Italy is the second largest hazelnut producer worldwide and Piedmont is one of the most productive regions in the country. The changing climatic condition and fungal trunk diseases (FTD) can have a severe impact on this crop. Particularly, the considerable spread of Cytospora cankers (‘Mal dello stacco’) and dieback represent a serious concern for producers. Thus, considering the limited studies on the causal agents, different surveys were conducted in seven hazelnut orchards during 2021 and 2022. Eight fungal species were identified: Anthostoma decipiens, Botryosphaeria dothidea, Diaporthe eres, Dia. rudis, Diplodia seriata, Dip. subglobosa, Dothiorella parva and Nothophoma brennandiae. Species identification was achieved through multilocus phylogeny and morphology assessment. All the fungal species were pathogenic on healthy hazelnut plants (cultivar Tonda Gentile) and A. decipiens and Dia. eres were the most aggressive. The present study is the first report of B. dothidea and Dia. eres as causal agents of FTD on hazelnut in Italy and of Dia. rudis, Dip. subglobosa and N. brennandiae worldwide. Moreover, the study provides clarification of the fungal pathogens associated with FTD on this crop in Piedmont, thus laying the base for further studies on epidemiology, ecology and management strategies.

意大利是全球第二大榛子生产国，皮埃蒙特是该国产量最高的地区之一。不断变化的气候条件和真菌性树干病（FTD）会对这种作物产生严重影响。特别是，细胞孢子溃疡病（“Mal dello stacco”）和枯萎病的大量传播引起了生产者的严重关注。因此，考虑到对致病因子的研究有限，2021年和2022年对七个榛子园进行了不同的调查。确定了八种真菌：Anthostoma decipiens、Botryosphaeria dothidea、Diaporthe eres、Dia。 rudis、Diplodia seriata、Dip。 subglobosa、Dothiorella parva和Nothophoma brennandiae。通过多位点系统发育和形态学评估实现了物种鉴定。所有真菌物种对健康榛子植物（品种 Tonda Gentile）以及A. decipiens和Dia 均具有致病性。厄里斯是最具攻击性的。本研究是B. dothidea和Dia的首次报道。是意大利榛子 FTD 和Dia 的致病因子。鲁迪斯，迪普。世界范围内的亚球形和布氏猪笼草。此外，该研究还阐明了皮埃蒙特地区该作物与 FTD 相关的真菌病原体，从而为流行病学、生态学和管理策略的进一步研究奠定了基础。