Metalaxyl is an acylalanine fungicide with systemic function. Its chemical name is methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate. It can be used to control ''

Pythium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but '' Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are fre ...

'' in a number of

vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems ...

crops, and ''

Phytophthora ''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species are capable of causing enormous economic losses on crops worldwide, a ...

'' in peas. Metalaxyl-M is the ISO common name and Ridomil Gold is the trade name for the optically pure (-) / D / R active stereoisomer, which is also known as mefenoxam. It is the active ingredient in the seed treatment agent

Apron XL LS An apron is a garment that is worn over other clothing to cover the front of the body. The word comes from old French ''napron'' meaning a small piece of cloth, however over time "a napron" became "an apron", through a linguistics process cal ...

. The fungicide has suffered severe problems. The fungicide was marketed for use against ''

Phytophthora infestans ''Phytophthora infestans'' is an oomycete or water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight. Early blight, caused by '' Alternaria solani'', is also often called ...

''. However, in the summer of 1980, in the

Republic of Ireland Ireland ( ga, Éire ), also known as the Republic of Ireland (), is a country in north-western Europe consisting of 26 of the 32 Counties of Ireland, counties of the island of Ireland. The capital and largest city is Dublin, on the eastern ...

, the crop was devastated by a potato blight epidemic after a resistant race of the

oomycete Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the resul ...

appeared.Working on potato blight in Northern Ireland
/ref> Irish

farmer A farmer is a person engaged in agriculture, raising living organisms for food or raw materials. The term usually applies to people who do some combination of raising field crops, orchards, vineyards, poultry, or other livestock. A farmer mig ...

s later successfully sued the company for their losses. Maximum pesticide residue limits for the EU/UK are set at 0.5 mg/kg for oranges and 1.0 mg/kg for apples. As early as 1998

was known to be widely developing resistance to metalaxyl which was the most effective control at the time. Various ''Pythium'' populations have been known to have resistance to mefenoxam since the 1980s and metalaxyl since 1984. There is wide variability in resistance/sensitivity between ''Pythium'' species, with some populations showing complete ineffectiveness.

References

External links

* * Fungicides Alkyl-substituted benzenes {{mycology-stub