Study for the development of a rapid and non-destructive method for copper analysis in vineyards towards a precision fungal defense strategy

Abstract. In the defense against downy mildew, copper is still widely used, particularly in organic management. At any rate, specific investigations are needed to significantly reduce the use of copper and minimize its environmental impact. This study, conducted in several farms in Friuli-Venezia Giulia (Northeast Italy), aimed to evaluate the concentration of copper on leaves in various climatic conditions, in order to create an important database for the development of a rapid control system through image analysis. The tests involved sampling leaves and grapes from bud break until the last treatment with copper-based products. After copper recovery using a nitric acid solution, the copper values were analyzed via ICP-AES analysis. Cuprotesmo imprints were also made on the same leaves to develop an application (APP) capable of quickly and non-destructively detecting copper on the leaf surface through image analysis. The analytical data revealed significant correlations between image analysis and copper values only in certain situations involving adult leaves. However, due to the variability in treatment situations, the use of the APP with image analysis for all copper defense scenarios is not yet feasible. Nevertheless, the results are encouraging and will serve for further extensive investigations to develop an image analysis system capable of detecting truly active copper and optimizing pesticide treatments for a precision defense strategy. This strategy aims to ensure low environmental impact, production sustainability, and grape quality.