Botryosphaeriaceae Species Causing Stem Blight and Dieback of Blueberries in Serbia.

In the main growing areas in Serbia, plants with symptoms of stem blight were sampled in nine orchards with American highbush blueberry (Vaccinium corymbosum), cultivar 'Duke', with high disease incidence, and 153 samples were taken. A total of 128 Botryosphaeriaceae isolates were characterized on the basis of morphology, sequence analysis, multilocus phylogeny based on ITS, TEF1-α and TUB2 sequences and pathogenicity, and belonged to one of the four species Neofusicoccum parvum, Botryosphaeria dothidea, Diplodia seriata and Lasiodiplodia iraniensis. Both D. seriata and L. iraniensis were detected for the first time on blueberries in Serbia, and L. iraniensis was detected for the first time on blueberries worldwide. Comparative morphological and TEF1-α sequence analyses allowed a clear separation of L. iraniensis from the phylogenetically closely related L. fujianensis, L. thailandica and L. endophytica. Of the nine blueberry cultivars 'Aurora', 'Barbara Ann', 'Bluecrop', 'Bluejay', 'Draper', 'Duke', 'Huron', 'Patriot' and 'Spartan' inoculated with L. iraniensis (isolate 421-19), the cultivar 'Duke' was the most susceptible. In our study, the majority of orchards were in their second or third year of production, implying that the planting material is likely to be the source of infection, emphasizing the importance of pathogen-free planting material.