Boscalid is a broad spectrum

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, ...

used in agriculture to protect crops from fungal diseases. It was first marketed by BASF in 2002 using their brand name Endura. The compound is an

biphenyl Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one ...

amide derived inhibitor of

succinate dehydrogenase Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory complex II is an enzyme complex, found in many bacterial cells and in the inner mitochondrial membrane of eukaryotes. It is the only enzyme that participates i ...

History

Inhibition of succinate dehydrogenase, the complex II in the

mitochondrial A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...

respiration chain, has been known as a fungicidal mechanism of action since the first examples were marketed in the 1960s. The first compound in this class was carboxin, which had a narrow spectrum of useful biological activity, mainly on basidiomycetes and was used as a seed treatment. Many companies made analogues with the aim of expanding the range of species controlled and boscalid was successful in doing so.

Synthesis

The first synthesis of boscalid was disclosed in patents filed by BASF in 1995. : Boscalid synthesis

The aminobiphenyl required for reaction with the acid chloride of 2-chloronicotinic acid is prepared in two steps. The first is a palladium-catalysed Suzuki reaction, followed by reduction. As the final product has been manufactured at the multi-tonne scale, considerable efforts have been made to optimise these reactions.

Mechanism of action

Succinate dehydrogenase inhibitors (SDHI) of this type act by binding at the quinone reduction site of the enzyme complex, preventing ubiquinone from doing so. As a consequence, the tricarboxylic acid cycle and

electron transport chain An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples th ...

cannot function.

Usage

Boscalid has fungicidal effects against a wide range of crop pests. These include '' Alternaria'', grey mold ('' Botrytis cinerea''), white mold ('' Sclerotinia sclerotiorum''), and powdery mildew ('' Uncinula necator''). As a result, it has use in crops including fruits, soybeans and vegetables. Boscalid use USA

The estimated annual use of boscalid in US agriculture is mapped by the US Geological Survey and shows that it is mainly applied to fruit crops, with a maximum use of over in 2016. Global sales in 2014 were estimated at $390 million. The compound lacks full control of important cereal diseases, especially septoria leaf blotch ''

Zymoseptoria tritici ''Zymoseptoria tritici'', synonyms ''Septoria tritici'', ''Mycosphaerella graminicola'', is a species of filamentous fungus, an ascomycete in the family ''Mycosphaerellaceae''. It is a wheat plant pathogen causing septoria leaf blotch that is d ...

'', which has limited its potential.

Human safety

Boscalid has low acute toxicity: the

Codex Alimentarius The Codex Alimentarius () is a collection of internationally recognized standards, codes of practice, guidelines, and other recommendations published by the Food and Agriculture Organization of the United Nations relating to food, food production ...

database maintained by the FAO lists the maximum residue limits for it in various food products.

Environmental effects

The compound is very persistent in field conditions and its environmental fate and consequent ecotoxicology have been reviewed.

Resistance management

Fungal populations have the ability to develop

resistance Resistance may refer to: Arts, entertainment, and media Comics * Either of two similarly named but otherwise unrelated comic book series, both published by Wildstorm: ** ''Resistance'' (comics), based on the video game of the same title ** ''T ...

to SDHI inhibitors. This potential can be mitigated by careful management. Reports of individual pest species becoming resistant are monitored by manufacturers, regulatory bodies such as the EPA and the Fungicides Resistance Action Committee (FRAC). The risks of resistance developing can be reduced by using a mixture of two or more fungicides which each have activity on relevant pests but with unrelated mechanisms of action. FRAC assigns fungicides into classes so as to facilitate this.

Brands

Boscalid is the ISO

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

for the active ingredient which is formulated into the branded product sold to end-users. It was also known as nicobifen. Endura and Emerald are the brand names first used by BASF's formulations but the compound has subsequently been sold under a range of product names.

References

{{Reflist

External links

PPDB
pesticides properties database entry for boscalid Fungicides Pyridines Chloroarenes Carboxamides Anilides Biphenyls