“Mal dello stacco”: a serious threat to hazelnut and preliminary attempts to develop biological control

Italy, the second-largest hazelnut producer with 105,048 tons in 2023, faces increasing challenges from wood diseases like “mal dello stacco,” particularly in Piedmont, a key hazelnut-growing region. A polyphasic study identified Anthostoma decipiens as the predominant fungal trunk pathogen. The pathogen spreads via reddish conidial masses on infected branches, a process potentially exacerbated by climate change. Morphological similarities with Cytospora spp. often lead to misidentification. Due to restricted fungicide use and progressive limitations on active ingredients in Italy, alternative management strategies are necessary. Preliminary trials on detached shoots treated with commercial Trichoderma spp.-based products showed promising results, with a 60–70% reduction in lesion lengths, comparable to chemical fungicides. Ongoing in planta trials aim to develop biological control tools for sustainable hazelnut disease management.