Managing spatially variable weed populations

This chapter describes the relationship between spatially variable weed populations and resulting weed management decisions. In addition, it uses spatial population distribution maps to simulate the potential for herbicide use reduction if intermittent herbicide application was commercially feasible. The chapter shows that weeds are indeed spatially aggregated and that intermittent herbicide applicators, based on real-time data acquisition, are a critical first-step in implementation of this technology on a field scale basis. The use of real-time sensing could reduce herbicide use by an average of 30 to 72 % if in-row plant species discrimination were possible. Intermittent herbicide application represents a significant change in herbicide application technology that addresses economic, environmental and agronomic concerns. Technology is available to apply herbicides only when weeds are present. This approach, whose value was suggested as early as 1987 by R. Cousens, lacks basic information on the spatial and temporal dynamics of weed populations in agricultural fields.