Effects of Leaf Wetness Duration, Temperature, and Host Phenological Stage on Infection of Walnut by Xanthomonas arboricola pv. juglandis

Bacterial blight, caused by Xanthomonas arboricola pv. juglandis, is a significant disease affecting walnut production worldwide. Outbreaks are most severe in spring, and closely tied to host phenology weather conditions. Pathogen infections mainly observed catkins, female flowers, leaves, fruits. In this study, the effect of wetness duration temperature on X. juglandis was determined through two independent experiments conducted under controlled environmental The combined both climatic parameters severity quantified using third-order polynomial equation. model obtained linear regression backward elimination technique fitted well data (R2 = 0.94 R2adj 0.93). predictive capacity forecasting evaluated pathogen-inoculated plants exposed different duration–temperature combinations Mediterranean field Observed all events aligned with predicted infection risk. Additionally, relationship between leaf fruit age modelled. A prediction model, which has been referred as WalBlight-risk proposed for evaluation an advisory system timing bactericide sprays manage bacterial blight orchards.