Distinct Drivers for Fungicide Uptake, Total Translocation, and Translocation Direction

Abstract

Fungicide distribution in planta affects the efficacy but lacks quantitative characterization. We used LC-MS/MS to separately quantify uptake, total translocation, and basal translocation of 14 structurally diverse fungicides and correlate each behavior with physicochemical properties. Formulation strongly affected uptake but not necessarily translocation. Uptake ranged 18-fold (1.5–27% of dose), total translocation 25-fold (3.3–83% of uptake), and basal translocation 90-fold (0.05–4.6% of translocated fungicide). Lipophilicity, the proposed primary predictor of systemic movement, did not alone explain these behaviors. Uptake and total translocation decreased with molecular weight, and uptake was further reduced for polar, chemically reactive, flexible, and highly lipophilic molecules. The basal movement increased with polarity. Warmer temperatures increased early total translocation and uptake and dissipation of flutriafol and cyproconazole. Systemic movement occurs on a continuum determined by active ingredient chemistry rather than formulation, with distinct physicochemical properties influencing uptake, total translocation, and translocation direction.