Droplet Size and Leaf Morphology Effects on Pesticide Spray Deposition

Studies were conducted to determine the effects of droplet size, leaf morphology, and a spray thickener onpesticide spray deposition using chlorpyrifos as the indicator compound. The predicted deposition efficiencies for 140 mdroplets were 99, 77, 65, and 55%, respectively, for cocklebur, entireleaf morninglory, velvetleaf, and coffee senna leaves.Predicted deposition efficiencies decreased as droplet size increased for all four leaf types. The slopes of the linearregression equations indicated that deposition efficiency would decrease by 16, 10, 8, and 6% , respectively, with each100 m increase in droplet diameter. Addition of a viscosity modifying adjuvant did not improve the deposition efficiencyon coffee senna leaves.