Weed populations occurring at the site contained a natural
infestation of Amaranthus retroflexus L., Convolvulus arvensis L., Solanum nigrum L., Chenopodium album L., Sorghum halepense (L.) Pers., Xanthium strumarium L., Cyperus rotundus L., Datura stramonium L., Portulaca oleracea L., Tribulus terrestris L., and Anagallis arvensis L. Weed infestations were evaluated at the completion of each treatment by classifying and counting weeds in a 0.5 m 1.0 m-quadrat per plot. Individual weed species composition and average densities in the season-long weedy treatment plots are provided in Table 2. Above-ground shoot dry biomass was determined by clipping weeds at the soil surface inside the quadrats and dried for 72 h at 70 C until a constant moisture content was reached. Final crop harvest was measured at physiological maturity in both years. Harvest dates were 18 August 2013 and 25