Effect of perennial ryegrass density on ragwort emergence

Abstract

The effect of the density of perennial ryegrass (Lolium perenne) swards on the emergence of ragwort (Senecio jacobaea) was investigated in the field and in trays Ragwort seeds were sown into established perennial ryegrass and white clover (Trifolium repens) swards and the seedlings were mapped at intervals to aid in identification of new seedlings In the trays seedlings were counted and mapped at four week intervals and the experiment was continued for four months In the field plots ragwort seedlings were counted before and after each grazing There was no evidence for any negative effect of ryegrass tiller density on the number of ragwort seedlings emerging The presence of white clover in trays and clover and volunteer weeds in the field also provided competition for ragwort