Published online by Cambridge University Press: 12 June 2017
Carboxyl labeled 2,4–dichlorophenoxyacetic acid (2,4–D) was applied to ironweed, a perennial composite, at various stages of growth in the field and greenhouse. During phases of rapid plant development, C14 tended to concentrate in new leaves, axillary buds, petioles and stems. As plants approached full vegetative development greater quantities were detected in rhizomes and roots and less in stems and leaves. The herbicide was translocated readily into new leaves, stems and roots of ironweed seedlings. Considerable quantities of 2,4–D–C14 absorbed by ironweed were rapidly metabolized to compounds not extracted by alcohol. Non-herbicide activity was also found in alcohol extracted fractions. C14 accumulations in field-treated ironweed were detected in roots and rhizomes 3 to 6 weeks after treatment.