Value of information about weed distribution for improving postemergence control decisions

Weeds apparently occur in patches within fields. This spatial distribution has implications for choosing the most profitable postemergence control measure, because weed distribution influences the yield loss from competition, the design of the optimal scouting plan and the feasibility of patch spraying. Simulation models that use data on the distribution and composition of actual populations may be used to examine these implications for choosing between many potential treatments for postemergence control of a mixed species population. Simulation experiments were carried out to investigate the value of information about weed patchiness for improving the recommendations of a decision model (HERB) for postemergence weed control in soybean. Information about weed patchiness was more valuable when used to account for the possible error in the density estimates obtained by scouting than when used to increase the accuracy of the yield loss prediction. Accurate scouting was shown to be important for choosing treatments when control is required, as well as determining if control is necessary. Simulation results may be used to identify the optimal scouting plan once information about the cost of scouting becomes available.