Environmental Variables in Relation to Canker Disease Development in Commercial Citrus Cultivars of Pakistan

Citrus canker is an economically devastating disease that causes millions of dollars in losses worldwide. The onset and progression of the disease are strongly influenced by favorable environmental conditions. In this study, correlation analysis was employed to determine the relationship between environmental factors and the severity of citrus canker. This approach enabled an assessment of disease epidemic development from its initiation to the appearance of symptoms. Fifteen commercial citrus cultivars were evaluated to determine their level of resistance to canker. Among them, Tangerine, Succari, Jaffa, Pineapple, Mungal Singh, and Kinnow exhibited moderate resistance, whereas Chinese lime, Blood red, Mayer lime, Grapefruit, and Musambi were highly susceptible. The cultivars sweet lime, Feutral’s early, Valencia late, and Malta showed moderate susceptibility to the disease. Environmental variables, including wind speed (km/h), relative humidity (%), and temperature (maximum and minimum), were significantly correlated with disease incidence and severity. Rainfall also exhibited a significant positive correlation with canker development. The disease initiated in July and reached peak intensity during August and October. Understanding the linkage between epidemiological parameters and pathogen behavior provides valuable insights for developing integrated management strategies to minimize fruit losses and ensure sustainable citrus production. Keywords: Xanthomonas axonopodis pv. citri, bacterial disease, pathogen, dieback, leaf miner.