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![Page 1: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/1.jpg)
Accurate Modeling for Drift Reduction:General Overview and Regulatory
Status
April 11th, 2014
Dan Dyer
On Behalf of the CLA Spray Drift Issue Management Team
![Page 2: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/2.jpg)
Spray Drift Regulation
• Spray drift is complex… Ground, aerial, orchard/airblast sprays Broad range of technologies of spray equipment Significant differences in geography/climate Conservative drift models (perceived drift issue)
• But can be well managed… Local applicators/growers understand appropriate
conditions for application and minimizing drift Training / certification / education Pesticide Label Restrictions – wind speed, buffers,
etc. Newer drift reducing technologies
![Page 3: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/3.jpg)
Spray Drift Regulation
• Recently released spray drift guidance for use of AgDRIFT in human and ecological exposure/risk assessment EPA-HQ-OPP-2013-0676 “Consideration of Spray
Drift in Pesticide Risk Assessment”
• CLA supports development of appropriate drift assessment methodologies
• However, EPA guidance is too restrictive and is limited in ability to make higher tier refinements
![Page 4: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/4.jpg)
Factors Influencing Spray Drift
• Spray Characteristics Droplet size
Chemical / Formulation / Adjuvants
• Equipment & Application Nozzle type, size, orientation Nozzle pressure Height of release
• Weather, etc. Air movement (direction and velocity) Temperature & humidity Air stability/inversions
![Page 5: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/5.jpg)
Droplet Categorization - ASABE
Need to select droplet size to
maximize efficacy and minimize drift
Category Symbol Color Code
Approximate
Dv0.5 (VMD)
(microns)
Extremely Fine XF Purple ≈50
Very Fine VF Red <136
Fine F Orange 136-177
Medium M Yellow 177-218
Coarse C Blue 218-349
Very Coarse VC Green 349-428
Extremely Coarse
XC White 428-622
Ultra Coarse UC Black >622
From: ASABE Standard S-572.1
![Page 6: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/6.jpg)
AgDRIFT to Calculate Buffers
• EPA 2014 guidance uses AgDRIFT to determine drift for terrestrial (plant/animal) and aquatic habitat
• AgDRIFT based on Spray Drift Task-force data 48 unique SDTF Deposition Datasets
Excellent quality & GLP Used older (1992-93) spray application technology
• Several conservative approaches result in unrealistic ground drift estimates
• Unable to refine drift estimation using drift reducing technologies (DRT) and best management practices
![Page 7: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/7.jpg)
AgDRIFT – Overestimation of Drift
• AgDRIFT produces unreasonably conservative drift estimates when compared to existing drift data sets
Figure Courtesy J. Wright
Comparison Between AgDrift Outputs vs. Field DataAgDrift Assumes 20 Spray Swaths, 90th% tile
Distance (ft)
0 200 400 600 800 1000
% o
f A
ppli
ed
0.0
0.2
0.4
0.6
0.8
1.0
SDTF 1992SDTF 1993Wolf (PMRA)GanzelemierAgDrift (20 swaths)
![Page 8: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/8.jpg)
Figure Courtesy J. Wright
AgDRIFT – Scale-up Overestimation
• SDTF Data is foundation for AgDRIFT, but use of multipliers to scale-up to a ‘typical’ field is much too conservative
• 90th %ile curves inappropriate
• Gross overestimate at far-field distance
![Page 9: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/9.jpg)
Downwind distance (m)
1 2 5 10 20 40 120
Dep
osi
t (%
of
app
lied
)
0.001
0.01
0.1
1
10 1
1
1
1
1
1
1
1
2
2
2
2
2
33
33
3
5
5
5
5
5
6 66 6
6
7 7
7 7 7
8 88 8
8
9 9
9 9 9
10 1010
1010
44
4 44
2011 AAFC Data – Multiple Swaths
• Dr. Tom Wolf of Agriculture and Agri-Food Canada (AAFC) developed drift dataset as basis for PMRA buffer zone calculator
• No significant deposition after 4-5 swaths (~250-300 ft)
![Page 10: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/10.jpg)
• In AgDRIFT, SDTF data was consolidated into two categories:
• Inappropriate to evaluate medium or coarser sprays
• Inadequate for current nozzle technology
AgDRIFT – Overestimation of DriftNozzle Trial “Data Lumping”
Very Fine to Fine
Fine to Medium/Coarse
Category Symbol Color Code
Approximate
Dv0.5 (VMD)
(microns)
Extremely Fine XF Purple ≈50
Very Fine VF Red <136
Fine F Orange 136-177
Medium M Yellow 177-218
Coarse C Blue 218-349
Very Coarse VC Green 349-428
Extremely Coarse
XC White 428-622
Ultra Coarse UC Black >622
![Page 11: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/11.jpg)
Nozzle Types
11
Flat Fan Nozzles
Air Induction Nozzles
![Page 12: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/12.jpg)
AgDRIFTWind Speed “Data Lumping”
12
1 10 1001E-3
0.01
0.1
1
10
Per
cent
of A
pplie
d (lo
g)
log - Down Field Distance (m)
8.4 8.8 11.6 12.8 20.5
Wind (mph)
AI11004
• Drift at distance, is influenced by data generated in high wind (25% of SDTF ground data with >20 mph wind!!)
• 90th percentile could be ‘off-label’
1 10 100
1E-3
0.01
0.1
1
10
Per
cent
of A
pplie
d
Down Field Distance (m) - log
90th Pct
50th Pct
Mean
Nozzle - 11004
Dr. T. Wolf AAFC '2000
![Page 13: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/13.jpg)
• Summary• Mathematical model used in AgDRIFT to
describe the conservative 90th percentile drift curves are subjective, and overestimate drift• ‘Best fit’ curves in AgDRIFT never
intersect zero
• Lumping of data for trials with different nozzles (spray quality / droplet sizes), and wind speed produces excessive overestimates* of drift from ground sprays, and removes capability to refine model
AgDRIFT – Overestimation of Drift
* in some circumstances AgDRIFT can predict movement of more off-target material than the amount applied
![Page 14: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/14.jpg)
Drift Overestimation – The Impact?
• AgDRIFT used to calculate proximity distances and buffers for FIFRA ecological and human health risk assessments, and Endangered Species Risk Assessments
• Appropriate for ‘screening’ assessment, but requires refinement options• Risk should be refined before buffer size is
determined (mitigation)
![Page 15: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/15.jpg)
Large Action Areas(Endangered Species)
• Spray Drift – 360 degrees, wind blowing in all directions, simultaneously
• Threshold’ = EEC / LOC
• EEC from AgDrift
Significant overestimate of action area and potential
buffer distances
![Page 16: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/16.jpg)
Drift Overestimation – Impact on Agriculture
• Impact on agriculture (example)
• ~600 feet of field or parts of field cannot be treated
![Page 17: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/17.jpg)
Drift Overestimation –Impact on Agriculture
• ‘Freedom to operate’ for grower Possible need to remove land from production as more
buffers and larger buffers are required (value / cost?) Cost effectiveness of having to use ground applications
instead of aerial
• Resistance Development Cutting rates to meet buffer requirements No applications to certain parts of field Incomplete coverage due to coarser spray droplet
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Spray Drift – A Pragmatic Solution
• Need to find appropriate balance between efficacy, drift and resistance management, to allow cost-effective pest control. Model refinement is necessary – reasonable
conservatism ‘Drift education’ / Best Management Practices are critical Automation is desirable to allow flexibility
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REGDISP
• Model built on AGDISP (v. 8.26) • USFS made code available to Industry • the current EPA accepted version of AGDISP • desire to keep the mechanistic ground model
• No changes to existing AGDISP code existing • Better interface for AGDISP calculators• Enables parsing of data/ addition of data• Addresses issues with AgDRIFT described
19
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Canada Drift Regulation
• Pest Management Regulatory Agency in Canada worked with Dr. Tom Wolf of Agriculture and Agri-Food Canada (AAFC) and developed their own dataset as basis for their buffer zone calculator
• Launched in 2011
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REGDISP Data Sets
• Agricultural Agri Food Canada (AAFC) ‘2000• Agricultural Agri Food Canada (AAFC) ‘2004• Agricultural Agri Food Canada (AAFC) ‘2011• 49 unique AAFC Deposition Datasets
• Spray Drift Task Force ‘1992• Spray Drift Task Force ‘1993• 48 unique SDTF Deposition Datasets
• 97 unique deposition datasets
21
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Canadian Field Study Design (‘00 and ‘04)
XR8001, XR8003, AI110025, AI11005, AI11004 Nozzles
Fine to V. Coarse sprays
60 and 90 cm boom heights
Wind speed = 3 to 12 m/s
Single pass, 18m (60 ft) spray boom
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Data Fit Method
23
Log/Log Transform Data
1. Log Transform2. Simple Regression (y=mx+b)
10 1001E-4
1E-3
Fra
ctio
n of
App
lied
Distance (m)
0 20 40 60 80 100 120
0.000
0.001
0.002
0.003
0.004
0.005
0.006
Fra
ctio
n of
App
lied
Distance (m)
Since Deposition Data is highly non-linear
• Accurate description of data• Doesn’t assume drift is unlimited
![Page 24: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/24.jpg)
Deposition Data Calculation Tab
24
1. Select Dataset2. Select Nozzle3. Boom Height4. Wind Speed5. Enter Rate6. Run
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Use Existing Calculators (and Code)
25
Toolbox
![Page 26: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/26.jpg)
Consideration of DRTs in Risk Assessment
• DRTs are proposed for use in reducing the size of required buffers Promote Best Management Practices (BMPs)
• Recommendations for specific Spray Quality or Droplet Size likely needed to ameliorate ESA restrictions – and maintain a viable product
• REGDISP facilitates consideration of specific field data or combinations of DRTs in determining a suitable action area or buffer distance
![Page 27: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/27.jpg)
Pragmatic Approach to Spray Drift
• Use of REGDISP as conservative, yet realistic drift model No ‘infinite’ drift
Ability to refine ground spray drift estimates – spray quality, wind, DRTs, BMPs, etc.
Defines reasonable proximity/buffer distances to expedite FIFRA and endangered species risk assessments
• Education / Stewardship Promote Best Management Practices
CropLife, chemical producers, nozzle manufacturers, product distributors, retailers, etc.
Ag extension, federal/state agencies, universities
Continued research
![Page 28: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/28.jpg)
Pragmatic Approach to Spray Drift
• Use of automation of spray technology e.g. GIS on conjunction with automated nozzle
switching allows precision application with respect to buffer areas
• Need to provide spray drift options that growers and applicators can use today to:• allow safe use of products (human and
ecological),• without unduly impacting growers’ ability to
effectively produce crops
![Page 29: Accurate Modeling for Drift Reduction: General Overview and Regulatory Status April 11 th, 2014 Dan Dyer On Behalf of the CLA Spray Drift Issue Management.](https://reader035.fdocuments.in/reader035/viewer/2022081514/56649cbb5503460f94982eda/html5/thumbnails/29.jpg)
Thank you