Systemicity of fungicides in grapevines assessed using 14C radiolabelling

Chemical control is among the most widely used strategies in plant disease management and remains essential in many agricultural pathosystems. Understanding the dynamics of fungicide absorption and translocation within plants is therefore critical for optimising control strategies. This study aimed to evaluate the foliar absorption and translocation of three systemic fungicides, epoxiconazole, pyraclostrobin, and fluxapyroxad, in grapevines. Commercial formulations containing (14C)-labelled molecules were used. Applications were performed with a micro-applicator on specific grapevine leaves, and absorption and translocation were quantified at five-time intervals (3, 9, 24, 48, and 72 hours after application) using liquid scintillation spectrometry and autoradiography. The results indicate that fluxapyroxad exhibited the lowest absorption throughout the evaluation period. After 72 hours, 64 % of the fluxapyroxad remained on the grapevine-treated leaf, which was twice the amount observed for epoxiconazole and pyraclostrobin. Therefore, in grapevine leaves, the majority of the absorbed products of all three systemic fungicides remained at the site of application, when intertissue mobility was low, below 0.2 %, with reduced but detectable systemic translocation. These findings contribute to a better understanding of the dynamics of the absorption and translocation of these compounds in grapevines, providing a basis for the development of more effective plant disease management strategies.