First report of Fusarium tricinctum on narrow-leaved ash (Fraxinus angustifolia Vahl.) in Serbia

Monitoring the health status of narrow-leaved ash tree seedlings (forest office Morović, locality Vinična) in the early spring of 2015, after the catastrophic floods in May 2014, revealed presence of large dark necrotic areas on 1-2 year old sprouts. The isola­tion of the fungal pathogen was done by standard phytopathological protocols. Three repre­sentative isolates (K41, K42 and K78) were preliminary detected and purified by a single-spore technique for further morphological, molecular analyses and pathogenicity testing. Morphological characteristics classified the isolates as Fusarium tricinctum. Tested isolates on narrow leaved ash sprouts caused reddish brown elongated necrotic lesions averaged 20.1 mm. Two marker genes, translation elongation factor 1-alpha (TEF1-α) and internal transcribed spacer (ITS1), were used in this study. Using the Basic Local Alignment Search Tool (BLAST) searching engine, nucleotide sequences were compared to all related sequences. Alignement score resulted in 98.9% identities with F. tricinctum for isolate K78, while isolates K41 and K42 showed 94.1% and 94.3% identities with F. tricinctum complex respectively. To the best of our knowledge, this is the first report of F. tricinctum pathogen infection on flood stressed narrow-leaved ash trees in Serbia.