Chlorimuron

A multiresidue analytical method based on sohd-phase extraction enrichment combined with ce has been reported to isolate, recover, and quantitate three sulfonylurea herbicides (chlorsulfuron, chlorimuron, and metasulfuron) from soil samples (105). Optimi2ation for ce separation was achieved using an overlapping resolution map scheme. The recovery of each herbicide was >80% and the limit of detection was 10 ppb (see Soil chemistry of pesticides). 

Soybeans CZE UV 11-85 ugkg- 50 mM acetate Acifluorfen, 2,4-D, bentazone, thifensulfuron-methyl, chlorimuron-ethyl, imazaquin 129... 

There are several commercially available sulfonylurea herbicides that contain a 2-pyrimidine group <2006H(68)561>. These compounds, which function by inhibition of acetolactate synthase (ALS), an enzyme involved in the early stage of branched-chain amino acid synthesis, include sulfometuron-methyl 1095, primisulfuron-methyl 1096, chlorimuron-ethyl 1097, bensulfuron-methyl 1098, ethoxysulfuron 1099, nicosulfuron 1100, and pyrazosulfuron-ethyl 1101. Related nonsulfonylureas include the sulfide pyrftalid 1102 and the ether pyriminobac-methyl 1103. 

Numerous cases of resistance to the ALS inhibitors have now been reported in other broadleaf weed species, including pigweed and cocklebur, as well as grasses such as shattercane. Walsh et al. (2001) reported that only a few years after the first case of ALS-resistant wild radish, a major weed in Australian wheat fields, 21% of randomly collected wild radish populations were found to be resistant to chlorsulfuron. Patzoldt and Tranel (2002) reported that cloransulam resistance was found in an Indiana population of giant ragweed during the first year of that herbicide s commercialization in 1998, and that the resistant plants were cross-resistant to imazethapyr and chlorimuron. Since 1989, the number of species resistant to ALS inhibitors has increased almost 10-fold in crops and on roadsides. The total ALS-resistant weed species now number 108, as seen in Tables 11.4a and b). 

Gaeddert et al. (1997) found that cross-resistance of the ALS-resistant Palmer amaranth biotype occurred among 16 postemergence ALS herbicides evaluated. Sprague et al. (1995) found that two suspected resistant populations of Palmer amaranth and common waterhemp were resistant to imazethapyr and cross-resistant to the sulfonylureas, chlorimuron and thifensulfuron, at 10 times higher than labeled rates. 

Soybean Chlorimuron-ethyl + thifensulfuron-methyl Post Good j... 

Chlorflurecol-methyl see Chlorflurenol-methyl Chlorflurenol-methyl carboxylic acid Chloridazon heterocyclic nitrogen, pyridazinone Chlorimuron sulfonyl urea... 

Guanidine amitrole, bensulfuron, chlorimuron, flazasulfuron, nicosulfuron, pirimiphos, primisulfuron,... 

Malonic acid alloxydim, bensulfuron, brodifacoum, chlorimuron, difenacoum, difethiolone, fenclorim, flazasulfuron, flocoumafen, glufosinate, nicosulfuron, isoprothiolane, oxolinic acid, primisulfuron, pyrazosulfuron, sethoxydim, tralkoxydim Malonic acid acetamide glufonisate Malonic acid dimitrile thicyofen Maneb mancozeb... 

Pyrimidine (2 amino 4.6 dichloro) bensulfuron, chlorimuron, flazasulfuron, nicosulfuron, pyrazosulfuron Pyrimidine (2 amino, 4 chloro, 6 methoxy) chlorimuron Pyrimidine (2 amino 4.6 difluoro methoxy) primisulfuron... 

Sodium methoxide benfuresate, chlorimuron, difenoxuron, difenzoquat, prometon, terbumeton Sodium methyl mercaptide see Methyl mercaptan Sodium methyl thiophenate see Methyl thiophenol... 

General LC/MS Conditions for Sulfonylurea Multiresidue Analysis. We have developed general thermospray LC/MS conditions for the purpose of separating and detecting six different sulfonylurea herbicides. These conditions can be used as a guide fra- a variety of LC/MS residue applications which may require the analysis of one or more of these herbicides. Our procedure includes GLEAN (chlorsulfuron), ALLY (metsulfuron methyl), HARMONY (thiameturon) and EXPRESS cereal herbicides, CLASSIC (chlorimuron ethyl) soybean herbicide and OUST (sulfometuron-methyl) noncrop land herbicide. (Structure 1)... 

Site-directed mutagenesis was used to make additional amino acid substitutions at these sites in yeast ALS. At some of the sites, e.g. alall7, prol92, or trp586, nearly any substitution for the wild type amino acid that was tested resulted in a herbicide-resistant enzyme (Table I). Each of the mutant enzymes was characterized by enzyme assays to compare its activity, and its sensitivity to the sulfonylurea herbicide chlorimuron ethyl, to the wild type enzyme. These analyses have indicated that some of the mutations have little adverse effect on the activity of the enzyme, while decreasing sensitivity to the herbicide from three to greater than one thousandfold. The characteristics of these mutant enzymes were further evaluated in vivo in order to investigate the utility of particular herbicide/mutant enzyme combinations (Falco et al., manuscript in preparation). 

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