Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 17, 2007
Publication Date: January 15, 2008
Citation: Williams, M., Boydston, R.A., Davis, A.S. 2008. Differential tolerance in sweet corn to wild proso millet (Panicum miliaceum) interference. Weed Science. 56:91-96. Interpretive Summary: Weeds cause serious losses in sweet corn yield and quality despite extensive use of herbicides. A non-chemical approach to reducing the negative affects of weeds in some agronomic crops is to improve the crop’s ability to endure competitive stress from the weed. We found large variation among commercially available sweet corn hybrids in their ability to endure stress from wild proso millet. In addition, we found specific factors driving crop yield loss for each hybrid tested. The impact is that we now know that not all hybrids endure weed interference the same, which could lead to improvements for weed management in sweet corn through either crop breeding or cultural tactics.
Technical Abstract: Several canopy properties are known to vary among sweet corn hybrids, leading to the hypothesis that crop tolerance (CT), the crop’s ability to endure competitive stress from weeds, is not uniform among hybrids. This hypothesis was tested using three sweet corn hybrids subjected to a range of wild proso millet densities under irrigated conditions in Washington and primarily rainfed conditions in Illinois. Variation in hybrid tolerance to wild proso millet was evaluated by comparing among hybrids the coefficients of regressions of yield loss on wild proso millet seedling density. A path analysis was used to identify relationships among CT and canopy properties. Crop tolerance varied among hybrids in three of four site-years. Hybrid Spirit suffered higher yield losses than hybrids WHT2801 and GH2547. Generally higher yield loss parameter estimates in Illinois, compared to Washington, suggests CT would have greatest contributions to weed management in the north-central United States; perhaps where water and nutrients are more limiting. Path analysis indicated that wild proso millet biomass and seedling density were both important factors driving yield loss in Spirit, whereas only early-season wild proso millet seedling density contributed to yield loss by WHT2801 and GH2547. The excellent weed suppressive ability and high CT of WHT2801 and GH2547 narrowed the focal point for weed control in these hybrids to early season weed establishment. Consideration of CT in sweet corn, coupled with knowledge of traits conferring weed suppressive ability, may improve weed managements systems through cultural tactics.