Viability of endemic endophyte (Neotyphodium lolii) and perennial ryegrass (Lolium perenne) seed at retail and wholesale outlets in south-eastern Australia

Perennial ryegrass (Lolium perenne L.) is an introduced grass that is widely sown for pasture throughout south-eastern Australia and may be infected with the fungal endophyte Neotyphodium lolii (Latch, Christensen and Samuels) Glenn, Bacon and Hanlin. This fungus/host grass association confers some advantages and disadvantages for the use of perennial ryegrass. Perennial ryegrass cultivars are sold with endemic endophyte, with selected endophytes or endophyte-free. However variable agronomic performance in the field raises the question if the endemic endophyte within cultivars is actually viable when sold, or in other cases if endophyte-free material is actually free. This survey was done to provide information on the status of endemic endophyte in perennial ryegrass seed in wholesale/retail outlets in south-eastern Australia. Of the samples where the age of the seed was known, two thirds were 2 years or less since harvest, while one sample was 7 years old. Seed viability generally remained high, although 15% of samples had a seedling establishment below 60%. Seedling establishments around 50% and below were evident in some samples 3 years and older, with one sample (5 years old) being nil. Seed-borne endophyte levels were in accordance with the way in which each cultivar is promoted, with the exception of one sample promoted as being low/nil endophyte. The seed-borne level for this sample was 73%, but the viable endophyte level was nil. Viable endophyte levels remained acceptable for most samples for 2 years after harvest, but then declined rapidly, with 75% of those samples where the seed-borne levels were high and age of the seed was known, having viable levels around 0%. Endophyte viability declined at a faster rate than seed viability and was significantly influenced by cultivar, age of the seed and the interaction between these two variables.