Resistance situation in <i>Alopecurus myosuroides</i> in Lower Saxony and activities to prevent resistance

Abstract

Worldwide entire groups of active substances are getting ineffective due to herbicide resistance. This phenomenon presents itself in Alopecurus myosuroides plants on numerous fields in Lower Saxony, Germany. Having first emerged in the river and coastal marshes of Lower Saxony, which have been intensely cultivated in narrow crop rotations for years, the herbicide resistances have spread to the fields in the Middle and the South of Lower Saxony in the past 10 years. Besides the ACCase inhibitors and photosynthesis inhibitors, the ALS inhibitors are also at increasing risk of becoming resistant. This development is based on the one-sided use of herbicides, the narrow crop rotations (winter wheat- winter wheat – oilseed rape) and the reduced use of ploughing. Alopecurus myosuroides already shows multiple resistance on many fields to several active substance groups on numerous fields. Seed samples from monitoring areas were tested in 541 bioassays in greenhouses from 2007 until 2016, in which different active substances from different HRAC groups were applied (see Tab. 1). Over the past 10 years, an ALS resistance against Atlantis WG has been detected in 40% (214 samples) of the examined 541 Alopecurus myosuroides provenances. Some of these 214 samples, showing a resistance against Atlantis WG, also showed a resistance to other active substances from the HRAC group B, but also to active substances from the HRAC groups A and C.