Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2008
Publication Date: 12/1/2008
Citation: Williams, M.M. II, Rabaey, T., Boerboom, C.M. 2008. Residual Weeds of Processing Sweet Corn in the North Central Region. Weed Technology. 22:646-653. Interpretive Summary: In order to improve weed management systems of sweet corn, specific knowledge about the weed species persisting in the crop is essential. Surveys of weeds in 175 grower fields were conducted from 2005 to 2007 in major processing sweet corn areas of the North Central U.S., including Illinois, Minnesota, and Wisconsin. Compared to weed surveys conducted over 40 years ago, frequency of individual weed species is lower and overall weed density has been reduced by approximately an order of magnitude. Nonetheless, over one-half of surveyed fields appeared to suffer yield loss due to weed interference. Dominant species persisting in sweet corn varied somewhat by state and month of harvest, although fall panicum, giant foxtail, wild-proso millet, common lambsquarters, and velvetleaf were the most abundant species across the North Central U.S. The impact of this work is that it identifies species that are not being adequately controlled in the NCR. The research will be useful in improving weed management systems and directing future research efforts to areas of highest priority.
Technical Abstract: Knowledge of weed community structure in vegetable crops of the North Central Region (NCR) is poor. To characterize weed composition of species persisting in sweet corn to harvest, hereafter called residual weeds, 175 sweet corn fields were surveyed in Illinois, Minnesota, and Wisconsin from 2005 to 2007. Weed density was enumerated by species in 30 1-m2 quadrats placed randomly along a 300- to 500-m loop through the field, and additional species observed outside quadrats were also recorded. Based on weed community composition, population density, and mean plant size, overall weed interference level was rated. A total of 56 residual weed species were observed and no single species dominated the community of the entire NCR. Several of the most abundant species, such as common lambsquarters and velvetleaf, have been problems for years, while other species like wild-proso millet have became problematic in only the last few decades. Compared to a survey of weeds in sweet corn more than 40 years ago, greater use of herbicides is associated with reductions in weed density by approximately an order of magnitude; however, 57% of fields appeared to suffer yield loss due to weeds. Sweet corn harvest in the NCR ranges from July into early October, and earlier harvests are characterized by some of the highest weed densities, while late-emerging weeds such as eastern black nightshade occurred in fields harvested after August. Fall panicum, giant foxtail, wild-proso millet, common lambsquarters, and velvetleaf were the most abundant species across the NCR, yet each state had some unique dominant weeds.