Foliar and nontarget deposition from conventional and reduced-volume pesticide application in greenhouses

Permethrin insecticide was applied to greenhouse-grown chrysanthemums using conventional highvolume (2300 L/ha) and air-assisted, electrostatic, reduced-volume (46 L/ha) spraying systems. The electrostatic reduced-volume application resulted in significantly greater foliar deposition (1.29 vs 0.35 pg/cm2). In winter, but not summer, applications, the reduced-volume spraying resulted in longer persistence of deposits. The conventional application resulted in significantly greater contamination of nontarget surfaces of the greenhouse benchtops and aisleways. Mass-balance analyses accounted for 49 and 73% of the permethrin applied by the conventional and electrostatic techniques, respectively. Dislodgeable foliar residue was removed by two techniques, viz., an aqueous surface extraction and a dry mechanical brushing. The ratios of mechanically removed to surfaced-extracted residue were 0.135 and 0.303 for the reduced-volume and conventional treatments, respectively.