Preemergence and Postemergence Activities of the (R) and (S) Enantiomers of Haloxyfop

The relative activities of (R) and (S) enantiomers of the methyl ester of haloxyfop were determined on annual grasses. Samples enriched in the (S) enantiomer were markedly less active than the (R) in petri dish evaluations and foliar applications. The pure (S) enantiomer was estimated by regression...

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Bibliographic Details
Published in:	Weed science Vol. 36; no. 4; pp. 453 - 456
Main Authors:	Gerwick, B. Clifford, Jackson, Lucinda A., Handly, Jack, Gray, Nick R., Russell, John W.
Format:	Journal Article
Language:	English
Published:	Cambridge, UK Cambridge University Press 01-07-1988 Weed Science Society of America
Subjects:	Acid soils Agricultural soils Biological and medical sciences Chemical control ECHINOCHLOA FRUMENTACEA Enantiomers Esters Fundamental and applied biological sciences. Psychology HERBICIDAS HERBICIDE Herbicides Isomers Parasitic plants. Weeds Physiology, Chemistry and Biochemistry Phytopathology. Animal pests. Plant and forest protection Propionates SETARIA (GRAMINEA) SETARIA (GRAMINEE) Silt loam soils Soil treatment Soil water SORGHUM HALEPENSE Weeds Haloxyfop, 2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid (D) and (L) isomers Optically active herbicides Soil Activity Enantiomer Optical inversion Herbicide
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Summary:	The relative activities of (R) and (S) enantiomers of the methyl ester of haloxyfop were determined on annual grasses. Samples enriched in the (S) enantiomer were markedly less active than the (R) in petri dish evaluations and foliar applications. The pure (S) enantiomer was estimated by regression to be 1000-fold or less active than the (R). The activity of the (S) enantiomer was found to be equivalent to that of the (R) following preemergence applications. Isolation and characterization of haloxyfop from soil treated with the methyl ester of haloxyfop indicated inversion of the (S) enantiomer to the (R) enantiomer within 7 days. Field trials confirmed the differential activity of enantiomers applied postemergence and their equivalence when applied preemergence. These findings indicate that inversion of the (S) enantiomer to the (R) occurs in soil following preemergence applications.
Bibliography:	H60 8857572
ISSN:	0043-1745 1550-2759
DOI:	10.1017/S0043174500075196