Mistletoes give away soil contamination

During Christmas time people exchange traditionally kisses under mistletoes. While mistletoes are welcome in private, they may not if populating trees in vast numbers. Scientists of Julius Kühn-Institut (JKI) in Braunschweig demonstrated that the semiparasite indicates heavy metal contamination of soils.

The proliferation of mistletoes is related to many factors such as the abundance of host trees, bird species which feed on the berries and distribute them in the environment, microclimate and last but not least individual resistance mechanisms of the host tree. The resistance of trees is reduced on soils which are polluted with heavy metals. Scientists of the Institute for Crop and Soil Science proved only recently in an extended study that in particular poplars are colonised by mistletoes and this in distinctly higher numbers than for instance maple and lime tree.

Ewald Schnug reports that “In the Goslar region in the Harz mountain soils are contaminated with lead, copper and zinc because of its mining history. On soils with a low pollution 9% and on highly contaminated sites 49% of all poplar trees are infested by mistletoes”. He further denotes that mistletoes were found more often on black poplar than Lombardy poplar. The scientists provided evidence that an increasing infestation of trees by mistletoes indicate heavy metal contamination of soils. Based on their research which started in 2003, the scientists started to develop a procedure for sensing soil contamination by employing poplars and their mistletoe infestation index as indicators.

Your scientific contact:
Prof. Dr. Dr. habil. Dr. h.c. Ewald Schnug
Institute for Crop and Soil Science
at Julius Kühn-Institut (JKI) – Federal Research Center for Cultivated Plants
Bundesallee 50, 38116 Braunschweig
phone.: +49 531/ 596-2102
e-mail: pb@jki.bund.de
Background information on the project:
The research project “A contribution to occurrence of hardwood mistletoe on heavy metal contaminated soils” is under investigation since 2003 and was finalised in 2008. Results have been published in two PhD and one MSc theses. Research was partly carried out with HISCIA in Dornach (Switzerland) and Jacobs University in Bremen. Interim results are published in the special issue 301 of FAL – Agricultural Research: Ramm, H. (2006): Einfluss bodenchemischer Standortfaktoren auf Wachstum und pharmazeutische Qualität von Eichenmisteln (Viscum album auf Quercus robur und petreae). In one of the next issues of vTI Agriculture and Forestry Research a paper on “Potential correlation of heavy metals in surface soils with infestation of Viscum album in poplar trees” by Sharma, Steckel, Koschinsky and Schnug (2009) will be published.