Increase in the proportion of endophyte-infected perennial ryegrass plants in overdrilled pastures

Abstract

Abstract “Low” and “high” endophyte (Acremonium lolii Latch, Christensen and Samuels) seed lines of ‘Grasslands Ariki‘ (Lolium(multiflorum x perenne) × perenne) and ‘Grasslands Nui’ ryegrasses (Lolium perenne L.) were overdrilled into herbicided old pasture on a Lismore stony Silt loam under dryland or irrigated conditions. In the 3 years after sowing, the proportion of endophytic plants in the “low” endophyt:e pasture increased to 67% for Nui and 83% for Ariki, from 3% infection measured in both seedlines. The most significant proportion of this increase occurred over the first 10 months. It is suggested that Argentine stem weeVil (Listronotus bonariensis Kuschel) did not play a large part in the increase in endophyte-infected plants since larval numbers were low. Endophyte infection may confer a competitive advantage to ryegrass plants.