Establishment of ryegrass pastures containing a novel endophyte

Abstract

An experiment was conducted at Dexcel, Hamilton from September 1999 to April 2001 to evaluate how pre-sowing pasture management and establishment method influenced the contamination of a newly sown AR1 endophyte-infected ryegrass dairy pasture with ryegrass infected with the wild endophyte (Neotyphodium lolii). Contamination level was estimated by counting the number of volunteer ryegrass plants between drill rows and by analysing bulk ryegrass samples for lolitrem B concentration. Hay, silage, grazed, grazed/topped and a turnip crop as pre-sowing managements generated large differences in viable ryegrass seed density (2555, 747, 348, 391 and 25 seeds/m2, respectively) on the soil surface after natural reseeding in March 2000. Measurements on 20 November 2000 showed the spray/cultivation and double-spray/fallow establishment methods were effective in reducing contamination with volunteer ryegrass plants (8 and 34 plants/m2, respectively), in contrast to drilling AR1 endophyte- infected ryegrass seed into hard-grazed existing pasture (581 plants/m2). On 14 March 2001, lolitrem B levels were lower in the spray/ cultivated and double-spray/fallow treatments compared to the hard-grazed treatment (0.3, 0.5, 1.1 μg/g, respectively). Information is also presented on sown plant density of AR1 endophyteinfected ryegrass. Keywords: AR1 endophyte, cultivation, glyphosate, Lolium perenne, natural reseeding, Neotyphodium lolii