Absorption, translocation and metabolism of ¹⁴C‐glyphosate in several weed species*

Summary: The pattern and extent of 14 C‐glyphosate [N‐(phosphonomethyl)glycine] translocation from the treated leaf and metabolism of 14 C‐glyphosate were studied in field bindweed ( Convolvulus arvensis L.), hedge bindweed ( Convolvulus sepium L.). Canada thistle [ Cirsium arvense (L.) Scop.] tall morning glory [ lpomoea purpurea (L.) Roth.] and wild buckwheat ( Polygonum convolvulus L.). 14 C was translocated throughout the plants within 3 days with accumulation in the meristematic tips of the roots and shoots evident. Cross and longitudinal sections of stems and roots showed that the 14 C was localized in the phloem. Field bindweed translocated 3–5% of the applied 14 C from the treated leaf, hedge bindweed 21.6%, Canada thistle 7.8%, tall morningglory 6.5%, and wild buckwheat 5%. Field bindweed, Canada thistle, and tall morningglory metabolized the parent glyphosate to aminomethylphosphonic acid to a limited extent. This metabolite made up less than 15% of the total 14C. Of the total 14 C applied to excised leaves, 50% had disappeared within 25 days.