Extent of infection by Viscum album L. and changes in its occurrence on ornamental woody species in the locality of Lednice (Czech Republic)

The main goal of the research conducted in the Lednice chateau park was to map the current spectrum of host trees and shrubs. The aim of the investigation was also to record changes in the host species, namely between the years 1985 and 2016, and to get an overview of the extent and degree of mistletoe infection on the most significant tree species present in the park. Furthermore, the occurrence of mistletoe across the developmental stages of woody species was monitored. Apart from taxonomic changes also the quantitative extent and the degree of infection reported in the last 31 years, and the impact on the development stages of woody plants in the past 20 years were analysed. Among the most frequently infected taxa are currently: Acer campestre, Acer platanoides, Acer pseudoplatanus, Crataegus monogyna, Robinia pseudoacacia, Tilia cordata and Tilia platyphyllos. The average share of infected specimens of the above host species amounts to 34.28%. A distinctive change in frequency and infection degree was recorded in the aggregate spectrum of hosts. The presence of mistletoe was recorded in a total of 1,362 specimens (almost 12% of the trees growing in the area). Compared to 1985, the occurrence of mistletoe was newly recorded in a total of 13 families (+3), 19 genera (+5) and 42 species (+18). In Aesculus ×marylandica, Fraxinus biltmoreana, Magnolia hypoleuca ×tripetala or Malus ×moerlandsii, it was probably described for the first time ever. At the moment, the most existentially endangered taxon is Tilia cordata.