In the field of agronomy the consistent control of problematic weed species is of paramount importance. As agricultural efforts have been performed in increasingly large scales the need for more predictive systemization of weed control efforts is demonstrated, and requires an approach that integrates the disciplines of agronomy, plant biology, systems ecology, meteorology, and mathematics. The model known as WISDEM (Weed Interference and Simple Demographic Model) is a decision-aid model developed initially by previous authors. This model in its latest generation is presented as an ecologically-based approach to the simulation of weed shifts as well as a realistic decision-aid management tool for glyphosate-tolerant cropping systems.