Metalaxyl is an acylalanine fungicide with systemic function.[3] Its chemical name is methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate. It can be used to control Pythium in a number of vegetable crops, and Phytophthora in peas. Metalaxyl-M is the ISO common name[4] and Ridomil Gold is the trade name for the optically pure (-) / D / R active stereoisomer, which is also known as mefenoxam.[5]
It is the active ingredient in the seed treatment agent Apron XL LS.[6]
The fungicide has suffered severe resistance problems. The fungicide was marketed for use against Phytophthora infestans. However, in the summer of 1980, in the Republic of Ireland, the crop was devastated by a potato blight epidemic after a resistant race of the oomycete appeared.[7] Irish farmers later successfully sued the company for their losses.[citation needed]
Maximum pesticide residue limits for the EU/UK are set at 0.5 mg/kg for oranges and 1.0 mg/kg for apples.[citation needed] As early as 1998 Pythium was known to be widely developing resistance to metalaxyl[8] which was the most effective control at the time.[8] Various Pythium populations have been known to have resistance to mefenoxam since the 1980s[9] and metalaxyl since 1984.[10] There is wide variability in resistance/sensitivity between Pythium species, with some populations showing complete ineffectiveness.[9]
Synthesis
The first synthesis of metalaxyl was disclosed in patents filed by Ciba Geigy.[11]
^Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 134
^O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition, Whitehouse Station, NJ: Merck and Co., Inc., 2001., p. 1058
^Sukul, P; Spiteller, M (2000). "Metalaxyl: persistence, degradation, metabolism, and analytical methods". Reviews of Environmental Contamination and Toxicology. 164: 1–26. PMID12587832.
^Monkiedje, Adolphe; Spiteller, Michael (2002). "Effects of the phenylamide fungicides, mefenoxam and metalaxyl, on the microbiological properties of a sandy loam and a sandy clay soil". Biology and Fertility of Soils. 35 (6): 393–398. doi:10.1007/s00374-002-0485-1. S2CID22642870.
^Blaser, Hans-Ulrich; Spindler, Felix (1997). "Enantioselective catalysis for agrochemicals. The case histories of (S)–metolachlor, (R)–metalaxyl and clozylacon". Topics in Catalysis. 4 (3/4): 275–282. doi:10.1023/A:1019164928084.
External links
Metalaxyl in the Pesticide Properties DataBase (PPDB)
Metalaxyl-M in the Pesticide Properties DataBase (PPDB)