PS&C Prairie Soils & Crops Journal Herbicide Resistance in Weeds: Influence of Farm Practices

Weed resistance across the Prairies affects over 10 million acres (4 M ha). The main herbicide-resistant weeds are wild oat, green foxtail, kochia, and chickweed. The risk of weed resistance is greatest in fields with cereal-based rotations and least in fields with forage crops, fallow (summer or green manure), or where three or more crop types are grown, such as cereal, oilseed, and pulse. Risk also is greatest in min-till and no-till systems, possibly due to greater herbicide use and/or more rapid weed seed bank turnover vs. conventional tillage. Large farms (>1,000 acres) have a greater risk of developing resistant weeds than smaller farms possibly due to greater time pressures resulting in less use of integrated weed management practices. Cropping system diversity is the foundation of proactive weed resistance management