Fosetyl

Fosetyl readily degrades to phosphonic acid (H3PO3) and carbon dioxide in aqueous solution, soil and plant tissue and phosphonic acid is considered to be the active and systemic principle through the disruption of phospholipid metabolism. 

The action of propamocarb is related to membrane function, causing efflux of cell constituents. Leakage ceases after the development of mycelium and can be inhibited by the addition of sterols. 

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For certain naturally occurring nontoxic a.i., an enforcement is not sensible (e.g., lecithin, rape seed oil). Analytical methods for residues in soil are not necessary if the DTgo values of the a.i. and relevant metabolites are less than 3 days (e.g., fosetyl), because in general, the results from residue analyses are not meaningful if the a.i. is rapidly degraded. 

CASRN 39148-24-8 molecular formula CeHisAlOgPs FW 354.10 Plant. Felsot and Pedersen (1991) reported that fosetyl-aluminum degrades in plants forming phosphonic acid which ionizes to the dianion phosphonate, HPOs. ... 

Fosetyl. Fosetyl (aluminium ethyl phosphate Figure 4.32) is a specific downy mildewicide (Oomycetes) used to control Plasmopara viticola in vines and Phytophthora blights in various fruit and nut crops. 

Dereks W, Creasy LL. 1989. Influence of fosetyl-Al on phytoalexin accumulation in the Plasmopara viticola-grapevine interaction. Physiol Mol Plant Pathol 34 203-13. 

Pathogens (Genera) prothiocarb/ propamo- carb hymex- azol cymox- anil fosetyl metalaxyl and related compounds... 

Similiarly variable is the systemic activity of these compounds, that is the translocation in the vascular system of the plant. In this respect, cymoxanil with its very localized distribution, and fosetyl with its fast and strong translocation both acropetally and basipetally, are the extremes (Table IV). From this point of view, fosetyl is the most remarkable structure it is the only commercial pesticide showing effective acropetal and basipetal translocation at normal use rates. 

Despite the act that the new compounds have been known and available for years, relatively little is known about their mode of action. Table VI reflects the state of the art. The lack of information is particularly surprising in the case of fosetyl and metalaxyl as far as their indirect effect is concerned, that is, the stimulation of the host plant s defense reactions (e.g. formation of phytoalexins). It is for the first time in the history of fungicides that such effects have been reported. 

At about the same time, the first information was received about product failure after continuous and exclusive use. The investigation of the pathogen populations of such fields yielded highly resistant strains (28, 29, 40), whereas so far no field resistance has been reported for cymoxanil or fosetyl. Thus, in contrast to the favorable results of a broad range of model studies, resistance had appeared very fast under field conditions. The lesson to be learned from this experience is that results of model studies have to be used with caution. Model studies must include the use of chemical mutagens and highly active, systemic fungicides should be used as if a risk of resistance exists until their mode of action is known. 

Fenn, M.E., and Coffey, M.D. 1984. Studies on the in vitro and in vivo antifungal activity of fosetyl-Al and phosphorous acid. Phytopathology 74, 606-611. 

Fosetyl-aluminium phosphoro organic, phosphonate Fosmethilan phosphoro organic, phosphoro dithioate, amide... 

Diethyl phosphite demeton-S-ethyl, demeton-S-methyl, fosetyl aluminum, glyphosate, penconazole... 

Phosphorus tribromide brodifacoum, difenacoum, fenpropidin, flocoumafen, pyriproxifen Phosphorus trichloride chloretoxyfos, disulfoton, EPN, ethephon, ethoprop, fonofos, fosamine ammonium, fosetyl aluminium, fosthiazate, glufosinate, glyphosate, isofenphos, merphos, propaphos, sulprofos, SSS-tributyl phosphorotrithioate, trichlorfon, trichloronat Phthalic acid pindone, tecloftalam... 

Compounds that affect Host Reactions. Examples of compounds which enhance or induce host reactions to pathogens include 2,2-dichloro-3,3-dimethyl-cyclopropane carboxylic acid (DDCC), probenazole, and fosetyl-Al (4). Although these chemicals do not stop the fungus from penetrating the plant, they are quite effective at preventing colonization through the enhancement of the host s resistance mechanisms. Further studies are needed to elucidate how these resistance mechanisms are triggered. 

More than 100 organophosphate componnds show fnngicidal action however, relatively few are of practical nse as fnngicides. Among these few are iprobenfos and aluminium-fosetyl, which are systemic in their activity, and tolclofos-methyl, which acts as a protectant or contact fungicide. 

Toxicity varies and is dependent on the active ingredient and the formulation (e.g., emulsifieable concentrates, wettable powders). Iprobenfos have a low oral LD50 and is classified in Toxicity Category 11 (Warning), whereas aluminum fosetyl (fosetyl-Al) is only slightly toxic and is classified in Toxicity Category III. 

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