Control of Apple Scab in Commercial Orchards Through Primary Inoculum Management

Abstract

Apple scab, caused by Venturia inaequalis, is one of the most important diseases in apples in all production regions and its sustainable control is still a challenge. The aim of this work was to optimize the control of apple scab through different environmentally friendly inoculum management strategies, specifically the removal of fallen leaves in winter and the treatment of ground leaves with the biological agent Trichoderma asperellum (T34 BIOCONTROL®) to inhibit or prevent inoculum development in commercial orchards. The results obtained from 4 years of trials in commercial orchards demonstrated that the combination of fungicide treatments and leaf litter management, particularly through aspiration, significantly reduced the development of apple scab in comparison with strategies commonly used by growers that are based solely on fungicide application. Both the incidence and severity of the disease in leaves and fruit decreased by over 90% when inoculum management and fungicide treatments were combined. These results highlight that reducing the source of inoculum by removing fallen leaves is an effective strategy that complements fungicide or biological control agent applications. In conclusion, combining eco-friendly strategies with standard fungicides and monitoring environmental conditions can help to reduce the frequency of phytosanitary applications, ultimately contributing to the goal of minimizing their use in the control of apple scab.