ABSTRACT
Management of weeds in agricultural fields with herbicides is under scrutiny because of off-target herbicide effects, primarily ground and surface water contamination. While reduced or nonchemical weed control alternatives are being sought, adoption of conservation tillage is increasing rapidly in the United States. Alternative weed control methods are needed that are compatible with reduced tillage. Mechanical cultivation for weed control in crops probably is the oldest method used except for hand-weeding. Recent developments in mechanical weed control are primarily in the area of plant ecology—increasing knowledge of how plants respond to tillage at different points in their life cycle. Tillage control of weeds is divided into four categories: primary, secondary, selective, and fallow-season repeated tillage. Herbicide use makes effective weed control possible with monocultures and short crop rotations.
