UPTAKE, TRANSLOCATION AND DEGRADATION OF [C-14] CYMOXANIL IN TOMATO PLANTS

[C-14]Cymoxanil was applied to either the root system or to the foliage of tomato plants and its uptake. translocation and degradation was followed using autoradiography, combustion and thin-layer chromatographic analyses of water or methanolic extracts. Cymoxanil was taken up by the root system within 1 h and translocated to cotyledons, stem and leaves within 16 h. The compound was degraded. mostly to glycine, within 16-44 h. in the root and all parts of the shoot. When applied to the surface of leaf of five-leaf plants, enhanced uptake, translocation and degradation (mainly to glycine) of [C-14] cymoxanil was observed in plants treated with a mixture of oxadixyl and [C-14]cymoxanil, compared with plants treated with [C-14]cymoxanil alone. Root application data confirm that cymoxanil is a systemic compound with a short persistence in tomato plants. Foliage application data suggest that the well-documented synergistic interaction between cymoxanil, oxadixyl and mancozeb in controlling plant diseases caused by Peronosporales docs not result from a delayed degradation of cymoxanil in the presence of the other fungicides; the mechanism of synergism has not yet been elucidated.