Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2009
Publication Date: 6/1/2009
Citation: Williams, M.M. II. 2009. Within-Season Changes in the Residual Weed Community and Crop Tolerance to Interference over the Long Planting Season of Sweet Corn. Weed Science. 57:319-325. Interpretive Summary: Risk of weed control failure can be reduced by knowing conditions that favor the crop over the weed. This research showed that sweet corn planted in the Midwest U.S. in June and July consistently tolerated weeds better than when the crop was planted in April and May. Moreover, common annual weeds observed in this study varied in their ability to complete their life cycle and produce viable seed, depending on the planting date. While demand for a perishable supply of sweet corn necessitates a long planting season from April to July, results demonstrated that weed control in early-season sweet corn plantings carried more risk of weed control failure and crop yield loss compared with later plantings. The impact of the work is it provides a biological basis for tailoring weed management systems in sweet corn to site-specific conditions.
Technical Abstract: Sweet corn is planted over a long season to temporally extend the perishable supply of ears for fresh and processing markets. Most growers’ fields have weeds persisting to harvest (hereafter called residual weeds), and evidence suggests the crop’s ability to endure competitive stress from residual weeds (i.e., crop tolerance) is not constant over the planting season. Field studies were conducted to characterize changes in the residual weed community over the long planting season and determine the extent to which planting date influences crop tolerance to weed interference in growth and yield traits. Total weed density at harvest was constant across five planting dates from mid-April to early-July; however, some changes in composition of species common to the Midwest U.S. were observed. Production of viable weed seed within the relatively short growth period of individual sweet corn plantings showed weed seedbank additions are influenced in part by species and planting date. Crop tolerance in growth and yield was variable in the mid-April and both May plantings, and the crop was least affected by weed interference in the mid-June and early-July planting dates. As the planting season progressed from late-May to early-July, sweet corn accounted for a great proportion of the total crop/weed biomass. A risk management perspective to weeds should recognize the significance of planting date on sweet corn competitive ability. This work suggests weed control in late-season sweet corn plantings carries less risk of failure and yield loss compared with earlier plantings.