Kinetic Resolution of the Interactions between Agrochemical Products and Adjuvant Systems upon Mixing

Abstract

The addition of an adjuvant to a pesticide usually occurs in a mix-tank, before spray application to the crop. Their interaction is potentially crucial to overall efficacy but has received little attention from a physical−chemical perspective. Study was undertaken by laser diffraction, Raman spectroscopy, and small-angle X-ray scattering to resolve these physical processes. It was shown that migration of the pesticide into the adjuvant droplet occurred in all cases studied. The level of transfer was dependent upon adjuvant level, adjuvant solubility, and surfactant level. For suspension pesticides, dissolution of crystallites within the droplet occurred to a degree limited by solubility. The results directly demonstrate the transfer of the pesticide into the adjuvant carrier. This indicates that for emulsion-based pesticides, application to the target is likely as a homogeneously mixed droplet, whereas for suspension pesticides, solubility may limit transfer and dissolution, leading to heterogeneity in the applied particles.

Tristearin as a Model Cuticle for High-Throughput Screening of Agricultural Adjuvant Systems

“…The conventional application of adjuvant products is through spray deposition onto the leaf surface of the crop with subsequent drying of the deposited droplets on the leaf surface through environmental exposure. 20 To that end, the application of the adjuvant products to a film of tristearin with subsequent drying was also undertaken to allow comparison of the premix and surface-applied methodologies. The study of the aqueous application of the individual components was not possible as homogeneous systems could not be formed due to immiscibility of the oils with water, consequently the aqueous surface application studies were limited to the complete adjuvant products.…”

“…Although demonstrated to give useful trending information, the use of the model cuticle for the study of adjuvants and their components are of greater values if they correlate with real world application conditions. The conventional application of adjuvant products is through spray deposition onto the leaf surface of the crop with subsequent drying of the deposited droplets on the leaf surface through environmental exposure . To that end, the application of the adjuvant products to a film of tristearin with subsequent drying was also undertaken to allow comparison of the premix and surface-applied methodologies.…”