Effects of Conventional and Reduced-Volume, Charged-Spray Application Techniques on Dislodgeable Foliar Residue of Captan on Strawberries

An air atomization, electrostatic charging spray system was used for reduced-volume (80 L/ha) applications of captan onto commercial strawberry plantings. Initial dislodgeable foliar residue from the charged reduced-volume application was higher (7.03 vs 5.33 microgram/cm2) and the first-order decay time constant was longer (9.07-vs 6.65 days) than from a conventional, high-volume (1870 L/ha) application. Comparison of charged vs uncharged reduced-volume sprays found the addition of electrostatic charging to increase spray deposit but not to increase the time constant of the decay. Pesticide deposition and decay curves for conventional application of 2.24 kg of ai/ha and reduced-volume, charged-spray application of 1.12 kg of ai/ha were found to be coincident. Implications for fruit-harvester exposure to foliar residue are discussed