Herbicidal Activity and Metabolism of Dyrene in Canada Thistle

Abstract

The fungicide, Dyrene [2,4-dichloro-6-(o-chloroanilino)-s-triazine], severely injured var.miteof Canada thistle [Cirsium arvense(L.) Scop.]; and the damage resembled that caused by bipyridylium herbicides. Regrowth from treated plants was abnormal. Other arylamino-s-triazines were from slightly to severely phytotoxic to leaf sections of the var.mite.The var.horridumof Canada thistle was not affected by Dyrene or related compounds. Dyrene and metabolites of Dyrene which were phytotoxic to var.miteleaf disks in bioassay tests were isolated from treated var.miteandhorridumplants, but none of these compounds injured the var.horridum.One metabolite was found only in the var.mite; the other five occurred in both varieties. The metabolites were apparently formed from Dyrene by conjugation reactions.