Long-term effects of Trichoderma asperellum and Trichoderma gamsii on the prevention of esca in different vineyards of Northeastern Italy

Abstract Among wood diseases, esca complex has increased over the last decades around Europe, and there are no chemical solutions that can limit its spread in vineyards. During a 7-year trial in 3 vineyards, half of the surface was sprayed every season with a solution of Trichoderma asperellum and Trichoderma gamsii at the phenological stage of bleeding, and half of the vineyard remained untreated. During August and September every year, the fate of esca symptoms on the single vines was monitored, distinguishing light, medium-to-severe leaf tiger stripe symptoms, and acute symptoms, including apoplexy. During the 7-year period, the vines affected by esca (all symptoms) increased over time in both the control and the sprayed treatments. Among the symptoms, Trichoderma was demonstrated to reduce the impact of both light tiger-stripe symptoms and apoplexy, while no significant differences were shown in the medium-to-severe symptoms A 22% reduction in the incidence of infected vines was ascertained after seven years of Trichoderma application. Regarding meteorological conditions, a significant positive correlation was found between the amount of rain in May and the occurrence of Esca in the field at the end of the season.