By Sumita Senand Gustavo A. Roa
Winter wheat, barley, oats, rye, and other small grains provide opportunities not only for additional farm revenues, but also for covering the soil during winter, improving soil health by providing living roots in the soil, diversifying rotations, and improving weed and disease management. Yet, small grains do not receive the focus in most of the Midwest due to barriers such as infrastructure, market availability, crop insurance, and farm schedules favoring corn and soybean. Increasing environmental concerns, declining crop diversity, pesticide resistance, nutrient losses, soil degradation, and climate variability have renewed the interest in integrating winter wheat and other small grains into Midwestern production systems.
Across the U.S. Midwest, soybean was initially promoted as high-protein animal feed and human food in the 1920s and since then corn–soybean rotation has dominated the cropping system for more than seven decades due to advances in corn and soybean genotypes, strong export markets, better industrial infrastructure, ethanol production, and overall high grain demand in the region (Li et al., 2025).
The predominance of corn–soybean rotations creates recurring management windows for summer annual weeds such as waterhemp, while repeated reliance on herbicides can intensify selection pressure for resistant populations (Yadav et al., 2023). Moreover, the effectiveness of the corn–soybean rotation for pest suppression has also been challenged by pest adaptation. Corn rootworm (CRW) and soybean cyst nematode (Heterodera glycines, SCN) have adapted to the corn–soybean rotation through different mechanisms. Northern CRW populations can exhibit extended diapause, while SCN populations often maintain higher egg densities in one- to two-year rotations than in three-year rotations that include a small grain such as wheat (Yin et al., 2024). Northern CRW (Diabrotica barberi) populations in parts of the Midwest have evolved extended diapause, allowing eggs to remain dormant and hatch when corn returns following soybean. Extended diapause has re-emerged as an important management concern in Minnesota, with northern CRW injury observed in first-year corn following soybean in 2025 (Yang & Wang, 2025). Rocha et al. (2021) observed that frequent soybean production can maintain substantial SCN populations in infested fields, whereas introducing nonhost crops can help interrupt nematode reproduction. In Illinois field experiments, winter wheat preceding double-crop soybean reduced SCN egg densities by approximately 32% compared with winter fallow.
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