Benzimidazole fungicides are a class of

fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

s including

benomyl Benomyl (also marketed as Benlate) is a fungicide introduced in 1968 by DuPont. It is a systemic benzimidazole fungicide that is selectively toxic to microorganisms and invertebrates, especially earthworms, but nontoxic toward mammals. Due to th ...

carbendazim Carbendazim is a widely used, systemic, broad-spectrum benzimidazole fungicide and a metabolite of benomyl. It is also employed as a casting worm control agent in amenity turf situations such as golf greens, tennis courts etc. and in some countr ...

(MBC),

thiophanate-methyl Thiophanate-methyl is an organic compound with the formula C6H4(NHC(S)NH(CO)OCH3)2. The compound is a colorless or white solid, although commercial samples are generally tan-colored. It is prepared from ''o''-phenylenediamine. Uses and analysis ...

thiabendazole Tiabendazole (INN, BAN), also known as thiabendazole (AAN, USAN) or TBZ and the trade names Mintezol, Tresaderm, and Arbotect, is a preservative, an antifungal agent, and an antiparasitic agent. Uses Preservative Tiabendazole is used primar ...

and fuberidazole. They can control many

ascomycete Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...

s and

basidiomycete Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...

s, but not

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 ...

s. They are applied to cereals, fruits, vegetables and vines, and are also used in

postharvest In agriculture, postharvest handling is the stage of crop production immediately following harvest, including cooling, cleaning, sorting and packing. The instant a crop is removed from the ground, or separated from its parent plant, it begins t ...

handling of crops. The

solubility In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...

of benzimidazole fungicides is low at physiological pH and becomes high at low pH. In plants, carbendazim, thiabendazole and fuberidazole are mobile, i.e. systemic, and benomyl and thiophanate-methyl are converted to carbendazim. This conversion also occurs in soils and animals. In soil and water, carbendazim is mainly degraded by microbes. They are metabolized through

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

and

photolysis Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by photons. It is defined as the interaction of one or more photons with one target molecule. ...

in plants. These fungicides kill cells during

mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is mainta ...

by distorting the

mitotic spindle In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a pr ...

; β-tubulin, a protein important in forming the

cytoskeleton The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is compos ...

, is targeted. They mostly inhibit polymerization of β-tubulin by interacting with it directly, but other interactions also exist. Starting in the late 1960s, they were widely used to control fungal pathogens such as ''

Botrytis cinerea ''Botrytis cinerea'' is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or ...

'', ''

Cercospora ''Cercospora'' is a genus of ascomycete fungi. Most species have no known sexual stage, and when the sexual stage is identified, it is in the genus ''Mycosphaerella''. Most species of this genus cause plant diseases, and form leaf spots. It is a ...

'',

powdery mildew Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant diseases to identify, as ...

and eyespot. These systemic fungicides were very effective at first. Because there is only one target site, –

fungicide resistance Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

to this class – quickly became a serious problem. When they were the only fungicides used, pathogens became resistant after two to four seasons; when mixed with other fungicides, resistance developed more slowly. Resistant genotypes with certain

point mutation A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Point mutations have a variety of effects on the downstream protein product—consequences ...

s were selected. Mutant pathogens resistant to one benzimidazole fungicide are usually resistant to all of them. The F200Y and E198A,G,K mutations are the most common. Because of resistance problems, use of benzimidazole fungicides has declined. They are suspected to be toxic to animals, including humans. The

Fungicide Resistance Action Committee Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

lists them as having a high risk of resistance evolution.

References

{{DEFAULTSORT:Benzimidazole fungicide Fungicides Benzimidazoles