INVESTIGATION ON THE INFLUENCE OF THE WHITE MISTLETOE (VISCUM ALBUM L.) ON DURABILITY OF TREE BRANCHES (FOLLOWING AN EXAMPLE OF THE COTTONWOOD TREE, POPULUS DELTOIDES MOENCH.)

Abstract

The White Mistletoe (Viscum album L.) is known to cause deterioration of tree health through increased defoliation and dieback, reduced growth and productivity as well as urban tree stands’ aesthetic appearance. We aimed at investigating the influence of the White Mistletoe’s (Viscum album L.) dwarves on the tree branch durability, following an example of the Cottonwood Tree (Populus deltoides Moench.), as one of the commonest urban tree species in the city of Kharkiv. Field samples comprising two sets of randomly cut poplar branches – 20 pieces of those infested by the mistletoe and 20 pieces of those without the mistletoe dwarves were collected from an industrial area in the southeast of the city of Kharkiv, Ukraine. Mass of the mistletoe dwarves was measured in the field, while branch characteristic diameters, branch weight and wood density were measured in the laboratory. To test branch durability measured as the break threshold pressure, Р, the laboratory hydraulic press PLG-5 was used. The hypothesis of normal distribution of variables was tested with the Kolmogorov-Smirnov test (with the Lillefors’ correction) and the Shapiro-Wilk tests. Hypothesis on the Mistletoe’s influence on the durability of the Cottonwood’s branches was tested with the Fisher’s F-criterion. Our results have shown that the White Mistletoe’s infestation did not affect the strength of the wood, but at the same time an infected branches featured a higher density. Further investigations are proposed to assess the wood durability of hardwood trees under infestation by the White Mistletoe.

Keywords: tree stands, tree branches, durability, the White Mistletoe, the Cottonwood.