The Mycobiota Diversity Associated with Mistletoe (Viscum album L.) in Poland

The spread of mistletoe, which mainly affects Scots pine in Europe’s managed forests, has become a serious ecological and economic problem, exacerbated by climate change and drought stress. Research into mistletoe-associated mycobiota provides crucial insights into the biology, ecology and distribution of these fungi and forms the basis for sustainable plant protection and effective management strategies. The aim of this study was to identify the fungal species associated with mistletoe (Viscum album L.) at 75 sites across Poland, with a focus on the northeastern regions of the country. The field work included a systematic and targeted search using the transect method, followed by laboratory analysis, during which fungal samples were prepared and examined under both light and scanning electron microscopes. The genetic analysis was carried out using ITS sequencing to confirm the presence of pathogen-specific fungi in the majority of V. album samples examined. The results showed four fungal species associated with the mycobiota of mistletoe: Sphaeropsis visci, Plenodomus visci, Cylindrodendrum hubeiense and Septoria krystynae. It is noteworthy that two of these species (P. visci and C. hubeiense) have not yet been detected in Poland. Based on these findings, the distribution areas of the identified fungal species were mapped accordingly.