Annual ryegrass ('Lolium rigidum' Gaudin) resistance to glyphosate and other herbicides in crops and pasture seed in northern New South Wales

Abstract

Annual ryegrass ('Lolium rigidum' Gaudin) is one of the most important weeds of the grain cropping regions of southern Australia (Pannell et al. 2004). The over reliance on herbicides with similar modes of action has resulted in the evolution of herbicide resistance in many 'L. rigidum' populations across Australia (Gill 1995, Preston et al. 1999, Llewellyn and Powles 2001). Recently, glyphosate-resistant 'L. rigidum' was discovered on the Liverpool Plains near Tamworth in northern NSW (Storrie and Cook 2002). In this preliminary experiment, seed of 'L. rigidum' was collected from one Liverpool Plains property which had confirmed glyphosate resistance.