Dynamics of <i>Xylella fastidiosa</i> and plum leaf scald: Insights from a long‐term study in Brazilian orchards

Abstract Xylella fastidiosa is one of the most dangerous plant‐pathogenic bacteria globally, affecting various host species. Plum leaf scald (PLS) is the primary disease affecting plum trees in Brazil, with plant eradication efforts significantly increasing in recent years. This study aims to elucidate the disease dynamics and its vector in three monitored orchards from 2010 to 2015 and associate the pattern of pathogen dispersal with mechanical pruning. The incidence was lower in Porto Amazonas, starting at 0% and reaching 14% after 5 years. In contrast, the orchards in Araucaria and Palmeira showed an initial incidence around 5% in the first year, exceeding 80% by the end of the study. Sharpshooter leafhoppers, the vectors, were collected at ground and plant canopy level during the last 3 years. In 2013, more leafhoppers were found near the ground, but their numbers equalized across heights in the following years. Kernel smoothing revealed spatial dependence, and an autologistic model indicated an aggregated infection pattern with increased PLS risk for neighbouring plants. The border effect at the epidemic's onset was linked to pathogen entry via external vectors. The disease's progression along rows was attributed to effective mechanical pathogen transmission through pruning. Therefore, in regions with several summer prunings, it is recommended to sanitize pruning shears to prevent pathogen transmission. Constant monitoring and control of the vector are essential for effective disease management.