The value of pre-emergence herbicides for combating herbicide-resistant Alopecurus myosuroides (black-grass)

摘要

The impact of resistance on the efficacy of pre-emergence herbicides used to control Alopecurus myosuroides was evaluated in outdoor containers and a field trial. The ranking order for the relative efficacy of individual herbicides was consistent, with flufenacet the most effective herbicide, followed by prosulfocarb and pendimethalin, with diflufenican the least effective. The degree of resistance varied considerably between the five populations studied, with differing levels of enhanced metabolismbeing the most likely mechanism. Enhanced metabolism resistance affected herbicides to varying degrees, but in a manner that appeared surprisingly consistent given that the herbicides belong to four different chemical families. The results showed that most herbicides could provide a useful level of control where partial resistance was present, especially when applied in mixtures. However, poor control did occur with some highly resistant populations. Maximising control from pre-emergence herbicides becomes increasingly important as resistance to post-emergence herbicides develops.