Significance, characterization, and pathogenicity of Diplodia and Dothiorella species associated with apple canker and dieback in northern Patagonia, Argentina

Abstract

Canker and dieback diseases affect apple production in northern Patagonia. This study aimed to estimate disease incidence and severity, identify the species of Botryosphaeriaceae associated with the outbreaks, and study their pathogenicity. Rapid increase of infection incidence and severity affecting branches and trunks, but not fruit, was registered after rains. Based on cultural and morphological characteristics, fungal isolates obtained from apple trees were identified as genus Diplodia, with two species and genus Dothiorella. Phylogenetic analysis based on sequencing of ITS, TEF-1α, and TUB-2 gene regions were used to identify Diplodia seriata as the main species, followed by Diplodia mutila and Dothiorella omnivora. Diplodia seriata were grouped by greater virulence in fruit, while D. seriata and D. mutila exhibited greater virulence in shoots. The lowest optimum growth temperature was observed for Do. omnivora. Optimization of orchard management practices is suggested to mitigate risks associated with Botryosphaeriaceae infections.