Grass herbicide

Stable in neutral to basic aqueous solution Unstable in acidic aqueous solution Flucarbazone-sodium is a post-emergent grass herbicide for use in winter wheat and spring wheat, including... 

Metolachlor is the active ingredient of Dual, one of the most important grass herbicides for use in maize and a number of other crops. In 1996, after years of intensive research, Dual Magnum with a content of approximately 90% (S)-diaste-... 

Metolachlor is the active ingredient of Dual , one of the most important grass herbicides for use in maize and a number of other crops. In 1997, after years of intensive research. Dual Magnum, with a content of approximately 90% (I S)-diastereomers and with the same biological effect at about 65% of the use rate, was introduced into the market. This chiral switch was made possible by the new technical process that is briefly described below. The key step of this new synthesis is the enantioselective hydrogenation of the isolated MEA imine, as depicted in Figure 1.3. 

Simetryn. Simetryn found its place exclusively as a mixing partner with thiobencarb and other grass herbicides for rice in Japan. Simetryn is sold mainly in Japan through Hokko and Kumiai. 

Premixes of Atrazine and Other Herbicides The first prepackaged mixture of a grass herbicide with atrazine was Primaze , a combination of two products prometryn (Caparol) and atrazine. The prepack was first sold in 1968. However the margin of crop safety for prometryn was narrow, and it was marketed for only 2 years. 

A combination of metolachlor (Dual ) and atrazine in a liquid prepack called Bicep facilitated the growing practice of mixing atrazine with grass herbicides. Test marketed in 1978 and 1979, Bicep was introduced nationally in 1980. In 1997, atrazine was combined with S-metolachlor to produce Bicep II Magnum , since. S -metolachlor contains more of the active isomer and reduces the amount of herbicide needed for efficacy. 

The ability of one product to complement the characteristics of another has also had an effect on product acceptance. Although alachlor initially was used by itself as a banded granular grass herbicide on com and soybean, it was the tank mixes with broadleaf herbicides that propelled its success. Combinations of atrazine-alachlor, metribuzin-alachlor, and linuron-alachlor became very common. Alachlor replaced essentially all propachlor use on field corn over the 4-year period from 1972 to 1976, not only as a result of less hazardous handling characteristics (Table 4.1), but also as a consequence of its success in tank mixes. 

Ahrens, J.F. and M. Cubanski (1985). Evaluation of postemergence grass herbicides in conifer seedbeds and Christmas trees. Proc. Northeast. Weed Sci. Soc., 39 243-246. 

A number of trifluoromethylpyridine-containing agrochemicals have found their way into commercial use. The grass herbicide fluazifop-P-butyl (Fusilade ), which is prepared from 2-chloro-5-trifluoromethylpyridine (Fig. 19), is one such product. 

In summary, with the discovery in Dow that a-(2,2,2-trichloroethyl) styrene possessed unique preemergent herbicidal activity and the synthesis and evaluation of close to one thousand related materials, a new product, tridiphane, the active ingredient in TANDEM will enter the marketplace in 1986. Tridiphane will be the first postemergent grass herbicide for use in corn and will be used in combination with triazine herbicides such as atrazine and cyanazine. 

Chiral 3-Benzyloxytetrahydrofuran Grass Herbicides Derived from D-Glucose... 

A novel series of chiral grass herbicides based on the benzyloxy substituted tetrahydrofuran ring system has been prepared. These compounds are readily accessible synthetically from diacetone-D-glucose which serves as a chiral template possessing the appropriate stereochemistry for elaboration to the active herbicides. The degree of herbicidal activity is related to the molecular shape of these compounds and especially to the orientation of the substituents around the tetrahydrofuran ring. The chemistry and empirical structure-activity relationships of these compounds will be discussed. 

Sugar herbicide RE 39571, 5,6-dideoxy-l,2-0-(l-methylethylidene)-3-0-(2-methylphenylmethyl)-a-D-xylo-hexofuranose (Figure 1), a representative of a novel series of chiral grass herbicides, has been demonstrated in our laboratories to possess a high level of preemergence herbicidal activity against grassy weeds with safety on soybeans, cotton, peanuts, and several other broadleaf crops. This herbicide has also been demonstrated to possess some broadleaf weed activity. 

In summary, these compounds represent a novel series of chiral grass herbicides that provide yet another example where chirality is very important for herbicidal activity. Additionally, the use of the sugar D-glucose as a chiral and enantiomerically pure starting material also offers the advantage of having the correct stereochemistry established inherently in the molecule. 

EPTC was repositioned in the marketplace as an annual grass herbicide in 1985, a rotational statement was added to prevent the repeated annual use of EPTC, and shattercane control claims were removed from the label. EPTC was targeted specifically for foxtail (Setaria spp.) and annual broadleaf weed control in the north where cool and wet soils prevail in the spring. EPTC has been a very successful product, provided excellent weed control, and increased in market share every year since its reintroduction as an annual grass and broadleaf herbicide. The other commercial carbamothioate herbicides, EPTC + dietholate and butylate, were positioned as difficult to control weed and southern corn belt herbicides, respectively. No rotational statements have been added to the EPTC + dietholate and butylate labels. 

Mixtures of R-40244 with appropriate grass herbicides such as linuron, trifluralin and terbutrine in sunflowers, linuron and metriburin in potatoes, chlortoluron and mitrofen -1- neburon in wheat show improved activity against grass weeds and several broad-leaved weeds. 

Ortho Select. [Chevron] Selective postemeigence grass herbicide. 

The discovery of pinoxaden is complemented by two further key findings leading to the invention of a family of novel and innovative postemergence grass herbicides safener efficacy and adjuvant response. 

Diclofop-methyl is a postemergence grass herbicide whose action is not related to photosynthetic electron transport. Its herbicidal effect, still not well known, probably involves an antagonism of auxin-mediated processes and an increase in membrane permeability (1,2). Its physiological effects have not been described. 

Inhibition of root growth in wheat caused by the grass herbicide haloxyfop [2-(4-[(3-chloro-5-trifluoromethyl)2-pyridinyl)oxo]phenoxy)propanoic acid) is accompanied by a relative increase in linolenate in the membrane lipids of the root tips (Banas et aL, 1993a). A number of substances which counteract the growth inhibition also counteract the increase in linolenate (Banas et aL, 1993b). In order to elucidate possible relationship between these antagonistic compounds and their effect on polyunsaturated fatty acid content, we report in this communication the effect of two of these substances, salicylic acid (SAL) and salicylhydroxamic acid (SHAM), on the production of polyunsaturated fatty acids in vivo and in vitro,... 

Differential herbicide sensitivity at the site of action is a second possible selectivity mechanism, with good precedence in the aryloxyphenoxy and cyclo-hexanedione grass herbicides (2Q, 51). However, several studies now clearly indicate that the inherent sulfonylurea crop selectivities listed in Table 1 are not based on differential sensitivity at the site of action. ALS preparations isolated fix>m crops and weeds are equally sensitive to several selective sulfonylurea herbicides (28.32.33). Although data have not appeared for all of the compounds shown in Table 1, we conclude that differential active site sensitivity is not a general sulfonylurea selectivity mechanism. The clear exceptions to this generalization are the cases of genetically-altered plants (crops and we s) which have acquired through mutation or deliberate transformation a resistant form of the ALS enzyme (see below). 

ISK first developed a selective grass herbicide, Fluazifop butyl, which is the first example of trifluoromethylpyridine agrochemicals and has been commercialized for use on soybeans, cotton and sugarbeets (1). The usefulness and properties of the trifluoromethylpyridine moiety in agrochemical research are described elsewhere in this volume T. Haga et al. 

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