SYMPOSIA PAPER Published: 01 April 2025
STP165220240015

Testing the Drift Reduction Potential of Some Adjuvants from Renewable Sources for Aerial Pesticide Applications

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Aerial pesticide applications in croplands can be a major source of pesticide exposure to pollinating insects, including off-target drift that occurs during and after the application of chemicals. Most pesticide applications in the lower Mississippi Delta are carried out by piloted agricultural aircraft. Pesticide adjuvants (PAs) are added to the tank mix to improve spray characteristics such as reducing drift. However, PAs can be as toxic as pesticide active ingredients. PAs with plant-based polymers appear to be less toxic to pollinators, and ongoing experiments have identified sodium alginate (SA) and fenugreek polymer (FP) as less toxic drift-reducing PAs. In this study, SA and FP were tested as drift-reducing PAs for potential aerial applications using a high-speed wind tunnel experimental setup. The droplet spectrum was analyzed by a Sympatec Helium-Neon Laser Optical System laser-diffraction instrument. The spray experiment was carried out with (1) water only as a control and (2) water and adjuvant as treatments. The drift reduction potentials of the adjuvants were analyzed based on droplet size (diameters of 10%, 50%, and 90% spray volume) and the proportion of driftable volume with droplets less than 150 µm. Our results indicate that SA, when added to water, reduced the droplet size instead of increasing it. Additionally, SA increased the proportion of driftable particles compared with water, which is not desirable. Although the FP polymer increased the droplet size, the reduction in the driftable proportion of droplets was modest and was significant only for the 1-g/L concentration tested using the 40-degree flat fan nozzle. In summary, neither SA nor FP at the concentrations tested can be used as adjuvants to reduce off-target drift for piloted aerial pesticide applications.

Author Information

Kannan, Narayanan
Pollinator Health in Southern Crop Ecosystems Research Unit, United States Department of Agriculture-Agricultural Research Service, Stoneville, MS, US
Fritz, Bradley
Aerial Application Technology Research Unit, United States Department of Agriculture-Agricultural Research Service, College Station, TX, US
Read, Quentin, D.
Southeast Area, United States Department of Agriculture-Agricultural Research Service, Raleigh, NC
Srinivasan, Rajani
Dept. of Chemistry, Geosciences and Physics, Tarleton State University, Stephenville, TX, US
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Pages: 134–147
DOI: 10.1520/STP165220240015
ISBN-EB: 978-0-8031-7752-9
ISBN-13: 978-0-8031-7751-2