Effects of Inorganic Substances Used in Late-Season Apple Scab Management on Disease Incidence and Productivity in Two Orchard Systems of cv. ‘Ligol’

Abstract In apple production, reducing the use of synthetic pesticides may be possible by using inorganic substances in the second part of the season against secondary scab infections. An investigation was conducted to evaluate strategies for controlling apple scab. The trial comprised the following treatments: synthetic fungicides applied to manually pruned slender-spindle canopy trees; synthetic fungicides applied during the primary scab infection period and inorganic substances during the secondary period; and synthetic fungicides applied only during the early stages of apple scab infection for mechanically pruned trees with a vertical axis canopy. The incidence of apple scab in ‘Ligol’ was strongly influenced by season, treatment, and canopy management, with secondary infection periods being critical for disease control. Combining synthetic fungicides in the primary period with inorganic substances in the secondary period effectively reduced fruit infection while limiting chemical use. Vertical-axis orchard systems showed higher yield efficiency per canopy volume. Overall, integrated management strategies, including pruning, canopy design, and targeted fungicide application are essential for optimising yield and fruit health under variable seasonal conditions.