

medium/coarse 

Fine to 

medium/coarse 

Fine to 

medium/coarse 

Percentile 90th 90th 90th 50th 

Application rate: 0.284 lb ai/ac 0.284 lb ai/ac 0.284 lb ai/ac 0.284 lb ai/ac 

Number of Swaths 20 20 1 1 

As shown in Table 6 below, utilizing the modeling changes noted above in Table 5 

significantly reduces the calculated buffers as compared to the results from the EPA 

modeling. Specifically, calculated buffers are reduced from 16.4 feet to 3.3 feet for 

monocot seedling emergence, and from >1000 feet to 282 feet for dicot vegetative vigor. 

7
Table 6. Comparison of Buffer Distances to Attain a Risk Quotient at the EPA LOC 

(Ground Applications) 

Endpoint Fraction of 

applied 

EPA Modeling, 

very fine to fine 

droplets, 90th

percentile curve 

EPA proposal - 

Requirement for 

coarse droplets 

ROW 

1 swath, 

90th

percentile 

curve 

ROW 

1 swath, 50th

percentile 

curve 

Seedling 

emergence, 

monocots 

0.169 16.4 ft. 3.3 ft. 3.3 ft. 3.3 ft. 

Seedling 

emergence, dicots 

0.00187 833 ft. 453 ft. 102 ft. 79 ft. 

Vegetative vigor, 

monocots 

0.0204 121 ft. 26 ft. 16 ft. 16 ft. 

Vegetative vigor, 

dicots 

0.000264 >1000 ft. >1000 ft. 394 ft. 282 ft. 

Although not specifically appropriate for assessing ROW applications, AgDRIFT 

modeling for ground applications using more realistic inputs simulating typical 

vegetation management use scenarios still results in significant reductions in the 

calculated buffers, and demonstrates that buffers should not be required for applications 

of aminocyclopyrachlor end-use products - especially when using low drift equipment 

and best management practices as proposed on the label. 

Logistics of Vegetation Management Applications and Impracticality of Buffers 

The requirement of buffers for aminocylopyrachlor end-use products for use in 

vegetation management would severely limit, or even prohibit, the use of the products in 

these markets. Feedback received from the Railroad industry, various state Departments 

of Transportation (DOTs), and commercial applicators indicates that buffers are 

impractical for utility rights-of-way, roadsides and other vegetation management use 

sites, and are inconsistent with the goals of weed control programs. Current practices, 

combined with advances in application technology and stewardship training in these 

market segments, address the concern for reducing off-target movement of pesticide 

applications. Reducing off-target movement is important to vegetation managers for a 

number of reasons, including the reduction of pesticide exposure to workers, residents 

and animals, and limiting any damage to susceptible crops or other desirable plants. In 

addition, applicators are keenly aware of the added cost to their business if off-target 

movement occurs. Applicators have many options available to them to reduce off-target 

movement of their applications including selection of the proper application equipment, 

nozzle type, application height and operating pressure. In addition, they also have a 

strong awareness of the effects of wind direction and other weather effects (temperature, 

humidity) on possible off-target movement of pesticide applications. Further, drift 

retardants are also commonly used in these applications. 

Feedback from the VM industry indicated that specifying buffers on 

aminocyclopyrachlor end-use products would be problematic in this market. Howard 

8
Peavey, Alabama DOT Senior Agronomist, indicated that “buffers would likely reduce 

efficiencies by requiring return trips to certain routes or result in areas that did not receive 

treatment.1

 Lines of sight may not be cleared as effectively and appurtenance protection 

may not be as efficient - possibly resulting in increased cost to tax payers”. Rand 

Swanigan, Roadside Management Specialist for the Missouri DOT, noted that the 

“majority of roadside right of way is very narrow and buffer areas would result in most 

areas being untreated - resulting in increased populations of noxious, invasive and 

problematic weeds.”2 Richard M. Loughery the Director of Environmental Activities for 

Edison Electric Institute (EEI) provided the following comments regarding the possible 

requirement of buffers and the subsequent impact on electric utilities: 

 “The application of buffer zones would be likely to severely diminish the 

ability of electric utilities to fully utilize integrated vegetation 

management (IVM). The environmental benefits of IVM are documented 

by over 60 years of research (Bramble & Byrnes in particular). EEI and 

member companies have participated in US EPA's Pesticide 

Environmental Stewardship Program (PESP). The PESP program has 

highlighted the electric utility industry's IVM practices. The no-spray 

buffer zone proposal seems to run counter to the PESP program. Utility 

rights-of-way can be part of the solution for providing wildlife migration 

corridors and habitat for pollinators. However, an IVM approach 

including the spraying of herbicides is necessary to provide necessary 

habitat within the rights-of-way. Mechanical clearing can be the most 

appropriate utility vegetation management in some cases, but not all. The 

proposed no-spray buffer zones would likely push utilities to use 

mechanical clearing more often to meet the NERC reliability standards for 

rights-of-way vegetation management.”3

Note that, in a public docket comment in response to proposed buffers for sulfometuron 

methyl, Robert E. Fronczack, Assistant Vice President Environment & Haz Mat, for the 

Association of American Railroads stated that “In order to safely and efficiently operate, 

effective control of unwanted vegetation along the nation's railroad rights-of-way is 

vitally important. Unwanted weeds and brush create safety and operational problems 

including; reduced visibility at grade crossings and signals, fire hazards, difficulties with 

inspections, rail wheel slippage, as well as compliance problems with state and local 

weed abatement regulations.” Feedback from the Railroad industry indicates that the 

assignment of buffers to non-target terrestrial and aquatic areas would be impractical, and 

that the use of buffers in railroad applications “are unrealistic and will make products 

virtually unusable in our industry.”4

 

1

 Email from Howard Peavey, Sr. Agronomist Alabama DOT, to Doug Wood, DuPont, dated June 28, 

2010. 

2

 Email from Rand Swanigan, Roadside Management Specialist Missouri DOT, to Doug Wood, DuPont, 

dated June 24, 2010. 

3

 Email from Richard Loughery, Director, Environmental Activities, Edison Electric Institute to Mark Rice, 

DuPont, dated June 28, 2010. 

4

 Comment to the public docket (EPA-HQ-OPP-2008-0129-0167) by Robert E. Fronczack, dated February 

3, 2009 

9
Gary Nyberg, Manager Vegetation Control, BNSF Railway, provided the following 

comments: 

“Requiring buffer zones for aerial application would eliminate helicopter spraying 

on railroads. Helicopter application is an effective tool to achieve the goals and 

objectives of railroad weed control. Many areas of the railroad are not accessible 

with conventional ground equipment and the use of helicopters is necessary to 

help comply with Federal and State vegetation and noxious weed laws that affect 

railroads.”5

Canadian PMRA – Decisions Regarding Vegetation Management Use Pattern 

It is of significance to note that in a number of Re-evaluation Decision Documents, 

Canada’s Pest Management Regulatory Authority (PMRA) has concluded that vegetation 

management uses are generally exempt from terrestrial buffers. In the re-evaluation 

decision document for 2,4-D (dated May 16, 2008)6

, PMRA explained “The PMRA has 

exempted rights-of-way uses from requiring buffer zones to protect terrestrial habitat 

because complete plant/weed control is required right up to edge of the application areas 

on these sites to ensure user safety.” Some additional examples of this exemption are 

listed below: 

Re-evaluation Decision: Metsulfuron Methyl, November 10, 20087

For application to rights-of-way, buffer zones for protection of sensitive terrestrial 

habitats are not required; however, the best available application strategies which 

minimize off-site drift, including meteorological conditions (e.g. wind direction, 

low wind speed) and spray equipment (e.g. coarse droplet sizes, minimizing the 

height above canopy), should be used. 

Buffer zones for the protection of terrestrial habitats are not required for use on 

rights-of-way including railroad ballast, rail and hydro rights-of-way, utility 

easements, roads, and training grounds and firing ranges on military bases. 

 

5

 Email from Gary Nyberg, Manager Vegetation Control, BNSF Railway, to Dan Mixon, DuPont, dated 

July 1, 2010. 

6

 Re-evaluation Decision: (2,4-Dichlorophenoxy) acetic Acid [2,4-D]; http://www.hc-sc.gc.ca/cpsspc/pubs/pest/_decisions/rvd2008-11/index-eng.php 

7

 Re-evaluation Decision: Metsulfuron Methyl; http://www.hc-sc.gc.ca/cps-spc/pubs/pest/_decisions/

rvd2008-35/ index-eng.php 

10
Re-evaluation Decision: Dicamba, 5 August 20088

For application to rights-of-way, buffer zones for protection of sensitive terrestrial 

habitats are not required; however, the best available application strategies to 

minimize off-site drift, including meteorological conditions (e.g. wind direction, 

low wind speed) and spray equipment (e.g. coarse droplet sizes, minimizing 

height above canopy), should be used. 

Buffer zones for the protection of terrestrial habitats are not required for use on 

rights-of-way, including railroad ballast, rail and hydro rights-of-way, utility 

easements, roads, and training grounds and firing ranges on military bases. 

Re-evaluation Decision: Picloram, January 14, 20099

Buffer zones for the protection of terrestrial habitats are not required for use on 

rights-of-way including railroad ballast, rail and hydro rights-of-way, utility 

easements and roads. 

For application to rights-of-way, buffer zones for protection of sensitive terrestrial 

habitats are not required; however, the best available application strategies that 

minimize off-site drift, including meteorological conditions (e.g. wind direction, 

low wind speed) and spray equipment (e.g. coarse droplet sizes, minimizing 

height above canopy), should be used. 

Industry Training 

The Railroad industry, state Departments of Transportation, commercial applicators and 

other entities responsible for applying vegetation management herbicides typically 

receive in-depth and frequent training regarding herbicide applications - including 

information on reducing any possible off-target movement of applied herbicide. As an 

example, Progress Solutions, LLC, a leading applicator in vegetation management 

servicing many electric companies, requires training for new hires and annual training for 

all applicators.10 Included in the training (attachment 1), is a module entitled “Drift 

Management” that includes instructions on choosing appropriate nozzle size, height of 

release spray, sprayer pressure and use of drift retardants to limit any possible off-target 

movement. Similar training is also conducted by Departments of Transportation. 

According to Charles Flowers of the Arkansas State Highway and Transportation 

Department (AHTD), all certification, recertification and training of applicator personnel 

 

8

 Re-evaluation Decision Document: Dicamba; http://www.hc-sc.gc.ca/cps-spc/pubs/pest/_decisions/

rvd2008-28/index-eng.php 

9

 Re-evaluation Decision: Picloram; http://www.hc-sc.gc.ca/cps-spc/pubs/pest/_decisions/rvd2009-

02/index-eng.php 

10 Email from Lee Atkins, Progressive Solutions, to Doug Wood, DuPont, dated June 24, 2010. 

11
is conducted by the Pesticide Coordinator for the University of Arkansas Cooperative 

Extension Service.11 In house training is also conducted periodically, utilizing expertise 

and training materials provided by basic manufacturers and suppliers of vegetation 

management products. Drift reduction and application technology relative to off-target 

movement of pesticides is addressed in each training session. Although general use 

pesticides are used by the Department, all AHTD applicators are required to be certified 

in the Rights-of-Way category. The Department utilizes weather instruments for 

documentation of environmental conditions, and uses drift control agents in all broadcast 

applications. Similarly, Alabama’s Department of Transportation conducts annual 

training which addresses off-target movement - including drift, volatility, runoff and 

ground water considerations. In addition, the Alabama DOT has issued “A Manual For 

Roadside Vegetation Management” (see attachment 2). According to Howard Peavey of 

the Alabama DOT, applicators are required to use a drift retardant in all applications and 

the DOT has set restrictions relative to wind speed and applications to sensitive areas. 

The members of the National Railroad Contractors Association (NRCA), who represents 

applicators of herbicides to the US Railroads, attend annual training conducted by Purdue 

University’s Department of Forestry and Natural Resources, which includes certification 

and offers continuing education topics. Spray drift and off-target movement of 

herbicides are an integral part of the certification and training. 

Application Technology 

Typical application scenarios for aminocyclopyrachlor end-use products include railroad 

application, utility rights-of-ways and roadsides. Control of unwanted vegetation in these 

areas is extremely important to provide safety to workers and the public, and to properly 

and efficiently maintain electrical, railroad and highway systems throughout the United 

States. Application technology used in these types of applications has been designed to 

reduce the possibility of off-target movement. (Refer to Attachment 3 for photographs of 

typical spray equipment) 

Railroad applications: 

The majority of railroad applications are made using "hi-rail" truck sprayers that actually 

have railroad wheels and ride on the tracks. These range from 500 - 3,000 gallon capacity 

and can spray from 24 - 100 foot wide patterns (12 - 50 feet from center of rail on both 

sides of the track). Routine railbed is sprayed 24 feet wide, while the 100 foot width is 

typical for railroad crossings where public safety is most crucial. 

Railroad contractors are generally equipped with low drift, large capacity spray systems, 

utilizing 25 - 40 gallons/acre spray volumes and nozzles which deliver 1 - 10 gallons of 

spray per minute. This configuration equates to droplet sizes in the range of >500 micron 

VMD, and in many cases > 1,000 micron VMD. 

 

11 Email from Charles Flowers, AHTD Facilities Management, Arkansas State Highway and Transportation 

Department, to Doug Wood, DuPont, dated June 30, 2010 

12
Railroad contractors also tend to use drift control agents as part of the spray mixture, 

which can result in a dramatic increase in droplet size depending on the specific product 

utilized. Specific nozzles used in railroad applications are "boomless" types such as 

boom busters, OC's (off center nozzles), XP boomjet, wobblers, solid streams, and radiarc's. Fixed nozzles used include floodjets, flat fans, 1/4 MEG low-angle flat fans, and 

OC's. 

Electric Utilities applications: 

Applications made to Electric Utilities facilities and rights-of-way are primarily for brush 

control for general vegetation management. The range of application equipment includes 

backpack sprayers for applicators on foot in electric utility right-of-ways, ATV mounted 

sprayers using boomless configurations with either XP boomjets or boom buster nozzles, 

skidders (rugged vehicle for clearing forest) using configurations similar to ATVs, and 

helicopter spray systems utilizing some of the most innovative spray booms on the 

market to apply sprays exactly where they are required (for example, Thru-valve booms 

with a >800 micron VMD). 

These applications will be of lower spray volume in some cases for efficiency (backpack 

5 - 20 gallons/acre) or higher in other cases - for example with helicopters (5 - 30 

gallons/acre). Backpack sprays can utilize "Constant Flow Valves" to maintain a steady 

droplet size at a low pressure, minimizing spray drift potential. In all scenarios, the spray 

nozzles will be large orifice/low pressure - producing coarse spray droplets, at a 

minimum, which allows the spray to be placed where intended. Placement is made easier 

with larger droplets since they are affected far less by any wind or vehicle movement. 

Roadside applications: 

Roadside applications are typically made using medium sized trucks, with tank sizes of 

500 - 2,000 gallons spray, from the shoulder of roads utilizing low-drift nozzle 

technology. Spray systems include Norstar nutating heads that use solid stream nozzles 

and oscillation to break up the streams into very large droplets, or boomless nozzles such 

as the boom-buster or XP boomjets, which again result in large droplet size spectrums. 

In summary, the vegetation management industry has pioneered the development of low 

to no drift nozzle technology over the last three decades to enable applications in close 

proximity to the public. The use of this technology, in combination with electronic 

controls and GPS, allows for rapid and consistent placement of herbicide applications - 

thereby reducing the risk of off-target movement. 

Adoption of Newer Chemistry

Requiring buffers for aminocyclopyrachlor end-use products will result in some land use 

managers continuing to use older, less efficacious, more problematic products that do not 

currently have specified buffers - thereby limiting the adoption of the new 

13
aminocyclopyrachlor technology. Other active ingredients currently used in vegetation 

management products that either have less stringent buffer requirements, or no buffer 

requirements at all, include aminopyralid, picloram, triclopyr and clopyralid. These 

active ingredients are not scheduled for registration review until 2014, which means that 

any proposed buffer language resulting from these reviews would likely not appear on 

relevant end-use product labels until 2016 or later. This would seriously impact the 

adoption of aminocyclopyrachlor end-use products if the current buffer proposals were 

retained for this new active ingredient. 

According to Tom Evans, a retired DuPont vegetation management manager with 

extensive experience in railroad and highway applications, assigning buffers to 

aminocyclopyrachlor end-use products would encourage applicators to continue to use 

products that otherwise require DOT HAZMAT placarding (such as Diuron), products 

designated as known carcinogens, products that are highly volatile (such as dicamba), 

products with known groundwater issues (such as picloram), and products containing 2,4-

D (which is considered highly toxic if absorbed through skin). In addition, Mr. Evans 

notes that the continued use of these products would greatly increase the pesticide load in 

the environment versus the adoption of lower use rate aminocyclopyrachlor end-use 

products.12

Control of Economically Important Weed Species

As BEAD concluded in its review of the Public Interest Finding statement for 

aminocyclopyrachlor, this new active ingredient demonstrates better long term control of 

Leafy Spurge (Euphorbia esula) than any currently registered herbicide product. In 

addition to Leafy Spurge, aminocyclopyrachlor is effective on a number of other invasive 

and noxious weed species that are not being optimally controlled by currently registered 

products. Attachment 4 illustrates the broad spectrum of control of aminocyclopyrachlor 

versus currently registered competitive products. 

Of particular note is recent efficacy work conducted with aminocyclopyrachlor on 

Cogongrass (Imperata cylindrica), an important new invasive weed of concern in 

southern and southeastern states. Over $8 million in federal monies was appropriated for 

the states of Alabama and Mississippi to aid in the control/eradication of cogongrass in 

2009. Of the currently registered products, glyphosate and imazapyr are very effective at 

controlling cogongrass - when applied at the correct rates and timing. However, these 

products also kill the desirable grasses that grow in the same locations as the cogongrass, 

resulting in erosion problems and the further burden to re-establish the desirable grasses. 

During this bareground roadside period following application of non-selective herbicides, 

many other unwanted weeds and grasses often invade the area causing secondary 

problems in the planting and establishment of desirable perennial grasses. An important 

attribute of aminocyclopyrachlor is the control of cogongrass without severely harming 

the desirable grasses. Data from Auburn University demonstrates that 

aminocyclopyrachlor controls cogongrass in bahiagrass roadsides in southern Alabama – 

with acceptable levels of phytotoxicity to established grasses as compared to glyphosate 

 

12 Email from Thomas Evans, consultant, to Dominic Watson, DuPont, dated July 9, 2010 

14
or imazapyr. Aminocyclopyrachlor offers an important new tool to help eradicate 

cogongrass in the southern and southeastern United States without causing permanent 

injury to desirable grasses. The ability to use aminocyclopyrachlor end-use products to 

control this, and other increasingly problematic weeds, would be severely limited if the 

currently proposed buffers are included on the product labels. 

Proposed Label Language

DuPont understands and supports the Agency’s effort to minimize any potential off-target 

movement of aminocyclopyrachlor containing end-use products which, in turn, will 

mitigate possible effects on non-target plant species. As an alternative to EPA’s 

suggested buffers to non-target terrestrial and aquatic areas, DuPont is proposing label 

language, similar to that found on current vegetation management products, for the 

relevant Aminocyclopyrachlor end-use products. DuPont believes that this language, 

combined with other recommended restrictions, will provide adequate margins of safety 

to terrestrial and semi-aquatic plants for Aminocyclopyrachlor uses. 

Use Restrictions: 

Do not make applications when circumstances favor movement from treatment site. 

Do not apply or otherwise permit DuPontTM (product name), or sprays containing 

(product name), to come into contact with any broadleaf crop or other desirable broadleaf 

plants. 

Do not contaminate water intended for irrigation. To avoid injury to crops and other 

desirable plants, do not treat or allow spray drift or run-off to fall onto banks or bottoms 

of irrigation ditches, either dry or containing water, or other channels that carry water that 

may be used for irrigation purposes. Do not apply to snow covered or frozen ground. 

Avoid Injurious Spray Drift 

Applications should be made only when there is little or no hazard from spray drift. Very 

small quantities of spray, which may not be visible, may seriously injury susceptible 

plants. Do not spray when wind is blowing toward susceptible crops, or other desirable 

plants, near enough to the application site to be injured. 

 Aerial Application 

Current Agency Proposal: 

“When applying by air, maintain a 50-foot buffer around non-target aquatic 

areas and between the point of direct application and the closest downwind edge 

of non-target terrestrial areas. Apply only using nozzles which will deliver coarse 

or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. 

Do not release spray at a height greater than 10 feet above the ground or crop 

canopy unless a greater height is required for aircraft safety. Do not apply when 

15
wind speed is greater than 10 mph. Do not apply during a temperature 

inversion.” 

DuPont Proposal: 

“When applying by air, apply only using nozzles which will deliver coarse or greater 

(VMD >350 microns) droplets as defined by ASABE S572 standard. Do not release 

spray at a height greater than 10 feet above the ground or canopy unless a greater height 

is required for aircraft safety. Do not apply when wind speed is greater than 10 mph. Do 

not apply during a temperature inversion.” 

For aerial applications near susceptible crops or other desirable plants, use a drift control 

additive as recommended by the manufacturer, or apply through a Micro-Foil or ThruValve boom, or use an equivalent drift control system. Thickened sprays prepared by 

using high viscosity invert systems or other drift control systems may be utilized if drift 

control is comparable to that obtained with drift control additives or the Thru-Valve 

boom. If a spray thickening agent is used, follow all recommendations and precautions 

on the product label. Do not use a thickening agent with the Micro-foil boom or other 

systems that cannot accommodate thick sprays. 

Ground Application Restriction 

Current Agency Proposal: 

“When applying by ground, maintain a 50-foot buffer around non-target aquatic 

areas and between the point of direct application and the closest downwind edge 

of non-target terrestrial areas. Apply only using nozzles which will deliver coarse 

or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. 

Do not apply with a nozzle height greater than 4 feet above the ground or crop 

canopy. Do not apply when wind speed is greater than 10 mph. Do not apply 

during a temperature inversion.” 

DuPont Proposal: 

“When applying by ground, apply only using nozzles which will deliver coarse or greater 

(VMD >350 microns) droplets as defined by ASABE S572 standard. Do not apply with a 

nozzle height greater than 4 feet above the ground or canopy unless necessitated by the 

application equipment. Apply with the spray boom or nozzle height as low as possible. 

Do not apply when wind speed is greater than 10 mph. Do not apply during a temperature 

inversion.” 

For ground applications, spray drift can be reduced by keeping the spray boom as low as 

possible by applying 20 gallons or more of spray per acre; by using spray pressures no 

greater than are required to obtain adequate plant coverage; by using large-droplet 

producing nozzle tips; by using drift control additives; by using shielded-sprayers or 

other drift control systems; and/or by spraying when wind velocity is low. 

16
Conclusion

DuPont believes that the Agency proposed buffers to non-target aquatic areas and nontarget terrestrial areas are not necessary to mitigate off-target movement of 

aminocyclopyrachlor end-use products used in vegetation management programs. 

Requiring such buffers will likely result in drastically reduced adoption of this new 

technology in Vegetation Management programs. 

At the same time, DuPont understands and supports the Agency’s effort to minimize any 

potential off-target movement of aminocyclopyrachlor containing end-use products 

which, in turn, will mitigate possible effects on non-target plant species. DuPont believes 

that this can be accomplished through the best management practices that are currently in 

place in the vegetation management industry. Therefore, as an alternative to EPA’s 

suggested buffers to non-target terrestrial and aquatic areas, DuPont is proposing label 

language, similar to that found on current vegetation management products, for the 

relevant Aminocyclopyrachlor end-use products. DuPont believes that this language, 

combined with other recommended restrictions, will provide adequate margins of safety 

to terrestrial and semi-aquatic plants for Aminocyclopyrachlor uses. 

17
18

Attachments 

1) Drift Management training module for Progressive Solutions, LLC. 

2) Excerpt on Spray Drift Management from “A Manual For Roadside Vegetation 

Management” (Alabama Department of Transportation). 

3) Examples of typical Herbicide Application Equipment for Vegetation 

Management 

4) Efficacy comparison of Aminocyclopyrachlor and Competitive Products on 

Noxious and Invasive Weed Species 
Attachment 1 

Drift Management training module for 

Progressive Solutions, LLC 
Progressive S
 According to the Environmental P

Agency (EPA), 500 million poundare applied annually in the United estimated that 3% of this total will 

That’s equal to 3000 tractor trailers full of chemical in the wrong place!
 Drift is defined as the off-target m

pesticides through the air at the timapplication.
 Pesticide drift can cause several pr

pesticide exposure to nearby workand animals, to damage to suscep
 Drift will also reduce the amount 

that is available to control the inteand may render an application inaSince the chemical and the applicamoney, drift not only is environmwrong, but it is also a costly and inof doing business. 
 Drift cannot be totally eliminated 

pesticide application because of teconstraints, but there are ways to mdrift to levels approaching zero
 Drift can occur in all forms of pest

application: 

 High Volume Low Volume backpack Roadside truck
 In general, drift can be influenced 

one of these four categories:

 Spray characteristics  Weather  Application equipment and setup  Operator skill
 The overwhelming factor influenc

droplet size. As a general rule of thdroplets do not have enough mass so they remain airborne and exposmovement longer than larger drop
 The height of release of spray will 

how much droplets will travel dowmay not be as critical for ground sit is very important for high volumapplication.

 No “shooting from the hip” with b

sprayers
 High Volume Applicators should 

far from the ground, generally no feet during the application. Any adistance will give droplets an oppinfluenced by wind and be deposi
 When using hydraulic nozzles, hig

pressures will produce more fine dincrease the drift potential of an apPressure has been demonstrated to effective way to increase coverage penetration. 
 Drift retardants are usually added 

mixture in order to increase the vispray solution. Increasing the viscspray will reduce the number of smAlthough drift retardants are a tooto decrease drift potential, their colimited. You should manage nozzheight and operating pressure corminimize drift potential. Do not redrift retardants. 
 Wind speed is the most important 

influencing drift. High wind speeddroplets downwind and deposit thtarget. Generally, pesticide applicabe avoided if wind speed is greatemph. The most effective way to chspeed is to use a wind meter.
 Wind direction will influence whe

spray droplets will be deposited. A operator will try to apply pesticidthe wind is blowing away from se
 High air temperature and low rela

humidity go hand-in-hand in creacase scenario for pesticide drift. Uconditions, spray droplets can evafast and become more susceptible forces. Air temperature can also inatmospheric stability and off-targeof spray droplets.
Evaporation will reduce the size of the 

released in the spray. For typical applicground applicators, droplets of 50 micrwill completely evaporate to a residual pesticide before reaching the target. Drthan 200 microns will have no significain size before deposition on the target. of droplets between 50 and 200 μm is saffected by temperature, humidity and weather conditions. Some pesticide formore volatile than others. For exampleMCPA esters are susceptible to vapor d2,4-D or MCPA amines are practically n
 Under a given spray situation, any 

previously mentioned factors may critical in reducing drift hazards. Uis the applicator’s job to determine factor and to take precautions agaexercising good judgment regardiequipment and weather factors reapplication, applicators can minimpotential in nearly every case.
 Drift is undesirable for economic, 

environmental and safety reasonsapplicators don't spend money for watch them drift away from their Chemicals are potent and require application. Unsatisfactory coveraresult if a significant portion of the lost in drift. This could require re-same area. We could be sued in codrift damages sensitive crops in a field. 
 The environmental effects of spray 

equally costly and unacceptable. Bdrift to a minimum, we can reduce potential for pollution of streams, other water supplies that could enand wildlife. 
 Regardless of how accurately an a

made, the possibility of drift is alwYou can minimize this possibility the right equipment and using souwhen applying pesticides. Your jumean the difference between an efeconomical application or one thadrift, damaging non-target crops aenvironmental pollution. 
Attachment 2 

Excerpt on Spray Drift Management from 

“A Manual For Roadside Vegetation 

Management” (Alabama Department of 

Transportation) 
Veg. Mgt. Man. Chapt. III 19

SPRAY DRIFT CONTROL 

 Physical drift can be defined as the movement of spray particles or droplets 

away from the spray site before they reach the target plant. Ground inversion can 

prevent the settling of very small droplets and allow their movement away from the 

spray site during calm conditions. The amount of drift depends upon (1) the size of 

the droplets, (2) weather conditions and wind speed, (3) target location/distance and 

(4) the height above the ground that the spray is released. 

 Droplet size is determined by the design of the nozzle, orifice or opening size 

and pump pressure. In general, low pressures and large orifice sizes tend to 

produce large droplets, whereas high pressures and smaller orifice sizes will 

produce small droplets. Target setback and height above ground that the spray is 

released become important since they determine the time required for droplets to 

reach the ground. 

 Weather factors include wind speed, temperature and humidity. Wind speed 

and direction principally determine the direction and movement of the spray droplet 

after release from the nozzle. Temperature and humidity can affect the rate of 

droplet evaporation. As the diameter of a drop decreases, the ratio of surface area 

(many smaller droplets) to volume increases and evaporation occurs at a faster rate. 

The time of exposure to evaporation conditions also increases with smaller droplet 

size. The potential amount of physical drift varies with the method of application. 

There is a large difference of risk between hand tank, ground and aerial spraying. 

The hazards from off-target drift depend on (1) nature of the hazard, such as water, 

plant species, growth state, etc.; (2) legal pesticide tolerances in crops; (3) distance 

from the application site, (4) wind direction and air stability; (5) type, form and rate of 

the herbicide; and (6) the mix carrier (water, fertilizer or oil). Herbicides require 

certain coverage or drops per unit area of leaf surface for effective control. 

 Spray droplets evaporate more slowly in (wetter) 70% relative humidity and 

faster in lower (drier) relative humidity. Droplets falling through dry air decrease in 

size and are subject to drift and possible chemical trespass.

 To reduce the possibility of chemical trespass, a drift control agent is 

frequently added to a spray tank in an attempt to minimize spray drift to adjacent 

sensitive areas. 

 Drift control products, such as Nalcotrol®, Ground Zero®, Control®, Valid®, 

Sta-Put®, and numerous others, usually contain some percentage of polyvinyl 
Veg. Mgt. Man. Chapt. III 20

polymers or acrylic copolymers. When added to a spray tank, a drift control agent 

hydrates in the spray solution resulting in larger spray droplets and fewer fine 

droplets. 

 There are several inherent problems associated with the use of these 

products. Some of these products can only be used with water soluble or 

emulsifiable pesticides. This means they shouldn't be used with wettable powders, 

dry flowables, water dispersible granules, flowables, aqueous suspensions, or liquid 

suspensions. Operators must read the drift control agent label carefully to determine 

if there is such a prohibition. 

 The use rate varies with the particular product used, the spray pressure and 

the type of spray tips used. Usually the rate is given in a range of fluid ounces per 

100 gallons of spray mix. An operator should, initially add the lowest rate 

recommended. Increase the rate as needed. A thickened or "stringy" spray mix 

indicates that too much drift control agent was added. Only the manufacturer of the 

agent knows if it is possible to "unthicken" a spray mix. This mistake can cause loss 

of time, equipment, possibly pesticides, and money. Operators must read the label 

and use the lowest labeled rate. 

 There is no standard mixing order among the different drift control agents. 

The proper mixing order discussed earlier is still correct for mixing different products 

of different formulations together. However, operators will have to read the label and 

determine the proper time to add the drift control agent in relation to the other 

formulated products. In general, products that require agitation to remain in 

suspension are added to the tank first and agitated well before the addition of any 

other product. If an operator mixes his pesticides in the wrong order or adds the drift 

control agent at the wrong time, he may end up with a "mayonnaise-like" mixture 

that can't be sprayed. 

 Wind conditions are obvious to the applicator and strict procedures must be 

followed. Spraying must stop anytime the spray solution cannot be maintained 

within the target area. ALDOT policy is to stop when wind velocity reaches 8 - 10 

mph. Often times the crew can treat the downwind side of highways and return later 

to treat the opposite side when wind conditions are more favorable. Following are a 

number of field observations that spray operators may use to alert them to wind 

speed changes. Hand-held wind gauges can verify observations. 
Veg. Mgt. Man. Chapt. III 21

Field Observations Wind Speed (mph)

Chimney smoke rises up, air motionless 0 

Chimney smoke drifts slowly, air rises 1 - 3 

Leaves quietly rustle, flags stir 4 - 7 

Leaves and twigs move 8 - 12 

Branches move and flags flap 13 - 18 

Small trees sway and flags ripple 19 - 24 

Large branches move and flags beat 25 - 30 

Whole trees move and flags extend 31 - 38 

Twigs break and walking is difficult 39 - 46 

 PERSONAL SAFETY 

 Toxicity is not the only factor that determines how dangerous a chemical is to 

humans or animals. Anyone who handles pesticides should also be concerned with 

the hazard of the chemical. The terms toxicity and hazard do not mean the same 

things. Toxicity is the capacity of a substance to produce injury or death. Hazard 

includes two factors: toxicity and exposure. It is defined as the possibility that injury 

will result from the use of a substance in a given formulation, quantity, or manner. 

 Some hazards do not include toxicity to humans or other animals. For 

example, sulfur, oils, and many other chemicals are considered safe or relatively 

safe to animals, but may pose considerable hazards to some plants (phytotoxicity). 

 A pesticide may be extremely toxic but present little hazard to the applicator 

or others when used: 

 In a very dilute formulation. 

 In a formulation that is not readily absorbed through the skin or readily 

inhaled. 

 Only occasionally and under conditions to which humans are not exposed. 

 Only by experienced applicators that are properly equipped to handle the 

chemical safely 
Attachment 3 

Examples of typical Herbicide Application 

Equipment for Vegetation Management 
Vegetation Manage

Sprayer & Nozzle Typ

2010
Thru-V

WaldrcompaWaldrand hasupplidrift tein the Manag

Helicopter Applications
Right-of-Way Applica

Examples of spray equipment used in right-of-way sprayinhandguns using rollover valves and CFV’s. ATV’s use “boothe heavy brush, while the handguns operate from backpaspecific species of brush. Helicopters are also used in this 
Railroad Applications

Railrotrain-pmainliextenslike thrail yalines. applic
Roadside Applicati

Roadside spraying is done almost exclusively with “Bosprayers, like the ones shown below, which allow for proad out to the target. The boomless spray nozzles or coarse droplet sizes to enable precise placement of sprequired. Nozzles like those shown inherently produce due to their sheer size, dictated by the spray width and 
Attachment 4 

Efficacy comparison of 

Aminocyclopyrachlor and Competitive 

Products on Noxious and Invasive Weed 

Species 
MAT28 Comparison on N

weeds

• Comparison of data from labels, Noxious 

Western States, Data from summary chafield trials were used for Aminocyclopyrac

– Picloram comparison was 8 oz ai/A– Aminopyralid comparison was 1.75 oz – Data on perennial weeds was taken at 

days after application

• Labeled claims of suppression or control 

early stages were rated yellow

• Aminocyclopyrachlor (MAT28)
MAT28 Amino 

pyralid

Dicamba Piclor 

am

Yellow Starthistle StarthistleDiffuse Knapweed Diffuse KnapweedRussian KnapweedSpotted Knapweed Spotted KnapweedKochiaLeafy Spurge Leafy SpurgeCanada Thistle Canada ThistleMusk Thistle Musk ThistleField Bindweed Field BindweedPoison Hemlock Poison Hemlock

Noxious Weeds Control Compa

Noxious Weeds Control Compa

80 to 100% 50 to 70% 
MAT28 Aminop 

yralid

Dicamba Piclora

Mesquite MesquiteNewer weed species to be added to labelKudzuCogongrass CogongrassGorse

Scotch broom

Rush skeletonweed skeletonweedWild carrot Wild carrot

Competitive Products Competitive Products –Noxious 

Noxious 

80-100% control 51-70%