Herbicide resistance in weeds

Resistance at the field level is best considered as 'shades of grey', with a continuum from complete susceptibility through to complete resistance. This poses a considerable challenge in detection and in assessing the severity and impact of resistance. Herbicide resistance often results in reduced herbicide activity, rather than no activity at all. The evolution of herbicide resistance as a practical problem in an individual field is dependent on the interaction of three risk factors, including herbicide risk, weed risk, and management practices. Early detection of resistance is very important so that effective management strategies can be introduced over the whole farm to minimise the impact and spread of resistance. Strategies for resistance prevention and management are of no use unless they are implemented. It is vital that the very considerable research effort worldwide produces sound, practical herbicide‐resistant weed management strategies solutions that are easily implemented by farmers.