JKK Antagonists

Regulation of mass occurrences of the ragwort (Senecio jacobaea L.) by natural antagonists

Since the middle of the last decade, extensively used grassland stands, which are valuable for nature conservation purposes, have been home to a strong spread of ragwort (syn. Jakobs-Kreuzkraut, "JKK", Senecio jacobaea L.) throughout Germany. Due to the feeding poisons (pyrrolizidine alkaloids, "PAs") produced by this plant species, a potential health hazard for humans and animals can be assumed. Pyrrolizidine alkaloids from ragwort can be taken up by humans via honey, for example, and by animals usually via canned fodder (hay, hay or silage). The potential risk of poisoning poses a threat to the usability and acceptance of conservationally valuable, species-rich, extensively used grassland stocks. Classical methods for combating undesirable grassland species such as intensification of use, upheaval and the use of herbicides are not limited in their effect to ragweed and thus endanger the species-rich grassland vegetation worthy of protection.

In addition to mechanical control strategies that are presumably justifiable in nature conservation terms, such as mowing and mulching the Jakobs-Greiskraut populations at various times, another option for regulating Jakobs-Greiskraut populations is the targeted use of herbivorous antagonists that have been propagated at high initial densities. So far, however, experience with the success of this measure has only been gained in countries where Jacob's ragwort and its antagonists are not native (e.g. North America and New Zealand). In the natural occurrence area, the targeted use of natural antagonists seems to make sense in particular on areas that are poor or impassable due to their micro-relief, advanced scrubland or high soil water content; on areas with mechanical regulation measures, this could improve the regulation of the Jakobs ragwort populations.

The aim of the research project is therefore to investigate the possibilities offered by the use of natural antagonists to regulate the populations of ragweed, the framework conditions (e.g. landscape structure, mowing or grazing) which influence the success of the measure, and whether there are other promising antagonists in addition to those already known and classified as effective. In the end, users of extensively managed grasslands will be provided with effective, nature conservation-compliant measures to regulate the populations of ragwort.


Project information

Duration: 2016-2020

Project participants: Kathrin Schwarz M.Sc., Prof. Dr. Tim Diekötter, Dr. John Herrmann, PD Tobias W. Donath

Project cooperations:

Stiftung Naturschutz Schleswig-Holstein

JKK-Kompetenzzentrum der Stiftung Naturschutz Schleswig Holstein

Landesamt für Landwirtschaft, Umwelt und ländliche Räume (LLUR)



Deutsche Bundesstiftung Umwelt (DBU)