Trifloxysulfuron controls green and false-green kyllinga more effectively than halosulfuron. Studies were conducted to evaluate the absorption, translocation, and metabolism of 14C-halosulfuron and 14C-trifloxysulfuron when foliar applied to green and false-green kyllinga. No differences were observed between the two kyllinga spp. with regard to absorption, translocation, or metabolism of either herbicide. The majority of 14C-halosulfuron and 14C-trifloxysulfuron was absorbed by 4 h, with an accumulation of 63 and 47% radioactivity, respectively. Accumulation of both herbicides occurred in the treated leaf and the primary shoot from whence the treated leaf was removed, with minor accumulation occurring in the roots and newly formed rhizomes. Of the total amount of 14C-halosulfuron absorbed into the plant, 77% remained in the form of the parent compound compared with 61% of 14C-trifloxysulfuron. The parent compound was distributed mainly in the treated leaf and primary shoot, whereas polar metabolites were concentrated in the roots and rhizomes. Nonpolar metabolites of 14C-trifloxysulfuron accumulated in the treated leaf and primary shoot. These data indicate that absorption, translocation, or metabolism could not explain the variation in green and false-green kyllinga control between halosulfuron and trifloxysulfuron.
Nomenclature: Halosulfuron; trifloxysulfuron; false-green kyllinga, Kyllinga gracillima L.; green kyllinga, Kyllinga brevifolia Rottb. KYLBR.