Crop Protection Database

Fungicides > Strobilurin fungicides

Summary | Products

Strobilurins are one of the most important classes of agricultural fungicide. The first strobilurin fungicides in this family were isolated from wood-rotting mushroom fungi, including one called Strobilurus tenacellus. The name strobilurin was coined for this chemical family of fungicides in recognition of the source of the first compounds of this type.

The discovery of the strobilurin fungicides was inspired by a group of natural b-methoxyacrylates, the simplest of which are strobilurin A and oudemansin A. The natural products were found to be unsuitable as agricultural fungicides, but a knowledge of their structures and properties provided a useful starting point for independent programmes of research within ICI (now part of Syngenta) and BASF. When ICI and BASF published their first patent applications, other companies also recognised the importance of this class of chemistry and began their own research in the area. ICI and BASF announced the first development strobilurins, azoxystrobin and kresoximmethyl, respectively, in 1992. These products were sold for the first time in 1996, for the control of diseases in temperate cereals. Since that time, other products have been announced, namely trifloxystrobin from Novartis (this product was recently sold to Bayer), metominostrobin from Shionogi, pyraclostrobin from BASF, and picoxystrobin from Syngenta. Azoxystrobin and picoxystrobin retain the methyl b-methoxyacrylate group of the natural fungicides, while the others contain modified toxophores. More recently, DuPont and Aventis, respectively, have discovered famoxadone and fenamidone, fungicides which are not structurally-related to the strobilurins, but which have the same mode of action.

The strobilurins are an outstanding new class of fungicides. Registrations have been obtained on a wide range of crops throughout the world, to the point where the strobilurins can now be considered to be one of the most valuable classes of single-site fungicides ever discovered by the agrochemical industry. They have set new standards in disease control and, more importantly for the grower, in the delivery of improved yields and quality. Indeed, the success of the strobilurins in the fungicide market simply reflects the benefits that they bring to those producing the crop.

Mode of action

The strobilurins act by inhibiting mitochondrial respiration in fungi. They bind at the Qo-centre on cytochrome b and block electron transfer between cytochrome b and cytochrome c1. This disrupts the energy cycle within the fungus by halting the production of ATP.

As a family, the strobilurin fungicides give high levels of activity against a wide range of crop diseases. Target diseases for nearly all strobilurin fungicides include downy mildew, rust, powdery mildew and many leaf spots (Alternaria, Cercospora, Myrothecium and Sphaceloma, which causes scab on poinsettia). Indeed, one of the key reasons for the outstanding commercial success of azoxystrobin is that it gives control of fungi from all four classes of plant pathogens, namely the Ascomycetes, Basidiomycetes, Deuteromycetes and Oomycetes. Therefore, azoxystrobin gives control of combinations of pathogens which was previously only possible through the mixture of two or more fungicides, e.g. downy and powdery mildew of grapevines. However, not all strobilurins are broad spectrum fungicides used on a wide range of crops. For example, metominostrobin from Shionogi has been developed for use exclusively on rice. Similarly, other strobilurins do not offer high level control of all four classes of fungal plant pathogens; kresoxim-methyl and trifloxystrobin are both relatively weak against rust diseases and downy mildews. Of the recently announced strobilurins, pyraclostrobin from BASF is a broad-spectrum strobilurin for use on a wide range of crops, whereas Syngenta’s picoxystrobin is a specialist cereal fungicide.

Resistance

Experience with the strobilurin fungicides worldwide indicates there is a high risk of development of resistant pathogen subpopulations. Worldwide, resistance has been reported in an increasing number of pathogens of field crops, fruit, vegetable, and nut crops, ornamentals and turfgrass.

There are two general types of fungicide resistance: quantitative and qualitative. With quantitative resistance, resistant strains are somewhat less sensitive to the fungicide as compared to the wild type, but they often can still be controlled with higher rates and/or more frequent applications (within labeled limits, of course). A good example of this type of resistance is that observed with strains resistant to the DMI (demethylation-inhibitor) fungicides, such as propiconazole or triadimefon. With qualitative resistance, the resistant strain is vastly less sensitive to the active ingredient, and is no longer controlled at labeled field rates. The effect on disease control is the same as if one were spraying water on the crop instead of a fungicide. A good example of this type of resistance is that observed with the benzimidazole fungicides, such as benomyl or thiophanate methyl. Natural occurrences of resistance to the strobilurin fungicides indicate that most cases of control failure are due to resistance of the qualitative type, but that instances of quantitative resistance to certain strobilurin fungicides have also been recorded.

Fungicides that share a common biochemical mode of action for poisoning the fungus are thought to be in the same "fungicide family". When different fungicidal products share a common mode of action, the fungus does not distinguish between the fungicides, even if the chemical structure of the active ingredients is different and the fungicides are produced by different manufacturers. Biochemically, the fungus sees them all as the same active ingredient. When a fungus is resistant to one fungicide in a chemical family, it is usually resistant to all fungicides in that family. This is called cross resistance. In many situations, fungal strains resistant to strobilurin fungicides exhibit cross-resistance to other strobilurin fungicides. In such cases, efficacy of all strobilurin fungicides may be compromised, even if some of them have never been used on that farm. Cross-resistance only applies within a given chemical family. Therefore, strobilurin -resistant subpopulations can be controlled with other fungicides not in the strobilurin family.

Products ( 16 )
Product NameCAS No.Category
mandestrobin
173662-97-0Fungicides > Strobilurin fungicides
Pyrametostrobin
唑胺菌酯
915410-70-7Fungicides > Pyrazole fungicides
Fungicides > Carbamate fungicides
Fungicides > Strobilurin fungicides
Lvdingjunzhi
氯啶菌酯
902760-40-1Fungicides > Pyridine fungicides
Fungicides > Strobilurin fungicides
Enestroburin
烯肟菌酯
 Fungicides > Strobilurin fungicides
Bifujunzhi
吡氟菌酯
 Acaricides / Miticides > Strobilurin acaricides
Fungicides > Strobilurin fungicides
Metominostrobin
苯氧菌胺
133408-50-1Fungicides > Strobilurin fungicides
Fungicides > Amide fungicides
Coumethoxystrobin
甲香菌酯
850881-30-0Fungicides > Strobilurin fungicides
Coumoxystrobin
丁香菌酯
850881-70-8Fungicides > Strobilurin fungicides
Pyraclostrobin
吡唑醚菌酯
175013-18-0Fungicides > Pyrazole fungicides
Fungicides > Carbamate fungicides
Fungicides > Strobilurin fungicides
Trifloxystrobin
肟菌酯
141517-21-7Fungicides > Strobilurin fungicides
Picoxystrobin
啶氧菌酯
117428-22-5Fungicides > Strobilurin fungicides
Orysastrobin
肟醚菌胺
248593-16-0Fungicides > Strobilurin fungicides
Fungicides > Amide fungicides
Kresoxim-methyl
醚菌酯
143390-89-0Fungicides > Strobilurin fungicides
Fluoxastrobin
氟嘧菌酯
361377-29-9Fungicides > Strobilurin fungicides
Dimoxystrobin
醚菌胺
149961-52-4Fungicides > Strobilurin fungicides
Azoxystrobin
嘧菌酯
131860-33-8Fungicides > Strobilurin fungicides

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