The critical period of competition defines how long weeds can compete with crops before affecting yields. Two critical periods are defined. The first involves weeds that emerge at the same time as the crop and compete until a postemergence strategy is applied. These weeds have the greatest potential to affect crop yields and are the focus of this article. The second critical period involves weeds that emerge after crop emergence. As the interval between crop and weed emergence increases there is less likelihood that the weeds will impact yields.
Iowa State University
Hartzler, Robert G., "Critical periods of competition in corn" (2001). Integrated Crop Management News. 1874.
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