Establishing and maintaining a toxin-free pasture: a review

This paper reviews how new pastures may become contaminated with perennial ryegrass (Lolium perenne) infected with wild-type fungal endophytes (Neotyphodium lolii). These wild-type endophyte strains may be toxic to domestic livestock. Sources are from seed (natural reseeding, buried seed, sown seed, in dung, hay, carried on farm machinery) and survival of existing infected ryegrass plants. In particular, seed in soil and dung are reviewed. Contamination may occur both pre- and postestablishment. It is recommended that steps should be taken to minimise contamination from all sources when establishing new pastures. Although normal establishment practices for successful rapid establishment of weed-free pastures (e.g., cropping, fallow, herbicides) will minimise the risk of contamination, a number of cases highlight that extra time (e.g., 18-24 months planning rather 6- 12 months) and consideration of all sources of contamination is needed to minimise risk. Once established, further measures should be taken to prevent seed being transferred in dung or hay. This has implications when establishing pastures with endophyte-free ryegrasses, ryegrasses with selected non-toxic endophytes, a new ryegrass cultivar, or other grasses (e.g., tall fescue), whether for grazing by animals or for seed production. Keywords: endophyte, endophyte survival, faeces, Lolium perenne, natural reseeding, Neotyphodium lolii, pasture establishment, perennial ryegrass, seed burial, seed survival, tall fescue