Variability in glyphosate efficacy in <i>Alopecurus myosuroides</i> HUDS. (blackgrass) in Lower Saxony

Abstract

Herbicide resistance has increased dramatically all over the world. Besides frequent occurrence of resistance in North America, South America and Australia, different active ingredient groups are currently affected by resistance also in Europe. In Germany, Alopecurus myosuroides has shown resistance to ALS-inhibitors, ACCaseinhibitors and photosynthesis-inhibitors. Recently, reduced efficacy or resistance to the EPSP-inhibitor glyphosate (HRAC group G) was suspected in A. myosuroides in Lower Saxony. That means that the active ingredient glyphosate might no longer be available as an affective instrument in herbicide resistance management for A. myosuroides. An effective control of A. myosuroides with additional resistance to other mode of action might become very difficult. Herbicide resistance was not confirmed according to the criteria defined by HEAP (2005), but a reduced efficacy of glyphosate on individual biotypes of A. myosuroides in Lower Saxony was observed.