Metalaxyl residue in potato tubers*

Metalaxyl residue was estimated in potato tubers obtained from the crop sprayed with Ridomil MZ-72 (metalaxyl 8% + mancozeb 64%) at Jalandhar (Punjab) and Modipuram (UP). Two sprays each of Ridomil and mancozeb were applied in alternation. Metalaxyl residue was detected in the produce of all the treatments at both the locations, upto 20 days after harvest. Extent of residue was more at 5 days (5.5–144.7 ng/g fr.wt.) than at 20 days after harvest (2.9–50.3 ng/g fr.wt.). At 40 days, the metalaxyl contents were drastically reduced. Higher dose (5 kg/ha) resulted in increased residue levels (59.2–144.7 ng/g fr. wt.) as compared to low (2.5 kg/ha) dose (5.5–92 ng/g fr.wt.). Residue level was much higher when the last spray applied was that of Ridomil (7.1–65.4 ng/g fr. wt.) instead of mancozeb (3.7–22.2 ng/g fr. wt.). However, it was still within the permissible limits (daily intake 0.03 mg/kg body wt.). It is concluded that application of metalaxyl (two sprays) though led to its accumulation in tubers but the level of accumulation was within the prescribed limits.