Beeinflusst die Bewirtschaftung das Vorkommen von Jakobskreuzkraut (Senecio jacobaea)?

Senecio jacobaea is a poisonous weed in grasslands of various countries (e.g. Great Britain, New Zealand, Central European states), and the further spread of the species into farmland must be prevented. Due to strong restrictions of curative measures, the prevention of S. jacobaea’s spread is of primary importance for organic farming. To assess the influence of management practice and site conditions on the occurrence of S. jacobaea, we conducted an on-farm survey in the northern and central part of Switzerland. Botanical assessments were carried out on grassland plots with S. jacobaea occurrence and on neighbour plots without S. jacobaea. For these plots, we analysed the soil nutrients and the details of management practice such as type and intensity of management and fertiliser application (mainly slurry). The most impor-tant factors influencing the occurrence of S. jacobaea were related to management: There was a considerably high risk for the occurrence of the species on parcels with low nitrogen fertilisation, continuous-extensive grazing (set stocking), and a high openness of the sward. S. jacobaea was not present in intensively managed meadows cut more than twice per year. We conclude that a long-term control of S. jacobaea can best be achieved by avoiding sward damage, by replacing continuous by rotational grazing, and by adjusting stocking rates