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Spray Drift – What causes it and how to avoid it Tom Wolf AgriMetrix Research and Training Saskatoon, Pesticide Applicator.

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Presentation on theme: "Spray Drift – What causes it and how to avoid it Tom Wolf AgriMetrix Research and Training Saskatoon, Pesticide Applicator."— Presentation transcript:

1 Spray Drift – What causes it and how to avoid it Tom Wolf AgriMetrix Research and Training Saskatoon, Pesticide Applicator Certification For: Professional Development Solutions

2 Drift – The Ambassador of Spraying

3 Application Goals 3 Es of Pesticide Application Effective Efficient Environmental Norman Morgan

4 Airborne movement of droplets or vapours from the treated area Spray Drift Droplet drift usually occurs within minutes of the application, vapour drift can occur minutes or days after application

5 On-Swath Deposit Low boom Slow speed High boom Fast speed

6 5-120 m 5 m 2 m 1.7% 5%82% 100% 0.3% Drift Spray Accountancy On TargetOff Target 1 m 10% 1%

7 45 M kg x 80% sprayed x 1.7% airborne loss = 612,000 kg The Size of the Problem

8 Drift Patterns

9 Deposit Patterns

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12 Drift Causes

13 Small Droplets WindDrift!

14 Droplet drift Wind speed Atmospheric turbulence - thermal - mechanical Droplet size Droplet velocity - sprayer type - pressure Initial size - sprayer type - nozzle type, size - pressure - formulation Rate of evaporation - temperature - RH Transit time - velocity - boom height Factors Involved in Spray Drift

15 What Causes Drift? Low Energy Exposure to Force Movement

16 Strategy Low Energy Increase size Increase velocity e.g. low drift nozzles, air assist Exposure to Force Protect Decrease exposure time e.g. shrouds, low booms, slow travel

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19 Areas of unequal pressure create vortices which remove small droplets from the spray cloud

20 Nozzle selection Sprayer settings Focus is droplet size and boom height Reducing the Problem

21 Drift Potential ER8003 DR SR psi 40 psi 75 psi Nozzle Type Flow Rate Fan Angle Spray Pressure Drift Potential

22 Droplet Size Distributions

23 Spray Quality

24 Field Tests

25 Flexi-Coil Field Sprayer XR8003, 40 psi AI110025, 58 psi Application volume = 100 L/ha Travel speed = 13 km/h

26 Medium

27 Very Coarse

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29 TT11005, 40 psi AI11004, 64 psi Gregson High-Clearance Sprayer Application volume = 100 L/ha Travel speed = 22.5 km/h

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31 Boom Height Drift potential doubles for higher boom Use auto boom-height controller

32 Auto-Boom

33 Reduced Spray Pressure? Conventional flat fans psi Pre-orifice psi Air-Induced 40 – 60 psi (low-pressure type) 60 – 80 psi (high pressure type) Ensure that patterns are optimal

34 Droplet Velocity (Energy)

35 Droplet Velocity Distributions

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37 Principle of HARDI TWIN air assistance

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39 Air OffAir On

40 Drift - at various wind speeds (data from Hardi)

41 Little DriftLots of Drift

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43 Courtesy of Paul Miller, SRI Models and Regulations

44 New Buffer Zone Label Language Untreated (Buffer Zone) 20 m Conventional application 15 m Low-drift application untreated 5 m Very low-drift application untreated

45 Do not apply with spray droplets smaller than ASAE medium classification …When using a shroud, BZ can be reduced by 70%...

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47 Buffer Zone Calculator

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54 spc/pest/agri-commerce/drift- derive/index-eng.php

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57 Atmospheric Conditions Courtesy George Ramsey, DuPont

58 Daily Wind Pattern Time of day (h) Wind speed at 1 m height (m/s)

59 Mechanical Turbulence

60 Thermal Turbulence

61 Unstable (Desirable normal daytime conditions) Stable (inversion) Spray cloud disperses, moving upward and downwind Spray cloud hangs over treated area in high concentration Warm Soil Cold soil Cold air - dense, still Warm, still air Inversion Conditions Dispersion

62 Height Temperature Height Temperature Unstable Stable (Inversion)

63 3 pm 11 pm Sunset 10 pm 3 am5 am Sunrise 5 am 7 am8 am9 am3 pm Temperature Height

64 3 pm 11 pm Sunset 10 pm 3 am5 am Sunrise 5 am 7 am8 am9 am3 pm

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70 Wind Calm conditions not well suited for spraying unpredictable wind direction sometimes mistaken for inversions Low, steady winds ideal Predictable direction Dilution of spray cloud High winds increase total loss, but do not always increase deposits

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72 Delta T (droplet evaporation)

73 Most Important Factors Governing Drift Trained, conscientious operator Communication / Relationships Weather Conditions Spray Quality Shrouds Boom Height Travel Speed


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