Further studies of the deposition and persistence of binapacryl,bupirimate and diflubenzuron on apple foliage and fruit

In an extension of previous work, deposits and residues of binapacryl, bupirimate and diflubenzuron on mature foliage and the peel of developing fruit of Worcester and Cox apple trees were monitored throughout the 1980 season following applications by mistblower sprayer. The three compounds were applied as commercial formulations in trials to compare integrated pest management with routine farm spray programmes. In contrast to previous results, all three compounds persisted on foliage until leaf-fall and were detected on the peel of harvested fruit. The mean residue of diflubenzuron on harvested Worcester fruit was 0.05 mg kg^?1 fresh weight and on harvested Cox fruit was 0.02 mg kg^?1 fresh weight. Binapacryl and bupirimate were present on harvested fruit of both cultivars. The unexpectedly long persistence of these chemicals in 1980 remains unexplained, but may be due to climatic factors.