Management of novel-endophyte ryegrass pastures

An endophyte is a fungus that grows inside a host plant and protects it from insect attack. Most perennial ryegrass (Lolium perenne) plants in Victoria are infected with a naturally occurring wild endophyte (Neotyphodium lolii) (Reed et al., 2000). This endophyte can only be seen under a microscope. Perennial ryegrass infected with endophyte produces chemical compounds called alkaloids that vary in concentration over the year. Some alkaloids enhance the persistence and productivity of ryegrass pastures in New Zealand and Australia by protecting them against insects. However, other alkaloids cause poor animal performance and health when consumed at too high a concentration. These include lolitrem B, which causes ryegrass staggers, and ergovaline, which can worsen heat stress.