Endophyte persistence and toxin (lolitrem b) production in a Danish seed crop of perennial ryegrass

The lolitrem B experiment was based on farm-scale results from endophyte-infected seed crops of perennial ryegrass cv. Delaware. The aim was to monitor the toxin content during the spring to autumn growing season in order to evaluate the fodder quality of secondary products from a seed crop, such as straw and regrowth taken after seed harvest. A clear seasonal variation in the lolitrem B level was observed in top and stubble fractions in 1998-2000. The highest level of lolitrem B occurred in the top fraction during July 1998 at Brorfelde. The mean concentration was 1.46 ppm, a level that is sufficient to induce mild ryegrass stagger.