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

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.