VOLATILIZATION OF PESTICIDES FROM PLANT AND SOIL SURFACES - FIELD VERSUS LABORATORY EXPERIMENTS

Comparative volatilization experiments were carried out using isoproturon and parathion-methyl sprayed on French beans in field experiments and on plant stands (0.5 m(2)) in the volatilization chamber developed by the SLFA Neustadt using both compounds C-14-labelled. The experimental conditions in the field experiments concerning wind speed, temperature and humidity fluctuations were simulated in the volatilization chamber. The laboratory experiment reflected the actual outdoor situation, showing only a negligible amount of volatile isoproturon directly measured in air samples, and providing no reduction of the A.I. residues in plants compared with the initial value in the corresponding field experiment. 77.2% of the parathion-methyl applied to the plants were volatilized and measured directly in air samples in the volatilization chamber while a reduction by 74.7% was found for the corresponding field experiment by residue analysis of the plants after 24 h. No details could be given concerning the nature of the evaporated portions in the field experiment.