Shtienberg, D. | Search bioRxiv

bioRxiv2026

Peacock Eye Disease Management (PedMan) System: Validation and Implementation in Addressing Key Biological Questions

Peacock eye disease, caused by Venturia oleaginea, is a major foliar disease of olive (Olea europaea) in Mediterranean regions, resulting in defoliation, reduced tree vigor, and yield losses. Effective disease management relies on precise fungicide timing. In this study, we validated a decision support system (DSS) named PedMan (Peacock eye disease Manager), designed to predict infection events and optimize fungicide application timing in highly susceptible olive cultivars based on rainfall and temperature conditions. The system was validated in seven independent grove experiments conducted during the 2023/24 and 2024/25 growing seasons in commercial olive orchards in Israel. In addition, simulation analyses were performed using weather data from 11 meteorological stations representing diverse climatic regions. Field validation showed that fungicide applications timed according to PedMan significantly reduced leaf abscission by approximately 60% compared with untreated controls. Applications made contrary to system recommendations did not improve disease control, confirming the reliability of both positive and negative predictions. Multi-season analyses indicated cumulative disease suppression, with up to 85% reduction in leaf abscission after three consecutive years of correctly timed applications. The system was implemented by olive growers in 2025/6 with applicable success. Simulation results showed that most infection events occurred in autumn and early winter, with rainfall as the primary driver in autumn and temperature as the main limiting factor in winter and spring. Across all regions and seasons, PedMan recommended 0-3 fungicide applications per season, comparable to or fewer than conventional spray programs. These findings demonstrate that PedMan is a robust, field-validated DSS that improves fungicide timing, enhances disease control efficiency, and supports sustainable management of peacock eye disease without increasing spray frequency under Mediterranean conditions.

plant biology↗

bioRxiv2023

Annual dynamics and distribution of Xylella fastidiosa in infected almond trees

This research focused on studying the dynamics of the bacterial pathogen Xylella fastidiosa in almond trees at different developmental stages and in various tree parts. The objective was to understand the annual distribution and concentration of X. fastidiosa within almond trees. Different tree parts, including leaf petioles, annual and perennial shoots, fruit parts, flowers, and roots, from ten X. fastidiosa-infected almond trees were sampled over two years. The distribution and concentration of X. fastidiosa were determined using qPCR and serial dilution plating. Throughout the study, X. fastidiosa was never found in the fruit, flowers, and roots of almond trees, but it was present in leaves and annual and perennial shoots. We show that the inability of X. fastidiosa to colonize roots is likely due to incompatibility with the GF677 rootstock. The presence of X. fastidiosa in shoots remained consistent throughout the year, while in leaf petioles it varied across developmental stages, with lower detection during early and late stages of the season. Similarly, viable X. fastidiosa cells could be isolated from shoots at all developmental stages, while in leaf petioles no successful isolations were achieved during the vegetative and nut growth stage. Examining the development of almond leaf scorch symptoms over time in trees with preliminary infections revealed that once symptoms have appeared on a single branch, other asymptomatic limbs were likely already colonized by the bacterium, hence, selective pruning of symptomatic branches is unlikely to cure the tree. Overall, this study enhances our understanding of X. fastidiosa dynamics in almonds and may have practical applications for its detection and control in almond orchards.

plant biology↗