Chlorsulfuron herbicide

Extensive use of two more recendy developed classes of herbicides will further dramatically reduce the amount of appHed to control weeds. The sulfonylurea herbicides are extremely active compounds first discovered in the mid-1970s at DuPont they have been discussed extensively (78). Sulfonjiurea herbicides have experienced a rapid and widespread success since thek commercial introduction in 1982 with chlorsulfuron (Table 5). The sulfonylureas are appHed at rates of 2—75 g/ha. The chemistry of the sulfonylurea molecule permits the synthesis of a very large number of useful analogues, consequentiy many new herbicides are anticipated for crop production. As of this writing (1996), over 350 patents have been issued to about 27 agricultural companies covering tens of millions of stmctures known or expected to be herbicidaHy active. 

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). 

The hydrilla 2-node explants were also sensitive to the herbicides chlorsulfuron. One part per billion chlorsulfuron (ca. 3 X 10 M reduced growth of new shoots by almost 80% but had no effect on new shoot initiation (Table XI). when the herbicide was removed after 14 days, new shoots began to elongate. 

C. J. McNeil, Determination of the herbicide chlorsulfuron by amperometric sensor based on separation-free bienzyme immunoassay. Sens. Actual. B 98, 254—261 (2004). 

The first ALS-resistant weeds were reported in 1987 when prickly lettuce (Mallory-Smith, 1990 Mallory-Smith et al, 1990b) and kochia (Primiani et al, 1990) control failures occurred in Idaho and Kansas, respectively, after 5 consecutive years of chlorsulfuron use. The kochia biotype proved to be cross-resistant to six other ALS-inhibitor herbicides, including sulfonylureas and imidazolinones. Within 5 years, sulfonylurea-resistant kochia had been identified at 832 sites in 11 states of the United States and in three Canadian provinces (Saari et al, 1994). ALS inhibitor-resistant kochia and Russian thistle have become widespread problems in cereal-producing regions of northwestern United States and Canada. The mobility of these tumble weeds as plants with mature seeds or pollen carried by wind has undoubtedly contributed to the rate at which resistance has spread. 

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). 

Christopher et al. (1992) reported that a chlorsulfuron-resistant rigid ryegrass in Australia was resistant to most other sulfonylurea and imidazolinone ALS inhibitors. However, a common cocklebur biotype resistant to several imida-zolinone herbicides was not resistant to sulfonylurea herbicides (Saari et al., 1994). It is, therefore, difficult to generalize as to patterns of resistance within the five classes of ALS inhibitors. Weed biotypes resistant to one herbicide will usually show some level of resistance to most herbicides within the same class, and may in addition show some resistance to ALS inhibitors in other classes. 

In 2001, Llewellyn and Powles reported a survey of fields in the Western Australian Wheat Belt, conducted to determine the extent of rigid ryegrass resistance to commonly used herbicides (i.e., diclofop-methyl, clethodim, chlorsulfuron, and sulfometuron). Of the randomly collected populations, 46% exhibited resistance to diclofop-methyl and 64% to chlorsulfuron, with 37% exhibiting resistance to both herbicides. 

In 1987, Moss first reported that a blackgrass biotype resistant to chlorotoluron and isoproturon (urea herbicides in WSSA Group 7) was also resistant to the ALS inhibitor chlorsulfuron. Menendez el al. (1997) also found that a chlorotoluron-resistant blackgrass biotype in Spain was resistant to ALS inhibitors (e.g., chlorsulfuron and imaza-methabenz), and that the resistance was due to its greater ability to metabolize the herbicides. 

Devine et al. (1991) and O Donovan et al. (1994) reported that chlorsulfuron-resistant chickweed populations were also resistant to other sulfonylurea herbicides. Primiani et al. (1990) reported cross-resistance to several sulfonylurea and imidazolinone herbicides in chlorsulfuron-resistant kochia. Lovell et al. (1996a) also documented that chlorsulfuron-resistant kochia biotypes from Idaho and Montana were cross-resistant to imazethapyr. 

Boutsalis, P. (2001). Herbicide Resistance Action Committee (HRAC) Web page http //plantprotection.org/HRAC Bradshaw, L.D., S.R. Padgette, S.L. Kimball, and B.H. Wells (1997). Perspectives on glyphosate resistance. Weed Technol., 11 189-198. Bravin, F., A. Onofri, G. Zanin, and M. Sattin (2004). Is malathion a useful tool to infer the chlorsulfuron-resistance mechanism in mul-tiresistant Italian populations of Lolium spp. 4th International Weed Science Congress, p. 52, S15MT08P00. 

Christopher, J.T., S.B. Powles, J.A.M. Holtum, and D.R. Liljegren (1991). Cross-resistance to herbicides in annual ryegrass (Lolium rigi-dum) II Chlorsulfuron resistance involves a wheat-like detoxification system. Plant Physiol., 100 1036-1043. 

Hall, L.M. and M.D. Devine (1990). Cross-resistance of a chlorsulfuron-resistant biotype of Stellaria media to a triazolopyrimidine herbicide. Plant Physiol., 93 962-966. 

Sweetser, P.B., G.S. Schow, and J.M. Hutchinson (1982). Metabolism of chlorsulfuron by plants Biological basis for selectivity of a new herbicide for cereals. Pestic. Biochem. Physiol., 17 18-23. 

Eremin, S.A., I.A. Ryabova, J.N. Yakovleva, et al. 2002. Development of a rapid, specific fluorescence polarization immunoassay for the herbicide chlorsulfuron. Anal. Chim. Acta 468 229-236. 

Ribo, J.M. (1988) The octanol/water partition coefficient of the herbicide chlorsulfuron as a function of pH. Chemosphere 17,709-715. 

Sulfonylureas form a group of selective herbicides. The general structure is given below in Table 7.4. Rj and Rj generally are substituted heterocyclic rings, e.g., 4,6-dimethylpyrimidin-2-yl and 2-(benzoic acid methyl ester) for sulfometuron methyl and 4-methoxy-6-methyl-l,3,5-triazin-2-yl and l-(2-chlorophenyl) for chlorsulfuron, respectively. The compoimds are thermally labile and cannot readily be derivatized and are therefore not amenable to GC-MS. 

A wide variety of organosulfur compounds show useful biological activity examples include the sulfonamide antibacterials and diuretics, penicillin and cephalosporin antibiotics, the antiulcer drug ranitidine, and agrochemicals such as the thiophosphoryl (P=S) insecticides like malathion, herbicides like chlorsulfuron, many fungicides like the dithiocarbamates (see Chapter 9, p. 148) and captan (see Chapter 9, p. 151), and sulfone acaricides like tetradifon (see Chapter 7, p. 104). 

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