Effects of seedbed preparation and different timing of herbicide applications on weed control and yield in wheat

Two field experiments were conducted during the 2021/2022 and 2022/2023 growing seasons to evaluate the effectiveness of different agronomic and chemical weed control strategies on weed suppression and wheat yield. The experiments compared false and traditional seedbed preparation combined with herbicide applications at pre-sowing, pre-emergence, early post-emergence, and late post-emergence stages. Weed infestation was dominated by Lolium multiflorum, Matricaria chamomilla, and Papaver rhoeas. False seedbed promoted early emergence of L. multiflorum, although its effectiveness depended on weather conditions. Pre-emergence and early post-emergence applications of residual herbicides consistently achieved high weed control efficacy (>90–95%), reduced weed biomass, and resulted in the highest wheat yields. In contrast, late post-emergence treatments, despite effectively controlling weeds, caused significant yield losses due to prolonged crop–weed competition, with an estimated yield reduction of 26 kg ha⁻¹ day⁻¹ when control was delayed from tillering to stem elongation. The combination of false seedbed, pre-sowing glyphosate, and early residual herbicide applications proved to be the most effective integrated strategy. Where false seedbed was not adopted, early pre-emergence herbicide application remained essential. These findings highlight the importance of early weed control within integrated weed management systems, particularly under increasing pressure from herbicide-resistant weed populations.