The critical period of weed control is an important concept in Integrated Weed Management (IWM) systems. This period has been defined as an interval in the life cycle of the crop when it must be kept weed-free to prevent yield loss. This concept helps in determining the most effective time for non-residual postemergent herbicide applications, and reduces the practice of season-long residual herbicides, and unnecessary late applications of herbicides.In central Greece, cotton is primarily grown as a spring-seeded, annual crop. The advent of soil-residual herbicides and the increased use of...