Forestry Pesticide Aerial Spraying: Spray Droplet Generation, Dispersion, and Deposition

224 Pages·1997·8.92 MB·English

by  J. J. C. Picot

Forestry Pesticide Aerial Spraying
Environmental Science and Technology Library
VOLUME 12
The titles published in this series are listed at the end of this volume.
Forestry Pesticide
Aerial Spraying
Spray Droplet Generation,
Dispersion, and Deposition
by
J.J.C. Picat
Department of Chemic al Engineering,
University of New Brunswick,
Fredericton, NB, Canada
and
0.0. Kristmansan
formerlyof
Department of Chemical Engineering,
University of New Brunswick,
Fredericro~NB,Canada
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
Library of Congress Cataloging-in-Publication Data
Picat, J. J. C.
Farestry pesticide aerial spray ing : spray draplet generatian,
dispersian, and depasitian I by J.J.C. Picat and 0.0. Kristmansan.
p. cm. -- (Enviranmental science and technalagy library ; v.
12)
Inc 1u des index.
ISBN 978-94-010-6375-3 ISBN 978-94-011-5634-9 (eBook)
DOI 10.1007/978-94-011-5634-9
1. Aerial spray ing and dusting in farestry--New Brunswick.
2. Farest insects--Cantral--New Brunswick. 3. Aerlal spray ing and
dusting In farestry. 4. Farest insects--Cantral. I. Kristmansan,
D. D. II. Title. III. Series.
SB764.C36P53 1997
634.9·694--dc21 96-37439
ISBN 978-94-010-6375-3
Printed on acid-free paper
AII Rights Reserved
© 1997 Springer Science+Business Media Dordrecht
OriginallY published by Kluwer Academic Publishers in 1997
Softcover reprint of the hardcover 1s t edition 1997
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical,
including photocopying, recording or by any information storage and
retrieval system, without written permission from the copyright owner.
T ABLE OF CONTENTS
CHAPTER 1 INTRODUCTION
1.1 Historical Perspective ................................... 1
1.2 Scope and Orientation of Text ............................. 3
CHAPTER 2 CHARACTERIZING FOREST STANDS
2.1 Foliage Density and Vertical Distribution .................... 5
2.2 Forest Micrometeorology ............................... 10
2.3 Foliage as Filter for Atmospheric Particulates ............... 15
2.4 Foliage Simulators ..................................... 19
2.5 Importance of Properly Defining the Biological Interface ...... 23
CHAPTER 3 PROPERTIES OF SPRAY FORMULATIONS
3.1 Biological Toxic Requirement and Droplet Size ............. 26
3.2 Effects of Viscosity, Surface Tension, and Volatility .......... 29
3.3 Summary ............................................ 39
CHAPTER 4 SPRA Y AIRCRAFT AND ATOMIZERS
4.1 Aircraft in Use ........................................ 41
4.2 Aircraft Wake Behaviour ............................... 44
4.3 Droplet Generation and Atomizer Types ................... 50
4.4 Atomizer Characterization Methods ....................... 54
4.4.1 The PMS Spectrometer .......................... 55
4.4.2 The Malvern Spectrometer ........................ 64
4.4.3 Other Spectrometer Devices ....................... 67
4.5 Atomizer Droplet Spectrum Data ......................... 67
4.6 Correlations for Atomizer Emission Characteristics ........... 73
4.7 Dry Material Dispensing Devices ......................... 73
CHAPTER 5 RESEARCH FIELD TRIALS
5.1 Introduction .......................................... 78
5.2 Measurements and Analytical Methods .................... 79
vi TABLE OF CONTENTS
5.3 The Mass Balance Test as a Measure of Accuracy In Field Trials 90
5.4 Experimental Design, Management, and Costs ............... 91
CHAPTER 6 MODELING SPRAY APPLICATION, DISPERSION,
AND DEPOSITION
6.1 Introduction .......................................... 97
6.2 Details of the PKBW model ............................. 99
6.1.1. Wake Velocity Distributions ...................... 99
6.1.2. Trajectory Calculations .......................... 99
6.1.3 Velocity and TurLulence in the Atmospheric Boundary
Layer ........................................ 102
6.1.4 Calculating Deposition on Canopy and Ground ...... 104
6.1.5 Input Data for a Typical Run ..................... 105
6.1.6 Output for the Example ......................... 105
6.3 Model Validations and Comparisons: PKBW Model ........ 1.11
6.4 Off-target Drift and Buffer Zone Estimation. . . . . . . . . . . . . . . . 114
6.4.1 Some Field Data ............................... 114
6.4.2 Use ofPKBW for Drift Analysis ................. 124
6.5 Simulation of Block Spraying, PKBW Model .............. 126
CHAPTER 7 SPRAYING IN COMPLEX TERRAIN
7.1 Introduction .................................... 130
7.2 Air flows in Well-defined Mountain Valleys ............... 130
7.3 Implications with Respect to Pesticide Spraying ............ 130
7.4 Predicting Pesticide Dispersion and Deposition in Valleys .... 134
7.5 Comment ........................................... 137
CHAPTER 8 SPRAYING INNOVATIONS
8.1 Introduction ......................................... 139
8.2 Drop Size Optimization ................................ 139
8.2.1 The Concept .................................. 139
8.2.2 Field Confirmation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
8.3 Field Trials for Dose Efficacy Measurements ............... 142
8.4 Aircraft Navigation and Data Logging ................... ~ 145
8.5 Investigating Possible Improvements in Application Methods
with PKBW ......................................... 148
8.5.1 Utilization and Drift ofa Phytotoxic Herbicide ....... 148
8.5.2 "Smart" Formulations .......................... 153
TABLE OF CONTENTS vii
CHAPTER 9 PESTICIDES AND GOVERNMENT REGULATIONS
9.1 Introduction ......................................... 156
9.2 Federal and Provincial Regulations in Canada .............. 157
9.3 Specific Excerpts from FIFRA .......................... 170
9.4 The Training of Pesticide Applicators and the Inspection of
Application Equipment ...... . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Appendix I SPRAY EFFICACY RESEARCH GROUP (SERG) 176
Appendix II ATOMIZER CHARAC1ERIZATION DATA .... 178
Appendix III DETAILS OF AGDISP, FSCBG, AND PKBW
MODELS .................................... 206
Index .................................................... 209
PREFACE
Introduced to the technical aspects of forestry aerial spraying in the mid-1970's,
we were immediately impressed by the complexity of the process of delivering
pesticide to foliage. At that time, there was a vigorous public debate in New
Brunswick about the ecological and public h~alth impacts of the annual spray
program for the control of defoliation of spruce and fir trees by the spruce
budworm. The forest industry is important to the province and changes to the
established procedures of budworm control could have major economic
implications. A rational debate required reliable information about the mechanics
of the spraying process. There was a need to supply missing information as to
required pesticide application rates, atomizer performance, off-target drift and
deposit, and the effects of weather and aircraft operating factors. We were invited
to initiate a research program in this domain by New Brunswick forest
management officials, and what follows in this book is a logical and quantitative
description of the overall process based on our own research and that of others
over the intervening years.
After a short introduction to aerial spraying, we begin (Chapter 2) by
describing forest stands in terms of their interaction with suspended atmospheric
particulate material carried along by the wind and susceptible to deposition on
foliage. We introduce foliage simulators and their use in measuring the deposit of
sprayed pesticide on foliage, the "biological interface" between pest and pesticide.
Chapter 3 treats the relationship between toxic requirement for pest control and
droplet size, and the effects of physico-chemical properties of the formulation on
droplet size. In Chapter 4, in addition to a cursory discussion of spray aircraft
types and wake behaviour, we present a detailed account of spray atomizer droplet
characterization methods and equipment, with an innovative use of the Malvern
droplet spectrometer for flux-based droplet spectrum measurements. Tables of
droplet spectrum data are given in Appendix II.
Chapter 5 summarizes spray field trial methods and management, with a
discussion of the importance of the mass balance criterion in assessing the overall
accuracy of results.
All of the mechanisms of the spray generation and deposition process are
brought together within the framework of the PKBW computer model in Chapter
6. This is a droplet trajectory model permitting the calculation of deposited droplet
size and density on the biological interface, as well as size and concentration in the
drift cloud. Long-distance drift calculations are presented, as are model validation
results.
x PREFACE
The last three chapters cover recent USDA Forest Service research on
spraying in complex terrain, a presentation of some recent spraying innovations,
and a review of some government regulations relating to pesticide application.
We claim here to have a unique quantitative treatment of the many
mechanisms involved in the pesticide application process. With the methods
described here, it is possible to get a detailed and accurate prediction, via
computer simulation, of droplet deposition and downwind drift of pesticide
droplets. This offers an unparalleled tool in the continued development of
pesticide application technology.
We strongly encourage scientists, regulators, and forest managers to use
the technology presented here in the i.-:terest of environmentally conscious forest
management.
J.J.C. Picot, Fredericton, N.B.
D.O. Kristmanson, Surrey, B.c.
ACKNOWLEDGEMENTS
We recognize here the central role played by Mr. H.J. (Bud) Irving, then Managing
Director of Forest Protection Ltd. of Fredericton, N.B., in initiating our interest in
spray technology research and continuing as a "pons or and mentor of our research
activities over the years. Acting on the advice of Dr. Frank Webb, former Director
of the Maritimes Forest Research Center, he was successful in getting the
collaboration of scientists from a wide range of disciplines in addressing problems
in pesticide application technology soon after assuming his responsibilities in
1975.
Our early learning experiences in this domain were greatly enhanced by
interaction with colleagues already active in various aspects of spray technology
research. Principal among these were R.S Crabbe of the National Research
Council (NRC), Ottawa (dispersion of atmospheric pollutants and field trials);
John Reid, Environment Canada, Ottawa (modelling the transport of atmospheric
particulates); W.I. Varty, Forestry Canada, Fredericton (first chairman of
interdisciplinary committee on monitoring of spray drift in N.B.); R.H. Wickens,
NRC, Ottawa (wind tunnel operation and design, aircraft vortex behaviour); and
Charles Wiesner, N.B. Research and Productivity Council (RPC), Fredericton,
N.B. (first coordinator of the New Brunswick Spray Efficacy Research Group
(now known as SERG)). Later, we were given valuable assistance by J.W. Barry,
USDA Forest Service, Davis, CA, and lE. Hirsh, Princeton Aeronautical Research
Associates, Princeton, N.J. in the area of aircraft spray transport and wake
modelling. We greatly benefited from discussions with Professors Norman
Akesson and Wesley Yates of the University of California at Davis, and earlier
with R. Courshee, S. Parkin, and V. Joyce of the Cranfield Institute of
Technology, Cranfield, England.
Our research team at the University of New Brunswick has included many
talented and dedicated individuals. Mr. Alfred Knappe, Chief Technician in our
Chemical Engineering Department, was responsible for constructing the
SERG/ONAIR prototype atomizers, and our wind tunnel with his assistant Brian
Hawkins. Excellent work was done by the following graduate students over the
years: Bruce Smedley, Terry Tornney, Malcolm Thompson, Xavier Bontemps,
Nusin Basak-Brown, Michael Pang, David Wallace, and Robert Goguen. Stability
and continuity in our wind tunnel and field trial work were assured by the efforts
of Research Engineer Mark van Vliet assisted by Gary Henderson, Research
Technician.