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Zhodnocení výskytu a růstu jmelí bílého (Viscum album) na vybrané lokalitě
Halfar, Jan
European mistletoe (Viscum album L.) is an evergreen semi-parasitic plant, with a wide host range of both deciduous and coniferous trees. As a native species, this plant is widespread throughout Europe. The first part of this paper is aimed as a literature review, which includes a description of European mistletoe, a general description of its occurrence and its effect on host woody plants. The second part focuses on a survey of a selected area between the villages of Bělá and Chuchelná (Opava district), where the degree of infestation of individual trees, the species of infested trees and their age are assessed. At the same time, the number of mistletoe plants, their distribution in the crown, and in the oldest mistletoe specimens their age and haustorium length were determined at three sites in the forest area belonging to the Lesy města Brno a.s. In this work it was found that mistletoe occurred mainly on Scots pine at site 1, but was also found on silver fir and small-leaved linden. At site 1, mistletoe began to invade pine after the age of 30. Mistletoe in young stands grew mainly on trees with the greatest high growth and in the upper part of the crown. On the basis of these results, I recommend to concentrate the management of mistletoe-infested forest stands on tree age above 30 years during planned thinning and to actively remove infested individuals from the stand. Changing the species composition of forest stands in favour of mistletoe-resistant species is also one of the ways to prevent the spread of mistletoe in threatened areas. At site 2, the age of the largest mistletoe shrubs ranged from 9 to 18 years. The longest measured haustorium was 18 cm in length and was measured on mistletoe at 17 years of age. From the measurement results, a relationship between mistletoe age and haustorium length was found. Knowing the haustorium length is important in the context of tree protection when performing branch pruning. Therefore, based on the results of this work, I recommend removing infested branches at a minimum distance of 30 cm from the mistletoe shrub, especially for older mistletoes.
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