Uptake and Translocation of Fluazifop by Three Annual Grasses

Abstract

The butyl ester of fluazifop {[(±)-2-[4-[[5-trifluoromethyl)-2-pyridinyl] oxy] phenoxy)propanoic acid} at 0.26 μM in nutrient solution inhibited root growth of hydroponically grown goosegrass (Eleusine indicaGaertn. ♯ ELEIN), large crabgrass [Digitaria sanguinalis(L.) Scop. ♯ DIGSA], and giant foxtail (Setaria faberiHerrm. ♯ SETFA). Treating the soil and plant foliage at 0.035 or 0.07 kg ai/ha did not result in greater phytotoxicity than exposing only the foliage of each grass to the herbicide. Foliar-applied fluazifop was retained on the foliage in similar amounts by each of the species. Translocation of14C to all plant parts was detected 6 h after foliar application of the butyl ester of14C-fluazifop to the grasses in the pretillering or tillering stage. The majority (90%) of14C absorbed by each of the species remained in the treated leaf. In hydroponic studies, each species exuded14C into nutrient solution following foliar application of the14C-labeled herbicide. The exuded material was predominantly fluazifop with small amounts of compounds more polar than the butyl ester of fluazifop. Uptake and translocation studies suggest that the greater sensitivity of goosegrass to fluazifop may be related to higher concentrations of the herbicide present in plant tissue.