Seasonal Dynamics and Distribution of in Infected Almond Trees.

This research focused on studying the dynamics of the bacterial pathogen in almond trees across different developmental stages. The objective was to understand the seasonal distribution and concentration of within almond trees. Different tree organs, including leaves, shoots, branches, fruits, flowers, and roots, from 10 -infected almond trees were sampled over 2 years. The incidence and concentration of were determined using qPCR and isolation. Throughout the study, was consistently absent from fruits, flowers, and roots, whereas it was detected in leaves as well as in shoots and branches. We demonstrate that the absence of in the roots is likely linked to the inability of this isolate to infect the peach-almond hybrid rootstock GF677. incidence in shoots and branches remained consistent throughout the year, whereas in leaf petioles, it varied across developmental stages, with lower detection during the early and late stages of the season. Similarly, viable cells were isolated from shoots and branches at all developmental stages, but no successful isolations were achieved from leaf petioles during the vegetative and nut growth stage. Studying the progression of almond leaf scorch symptoms in trees with initial infections showed that once symptoms emerged on one branch, symptomless branches were likely already infected by the bacterium. Therefore, selectively pruning symptomatic branches is unlikely to cure the tree. This study enhances our understanding of dynamics in almond trees and may have practical applications for its detection and control.