THE KINETICS OF INSECTICIDE ACTION .5. DETERMINISTIC MODELS TO SIMULATE THE MOVEMENT OF PESTICIDE FROM DISCRETE DEPOSITS AND TO PREDICT OPTIMUM DEPOSIT CHARACTERISTICS ON LEAF SURFACES FOR CONTROL OF SEDENTARYCROP PESTS

Mathematical models have been used to identify combinations of deposit size, density and concentration which result in effective control of sedentary crop pests using minimal amounts of insecticide. A model bas ed on point source diffusion gave an adequate description of the sprea d of biocidal areas around deposits with time; the more complex disc s ource model gave similar results. The point source model has been deve loped further to investigate how pesticide inputs might be reduced whi le maintaining adequate control. Models based on the cumulative effect s of toxicant with time gave marginally better fits in the tails of th e tolerance distribution. Prediction of LN(50) values using a model wh ich takes account of overlapping biocidal areas was in reasonable agre ement with experimental results. Models which have been developed to i nvestigate the factors which affect the control of sedentary crop pest s by insecticides and acaricides may also be used to predict optimal s pray patterns for contact herbicides and fungicides.