The relationship between herbicide resistance and the use of integrated weed management: Is it simply reactive?

Herbicide resistance (HR) has been a major management challenge and ongoing threat in cropping regions over several decades, particularly in the time since the widespread adoption of no-tillage cropping systems. Despite extensive and severe development of resistance in Australian cropping regions, growers have been able to maintain control of new weed populations by introducing new herbicides and non-herbicide practices. These integrated weed management (IWM) practices have helped farming systems maintain productivity and adapt to changing environmental and agronomic conditions. Earlier studies found that the adoption of these alternative practices was associated with a reaction to the initial development of forms of HR on a farm. Practices include those classified as harvest weed seed control (HWSC) that kill potentially herbicide resistant weed seeds and reduce overall weed seedbank populations without increasing HR selection pressure. A largely unexplored aspect of the socioeconomics of HR management is whether the initial ‘reactive’ adoption of IWM has a ‘preventative’ effect on the further spread or proliferation of resistance development to other herbicides and in other weed species.