Mistletoe-induced growth reductions at the forest stand scale

Some characteristics of woody plants inhabited by Viscum album (Santalaceae) in the city of Kyiv

As a result of the study, a wide range of tree species parasitized by white mistletoe (Vіscum album) in the city of Kyiv, Ukraine, was identified. Some species, such as Quercus robur, Ulmus pumila, and Alnus glutinosa, remained uninfested even in the case of a high degree of infestation of surrounding trees. It has been found that among the infested plants only 4.34% of deciduous species and 5.05% of conifers demonstrated a severe damage caused by the hemiparasite (more than 20 plants of V. album in one crown). The largest number of trees and the highest level of damage were observed for Acer saccharinum, A. platanoides, Salix alba, Robinia pseudoacacia, Populus nigra, Tilia cordata, and Betula pendula aged in average 45–50 years. In the study of genetic characteristics of affected and unaffected by V. album trees of Pinus sylvestris at the molecular level by TBP markers, no differences have been revealed.

Mitigating the Mistletoe Menace: Biotechnological and Smart Management Approaches

Mistletoes have been considered a keystone resource for biodiversity, as well as a remarkable source of medicinal attributes that attract pharmacologists. Due to their hemiparasitic nature, mistletoes leach water and nutrients, including primary and secondary metabolites, through the vascular systems of their plant hosts, primarily trees. As a result of intense mistletoe infection, the hosts suffer various growth and physiological detriments, which often lead to tree mortality. Because of their easy dispersal and widespread tropism, mistletoes have become serious pests for commercial fruit and timber plantations. A variety of physical and chemical treatment methods, along with silvicultural practices, have shaped conventional mistletoe management. Others, however, have either failed to circumvent the growing range and tropism of these parasitic plants or present significant environmental and public health risks. A biocontrol approach that could sidestep these issues has never achieved full proof of concept in real-field applications. Our review discusses the downsides of conventional mistletoe control techniques and explores the possibilities of biotechnological approaches using biocontrol agents and transgenic technologies. It is possible that smart management options will pave the way for technologically advanced solutions to mitigate mistletoes that are yet to be exploited.

The future of Viscum album L. in Europe will be shaped by temperature and host availability

Viscum album L. is a plant of great importance due to its influence on the host trees and, by extension, entire ecosystems. The species is also significant to humans-on the one hand, because of its use in medicine, and on the other, because of the growing threat it poses to the stability of conifer stands. Therefore, it is important to recognize the future range of three mistletoe subspecies (Viscum album subsp. album, V. album subsp. austriacum, and V. album subsp. abietis). Modelling of the potential range of these subspecies was performed using MAXENT software. Locations were collected from literature and databases. A total number of 3335 stands were used. Bioclimatic data for the current conditions and three future scenarios (SSP 1.26, SSP 3.70, SSP 5.85) were downloaded from the CHELSA database. The results confirmed that the temperature is the key variable on the potential range of the analysed subspecies. V. album subsp. abietis is withdrawing from its range according to all scenarios. In the case of V. album subsp. austriacum, a slight range shift is visible. Only the V. album subsp. album will expand non-directionally. The reason is most likely a very large number of host species and greater genetic variability compared to the subspecies found on conifers.

Impact of Common Mistletoe (Viscum album L.) on Scots Pine Forests—A Call for Action

Common mistletoe is increasingly mentioned as contributing not only to the decline of deciduous trees at roadside and in city parks, but to conifers in stands. The presence of Viscum in fir stands has been known for many years, but since 2015 has also been the cause of damage to pine. In 2019, mistletoe was observed on 77.5 thousand hectares of Scots pine stands in southern and central Poland. Drought resulting from global climate change is implicated as an important factor conducive to weakening trees and making them more susceptible to the spread of mistletoe and other pests. This paper presents an overview of the latest information on the development of this semi-parasitic plant in Poland, its impact on tree breeding traits and raw material losses, as well as current options for its prevention and eradication.