Isoxadifen-ethyl

Isoxadifen-ethyl has a favorable toxicological profile according to the U.S. Environmental Protection Agency notice of filing (Table 5.8) [19]. 

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Foramsulfuron (AE FI30360) [48] is a postemergence sulfonylurea herbicide for the control of major grass species and certain broadleaf weeds in maize (Table 2.2.21). It is applied with the safener isoxadifen-ethyl (AE F122006) (Fig. 2.2.7) and in some products in combination with small quantities iodosulfuron-methyl-sodium [49]. 

Introduced in 2001 and subsequently commercialized by Bayer CropScience, the three-way mixture of foramsulfuron with iodosulfuron-methyl-sodium and isoxadifen-ethyl is used for postemergent weed control in maize. Foramsulfuron,... 

The basis of selectivity of foramsulfuron in the presence of the safener isoxadifen-ethyl is a more rapid rate of metabolic detoxification in maize compared with target weeds, in which little or no degradation of the parent sulfonylurea occurs [51]. Three main routes of metabolism have been established in maize - a hydrolytic cleavage of the sulfonylurea bridge, a deformylation of the amino group and oxidative metabolism of the dimethoxypyrimidine ring. 

Foramsulfuron is commercialized with the safener isoxadifen-ethyl under the trade names Option and "Equip ", whereas in combination with iodosulfuron-methyl-sodium the ternary mixture is sold as "MaisTer ", "Mester ", "Fortuna " or "Equip Plus" and "Option 360" (Table 2.2.22). The... 

The synthesis of isoxadifen-ethyl claimed in WO 1995007897 is via a one-step route (Scheme 5.7). 

This compound was recently developed as a safener for the sulfonylurea herbicide foramsulfuron in maize. Metabolism studies revealed that isoxadifen-ethyl also acts by enhancement of foramsulfuron metabolism in maize, while it does not influence the rate of metabolism of this herbicide in susceptible weed species [17, 18]. 

New herbicides continue to be introduced. Resolve Q is an herbicide for use on corn, which contains rimsulfuron, 24.10 thifensulfuron, 24.11 and isoxadifen ethyl, 24.12.24.10 and 24.11 are part of a new family of environmentally compatible sulfonyl urea herbicides, which target the acetolactate synthase enzyme. Alachlor, 24.13, is used for grasses and broad-leaved weeds in corn, soya, and peanuts but is banned in the EU because of its toxicity. Mesotrione, 24.14, based on a substance isolated from the Californian bottlebrush plant, is more generally accepted and can be applied both pre- and postemergence it inhibits the plant enzyme 4-hydroxyphenylpyruvate dioxygenase. 

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