FORMATION AND PERSISTENCE OF METABOLITES OF IMAZAMETHABENZ-METHYL IN A SANDY LOAM SOIL

The fate of imazamethabenz-methy1 was studied in a sandy loam soil aft er application in spring to winter wheat (Triticum aestivum L.). Imaza methabenz-methyl and its metabolite 2 (2-(4, thylethyl)-5-oxo-H-1-imid azol-2-yl)4-methylbenzoic acid, in mixture with the 5-methylbenzoic ac id isomer) were further transformed into the metabolites 3 )-5-oxo-H-1 -imidazol-2-yl)-1,4-benzenedicarboxylic acid, in mixture with the 1,5- benzenedicarboxylic acid isomer), and 4 (1,2,4-benzenetricarboxylic ac id, in mixture with the 1,2,5-isomer). Meta-bolites 3 and 4 reached ma ximum concentration levels in the 0-13 cm layer corresponding to 14-17 % and 9-14% of the imazamethabenz-methy1 dose, respectively. These max ima were reached be tween 105 and 177 days after application. Imazamet habenz-methyl metabolism was slower in plots treated with organic fert ilizers than in untreated plots. After 196 days the concentrations of all metabolites in the 0-13 cm layer had declined to, at most, 0.01 mg kg(-1). There was no carry-over of residues that could be phytotoxic to the next crop.