Evaluation of Equisetum arvense (Horsetail Macerate) as a Copper Substitute for Pathogen Management in Field-Grown Organic Tomato and Durum Wheat Cultivations

Effective pathogen management, as an aspect of agroecological crop protection (ACP) necessitates the replacement of copper (Cu) fungicides, but there is little knowledge relating to the performance of potentially suitable alternatives in large-scale, open-field agricultural settings. The present study was aimed at investigating the potential of Equisetum arvense (horsetail macerate) compared to Cu-based treatments for the control of Solanum lycopersicum. and Triticum turgidum ssp. durum fungal pathogens in established organic commercial farms located in Emilia Romagna (Italy) over a three-year period (2017-2019). Both the Cu-based and horsetail foliar sprays were routinely applied as preventative treatments and in the event of pathogen establishment as curative treatments. The Cu-based and horsetail macerate treatments were both equally effective at significantly reducing Phytophthora infestans (late blight) and increasing yield in tomato compared to the untreated control. For durum wheat, the horsetail macerate and Cu-based treatments were successful at significantly reducing Puccinia triticina (brown rust) infection and increasing yield under moderate infection, but unsuccessful under unfavorable meteorological conditions resulting in the combined and severe spread of Puccinia triticina, Fusarium graminearum, and Zymoseptoria tritici. From the present results, horsetail macerate is a promising and suitable Cu-free ACP alternative for late blight management of tomato.