Translocation and Metabolism of Atrazine in Canada Thistle

Abstract

Canada thistle (Cirsium arvense L.) plants containing one elongated and one recently emerged shoot from the same root segment were treated with14C-ring labeled atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]. Fourteen days after atrazine application to the elongated shoot 98% of the recovered activity remained in this shoot. The distribution pattern of14C suggested movement with the transpiration stream. Of the14C in the treated shoot, 82% was in the form of unaltered atrazine at 14 days after application. Greenhouse studies with nonlabeled atrazine indicated that this herbicide had only an indirect effect on portions of the plant located basipetally to the area of application.