Senecio aquaticus shows rapid and high seed germination

Senecio aquaticus (marsh ragwort), poisonous to livestock, has become increasingly abundant in agricultural grassland. In this study, the germination and seed survival of S. aquaticus were investigated in a series of standardised tests with the aim to improve the species’ control in managed grassland. Germination percentages of fresh ripe seeds of S. aquaticus were on average 68 % in 2008, but only 45 % in 2010, indicating yearly variation. In many cases, over 45 % of all the seeds had germinated ten days after the start of testing with almost no germination occurring after eight weeks. Seeds buried in the soil for one and two years had a germination of 78 % – significantly higher than that of fresh ripe seeds – suggesting that cold-wet stratification had a stimulating effect on germination and indicating longterm seed survival in the soil. The rapid and high germination of S. aquaticus suggests that strategies to control the species in agricultural grassland should initially focus on the prevention of seed production and dispersal. Once the species is present in large numbers, it will already have established a large and permanent soil seed bank. In such cases, successful reduction of S. aquaticus may take several years until the soil seed bank is depleted.