Exploring the phylogenetic diversity of Botryosphaeriaceae and Diaporthe species causing dieback and shoot blight of blueberry in Serbia

Abstract

Identifying the precise pathogens responsible for specific plant diseases is imperative for implementing targeted and efficient interventions and mitigating their spread. Dieback and shoot blight significantly diminish the lifespan and productivity of blueberries, yet the causative agents remain largely unidentified. To determine the identity and prevalence of the causal agents of branch dieback and shoot blight, we conducted multi-year and multi-site sampling of diseased highbush blueberries (Vaccinium corymbosum cv. Duke) in Serbia. Sixty-nine monosporic isolates were collected and characterized based on morphological, physiological features and multi-locus phylogenetic analysis of internal transcribed spacer (ITS), β-tubulin (TUB2) and translation elongation factor 1-alpha (TEF1) sequence data. Five species were identified as causal agents: Diaporthe eres (36 isolates), D. foeniculina (3 isolates), Neopestalotiopsis vaccinii (9 isolates), N. rosae (6 isolates) and Neofusicoccum parvum (15 isolates). The results of the pathogenicity tests performed with the 23 representative isolates confirmed the role of these species as primary pathogens in causing dieback and shoot blight of blueberry, with N. parvum being the most aggressive and D. eres the least. Our study underscores the diversity of genera and species of ascomycetes capable of causing blueberry dieback and shoot blight. Furthermore, our findings indicate that the agents responsible for the disease in Serbia differ from those identified in other regions worldwide.