Integrated weed management strategies for maize (Zea mays) production on the southeastern coastal plains of North America

A 2-yr field study was conducted near Florence, South Carolina, to compare alternative versus traditional Zea mays (L.) production practices for effectiveness of weed control on the southeastern Coastal Plain. Alternative practices included conservation tillage, 38-cm row widths, cover crops, and glyphosate, whereas traditional production practices involved surface tillage, 76-cm row widths, and atrazine plus metolachlor. Ipomoea lacunosa (L.) and Brachiaria platyphylla (Griseb.) Nash were present in the study both years, whereas Senna obtusifolia (L.) Irwin and Barneby was present only in 2002 and Amaranthus palmeri (S.) Wats. and Sida rhombifolia (L.) in 2003. Glyphosate applied at the V6-V7 Z. mays growth stage and a pre-emergence application of atrazine plus S-metolachlor both resulted in greater than 90% control of all weed species and similar weed biomass and yields both years. A Secale cereale (L.) or Triticum aestivum (L.) cover crop usually suppressed most weed species prior to glyphosate application, but had no effect on late-season weed control or grain yield in either year. Surface tillage had little effect on weed control or weed biomass, but omitting surface tillage increased yields an average of 310-400 kg/ha. Reducing the row width of Z. mays improved S. obtusifolia and Sida rhombifolia control while increasing grain yields 10-15%. In addition to increasing grain yields, the use of glyphosate, cover crops, conservation tillage, and narrow rows are important weed management practices that can be integrated into Z. mays production systems on the southeastern Coastal Plain of the United States.