Drifting of fine droplets during the application of pesticides is an issue of increasing commercial and regulatory importance. Spray drift damages susceptible crops, wastes resources, and results in inconsistent weed control. Several strategies are currently used to mitigate this problem. These include enhanced nozzle technology, improved application techniques, and inclusion of drift control additives in the final tank mix. Elimination of small diameter droplets ("driftable fines") is a key goal. Measurements were made of droplet size distributions of sprayed pesticide formulations containing commercial products representative of the leading drift control technologies, including guar, polyacrylamides, lecithin, and oil/surfactant mixtures. Effects of spray nozzle and pressure were also evaluated. Nozzle technology plays a large role in determining the spray droplet size spectrum. However, there is a strong interplay between nozzle design and formulation variables. We found that drift control agents have greater impact on spray from flat fan nozzles. Also, the ranking of adjuvants depends on the nozzle technology in use: for glyphosate/ammonium sulfate solutions, polymers were more effective in reducing fines from a flat fan nozzle, while surfactant-based products were marginally superior when an air induction nozzle was used. The regulatory community is currently focused on mitigating the generation of small droplets. However, the generation of oversized droplets also effects spray efficacy. The impact of drift control agents on the breadth of the droplet size spectrum is an aspect of drift control which is often overlooked. We found that emulsion-based products tighten the droplet size distribution, while the polymer-based products shift the mean droplet diameter up, broadening the distribution in the process: while the latter effect may earn better ratings from regulatory agencies concerned exclusively with spray drift mitigation, it may be less helpful in enhancing application efficacy.

Increased public concern about pesticides requires that foresters reduce drift and insure precise application of herbicides to the areas requiring treatment. Drift control is necessary near waterways and other ecologically sensitive areas. This publication discusses available drift control adjuvants for herbicidal sprays. These include invert emulsions, thickening agents, particulating agents, and foam sprays. Commercially available adjuvants are described and their use, advantages, and disadvantages are discussed. Thickening agents and foam sprays show special promise for drift reduction in aerial application of herbicides on forest lands.

This practical guide focuses on managing the risks of spray drift and includes information on appropriate handing practices to ensure a safe workplace.

Studies of Adjuvants involve many scientific fields from basic research of the chemistry, through investigations into physiological effects and environmental impact, to mixture formulation and field use. These important areas are illustrated in these two volumes, which are contributions from the First International Symposium on Adjuvants for Agrochemicals, held in Brandon, Manitoba on August 5 to 7, 1986. A total of 200 participants from 19 countries met to discuss their common interest in adjuvant science, technology, and application. It is the editors hope that these volumes will stimulate interest in and promote a better understanding of the chemical, physiological, and agronomic aspects of adjuvants as they relate agrochemicals. In addition, the revisedAdjuvants for Agrochemicals: A Selected Bibliography of World Literature in the English Language will be a valuable resource for agricultural researchers and other users. We hope that adjuvant research will lead to even safer, more efficient, and more economical use of chemicals in agriculture and forestry.

Drift Reduction Agent has been defined in ASTM Standard E1519 Terminology Relating to Agricultural Tank Mix Adjuvants as "a material used in liquid spray mixtures to reduce spray drift." ASTM Standard E609 Terminology Relating to Pesticides defines drift as "the physical movement of an agrochemical through the air at the time of application or soon thereafter to any non- or off-target site. Drift shall not include movement to non- or off-target sites caused by erosion, migration, volatility or wind blown soil particles that occur after application unless specifically advertised on the label." Because there are many commercial tank mix adjuvants designed to reduce spray drift, there is a need to establish an ASTM Standard Test Method to evaluate their effectiveness. ASTM Standard E2798 is the new test method developed for the Characterization of Performance of Pesticide Spray Drift Reduction Adjuvants for Ground Application. This paper presents the data generated from the round-robin testing of this method. The method provides guidelines for the measurement of parameters pertaining to the performance of drift reduction adjuvants under simulated field application conditions. The measurements can be made in a wind tunnel or a spray chamber. The method describes the preparation, composition, and test/application conditions for droplet size, spray pattern measurements, and fines reduction. The exact selection of application conditions such as nozzle type and tank mix partner may vary according to the intended use conditions.

Pesticide Formulation and Adjuvant Technology brings together experts from industry, academia, regulatory offices, and the legal profession to provide a complete and international reference on agrichemical formulations and modern adjuvant technology. Global specialists discuss key topics, from scientific and technical issues to regulatory and legal aspects, including: