Fluxapyroxad is a broad-spectrum

pyrazole Pyrazole is an organic compound with the chemical formula, formula . It is a heterocycle characterized as an azole with a 5-membered ring of three carbon atoms and two adjacent nitrogen atoms, which are in Arene substitution pattern, ortho-substi ...

carboxamide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent any group, typically organyl groups or hydrogen atoms. The amide group is called a pe ...

fungicide Fungicides are pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in losses of yield and quality. Fungicides are used both in agriculture and to fight fungal infections in animals, ...

used on a large variety of commercial crops.abstract
/ref> It stunts fungus growth by inhibiting the

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 ...

(SQR) enzyme. Application of fluxapyroxad helps prevent many wilts and other fungal infections from taking hold. As with other systemic pesticides that have a long chemical half-life, there are concerns about keeping fluxapyroxad out of the

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

, especially when combined with

pyraclostrobin Pyraclostrobin is a quinone outside inhibitor ( QI)-type fungicide used in agriculture. Among the QIs, it lies within the strobilurin chemical class. Use Pyraclostrobin is used to protect ''Fragaria'', ''Rubus idaeus'', ''Vaccinium corymbosum'' ...

. There is also concern that some fungi may develop resistance to fluxapyroxad.

Chemical structure

The compound is an

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula , where R, R', and R″ represent any group, typically organyl functional group, groups or hydrogen at ...

3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid 3-(Difluoromethyl)-1-methyl-1''H''-pyrazole-4-carboxylic acid is a chemical compound which is used commercially as an intermediate to seven fungicides which act by inhibition of succinate dehydrogenase (SDHI). It consists of a pyrazole ring with ...

combined with an

aniline Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an in ...

having an ortho-substituted triflurorobenzene group.

Biological action

Fluxapyroxad is a succinate dehydrogenase inhibitor (SDHI). It interferes with a number of key fungal life functions, including spore germination,

germ tube A germ tube is an outgrowth produced by spores of spore-releasing fungi during germination. The germ tube differentiates, grows, and develops by mitosis to create somatic hyphae.C.J. Alexopolous, Charles W. Mims, M. Blackwell, ''Introductory My ...

growth, appresoria formation and

mycelium Mycelium (: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are fo ...

growth. Specifically it interferes with the production of succinate dehydrogenase, the complex II in the mitochondrial respiration chain, which in turn interferes with the tricarboxylic cycle and mitochondrial electron transport.

Crops

Fluxapyroxad is commonly used as a fungicide for grains,

row crop A row crop is a crop that can be planted in rows wide enough to allow it to be tilled or otherwise cultivated by agricultural machinery, machinery tailored for the seasonal activities of row crops. Such crops are sown by drilling or transplanti ...

s, vegetable crops, and fruit trees (

pome In botany, a pome is a type of fruit produced by flowering plants in the subtribe Malinae of the family Rosaceae. Pome fruits consist of a central "core" containing multiple small seeds, which is enveloped by a tough membrane and surrounded by a ...

and

prunus ''Prunus'' is a genus of flowering plant, flowering trees and shrubs from the family (biology), family Rosaceae. The genus includes plums, cherries, peaches, nectarines, apricots and almonds (collectively Drupe, stonefruit). The genus has a cosm ...

), including:

Fungal diseases

Fluxapyroxad provides protection against many fungal diseases. Studies have shown specific efficacy against diseases such as black point, Botrytis gray mold,

early blight ''Alternaria solani'' is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tube ...

, and

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

; however, fluxapyroxad was found to have no efficacy against

anthracnose A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticultur ...

on lentils.

Toxicity

Fluxapyroxad has a low toxicity for humans, slightly toxic after a single ingestion, and relatively non-toxic after single inhalation or topical skin contact. However, fluxapyroxad is highly toxic to fish, fresh-water and salt-water invertebrates, and to aquatic plants, as well as being toxic to small mammals. The primary target organ for fluxapyroxad exposure is the liver. ''As the dose or duration of exposure to fluxapyroxad increased, clinical chemistry changes related to liver function also occurred, followed by hepatocellular necrosis, neoplastic changes in the liver, and tumors.'' Fluxapyroxad was found "not likely" to be

carcinogen A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

ic in humans and there was no evidence of

neurotoxicity Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specifical ...

. The United States Environmental Protection Agency has established tolerance amounts that are allowed to be present on consumer food. These range from 0.05 ppm on almonds and pecans to 3.0 ppm on leafy ''

brassica ''Brassica'' () is a genus of plants in the cabbage and mustard family (Brassicaceae). The members of the genus are informally known as cruciferous vegetables, cabbages, mustard plants, or simply brassicas. Crops from this genus are sometim ...

'', and 15 ppm on other leafy vegetables. The EPA is currently considering reducing those tolerances.

Registration and approval

Fluxapyroxad has been approved for use as a fungicide in the United States, Canada and the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...

. In the spring of 2012, fluxapyroxad, trademarked under the names Sercadis, Imbrex and XemiumEPA Registration Number 7969-308 and manufactured by BASF Corporation, was registered for use as a fungicide in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. Fluxapyroxad is also one of the two active ingredients in Priaxor fungicide and Merivon fungicide, the other active ingredient being a

strobilurin Strobilurins are a group of natural products and their synthetic analogs. A number of strobilurins are used in agriculture as fungicides. They are part of the larger group of QIs (Quinone outside Inhibitors), which act to inhibit the respiratory ch ...

called pyraclostrobin.

References

{{DEFAULTSORT:Fluxapyroxad Fungicides Carboxamides Pyrazoles Fluoroarenes Biphenyls