Submitted to: Weed Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2007
Publication Date: 1/11/2008
Citation: Williams, M., Boydston, R.A., Davis, A.S. 2008. Crop competitive ability contributes to herbicide performance in sweet corn. Weed Research. 48(1):56-67. Interpretive Summary: Reducing herbicide use in crop production requires improving the effectiveness of non-chemical weed management tactics. This study demonstrates that under suboptimal conditions, an herbicide is less important with a more competitive sweet corn hybrid. The commercially available hybrids in this study performed consistently under a wide range of environmental conditions, suggesting the aforementioned results may have broad application to North American sweet corn production. The impact of this work is knowledge that crop competitive ability has practical value when combined with other forms of weed management.
Technical Abstract: Crop variety effect on herbicide performance is not well characterized, particularly for sweet corn, a crop that varies greatly among hybrids in competitive ability with weeds. Field studies were used to determine the effect of crop competitive ability on season-long herbicide performance in sweet corn. Two sethoxydim-tolerant sweet corn hybrids were grown in the presence of Panicum miliaceum and plots were treated postemergence with a range of sethoxydim doses. Significant differences in height, leaf area index, and intercepted light were observed between hybrids near anthesis. Across a range of sublethal herbicide doses, the more-dense canopy hybrid Rocker suppressed P. miliaceum shoot biomass and fecundity to a greater extent than hybrid Cahill. Yield of sweet corn improved to the level of the weed-free control with increasing sethoxydim dose. The indirect effect of herbicide dose on crop yield, mediated through P. miliaceum biomass reduction, was significant for all of Cahill’s yield traits but not Rocker. These results indicate a less competitive hybrid requires relatively more weed suppression by the herbicide to not only reduce weed growth and seed production, but also to maintain yield. Sweet corn competitive ability consistently influences season-long herbicide performance.