Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/1/2007
Publication Date: 4/1/2007
Citation: Shaner, D.L., Stidham, M.A., Singh, B.K. 2007. Imidazolinone herbicides. Book Chapter.
Interpretive Summary: The imidazolinones are a class of widely used herbicides in legumes, cereals and resistant crops. These herbicides kill plants by inhibiting acetohydroxyacid synthase, the first common enzyme in the biosynthesis of the branched chain amino acids. This mechanism of action is shared by four other classes of herbicides. This paper reviews the discovery, mode of action, commercial uses and mechanism of selectivity of the imidazolinones.
Technical Abstract: The imidazolinone herbicides (Table 1.1) are a family of six compounds that were discovered and developed by American Cyanamid Corporation. The herbicides as a class are broad spectrum and are active both pre- and post-emergence. Selectivity is based most often on metabolic inactivation except for selection-developed target site based resistance. Imidazolinones are uncompetitive inhibitors of AHAS, the first enzyme in the biosynthesis of branched chain amino acids, valine, leucine and isoleucine. Recent crystallographic studies demonstrate that the imidazolinone bind in the active site seven angstroms from the C2 atom of the TPP cofactor. The imidazolinone herbicides have been and continue to be highly successful products. The ability to mix and match different imidazolinones to take advantage of their differing weed control spectrum and pre and post emergent activity has proved invaluable in designing products for imidazolinone-resistant crops throughout the world.