Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Zurich

Ragwort and grassland-management – a connection?

Ragwort (Senecio jacobaea L.) is an important weed in various countries (Great Britain, New Zealand). In recent years, the species has also gained attention in Switzerland. Our investigation involved a survey to assess the influence of grassland management on the presence of ragwort and to identify important site conditions associated with the species. Botanical relevés were carried out on grassland with S. jacobaea occurrence and on neighbour sites that showed no S. jacobaea.S. jacobaea was most abundant at sites with low nitrogen fertilization and set stocking. Furthermore, the species revealed a high occurrence at open swards and steep slopes. Ragwort was not present in meadows managed at high intensities. Exceptionally, with high seed pressure from neighbour sites, S. jacobaea could also be found in intensively managed pastures and in extensively managed meadows.We conclude that a long-term control of ragwort can be achieved by promoting dense swards and by preventing S. jacobaea of seed formation in the pasture and its environment.

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