Abstract: Producers in the semiarid Great Plains are including corn (Zea mays) in dryland rotations; however, weed management is difficult because the corn canopy is not competitive with weeds. My objective was to determine if cultural practices can enhance corn's competitiveness with weeds, thus supplementing current weed management strategies. Cultural systems, comprised of different row spacing, plant population, and nitrogen placement, were evaluated for effects on foxtail millet (Setaria italica) growth during three growing seasons. A cultural system comprised of 38-cm row spacing, 47,000 plants/ha, and N banded near the seeds reduced foxtail millet biomass 60% compared with the conventional system of 76-cm row spacing, 37,000 plants/ha, and N broadcast. Narrow rows had the greatest effect on foxtail millet growth. Corn's tolerance to foxtail millet interference also was improved, as yield loss in the system with narrow rows, high population, and banded fertilizer was reduced threefold compared with the conventional system. Integrating cultural systems with rotation design and residue management will further strengthen weed management in semiarid corn production.

Nomenclature: Corn, Zea mays L. ‘Pioneer 3893’; foxtail millet, Setaria italica (L.) Beauv. ‘Golden German’.

Additional index words: Increased seeding rate, nitrogen placement, row spacing.