Effects of Molluscides on Seedlings of Four Grassland Plant Species

Abstract

We tested the hypothesis that molluscicides may affect seedling germination and survival, as well as reducing herbivory, thereby influencing the results of experiments in which molluscicides are used to exclude molluscs from plant communities. The effects of two molluscicides, Fertosan and Draza, on seed germination of four common grassland herbs, Plantago lanceolata, Ranunculus acris, Senecio jacobaea and Taraxacum officinale, were examined over a 100-day study. Draza slug pellets reduced seedling numbers in Plantago, while increasing numbers of Ranunculus seedlings. The molluscicides, either separately or together, had no effect on numbers of Senecio or Taraxacum. The implications of the results are discussed in relation to the interpretation of field experiments where molluscicides are used as experimental tools. We also raise the question of how molluscicides may influence field populations of native weed species in agricultural systems.