I. W. Kirk
USDA - ARS Areawide Pest Management Research Unit
College Station, Texas
"An extensive research effort has been conducted on spray drift and related issues
by the SDTF through their various contractors. Some of the studies documented
principles/issue/questions in a systematic way that were generally acknowledged and
accepted in the agricultural aviation industry based on data from previous research
reports and/or experience. But credit where credit is due: there is no way that we would
have the current understanding and associations related to spray drift had not the
agricultural chemical industry and the EPA worked together through the SDTF to conduct and
document these studies."
Charles L. Mulchi, Ph.D.
Professor of Environmental Sciences
Department of Natural Resource Sciences and Landscape Architecture
University of Maryland
"The number of reports and overall volumes of information on the individual tasks were vary extensive. The individual field and laboratory studies were well designed and carried out very close to specifications described in the protocols. There were minor deviations in the field studies from case to case, but nothing that would substantially influence the quality of results or affect the outcome of the study. Each study report provided a large data base on the treatments under investigation which, when viewed collectively, (Johnson 194-001; Johnson 194-002: Johnson 195-004; Johnson, and T95-004) gave the reviewer an excellent overview of the SDTF program. Each individual study was designed to provide the SDTF with specific information concerning the general behavior of spray droplets when applied in modes as illustrated in the "application matrix" for both ground and aerial applications. Thus, the individual studies were never intended to be "all inclusive with respect to supplying information on all possible combinations of treatment variables suspected of affecting spray drift. However, when viewed collectively, the investigation span a very broad spectrum of variables affecting the current modes of application for agrichemicals in the USA. Collectively, the SDTF reports likely represents the most comprehensive such data base ever assembled concerning spray drift and provides the foundation for the development and testing of models to depict the behavior of spray droplets representing a broad array of agricultural chemicals and application modes. I found the report by Kidd (L 92-001) summarizing survey information supplied by aerial applicators to be both interesting and alarming. The Kidd reports revealed the need by both industry and government regulators to supply more information to applicators concerning the drift potential for individual chemicals when applied in specific modes. The SDTF program as outlined in the various reports should effectively address this information deficit regarding off target deposition of agrichemicals."
Naiqian Zhang
Dennis K. Kuhlman Professor and Dean
College of Technology and Aviation
Kansas State University
"
The field tests conducted by SDTF, including the field tests for ground application, aerial application, and airblast application, studied the effects of many factors on off-target drift. In an attempt to address the combined effect of several factors on drift, an application matrix was designed to divide treatments into groups. In order to study the effects of meteorological conditions on drift, a covariate analysis method, which pared each treatment with a ‘standard’ treatment, was used. Considering the complexity of the combined effects of various factors on drift and the cost related to the large-scale tests, the reviewers fully appreciate the merits in the experimental design. However, the reviewers also felt that several problems need to be further addressed in order to insure the validity of the data collected during the field tests and the conclusions drawn from statistical analyses of the data."
Norman B. Akesson, Professor (Em)
Bio-Agr Engineering Department
University of California, California 95616-5294
"A few general comments would seem to be in order which can serve as an introduction to my technical report. In respect to the SDTF pesticide drift project it should be clearly stated that the undertaking of this work by the members of the pesticide chemical industry is highly commendable and unquestionably needed as a further step in all of our interest, for a wholesome and pesticide free food supply. The industry has provided not only generously of manpower to conduct this work, but an almost universal support has been given to the project by the pesticide chemical formulators, manufacturers and distributors who have provided the funds to enable the conduct of the project.
"There is a wealth of pesticide drift field data and atomization studies which I and others have contributed to since the early 1960’s. But this work, conducted primarily by Agricultural Experiment Station, USDA and Forest Service personnel, was quite individualistic and was seldom carried beyond a limited set of field studies, generally in relation to a particular pesticide chemical in a particular locality and on a specific drop or forest or brush problem. Papers on the subject of pesticide drift were presented to a variety of meetings and conferences including ASAE, ASTM, ILASS and ICLASS (these latter two being atomization congresses) and occasionally at Entomological, Toxicological (ACS), Atmospheric Science and Weed Science conferences. The wide range of disciplines represented reflects the very broad involvement of scientists in pesticide use and safe use. But there is also a lack of continuity where several disciplines are involved and there was no national group seemingly involved enough to take on the gathering of data and organizing this into a national level standard of safe and effective pesticide use. Instead the work was largely at the local state and even specific localities within a state such as the Sacramento, San Joaquin, Salinas and Imperial valleys of California.
"The decision by the pesticide chemical industry to pursue this work represents a giant stride towards better understanding of the problems, limitations and potential hazards of pesticide chemical use nation wide. The public concept of pesticide chemical use continues to be critical, a recent survey by a national newspaper indicated that of the top twenty "fears" that people had, pesticide chemical exposure continues to rate at a surprising seventh from the top, representing 35% of those in the survey. The pesticide "fear" appeared to be related to food in that an equal fear was identified for meat poisoning with Alzheimer’s coming in at about the same level. However, fears of automobile crashes and getting cancer, and financial fears rated the three highest on the list of "fears".
"In terms of food production, in which we all hold a critical stake, the decision by the pesticide chemical industry to support this project represents a bold move toward facing up to the responsibility we all have as members of the Agriculture and Food Production Community. However, many questions concerning pesticide application and mitigation of drift losses have either not been addressed or only partially so. Support for continuation of this highly necessary work should logically come from the pesticide industry people who have shown that they can work as a cooperative support group to help define the effective and safe us of pesticides."
J. R. Williford
Heinz Biermann, Ph.D.
"In general, the design of the Spray Drift Task Force’s research efforts was quite thorough; and the use of standard (covariate) applications to control for inter-treatment environmental variability seem to have been a sound approach, even if it did work only for the series of aerial application trials."
Data Analysis
"The one problem we see with the use of any statistical data analysis methodology, including that used to generate these reports, is that such analysis focuses attention on the central tendencies of the data sets. In general, it can be assumed that in the real world, serious drift problems occur under unusual or extreme conditions, be the causative agent meteorological conditions, equipment, or spray material. It is likely that the extremes of the distributions of the data sets will yield the most interesting tales about drift."