Managing herbicide resistance in Southern Great Plains cropping systems

Herbicide-resistant weeds are a growing problem, reducing crop yield and profitability for wheat, sorghum, and soybean producers in the Southern Great Plains. Herbicide-resistant weed pressure is particularly challenging for rainfed, no-till winter wheat systems, which are common in this region. The objective of this study is to determine the economic effectiveness of various herbicide resistance management strategies within rainfed winter wheat cropping systems in the Southern Great Plains. The study investigates how these strategies can limit the spread of herbicide-resistant weeds and support profitable crop production. Three cropping systems were evaluated: continuous wheat-soybean-fallow, wheat-sorghum-fallow, and wheat-fallow rotations. Herbicide management strategies analyzed include combinations of pre-emergent, post-emergent, and glyphosate burndown applications, as well as variations in application frequency. A dynamic, bioeconomic weed population model was employed to evaluate the economic implications of proactive weed management strategies for each cropping system. Additionally, yield loss due to weed pressure was estimated through a crop growth simulation model linked to a weed competition model. Results indicated optimal herbicide management strategies delayed the spread of herbicide-resistant genes in weed populations. The proliferation of herbicide-resistant genes took longer in wheat-double crop systems than in a wheat-fallow system. Moreover, the inclusion of summer crops increased revenue through additional crop revenue. The findings indicate that adopting wheat-double crop rotations with targeted herbicide strategies can slow the development of herbicide resistance in the Southern Great Plains. This research highlights the importance of diversified crop rotations and careful herbicide management for sustainable and effective long-term weed control. • A bioeconomic model analyzed economics of herbicide resistance in wheat-based systems. • Wheat-soybean-fallow systems yielded the highest net returns. • Optimal glyphosate use slowed resistance compared to suboptimal use strategies. • Double-crop systems delayed glyphosate-resistant weed growth. • Findings highlight the profitability of double-cropping and prudent glyphosate use.