Foliar fungal diseases across 12 Caragana species and the underlying factors in a common garden experiment

Predicting the occurrence pattern of plant diseases in natural ecosystems is of great practical importance. Different plant species harbor different plant pathogens, and consequently, different incidences and severity of fungal diseases. Previous studies have confirmed that both temperature and precipitation can significantly affect plant diseases. However, whether differences in disease among plant species from different origins grown in the same environment are also influenced by the climate of the origins is still poorly understood. In this study, 12 Caragana species collected from a 300 km transect from the east to the west China were used as the focal species. In a common garden experiment, foliar fungal pathogens were identified that caused foliar fungal diseases in the same environment and the incidence, severity, and colony diameters of foliar fungal diseases of the 12 Caragana species were quantified. Moreover, the mean annual temperature and mean annual precipitation in the origins were used to analyze the sources of variation in foliar fungal disease incidence, severity, and colony diameter in different Caragana species. It was found that neither the mean annual temperature nor the mean annual precipitation of the origins significantly influenced the incidence of foliar fungal diseases in the 12 Caragana species (P > 0.05). The severity of the foliar fungal disease decreased significantly with mean annual precipitation of the origins (P < 0.01), and the foliar fungal colony diameter increased significantly with mean annual precipitation (P < 0.05), whereas both the foliar fungal disease severity and colony diameter did not vary with mean annual temperature. In conclusion, this study shows that the climate factors of plant origins have a significant impact on plant diseases. This study can provide data support for effectively managing foliar fungal diseases when planting artificial vegetation and introducing garden plants.