Influence of temperature and relative humidity on the volatilisation of pesticides

The volatilisation of parathion-methyl, bromoxynil and fluroxypyr has been investigated in wind tunnel experiments under stable and reproducible condi tions. For parathion-methyl the highest volatilisation rate could be notice d. During a period of 48 hours, 45.3 % of the applied compound has been vol atilised. Bromoxynil and fluroxypyr showed a volatilisation rate of 33 and 12.3 %, respectively. For parathion-methyl and bromoxynil the highest volat ilisation rates have been observed at the beginning of the experiment (25 a nd 5.6 %), fluroxypyr volatilised with an almost constant rate over the who le period. Changing temperature and relative humidity in the experiments, the effect o f climate conditions on the volatilisation rate could be investigated. Incr easing temperature from 20 to 30 degrees C lead also to an increase in vola tilisation for all tested compounds, up to 86 %. For bromoxynil and fluroxy pyr, an increase in relative humidity (from 50 to 75 %) showed decreasing v olatilisation up to 22 %. But for parathion-methyl the volatilisation rate still increased about 10 % using higher relative humidity in the experiment s.