Molecular and morphological characterization of Calonectria quinqueramosa causing leaf blight on Eucalyptus urophylla in Brazil

One of the most damaging diseases of Eucalyptus is Calonectria leaf blight, and it causes significant economic losses. In March 2021, symptoms of leaf blight disease were observed in a Eucalyptus commercial plantation in northeastern Brazil. The present study aimed to identify the causal agent based on morphological features, phylogenetic analyses and pathogenicity tests. Based on phylogenetic analyses of the cmdA, his3, tef1 and tub2 gene regions and morphological characteristics, the fungal isolates were identified as Calonectria quinqueramosa, and their pathogenicity to Eucalyptus urophylla was confirmed. The results of this study confirmed the importance of multi-locus phylogeny supported by morphological characteristics for the proper identification of Calonectria species. To the best of our knowledge, this study highlights the first report of C. quinqueramosa causing leaf blight on E. urophylla trees in northeastern Brazil. This information will be valuable to promote the development of disease management strategies and to lead the development of Eucalyptus genotypes with resistance to Calonectria.