Changes in the incidence of herbicide-resistant Alopecurus myosuroides (black-grass) in England, based on sampling the same randomly selected fields on two occasions

摘要

Seeds of Alopecurus myosuroides from 19 randomly selected fields, sampled in 2002 and again 7 to 9 years later (2009-2011), were used to assess changes in resistance to five herbicides. There was a significant (P=<0.001) mean decline in activity of all herbicides which was greater (15-26%) with mesosulfuron + iodosulfuron, clodinafop and cycloxydim than with chlorotoluron and pendimethalin (6-8%). All the 2002 samples were susceptible to mesosulfuron + iodosulfuron, which was introduced into the UK in 2003. However, resistance, (RR or RRR) to mesosulfuron+iodosulfuron was detected in 47%, to clodinafop in 100%, to chlorotoluron in 47%, to cycloxydim in 58% and to pendimethalin in 79% of the resampled fields. The presence of two different ALS targetsite mutations (Pro-197-Thr & Trp-574-Leu) and non-target site resistance mechanisms, within the mesosulfuron+iodosulfuron resistant populations, highlighted the complexity of multiple-resistance mechanisms in A. myosuroides. Resistance to this herbicidewas correlated with greater of use of ALS inhibiting herbicides, despite the additional use of other modes of action. Greater use of non-chemical methods is essential to reduce dependence on herbicides.