Emergence Pattern of Five Weeds in the Central Great Plains

Seedling emergence was characterized for five weeds that infest summer annual crops in the central Great Plains as affected by crop canopy or tillage. The study was established in winter wheat stubble between 1987 and 1990, with seedling emergence recorded weekly between April 1 and November 1. Kochia emerged primarily from early April to late June, whereas green foxtail, wild-proso millet, and redroot pigweed began emerging in late May and continued until August. Volunteer wheat emerged throughout the growing season. Tillage did not affect the emergence pattern of any species, but the numbers of kochia, volunteer wheat, and green foxtail seedlings were increased in no-till. Conversely, wild-proso millet emergence was greater with tillage. Only volunteer wheat's emergence was affected by crop canopy, as fall emergence of volunteer wheat was more than three times greater in corn than in proso millet. Nomenclature: Green foxtail, Setaria viridis (L.) Beauv. # 3 SETVI; kochia, Kochia scoparia (L.) Schrad. # KCHSC; redroot pigweed, Amaranthus retroflexus L. # AMARE; volunteer wheat, Triticum aestivum L.; wild-proso millet, Panicum miliaceum L. # PANMI; corn, Zea mays L.