Weed decision threshold for herbicide reduction in site-specific management

Weed decision threshold and spatial distribution significantly affect herbicide reduction in site-specific weed management. In a central Spain corn field, simulations showed up to 66% herbicide savings for sparse, patchy weeds like johnsongrass when using higher decision thresholds (6–12 plants m⁻²), compared to 10–20% savings for dense, uniformly distributed species such as velvetleaf. Ground-based sensors outperformed aerial sensors in reducing herbicide use. Higher thresholds reduced application rates but risked untreated patches, potentially leading to yield loss and herbicide-resistant weed development. Optimal thresholds depend on weed density and spatial pattern, with higher thresholds most effective for patchy distributions.