Leaf-spot disease on European mistletoe (Viscum album) caused by Phaeobotryosphaeria visci: a potential candidate for biological control

Abstract

Viscum album (European mistletoe), a perennial, evergreen, hemiparasitic shrub, infects a wide range of woody species. It adversely affects the height and diameter of growth and it is associated with increased mortality of its hosts. There is no effective control methods against it. We have found a specific hyperparasitic fungus, which can completely destroy European mistletoe by infecting its branches, leaves and berries. Both morphological and molecular identification, based on ribosomal internal transcribed spacer sequences (rDNA-ITS), established its identity as Phaeobotryosphaeria visci. Our analysis also revealed unexpected ITS variability, as compared to the previous studies, that needs to be considered in identifying of this pathogen. Because of its efficient pathogenicity this fungus might be a good candidate for biological control of mistletoe.

Do the arthropod communities on a parasitic plant and its hosts differ?

“…The arthropod community on V. album is well studied and there are several host specifi c insects associated with this plant in Central Europe (Hellrigl, 2006;Briggs, 2011;Varga et al, 2012;Schumacher, 1918in Zuber, 2004). In addition, some studies on arthropod assemblages support the contention of a high degree of host specifi city of the psyllids on European mistletoe (Hansen & Hodkinson, 2006;Struwe et al, 2009) and other species of mistletoes (Whittaker, 1982;Burns & Watson, 2013).…”

“…Despite these differences the mistletoe parasitizing them harbour a simpler and specifi c arthropod community, consisting of two herbivores and their predator, and a lower abundance itinerant spiders (Burns & Watson, 2013). The herbivores are Cacopsylla visci and Pinalitus viscicola, which are recorded inhabiting V. album across Europe (Zuber, 2004;Hansen & Hodkinson, 2006;Struwe et al, 2009;Varga et al, 2012) and their main predator Anthocoris visci (Hellrigl, 2006;Briggs, 2011). In line with this, the arthropod community recorded on V. album in these studies there are 8 host specifi c insects inhabiting mistletoes in Hungary (Varga et al, 2012) and northern Italy (Hellrigl, 2006), 6 in England (Briggs, 2011), 5 in France (Schumacher, 1918in Zuber, 2004) and a few less (minimum 3) in Sweden (Struwe et al, 2009).…”

“…Of these, Burns et al (2011) and Tassone & Majer (1997) compare the arthropod communities' on mistletoes and their hosts in Australia at an ordinal level and restricted to the genus Psylloidea (Burns et al, 2014). In addition, the community assemblage on Viscum album is described at the species level in Central (Zuber, 2004;Hellrigl, 2006;Briggs, 2011;Varga et al, 2012) and Northern Europe (Hansen & Hodkinson, 2006;Struwe et al, 2009), but parallel studies on the arthropod communities on their hosts are lacking. Thus, this is the fi rst comparative study of a community assemblage at a higher taxonomic resolution in terms of the composition of arthropods inhabiting Viscum album and its host, pine trees.…”

Botryosphaeriaceae associated with the die-back of ornamental trees in the Western Balkans

“…S. visci is known to occur only on V. album in Europe and is commonly found in the crowns of a wide range of woody species (Varga et al 2012;Phillips et al 2013). This host-association was confirmed in the present study.…”

“…This host-association was confirmed in the present study. The species has been reported from Hungary (Varga et al 2012), Luxemburg, Germany and (based on morphological identification) Serbia (Karadžić et al 2004). P. cupressi was previously known to occur only on C. sempervirens and Juniperus scopulorum in Iran and the USA, respectively ) and it was not surprising to isolate it from C. sempervirens in Montenegro.…”