A fenyőfagyöngy (Viscum album subsp. austriacum) elterjedése és gyakorisági viszonyai Magyarországon

Based on the data collected between 2015 and 2023, we present a detailed account of the occurrences and current distribution of Viscum album subsp. austriacum in Hungary. We present its fre­quency and abundance, and also examine the factors influencing its distribution and prevalence. The taxon is generally widespread in the western half of Western Transdanubia, where it is a characteristic (and partially native) element of the mixed pine forests of the Vendvidék, Felső-Őrség, Kőszeg Hills, and the Pinka Plain. Its occurrence has been confirmed in almost all (older) Scots pine and black pine stands of the Sopron Hills, where it has become a mass pest in several locations. Based on our studies, the current distri­bution of the taxon in Southwestern Transdanubia follows the border of the native distribution of Scots pine, but in the Kemeneshát and the Sopron–Vas Plain, the regional boundary extends 10–25 km beyond it. The frequency of pine mistletoe within the subcompartments was highest in mixed coniferous stands. We also recorded a mass infection that played a significant role in the degradation of the stands. The notable increase in the number of occurrences can be explained by the significant under-mapping of the taxon to date, as well as its documented spread throughout Europe. It is also assumed to be linked to the increasing­ly unfavorable health status of coniferous forests in Hungary. This process may be facilitat­ed by the fact that the resistance of Scots pine forests in both hilly and lowland regions has significantly declined due to the increasing length and frequency of drought periods. Compared to previous years, forest stands in weakened condition are more susceptible to infections by pathogenic organisms, such as mistletoe.