Submitted to: Plant Growth Regulator Society of America Meeting
Publication Type: Proceedings
Publication Acceptance Date: 9/15/2002
Publication Date: N/A
Citation: Interpretive Summary: Weeds growing in U.S. agricultural crops cost an estimated $33 billion in economic loss as a result of up to 12% yield reduction. In part, the economic loss is associated with organic agriculture, where growers won¿t use a synthetic herbicide. One option that these growers have is the use of natural products that posses herbicidal activity. These may include vegetable oils and formulations of fatty acids. Previous work in our laboratory demonstrated that the essential oil of cinnamon had high herbicidal effects and the active ingredient was determined to be eugenol. Field experiments using eugenol showed this compound had good promise as an herbicidal agent. To further enhance the biological properties of eugenol, several new compounds were synthesized to provide a derivative of eugenol that might have better plant penetration. Of the fifteen compounds tested, six inhibited wheat seedling growth from 100 to 34% and two were shown to be nearly as active against intact weeds as the lead compound, eugenol. Although the derivatives generally were not as phytotoxic as eugenol in the whole plant assay, it is possible that new formulations will improve their herbicidal activity.
Technical Abstract: The natural product eugenol is known to exhibit certain medicinal properties and agrochemical effects. Because of its functional hydroxyl group, it became an ideal template to construct synthetic derivatives that might be useful as agrochemicals. Subsequently, these were tested for plant growth regulatory activity in the etiolated wheat coleoptile assay, Triticum aestivum cv. Wakeland, and as phytotoxic agents against common ragweed, Ambrosia artemisifolia, and johnsongrass, Sorghum halapense. Of the 15 compounds tested, 6 inhibited coleoptile growth from 100 to 34% at 10-3 M, and 1 promoted growth 34% at 10-3 M. Two were shown to be active against intact plants and one was as active as the lead compound, Eugenol, in the coleoptile bioassay.