EFFECT OF APPLICATION METHOD ON UPTAKE AND PERSISTENCE OF CADUSAFOS IN TOMATO CROP

摘要

Uptake and persistence of Cadusafos, an organophosphatic nematicide, in root, shoot and fruit of tomato (Lycopersicon esculentum) [Mill.] cv. Pusa Ruby was evaluated following soil application of the chemical as broadcast @ 2.0 kg ha~(-1), furrow @ 1.0 kg ha~(-1) and spot treatment @ 0.5 kg ha~(-1) at the time of transplanting of one month old seedlings in winter. Root and shoot samples were taken at different time intervals from 7-150 days after application and processed for residues using a FPD-GC.The residues of Cadusafos persisted in both root and shoot up to 105-120 days. Absorption of Cadusafos by roots was rapid but further translocation to shoot was slow. The residues accumulated in roots up to 15 days. The concentration of residues (mu g g~(-1)) in roots reached a maximum of 15.44 in spot, 2.24 in broadcast and 1.22 in furrow treatments after 15 d of application. The level of residues in shoot was highest after 7 days of treatments accounting for 3.22, 0.56 and 0.38 mu g g~(-1) in spot, broadcast and furrow applications, respectively. Application method affected uptake of Cadusafos from soil, it was maximum in spot treatment followed by broadcast and furrow application. Despite differential plant uptake, the residue levels (mu g g~(-1) in fruits were very low to non-detectable in broadcast (0.003-0.001) and furrow (0.007-0.002) applications but slightly higher (0.024) in earlier pickings of tomato in spot application. The levels of 0.003-0.018 mu g g~(-1) were, however, considered safefrom the angle of toxic residues following broadcast, furrow and spot applications of Cadusafos in soil.