Occasional mouldboard ploughing slows evolution of resistance and reduces long-term weed populations in no-till systems

The PERTH simulations showed that the use of an occasional strategic MB slowed the development of resistance, but did not fully “reset the resistance clock” to susceptible population levels. The development of resistance was delayed appreciably with regular use of the MB. When we assumed higher weed seed predation and herbicide efficacy in the NT system, weed control improved markedly, although the rate of evolution of resistance to the soil residual herbicide was little changed. Higher seed dormancy resulted in slower development of resistance. Occasional use of the MB for weed control relies on a high seed burial efficacy, and the less frequent the MB, the greater the efficacy of burial required; more research on this aspect is required as it is so critical. There are likely to be regional and local issues and environmental and economic considerations that influence how often the occasional strategic MB is used, if indeed at all, but these results indicate that even very occasional use of the MB may be of benefit as a weed management option.