Endophytes are naturally occurring fungi or bacteria that live within a very wide range of plants, including grasses. They have a symbiotic relationship with the host plant, drawing nutrient from the host while providing a degree of protection to the plant from diseases and pests. Grass endophytes are fungi which spend their entire life cycle within their grass host. They confer advantages for pasture productivity, including protection against pests and abiotic stress factors. New strains of endophyte have been identified and widely are used in temperate grassland production, in the southern hemisphere, to provide protection against pests and diseases that would otherwise require the use of pesticides. Animal protein (meat and milk) from grass is an environmentally desirable production system provided that forage is available at critical times and the costs of re-seeding provide reliable economic returns. This project will examine for the first time newly developed safe endophyte strains in the UK environment, and characterise their ability to enhance forage grass productivity under different stresses and lower input systems. The aim is to provide a route to commercialisation through demonstration of safety and benefit of endophyte.