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Fungicide

April 13, 2024

Fungicides are pesticides used to kill parasitic fungi or their spores.[1] Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, and profit. Fungicides are used both in agriculture and to fight fungal infections in animals. Fungicides are also used to control oomycetes, which are not taxonomically/genetically fungi, although sharing similar methods of infecting plants. Fungicides can either be contact, translaminar or systemic. Contact fungicides are not taken up into the plant tissue and protect only the plant where the spray is deposited. Translaminar fungicides redistribute the fungicide from the upper, sprayed leaf surface to the lower, unsprayed surface. Systemic fungicides are taken up and redistributed through the xylem vessels. Few fungicides move to all parts of a plant. Some are locally systemic, and some move upward.[2][3] Most fungicides that can be bought retail are sold in liquid form, the active ingredient being present at 0.08% in weaker concentrates, and as high as 0.5% for more potent fungicides. Fungicides in powdered form are usually around 90% sulfur.

Safety edit

Fungicide residues have been found on food for human consumption, mostly from post-harvest treatments.[4] Some fungicides are dangerous to human health, such as vinclozolin, which has now been removed from use.[5] Ziram is also a fungicide that is toxic to humans with long-term exposure, and fatal if ingested.[6] A number of fungicides are also used in human health care.

Types of fungicides edit

Further information: List of fungicides

Like other pesticides, fungicides are numerous and diverse. This complexity has led to diverse schemes for classifying fungicides. Classifications are based on inorganic vs organic, chemical structures, and, most successfully, mechanism of action (MOA). These respective classifications reflect the evolution of the underlying science.

Traditional edit

Traditional fungicides are simple inorganic compounds like sulfur,[7] and copper salts. While cheap, they must be applied repeatedly and are relatively ineffective.[1] Other active ingredients in fungicides include neem oil, rosemary oil, jojoba oil, the bacterium Bacillus subtilis, and the beneficial fungus Ulocladium oudemansii.

Nonspecific edit

In the 1930s dithiocarbamate-based fungicides, the first organic compounds used for this purpose, became available. These include ferbam, ziram, zineb, maneb, and mancozeb. These compounds are non-specific and are thought to inhibit cysteine-based protease enzymes. Similarly nonspecific are N-substituted phthalimides. Members include captafol, captan, and folpet. Chlorothalonil is also non-specific.[1]

Specific edit

Specific fungicides target a particular biological process in the fungus.

Nucleic acid metabolism edit

Cytoskeleton and motor proteins edit

Respiration edit

Some fungicides target succinic dehydrogenase, a metabolically central enzyme. Fungi of the class Basidiomycetes were the initial focus of these fungicides. These fungi are active against cereals.

Amino acid and protein synthesis edit

Signal transduction edit

Lipid synthesis / membrane integrity edit

Melanin synthesis in cell wall edit

  • tricyclazole

Sterol biosynthesis in membranes edit

Cell wall biosynthesis edit

Host plant defence induction edit

Mycoviruses edit

Some of the most common fungal crop pathogens are known to suffer from mycoviruses, and it is likely that they are as common as for plant and animal viruses, although not as well studied. Given the obligately parasitic nature of mycoviruses, it is likely that all of these are detrimental to their hosts, and thus are potential biocontrols/biofungicides.[9]

Resistance edit

See also: Antimicrobial resistance

Doses that provide the most control of the disease also provide the largest selection pressure to acquire resistance.[10]

In some cases, the pathogen evolves resistance to multiple fungicides, a phenomenon known as cross resistance. These additional fungicides typically belong to the same chemical family, act in the same way, or have a similar mechanism for detoxification. Sometimes negative cross-resistance occurs, where resistance to one chemical class of fungicides increases sensitivity to a different chemical class of fungicides. This has been seen with carbendazim and diethofencarb. Also possible is resistance to two chemically different fungicides by separate mutation events. For example, Botrytis cinerea is resistant to both azoles and dicarboximide fungicides.

A common mechanism for acquiring resistance is alteration of the target enzyme. For example, Black Sigatoka, an economically important pathogen of banana, is resistant to the QoI fungicides, due to a single nucleotide change resulting in the replacement of one amino acid (glycine) by another (alanine) in the target protein of the QoI fungicides, cytochrome b.[11] It is presumed that this disrupts the binding of the fungicide to the protein, rendering the fungicide ineffective. Upregulation of target genes can also render the fungicide ineffective. This is seen in DMI-resistant strains of Venturia inaequalis.[12]

Resistance to fungicides can also be developed by efficient efflux of the fungicide out of the cell. Septoria tritici has developed multiple drug resistance using this mechanism. The pathogen had five ABC-type transporters with overlapping substrate specificities that together work to pump toxic chemicals out of the cell.[13]

In addition to the mechanisms outlined above, fungi may also develop metabolic pathways that circumvent the target protein, or acquire enzymes that enable the metabolism of the fungicide to a harmless substance.

Fungicides that are at risk of losing their potency due to resistance include Strobilurins such as azoxystrobin.[14] Cross-resistance can occur because the active ingredients share a common mode of action.[15] FRAC is organized by CropLife International.[16][14]

See also edit

Further reading edit

  • Haverkate, F.; Tempel, A.; Held, A. J. (1969). "Interaction of 2,4,5-trichlorophenylsulphonylmethyl thiocyanate with fungal spores". Netherlands Journal of Plant Pathology. 75 (5): 308–315. doi:10.1007/BF02015493. S2CID 23304303.

References edit

  1. ^ a b c Dreikorn, Barry A.; Owen, W. John (2000). "Fungicides, Agricultural". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.0621140704180509.a01. ISBN 978-0-471-48494-3.
  2. ^ Mueller, Daren. "Fungicides:Terminology". Iowa State University. Retrieved June 1, 2013.
  3. ^ Latijnhouwers, Maita; de Wit, Pierre; Govers, Francine (2003). "Oomycetes and fungi: similar weaponry to attack plants". Trends in Microbiology. 11 (10). Cell Press: 462–469. doi:10.1016/j.tim.2003.08.002. ISSN 0966-842X. PMID 14557029. S2CID 22200121.
  4. ^ Pesticide Chemistry and Bioscience edited by G.T Brooks and T.R Roberts. 1999. Published by the Royal Society of Chemistry
  5. ^ Hrelia et al. 1996 - The genetic and non-genetic toxicity of the fungicide Vinclozolin. Mutagenesis Volume 11 445-453
  6. ^ National Center for Biotechnology Information. PubChem Compound Database; CID=8722, https://pubchem.ncbi.nlm.nih.gov/compound/8722 (accessed Jan. 13, 2019)
  7. ^ C.Michael Hogan. 2011. Sulfur. Encyclopedia of Earth, eds. A.Jorgensen and C.J.Cleveland, National Council for Science and the environment, Washington DC October 28, 2012, at the Wayback Machine
  8. ^ Thao, Hoang Thi Bich; Yamakawa, Takeo (April 2009). "Phosphite (phosphorous acid): Fungicide, fertilizer or bio-stimulator?". Soil Science and Plant Nutrition. 55 (2): 228–234. Bibcode:2009SSPN...55..228T. doi:10.1111/j.1747-0765.2009.00365.x.
  9. ^ PEARSON, MICHAEL N.; BEEVER, ROSS E.; BOINE, BARBARA; ARTHUR, KIEREN (2009). "Mycoviruses of filamentous fungi and their relevance to plant pathology (Review)". Molecular Plant Pathology. 10 (1). British Society for Plant Pathology (Wiley-Blackwell): 115–128. doi:10.1111/j.1364-3703.2008.00503.x. ISSN 1464-6722. PMC 6640375. PMID 19161358. S2CID 34331588.
  10. ^ Metcalfe, R.J. et al. (2000) The effect of dose and mobility on the strength of selection for DMI (sterol demethylation inhibitors) fungicide resistance in inoculated field experiments. Plant Pathology 49: 546–557
  11. ^ Sierotzki, Helge (2000) Mode of resistance to respiration inhibitors at the cytochrome bc1 enzyme complex of Mycosphaerella fijiensis field isolates Pest Management Science 56:833–841
  12. ^ Schnabel, G., and Jones, A. L. 2001. The 14a-demethylase (CYP51A1) gene is overexpressed in V. inaequalis strains resistant to myclobutanil. Phytopathology 91:102–110.
  13. ^ Zwiers, L. H. et al. (2003) ABC transporters of the wheat pathogen Mycosphaerella graminicola function as protectants against biotic and xenobiotic toxic compounds. Molecular Genetics and Genomics 269:499–507
  14. ^ a b "Fungicides Resistance Action Committee website".
  15. ^ (PDF). 2020. Archived from the original (PDF) on 2021-08-16. Retrieved 2020-09-04.
  16. ^ "Resistance Management". CropLife International. 2018-02-28. Retrieved 2020-11-22.

External links edit

  • Fungicide Resistance Action Committee
  • , United Kingdom
  • General Pesticide Information 2007-12-29 at the Wayback Machine - National Pesticide Information Center, Oregon State University, United States

April 13, 2024
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Fungicides are pesticides used to kill parasitic fungi or their spores 1 Fungi can cause serious damage in agriculture resulting in critical losses of yield quality and profit Fungicides are used both in agriculture and to fight fungal infections in animals Fungicides are also used to control oomycetes which are not taxonomically genetically fungi although sharing similar methods of infecting plants Fungicides can either be contact translaminar or systemic Contact fungicides are not taken up into the plant tissue and protect only the plant where the spray is deposited Translaminar fungicides redistribute the fungicide from the upper sprayed leaf surface to the lower unsprayed surface Systemic fungicides are taken up and redistributed through the xylem vessels Few fungicides move to all parts of a plant Some are locally systemic and some move upward 2 3 Most fungicides that can be bought retail are sold in liquid form the active ingredient being present at 0 08 in weaker concentrates and as high as 0 5 for more potent fungicides Fungicides in powdered form are usually around 90 sulfur Contents 1 Safety 2 Types of fungicides 2 1 Traditional 2 2 Nonspecific 2 3 Specific 2 4 Nucleic acid metabolism 2 5 Cytoskeleton and motor proteins 2 6 Respiration 2 7 Amino acid and protein synthesis 2 8 Signal transduction 2 9 Lipid synthesis membrane integrity 2 10 Melanin synthesis in cell wall 2 11 Sterol biosynthesis in membranes 2 12 Cell wall biosynthesis 2 13 Host plant defence induction 2 14 Mycoviruses 3 Resistance 4 See also 5 Further reading 6 References 7 External linksSafety editThis article needs to be updated The reason given is https pubmed ncbi nlm nih gov 38288970 Please help update this article to reflect recent events or newly available information February 2024 Fungicide residues have been found on food for human consumption mostly from post harvest treatments 4 Some fungicides are dangerous to human health such as vinclozolin which has now been removed from use 5 Ziram is also a fungicide that is toxic to humans with long term exposure and fatal if ingested 6 A number of fungicides are also used in human health care Types of fungicides editFurther information List of fungicides Like other pesticides fungicides are numerous and diverse This complexity has led to diverse schemes for classifying fungicides Classifications are based on inorganic vs organic chemical structures and most successfully mechanism of action MOA These respective classifications reflect the evolution of the underlying science Traditional edit Traditional fungicides are simple inorganic compounds like sulfur 7 and copper salts While cheap they must be applied repeatedly and are relatively ineffective 1 Other active ingredients in fungicides include neem oil rosemary oil jojoba oil the bacterium Bacillus subtilis and the beneficial fungus Ulocladium oudemansii Nonspecific edit In the 1930s dithiocarbamate based fungicides the first organic compounds used for this purpose became available These include ferbam ziram zineb maneb and mancozeb These compounds are non specific and are thought to inhibit cysteine based protease enzymes Similarly nonspecific are N substituted phthalimides Members include captafol captan and folpet Chlorothalonil is also non specific 1 Specific edit Specific fungicides target a particular biological process in the fungus Nucleic acid metabolism edit bupirimate metalaxylCytoskeleton and motor proteins edit carbendazim pencycuronRespiration edit Some fungicides target succinic dehydrogenase a metabolically central enzyme Fungi of the class Basidiomycetes were the initial focus of these fungicides These fungi are active against cereals azoxystrobin binapacryl boscalid carboxin cyazofamid pydiflumetofenAmino acid and protein synthesis edit blasticidin S kasugamycin pyrimethanilSignal transduction edit fludioxonil procymidoneLipid synthesis membrane integrity edit propamocarb pyrazophos tecnazeneMelanin synthesis in cell wall edit tricyclazoleSterol biosynthesis in membranes edit fenpropimorph hexaconazole imazalil myclobutanil propiconazoleCell wall biosynthesis edit dimethomorph polyoxinsHost plant defence induction edit acibenzolar fosetyl Al phosphorous acid 8 Mycoviruses edit Some of the most common fungal crop pathogens are known to suffer from mycoviruses and it is likely that they are as common as for plant and animal viruses although not as well studied Given the obligately parasitic nature of mycoviruses it is likely that all of these are detrimental to their hosts and thus are potential biocontrols biofungicides 9 Resistance editSee also Antimicrobial resistance Doses that provide the most control of the disease also provide the largest selection pressure to acquire resistance 10 In some cases the pathogen evolves resistance to multiple fungicides a phenomenon known as cross resistance These additional fungicides typically belong to the same chemical family act in the same way or have a similar mechanism for detoxification Sometimes negative cross resistance occurs where resistance to one chemical class of fungicides increases sensitivity to a different chemical class of fungicides This has been seen with carbendazim and diethofencarb Also possible is resistance to two chemically different fungicides by separate mutation events For example Botrytis cinerea is resistant to both azoles and dicarboximide fungicides A common mechanism for acquiring resistance is alteration of the target enzyme For example Black Sigatoka an economically important pathogen of banana is resistant to the QoI fungicides due to a single nucleotide change resulting in the replacement of one amino acid glycine by another alanine in the target protein of the QoI fungicides cytochrome b 11 It is presumed that this disrupts the binding of the fungicide to the protein rendering the fungicide ineffective Upregulation of target genes can also render the fungicide ineffective This is seen in DMI resistant strains of Venturia inaequalis 12 Resistance to fungicides can also be developed by efficient efflux of the fungicide out of the cell Septoria tritici has developed multiple drug resistance using this mechanism The pathogen had five ABC type transporters with overlapping substrate specificities that together work to pump toxic chemicals out of the cell 13 In addition to the mechanisms outlined above fungi may also develop metabolic pathways that circumvent the target protein or acquire enzymes that enable the metabolism of the fungicide to a harmless substance Fungicides that are at risk of losing their potency due to resistance include Strobilurins such as azoxystrobin 14 Cross resistance can occur because the active ingredients share a common mode of action 15 FRAC is organized by CropLife International 16 14 See also editAntifungal drug Index of pesticide articles PHI base Pathogen Host Interaction database Phytopathology Plant disease forecastingFurther reading editHaverkate F Tempel A Held A J 1969 Interaction of 2 4 5 trichlorophenylsulphonylmethyl thiocyanate with fungal spores Netherlands Journal of Plant Pathology 75 5 308 315 doi 10 1007 BF02015493 S2CID 23304303 References edit a b c Dreikorn Barry A Owen W John 2000 Fungicides Agricultural Kirk Othmer Encyclopedia of Chemical Technology doi 10 1002 0471238961 0621140704180509 a01 ISBN 978 0 471 48494 3 Mueller Daren Fungicides Terminology Iowa State University Retrieved June 1 2013 Latijnhouwers Maita de Wit Pierre Govers Francine 2003 Oomycetes and fungi similar weaponry to attack plants Trends in Microbiology 11 10 Cell Press 462 469 doi 10 1016 j tim 2003 08 002 ISSN 0966 842X PMID 14557029 S2CID 22200121 Pesticide Chemistry and Bioscience edited by G T Brooks and T R Roberts 1999 Published by the Royal Society of Chemistry Hrelia et al 1996 The genetic and non genetic toxicity of the fungicide Vinclozolin Mutagenesis Volume 11 445 453 National Center for Biotechnology Information PubChem Compound Database CID 8722 https pubchem ncbi nlm nih gov compound 8722 accessed Jan 13 2019 C Michael Hogan 2011 Sulfur Encyclopedia of Earth eds A Jorgensen and C J Cleveland National Council for Science and the environment Washington DC Archived October 28 2012 at the Wayback Machine Thao Hoang Thi Bich Yamakawa Takeo April 2009 Phosphite phosphorous acid Fungicide fertilizer or bio stimulator Soil Science and Plant Nutrition 55 2 228 234 Bibcode 2009SSPN 55 228T doi 10 1111 j 1747 0765 2009 00365 x PEARSON MICHAEL N BEEVER ROSS E BOINE BARBARA ARTHUR KIEREN 2009 Mycoviruses of filamentous fungi and their relevance to plant pathology Review Molecular Plant Pathology 10 1 British Society for Plant Pathology Wiley Blackwell 115 128 doi 10 1111 j 1364 3703 2008 00503 x ISSN 1464 6722 PMC 6640375 PMID 19161358 S2CID 34331588 Metcalfe R J et al 2000 The effect of dose and mobility on the strength of selection for DMI sterol demethylation inhibitors fungicide resistance in inoculated field experiments Plant Pathology 49 546 557 Sierotzki Helge 2000 Mode of resistance to respiration inhibitors at the cytochrome bc1 enzyme complex of Mycosphaerella fijiensis field isolates Pest Management Science 56 833 841 Schnabel G and Jones A L 2001 The 14a demethylase CYP51A1 gene is overexpressed in V inaequalis strains resistant to myclobutanil Phytopathology 91 102 110 Zwiers L H et al 2003 ABC transporters of the wheat pathogen Mycosphaerella graminicola function as protectants against biotic and xenobiotic toxic compounds Molecular Genetics and Genomics 269 499 507 a b Fungicides Resistance Action Committee website Fungal control agents sorted by cross resistance pattern and mode of action PDF 2020 Archived from the original PDF on 2021 08 16 Retrieved 2020 09 04 Resistance Management CropLife International 2018 02 28 Retrieved 2020 11 22 External links editFungicide Resistance Action Committee Fungicide Resistance Action Group United Kingdom General Pesticide Information Archived 2007 12 29 at the Wayback Machine National Pesticide Information Center Oregon State University United States Retrieved from https en wikipedia org w index php title Fungicide amp oldid 1218622884, wikipedia, wiki, book, books, library,

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