Competitive Interference and Critical Period of Weed Control for Xanthium strumarium in Soybean Fields

Abstract

Competitive interference and critical period of weed control for Xanthium strumarium in soybean fields were investigated to determine its impact on crop growth and yield loss dynamics. Field experiments were conducted under varying weed infestation durations and densities to assess crop–weed interactions and identify the period during which soybean is most sensitive to weed competition. Parameters such as weed biomass, soybean growth attributes, yield components, and competitive indices were recorded throughout the growing season. Results indicated that X. strumarium exerted strong competitive pressure on soybean, particularly during the early vegetative stages when crop canopy development was limited. Extended weed interference significantly reduced soybean growth, pod formation, and final grain yield due to competition for light, nutrients, and soil moisture. Conversely, early weed removal substantially improved crop performance, highlighting the importance of timely weed management. The critical period of weed control was identified during the early growth phase of soybean, where even short durations of weed competition resulted in measurable yield losses. Beyond this period, the crop showed improved competitive ability and reduced sensitivity to weed interference. The study emphasizes that effective management of X. strumarium requires timely intervention during the critical growth window to minimize yield losses. These findings support the integration of precise weed control scheduling and cultural practices for sustainable soybean production systems.