Adjuvant Effects on Absorption, Translocation, and Metabolism of Haloxyfop-Methyl in Corn (Zea mays)

The effects of adjuvants and relative humidity (RH) on absorption, translocation, and metabolism of the methyl ester of 14 C-haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy] propanoic acid} in corn ( Zea mays L. ‘B73 X Mo17’ hybrid) were evaluated. Addition of 1.0% (v/v) petroleum oil concentrate (POC) to the treatment solution resulted in greater foliar absorption and translocation of 14 C than addition of 1.0% (v/v) soybean oil concentrate (SBOC), 0.1% (v/v) oxysorbic (20 POE) (polyoxyethylene sorbitan monolaurate) (OXY), or no adjuvant (NONE). The least amount of 14 C absorption occurred in the treatment containing OXY. Absorption and translocation of radioactivity were significantly greater at 70% RH than at 30% RH. Thin-layer chromatography revealed that most of the 14 C recovered from treated plants was in haloxyfop-methyl 5 h after treatment (HAT). The remaining 14 C recovered was haloxyfop and an unidentified polar metabolite. The average percentage of 14 C-haloxyfop in the nonabsorbed fraction was 5, 39, 7, and 7% for treatments containing NONE, OXY, POC, and SBOC, respectively. The ratio of haloxyfop-methyl to haloxyfop and the percentage of polar metabolite in the absorbed 14 C fraction was not different among adjuvant treatments or between levels of RH.