NSW Agriculture reports that two populations of glyphosate-resistant annual ryegrass have been identified in the state. NSW agriculture weed agronomist Jim Dellow said that one resistant population had received about 40 applications of glyphosate since 1982 and was showing up to 11-fold greater resistance to glyphosate (Roundup) compared with a susceptible population of annual ryegrass.

Mr Dellow urged farmers to re-assess the pattern of their glyphosate applications to prevent widespread weed resistance from developing. When in doubt, farmers should have a herbicide resistance test carried out.

Contact: Mr Jim Dellow 02 6391 3800