SIMULATION OF CROP-WEED COMPETITION - MODELS AND THEIR APPLICATIONS

Competition between crops and weeds is a complex phenomenon. Comprehen sive, process-oriented simulation models which treat competition in a mechanistic rather than an empirical fashion, can offer insight into r elationships among competition, crop and weed density, relative time o f emergence, various morphological and physiological traits, and resou rce levels. They can also be used for prediction as part of a systems approach to weed management. This paper reviews the features of a numb er of recent simulation models of crop-weed competition, the species f or which they have been parameterized, and their applications. To date , these models have been used primarily to predict crop yield losses d ue to weed competition. Their ability to simulate weed seed production in response to the environment has not been exploited. The next step is to link simulation models of crop-weed competition to weed populati on dynamics models, in order to improve our ability to predict the eff ect of various weed management strategies over time. Advantages and dr awbacks of a modeling approach to weed management problems are discuss ed.