Dissipation of Curzate (cymoxanil 8%+mancozeb 64%) in potato tuber and cropped soil.

The dissipation of the fungicide Curzate M-8 which is a mixture of cymoxanil(8%) and mancozeb (64%) was studied using potato variety Kufri Chandramukhi. The crop was sprayed four times @ 1080 and 2160 g a.i. ha−1 at an interval of 10 days starting from the first appearance of late blight symptoms. The residue estimation was done by carbon disulphide evolution method for mancozeb and HPLC for cymoxanil. The cumulative residues of mancozeb in/or on potato tuber and cropped soil sampled 2hr after last spray ranged from 17.90–20.80 and 4.03–9.00 mg g−1, respectively whereas in case of cymoxanil cumulative residues were in the range of 0.16–0.36 and 0.019–0.12 mg g−1 respectively. The calculated half-life values were found to be 0.68–0.71 and 0.75–0.79 days for mancozeb and 1.08–1.30 and 0.75–2.15 days for cymoxanil in/on potato tuber and cropped soil, respectively. The residue was below determination limit at harvest in both tuber and soil.