title: Slow-release formulations of sulfometuron incorporated in micelles adsorbed on montmorillonite.
abstract: The design and tests of slow-release formulations of sulfometuron (SFM), an anionic sulfonylurea herbicide, are described. The formulations are based on incorporation of the herbicide in octadecyltrimethylammonium (ODTMA) micelles, which adsorb on a clay mineral, montmorillonite. An optimization of herbicide/micelle clay ratios yielded high adsorption of SFM (95%), and at a 1% (w/w) water suspension only 0.5% of the adsorbed SFM was released at times varying from hours to 9 days. An analytical test in Seville soil showed that under excessive irrigation (400 mm) 100% of the commercial formulation leached, whereas the micelle-clay formulations showed only 50-65% elution. A plant bioassay in Rehovot soil showed that the commercial dispersible granule formulation (Oust, 75% ai sulfometuron methyl) yielded only 23% root elongation inhibition at the top 5 cm of the soil, whereas complete inhibition was achieved with the micelle-clay formulation. The detected concentration of SFM for the micelle-clay formulation at a depth of 15-20 cm was half of that detected for the commercial one, indicating a reduction in leaching when applying the micelle-clay formulation. A 10-fold reduction in the applied dose of SFM in the micelle-clay formulations resulted in good herbicidal activity of 60-87% inhibition. These characteristics make the new formulation promising from the environmental and economic points of view.
authors: Seagram Center for Soil and Water Sciences, and Department of Field Crops, Vegetables and Genetics, Faculty of Agricultural, Food and Environmental Sciences, Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors: Yael Golda
authors: YG
authors: Mishael
authors: Tomas
authors: T
authors: Undabeytia
authors: Onn
authors: O
authors: Rabinovitz
authors: Baruch
authors: B
authors: Rubin
authors: Shlomo
authors: S
authors: Nir
mesh_terms: D000327:Adsorption; D001546:Bentonite; D004787:Environmental Pollution / Q000517:prevention & control; D006540:Herbicides / Q000008:administration & dosage*; D008823:Micelles; D018517:Plant Roots / Q000187:drug effects; D012987:Soil; D013453:Sulfonylurea Compounds / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D006540:Herbicides; D008823:Micelles; D012987:Soil; D013453:Sulfonylurea Compounds; D001546:Bentonite; C042031:sulfometuron methyl