Fluxapyroxad Explained

Fluxapyroxad is a broad-spectrum pyrazole-carboxamide fungicide used on a large variety of commercial crops.[1] [2] It stunts fungus growth by inhibiting the succinate dehydrogenase (SQR) enzyme.[3] 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, especially when combined with pyraclostrobin.[4] There is also concern that some fungi may develop resistance to fluxapyroxad.[5] [6]

Chemical structure

The compound is an amide of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid combined with an aniline having an ortho-substituted triflurorobenzene group.[7]

Biological action

Fluxapyroxad is a succinate dehydrogenase inhibitor (SDHI). It interferes with a number of key fungal life functions, including spore germination, germ tube growth, appresoria formation and mycelium 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 crops, vegetable crops, and fruit trees (pome and prunus), including:[8] [9] [10]

Fungal diseases

Fluxapyroxad provides protection against many fungal diseases.[11] Studies have shown specific efficacy against diseases such as black point, Botrytis gray mold,[12] early blight,[13] and powdery mildew;[14] however, fluxapyroxad was found to have no efficacy against anthracnose on lentils.[15]

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.[16] [17] 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 carcinogenic in humans and there was no evidence of neurotoxicity.

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, and 15 ppm on other leafy vegetables. The EPA is currently considering reducing those tolerances.[18]

Registration and approval

Fluxapyroxad has been approved for use as a fungicide in the United States, Canada and the European Union.[19] In the spring of 2012, fluxapyroxad, trademarked under the names Sercadis,[20] Imbrex[21] and Xemium[22] and manufactured by BASF Corporation, was registered for use as a fungicide in the United States. Fluxapyroxad is also one of the two active ingredients in Priaxor fungicide and Merivon fungicide, the other active ingredient being a strobilurin called pyraclostrobin.[23]

References

Notes and References

  1. Strathmann, S. . Walker, S. . Barnes, J. . 2011. Fluxapyroxad: A new broad-spectrum fungicide. Phytopathology. 101. 6. 172. abstract
  2. Web site: July 2012. Fluxapyroxad. New Active Ingredient Review. Minnesota Department of Agriculture . https://web.archive.org/web/20130625011931/http://www.mda.state.mn.us/chemicals/pesticides/regs/~/media/7328555591A7441FA677AD52A7A80858.ashx. 25 June 2013. live.
  3. Web site: BASF . Crop Protection . Xemium® for Seed Treatment . BASF Crop Protection . https://web.archive.org/web/20180623185144/https://www.seedquest.com/id/b/basf/pdf/306842_BASF_Xemium_for_Seed_Brosch_AS05_final.pdf . 23 June 2018 . live . dmy.
  4. Web site: Office of Chemical Safety and Pollution Prevention, United States Environmental Protection Agency. 2 May 2012. Pesticide Fact Sheet: Fluxapyroxad. https://web.archive.org/web/20130708155945/http://epa.gov/pesticides/chem_search/reg_actions/registration/fs_PC-138009_02-May-12.pdf. 8 July 2013. live.
  5. Web site: SDHI Fungicides. Fungicide Resistance Action Committee. https://web.archive.org/web/20130622062708/http://www.frac.info/work/work_sdhi.htm. 22 June 2013. live.
  6. Veloukas, Thomas . Markoglou, Anastasios N. . Karaoglanidis, George S. . 2013. Differential Effect of SdhB Gene Mutations on the Sensitivity to SDHI Fungicides in Botrytis cinerea. Plant Disease. 97. 1. 118 - 122. 10.1094/pdis-03-12-0322-re. 30722271 . abstract
  7. Book: 10.1002/9783527693931.ch31 . Fungicidal Succinate-Dehydrogenase-Inhibiting Carboxamides . Bioactive Carboxylic Compound Classes: Pharmaceuticals and Agrochemicals . 2016 . Walter . Harald . Lamberth . Clemens . Jürgen . Dinges . Wiley . 405–425 . 9783527339471 .
  8. Web site: United States Environmental Protection Agency. 26 February 2014. Fluxapyroxad; Pesticide Tolerances. Federal Register.
  9. Web site: BASF . Crop Protection. Priaxor Fungicide Product Label, Specimen, NVA 2013-04-372-0088. BASF Crop Protection. https://web.archive.org/web/20141025163629/http://www.cdms.net/LDat/ldAK6001.pdf. 25 October 2014. live.
  10. Web site: BASF. Crop Protection. Merivon Fungicide Product Sheet. https://web.archive.org/web/20141025161243/http://www.cdms.net/LDat/ldAKA006.pdf. 25 October 2014. live.
  11. Web site: In-Field Research Shows Disease Control, Yield Advantages of Priaxor Fungicide and Merivon Fungicide From BASF. 27 March 2012. PMN Crop News. Plant Management Network . https://web.archive.org/web/20120428083058/http://www.plantmanagementnetwork.org/pub/php/news/2012/Priaxor. 28 April 2012 . live.
  12. Amiri, A. . Heath, S. M. . Peres, N. A. . 2012. Sensitivity of Botrytis cinerea field isolates to the novel succinate dehydrogenase inhibitors fluopyram, penthiopyrad, and fluxapyroxad . Phytopathology. 102. 7 (supplement). S4.4. Abstract
  13. Gudmestad, Neil C.. 2013. Prevalence and Impact of SDHI Fungicide Resistance in Alternaria solani . Plant Disease . 97. 7. 952–960. 10.1094/PDIS-12-12-1176-RE. etal. 30722567 . Abstract
  14. Web site: Powdery Mildew on Peaches. 6 May 2011. Tree Fruit IPM Advisory. Utah State University. https://web.archive.org/web/20110515175028/http://utahpests.usu.edu/IPM/htm/advisories/treefruit/articleID%3D12736#pm. 15 May 2011. live. dmy-all.
  15. Web site: Wunsch, Michael. Recommendations for optimizing the control of anthracnose on lentils with fungicides . NDSU Carrington Research Extension Center, North Dakota State University. https://web.archive.org/web/20141025191632/http://www.ag.ndsu.edu/carringtonrec/documents/plantpathologyrd/noyeardocs/Mar4WCropPestLentilFungicides.pdf. 25 October 2014. live.
  16. Web site: Safety Data Sheet Priaxor (4.0). 29 September 2014. Crop Data Management Systems, Inc.. https://web.archive.org/web/20141025222449/http://www.cdms.net/LDat/mpAK6010.pdf. 25 October 2014. live.
  17. Book: 2014. Plant Disease Control. Guide to Field Crop Protection. Carman, Manitoba. Manitoba Agriculture, Food and Rural Development (MAFRD), Government of Manitoba. 307 - 452, page 352. https://web.archive.org/web/20141025182308/http://www.gov.mb.ca/agriculture/crops/guides-and-publications/pubs/crop-protection-guide-disease.pdf. 25 October 2014. live.
  18. Web site: 2020-09-30. Receipt of a Pesticide Petition Filed for Residues of Pesticide Chemicals in or on Various Commodities (August 2020). 2020-09-30. Federal Register.
  19. Web site: BASF's new fungicide fluxapyroxad got EU approval. https://web.archive.org/web/20120724123146/http://news.agropages.com/News/NewsDetail---7356.htm. 24 July 2012. live.
  20. EPA Registration Number 7969-309
  21. EPA Registration Number 7969-306
  22. EPA Registration Number 7969-308
  23. Web site: BASF. Newsroom. New Priaxor fungicide and Merivon fungicide now registered for use . BASF Crop Protection . https://web.archive.org/web/20180623183212/https://www.basf.com/us/en/company/news-and-media/news-releases/2012/05/p-12-101.html . 23 June 2018 . live . dmy.

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