Volatilisation of pesticides from soil and plant surfaces

Volatilisation rates of five pesticides (parathion-methyl, endosulfan, fenpropimorph, lindane, trifluralin) applied in formulations were determined from soil surfaces and French beans. Tests were performed in a wind tunnel under defined conditions (20 deg C, air velocity 1 m/s., relative air humidity 40 - 60 per cent). Volatilised substances in the air were trapped by passing a part of the whole air stream of the wind tunnel through polyurethane foam. Toluene extracts of the adsorbent were analyzed by gas chromatography. Volatilisation from soil surfaces within 24 hours increased in the order parathion-methyl = fenpropimorph < endosulfan < lindane < trifluralin. For all compounds volatilisation from French beans was higher as compared to volatilisation from soil surfaces. Volatilisation rates from plant surfaces were 50 - 70 per cent for parathion-methyl, endosulfan, fenpropimorph, and lindane. Trifluralin was nearly completely volatilised within 24 hours. Volatilisation and vapour pre ssure seemed to be correlated for the tested pesticides.