Field trials were carried out to evaluate whether folpet sprayed on grapevi
nes penetrated the epicuticular wax and cell walls of grapes. Folpet showed
poor penetration into the epicuticular wax; it was found almost totally on
the surface. Despite its low solubility in water, perhaps due to the prese
nce of adjuvants, its residues showed such a high resistance to washing tha
t the action of rain was negligible in decreasing residues.