Kinetics of Lipophilic Pesticide Uptake by Living Maize

We report the uptake of a lipophilic fungicide into the cuticle of living leaves of young maize from droplets of a suspension concentrate. The action of a coffee-ring effect is demonstrated during fungicide formulation drying, and the fungicide particle distribution is quantified. We develop a simple, two-dimensional model of uptake leading to a reservoir of cuticular fungicide. This model allows inferences of physicochemical properties for fungicides inside the cuticular medium. The diffusion coefficient closely agrees with literature penetration experiments (Dcut approximate to 10-18 m2 s-1). The logarithm of the inferred cuticle-water partition coefficient log10 Kcw = 6.03 +/- 0.04 is consistent with ethyl acetate as a model solvent for the maize cuticle. Two limiting kinetic uptake regimes are inferred from the model for short and long times, with the transition resulting from longitudinal saturation of the cuticle beneath the droplet. We discuss the strengths, limitations, and generalizability of our model within the cuticle reservoir approximation.

Automated summary

This study reports the uptake of a lipophilic fungicide into living leaves of young maize from droplets of a suspension concentrate. The coffee-ring effect during fungicide formulation drying and the fungicide particle distribution are studied. A simple, two-dimensional model of uptake is developed, which leads to a reservoir of cuticular fungicide. The model allows inference of physicochemical properties for fungicides inside the cuticle.