Modelling crop-weed competition: Why, what, how and what lies ahead?

Weeds are one of the major constraints to food production in agricultural systems throughout the world, with their main impact being reducing crop yields through competition for water, light, space, and nutrients. Computer simulation modelling provides an important tool for helping to understand and predict crop-weed competition and the role it can play in integrated agricultural systems in increasing crop yields and managing weeds. In this paper we discuss (1) why it is useful or important to model crop-weed competition, (2) what management options likely to affect crop-weed competition should be addressed with modelling, (3) how crop-weed competition and its effects have been modelled, and (4) what potential new developments in crop-weed competition modelling lie ahead.