[ They bind at the quinol outer binding site of the cytochrome b-c1 complex, where ubiquinone (]coenzyme Q10
Coenzyme Q, also known as ubiquinone and marketed as CoQ10, is a coenzyme family that is ubiquitous in animals and most bacteria (hence the name ubiquinone). In humans, the most common form is coenzyme Q10 or ubiquinone-10.
It is a 1,4-ben ...
) would normally bind when carrying electrons to that protein. Thus production of ATP
ATP may refer to:
Companies and organizations
* Association of Tennis Professionals, men's professional tennis governing body
* American Technical Publishers, employee-owned publishing company
* ', a Danish pension
* Armenia Tree Project, non ...
is prevented. The generic name for this mode of action is "Quinone Outside Inhibitors" QoI
Qo inhibitors (QoI), or quinone outside inhibitors, are a group of fungicides used in agriculture. Some of these fungicides are among the most popular in the world. QoI are chemical compounds which act at the quinol ''outer'' binding site of th ...
.
Formulations
Azoxystrobin is made available to end-users only in formulated products. Since the active ingredient has moderate solubility in water, formulations aid its use in water-based sprays by creating an emulsion
An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Althou ...
when diluted. Modern products use non-powdery formulations with reduced or no use of hazardous solvents, for example suspension concentrates. The fungicide is compatible with many other pesticides and adjuvants In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to:
* Adjuvant therapy in cancer management
* Analgesi ...
when mixed by the farmer for spraying.
Usage
Azoxystrobin is a xylem
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived fr ...
-mobile systemic fungicide with translaminar, protectant and curative properties. In cereal crops, its main outlet, the length of disease control is generally about four to six weeks during the period of active stem elongation. All pesticides are required to seek registration
Register or registration may refer to:
Arts entertainment, and media Music
* Register (music), the relative "height" or range of a note, melody, part, instrument, etc.
* ''Register'', a 2017 album by Travis Miller
* Registration (organ), the ...
from appropriate authorities in the country in which they will be used. In the United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
, the Environmental Protection Agency
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
(EPA) is responsible for regulating pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) is a United States federal law that set up the basic U.S. system of pesticide regulation to protect applicators, consumers, and the environment. It is administered and regulated by th ...
(FIFRA) and the Food Quality Protection Act
The Food Quality Protection Act (FQPA), or H.R.1627, was passed unanimously by Congress in 1996 and was signed into law by President Bill Clinton on August 3, 1996. The FQPA standardized the way the Environmental Protection Agency (EPA) would man ...
(FQPA). A pesticide can only be used legally according to the directions on the label that is included at the time of the sale of the pesticide. The purpose of the label is "to provide clear directions for effective product performance while minimizing risks to human health and the environment". A label is a legally binding document that mandates how the pesticide can and must be used and failure to follow the label as written when using the pesticide is a federal offence.
Within the European Union, a 2-tiered approach is used for the approval and authorisation of pesticides. Firstly, before a formulated product can be developed for market, the active substance must be approved for the European Union. After this has been achieved, authorisation for the specific product must be sought from every Member State that the applicant wants to sell it to. Afterwards, there is a monitoring programme to make sure the pesticide residues in food are below the limits set by the European Food Safety Authority
The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002 ...
.
Agriculture and Horticulture
Azoxystrobin possesses a broad spectrum of activity, in common with other QoI inhibitors. Examples of the fungal groups on which it is effective are Ascomycota
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 de ...
, Deuteromycota, and Basidiomycota
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 ...
, as well as the oomycetes
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 resu ...
. In addition, its properties mean that it can move systemically through plant tissue to protect parts of the crop that were not in contact with the spray. This combination of properties has meant that it achieved widespread use very quickly and has reached annual sales of more than $500 million. Important diseases which it controls include leaf spot
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesion ...
, rusts
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (Fe ...
, 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 ...
, downy mildew
Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to the Peronosporaceae family. In commercial agriculture, they are a particular problem for growers of c ...
, net blotch
''Pyrenophora teres'' is a necrotrophic fungal pathogen of some plant species, the most significant of which are economically important agricultural crops such as barley. Toxins include aspergillomarasmine A and related compounds.
Host & sympt ...
and blight
Blight refers to a specific symptom affecting plants in response to infection by a pathogenic organism.
Description
Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organ ...
.
Worldwide, azoxystrobin is registered for use on all important crops. For example, in the European Union and United States, it is registered for use in wheat, barley, oats, rye, soya, cotton, rice, strawberry, peas, beans, onions and many other vegetables.[ The advantage to the farmer comes in the form of improved yield at harvest. Farmers can act in their best economic interest: the value of the additional yield can be estimated and the total cost of using the fungicide informs the decision to purchase. This cost-benefit analysis by the end user sets a maximum price which the supplier can demand and in practice pesticide prices fluctuate according to the current market value of the crops in which they are used. The estimated annual use of azoxystrobin in US agriculture is mapped by the US Geological Survey and shows an increasing trend from its introduction in 1997 to 2019, the latest date for which figures are available, and now reaching .
]
Home and garden
One of the earliest uses of azoxystrobin was to control fungal diseases of turf and it has been used on golf courses and lawns. It is now available for domestic markets under brand names such as Heritage and Azoxy 2SC.
Azoxystrobin is added to mold-resistant Purple wallboards (optiSHIELD AT, mixture of azoxystrobin and thiabendazole) and can leach into house dust, potentially providing a source of life-long exposure to children and adults.
Human safety
Azoxystrobin has little toxicity to mammals with an LD50 of over 5000 mg/kg (rats, oral).[ However, it can cause skin and eye irritation. First aid information is included with the label.][
The ]World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...
(WHO) and Food and Agriculture Organization
The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
(FAO) joint meeting on pesticide residues has determined that the acceptable daily intake
Acceptable daily intake or ADI is a measure of the amount of a specific substance (originally applied for a food additive, later also for a residue of a veterinary drug or pesticide) in food or drinking water that can be ingested (orally) daily ove ...
for azoxystrobin is 0-0.2 mg/kg bodyweight per day.
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 azoxystrobin in various food products.
Effects on the environment
Azoxystrobin is categorized as having a low potential for bioconcentration
Bioconcentration is the accumulation of a chemical in or on an organism when the source of chemical is solely water. Bioconcentration is a term that was created for use in the field of aquatic toxicology. Bioconcentration can also be defined as the ...
and of moderate risk to fish, earthworms and bees but of high risk to aquatic crustaceans,[ so care must be taken to avoid runoff into water bodies.][ Its main degradation product, the carboxylic acid resulting from hydrolysis of its methyl ester, is also potentially harmful to aquatic environments.] The benefits and risks of use of QoI fungicides have been reviewed and there is extensive literature on azoxystrobin's environmental profile.[
Ultimately it is the regulatory authorities in each country who must weigh up the benefits to end users and balance these against the compound's inherent ]hazard
A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would allow them, even just theoretically, to cause damage to health, life, property, or any other interest of value. The probab ...
s and consequent risk
In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environme ...
s to consumers and the wider environment.
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 QoI inhibitors. This potential can be mitigated by careful management
Management (or managing) is the administration of an organization, whether it is a business, a nonprofit organization, or a government body. It is the art and science of managing resources of the business.
Management includes the activities ...
. Reports of individual pest species becoming resistant to azoxystrobin[ are monitored by manufacturers, regulatory bodies such as the EPA and the Fungicides Resistance Action Committee (FRAC), who assign fungicides into classes by mode of action. In some cases, 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. On cereal crops in the US, for example, azoxystrobin may only be used in mixture,][ usually with an ]azole fungicide
Azoles are a class of five-membered heterocyclic compounds containing a nitrogen atom and at least one other non-carbon atom (i.e. nitrogen, sulfur, or oxygen) as part of the ring.
Their names originate from the Hantzsch–Widman nomenclature ...
such as difenoconazole.
Brands
By international convention and in many countries the law, pesticide labels are required to include the common name of the active ingredients. These names are not the exclusive property of the holder of any patent or trademark
A trademark (also written trade mark or trade-mark) is a type of intellectual property consisting of a recognizable sign, design, or expression that identifies products or services from a particular source and distinguishes them from oth ...
and as such they are the easiest way for non-experts to refer to individual chemicals. Companies selling pesticides normally do so using a brand name or wordmark
__notoc__
A wordmark, word mark, or logotype, is usually a distinct text-only typographic treatment of the name of a company, institution, or product name used for purposes of identification and branding. Examples can be found in the graphic iden ...
which allows them to distinguish their product from competitor products having the same active ingredient. In many cases, this branding is country and formulation-specific so after several years of sales there can be multiple brand names for a given active ingredient. The situation is made even more complicated when companies license their ingredients to others, as is often done. In addition, the product may be pre-mixed with other pesticides under a new brand name.
It is therefore difficult to provide a comprehensive list of brand names for products containing azoxystrobin. They include Amistar, Abound, Heritage, Olympus, Ortiva, Priori Xtra, Scotts
Scotts or Scott's may refer to:
Businesses and brands
*Scott's (restaurant), in London
*Scott's Food & Pharmacy, an American supermarket chain
*Scotts Miracle-Gro Company, an American multinational corporation
*Scott's Porage Oats, a Scottish bre ...
DiseaseEx, Haedes and Quadris. Suppliers and brand names in the United States are listed in the National Pesticide Information Retrieval System.
References
Further reading
*
*
*
*
*
*
External links
National Pesticide Information Center
Quadris Fungicide Product - Syngenta US
* {{PPDB, 54
Azoxystrobin
on Pubchem
Fungicides
Pyrimidines
Phenol ethers
Benzonitriles
Methyl esters
Strobilurins
Diaryl ethers