Agronomic drivers of Tribenuron-methyl resistance in wild mustard (Sinapis arvensis) in dryland wheat fields of western Iran.

Understanding the impact of common agronomic practices on the evolution of herbicide resistance is essential for developing sustainable weed management strategies that incorporate non-chemical control methods. In this study, we investigated the frequency of Tribenuron-methyl (TBM) reduced-sensitivity in wild mustard (Sinapis arvensis L.) by analyzing survival patterns and their association with agronomic management across 313 dryland wheat fields in the Eslamabad-e-Gharb district, Kermanshah, Iran. The results showed that survival levels in the studied fields varied notably, with 47.3% exhibiting survival between 0% and 20%, 14.0% falling within the 20% to 30% range, and 38.7% showing survival above 30%, highlighting the diverse survival patterns across the region. Logistic regression analysis identified intensive TBM application as the strongest factor promoting survival proportion, with triennial applications (3×) over a five-year period increasing the risk of reduced-sensitivity in wild mustard more than tenfold (Exp(B)=10.651) compared to no use. The selection of wheat cultivar also played a significant role; using Azar-2 raised the survival by more than twofold (Exp(B)=2.218) relative to Sardari. Furthermore, field area significantly influenced survival dynamics, with larger farms (15 ha and more) showing higher mean survival proportions (42.1%) and greater frequencies of intensive TBM application. Conversely, incorporating chickpea into the crop rotation significantly reduced survival proportions. These findings highlight the necessity of adopting diversified agronomic practices-including herbicide rotation, crop rotation, and competitive cultivar selection-to mitigate herbicide resistance frequency. Furthermore, strengthening grower awareness regarding resistance mechanisms and improving the outreach of effective management protocols are critical.