Sordaria macrospora: A New Fungal Pathogen Causing Leaf Tip and Shoot Blight on Olive (Olea europaea L.)

Olive is a perennial tree able to grow and survive in Mediterranean conditions due to its climate adaptations. In this study, we observed a new disease characterised by leaf tip blight, shoot blight, and dieback in olive trees in the Southeast Anatolian region of Türkiye. Six fungal isolates were obtained from the symptomatic trees. Classical methods based on macroscopic and microscopic observations revealed that the isolates were similar to Sordaria macrospora. Total DNA was isolated and PCR-amplified with primer pairs for the ITS, LSU, β-tubulin, and Tef-1α gene regions, and the resulting sequences were BLASTed in the NCBI database. The similarity was 99%–100% to isolates of S. macrospora. The similarity of the pathogen to other Sordaria spp. isolates was determined by constructing a phylogenetic tree using MEGA X software and the neighbour-joining method. Out of six isolates, one representative isolate was selected for subsequent studies. In pathogenicity tests on 2-year-old olive seedlings, blight was observed starting from the tips of leaves and shoots to the base, and the pathogen was successfully reisolated, fulfilling Koch's postulates. This is the first report of S. macrospora acting as a pathogen in olive trees.