Herbicides have been pivotal tools but decreasing their use is currently a political and societal priority to minimize the risk for human health and the environment and to hinder the evolution of herbicide resistance. A 3-year experiment was conducted to compare three weed management strategies in winter wheat fields in northern Italy: (1) sole chemical control, (2) sole mechanical control, or (3) their combination. Agronomic and economic performances of the three strategies were assessed. Large variability of weed presence and crop yield was observed across the three years. Higher weed biomass was observed in the mechanical management, while the lowest weed presence and cost for weed control was estimated for the chemical management. Conversely, no differences were observed across the three management strategies in terms of crop yield or net return. The results confirmed that herbicides are currently the most cost-effective control tools, but the continuous variation in prices and costs can modify this situation. Thus, the economic assessment should be periodically updated to remain valid. However, the lack of differences between managements in terms of wheat grain yield or net profit suggested that mechanical or combined weed control can be sustainable alternatives for wheat production in northern Italy. Nevertheless, to ensure the long-term sustainability of weed management strategies with low or no herbicide use, a more holistic approach should be considered, involving a diversified set of control tactics arranged throughout the whole crop rotation.
Loddo et al. (Sun,) studied this question.