AbstractRadioisotope techniques have been used to study the breakdown products that are formed from the herbicide cyanazine (BLADEX)a, 2‐chloro‐4‐(1‐cyano‐1‐methylethyl‐amino)‐6‐ethylamino‐1,3,5‐triazine, in soils and in maize grown in the soils under indoor conditions.In soils of different types cyanazine broke down mainly by conversion of the nitrile group to amide (II) and then to an acid (III) followed by hydrolysis of the ring chlorine to hydroxyl (IV). Dealkylation reactions occurred to only a limited extent in soils.In maize plants grown in treated soils the hydrolysis products, the amide (II) and the hydroxy acid (IV) were detected as well as appreciable quantities of products (VI) and (VIII) formed from these by loss of theN‐ethyl group. In plants the hydroxy acids (IV) and (VIII) were present in the free form and there was also evidence for conjugates which were not identified but could be converted to these hydroxy acids, (IV) and (VIII), on treatment with acids.In these indoor studies the major residues appear to be the hydroxy acid (IV) in soils and (IV) and its dealkylated analogue (VIII) in plants grown in treated soils. These compounds are not herbicides and are of a low order
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