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 "title": "Amisulbrom",
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 "excerpt": "Amisulbrom (LEIMAY) is a sulfonamide QiI fungicide, FRAC Group 21, inhibiting the cytochrome bc1 Qi site; oomycete-specific, controlling potato late blight and downy mildews, EU-approved to 15 September 2026.",
 "snippet": "Amisulbrom (LEIMAY) is a sulfonamide QiI fungicide, FRAC Group 21, inhibiting the cytochrome bc1 Qi site; oomycete-specific, controlling potato late blight and downy mildews, EU-approved to 15 September 2026.",
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 "markdown": "# Amisulbrom\n\n**Amisulbrom** is a sulfonamide fungicide used to control oomycete (water mold fungus-like organism, not a true fungus) pathogens such as potato late blight (*Phytophthora infestans*) and grape downy mildew (*Plasmopara viticola*). It belongs to FRAC Group 21, the quinone inside inhibitors (QiI), which act by binding the Qi site of the cytochrome bc1 complex in mitochondrial respiration.<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup> It was developed by Nissan Chemical Corporation and is sold in products such as LEIMAY.<sup>[2](https://pubchem.ncbi.nlm.nih.gov/compound/Amisulbrom)</sup><sup> • </sup><sup>[3](https://agrometea.com/productos/leimay-25362)</sup>\n\n| Key fact | Detail |\n|---|---|\n| Chemical class | Sulfonamide (sulfamoyl-triazole); bromoindole derivative<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup><sup> • </sup><sup>[2](https://pubchem.ncbi.nlm.nih.gov/compound/Amisulbrom)</sup> |\n| Mode of action | FRAC Group 21, target site C4: inhibition of complex III (cytochrome bc1, ubiquinone reductase) at the quinone 'inside' (Qi) site<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup> |\n| Disease spectrum | Oomycetes only: late blight and downy mildews; no spectrum overlap with the picolinamide QiI compounds<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup> |\n| Identifiers | CAS 348635-87-0; molecular formula C13H13BrFN5O4S2; molecular weight 466.3 g/mol<sup>[2](https://pubchem.ncbi.nlm.nih.gov/compound/Amisulbrom)</sup> |\n| EU approval | Approved 1 July 2014 under Regulation (EU) No 193/2014; approval extended to 15 September 2026<sup>[4](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32024R1892)</sup> |\n| Toxicology reference values | ADI 0.1 mg/kg bw/day; ARfD 0.3 mg/kg bw; AOEL 0.15 mg/kg bw/day (EFSA, 2013)<sup>[5](https://new.pesticidi.org/eu-podaci/supstanca/915)</sup> |\n| Resistance risk | Medium to high assumed for QiI fungicides; resistance management required<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup> |\n\n## Mode of action and spectrum\n\nQiI fungicides inhibit mitochondrial respiration by binding to the quinone 'inside' (Qi) site of the cytochrome bc1 complex, the ubiquinone reductase of respiratory complex III.<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup> Although the four QiI compounds share this target, their disease spectra differ sharply. Amisulbrom and the cyanoimidazole [cyazofamid](https://www.edgepedia.org/cyazofamid) target oomycete pathogens such as late blight and downy mildews, whereas the picolinamides [fenpicoxamid](https://www.edgepedia.org/fenpicoxamid) and [florylpicoxamid](https://www.edgepedia.org/florylpicoxamid) act against ascomycete and basidiomycete fungi and show no activity on oomycetes. FRAC therefore treats the oomycete and non-oomycete QiI uses as requiring separate resistance-management approaches.<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup> A review of respiratory-inhibitor fungicides likewise notes that the agricultural QiIs, including cyazofamid and amisulbrom, are active only against oomycetes.<sup>[6](https://journals.asm.org/doi/10.1128/aem.00931-10)</sup>\n\n## Chemistry\n\nChemically, amisulbrom belongs to the bromoindole class: its core is 3-bromo-6-fluoro-2-methylindole, with a 1-(dimethylsulfamyl)-1,2,4-triazole-3-sulfonyl group attached at position 1. Its IUPAC name is 3-(3-bromo-6-fluoro-2-methylindol-1-yl)sulfonyl-N,N-dimethyl-1,2,4-triazole-1-sulfonamide.<sup>[2](https://pubchem.ncbi.nlm.nih.gov/compound/Amisulbrom)</sup> It is classified as a sulfonamide, a triazole, an organofluorine compound, and a bromoindole.<sup>[2](https://pubchem.ncbi.nlm.nih.gov/compound/Amisulbrom)</sup>\n\n## Uses and products\n\nAmisulbrom is formulated mainly as suspension concentrate (SC) products. In Spain, LEIMAY (Nissan Chemical Europe, MAPA registration 25362) contains 20% amisulbrom and is authorized for downy mildew on eggplant, lettuce, potato, tomato, and grape, with per-hectare doses of 0.375 to 0.6 L and pre-harvest intervals of 3 days (7 days on potato, 28 days on grape).<sup>[3](https://agrometea.com/productos/leimay-25362)</sup> In France, HM AMISULB 200 SC (200 g/L amisulbrom) is authorized on potato at up to 0.5 L/ha with 6 applications and on grape at 0.375 L/ha with 2 applications.<sup>[7](https://ephy.anses.fr/ppp/hm-amisulb-200-sc)</sup>\n\n**Mixtures.** Corteva's Zorvec Entecta contains 240 g/L amisulbrom and 48 g/L oxathiapiprolin for late blight control in potatoes; the label directs application in strict alternation with effective chemistry of a different mode of action, other than a QiI (amisulbrom, cyazofamid).<sup>[8](https://www.corteva.com/uk/products-and-solutions/crop-protection/zorvec-entecta.html)</sup> [Oxathiapiprolin](https://www.edgepedia.org/oxathiapiprolin) is also co-formulated with amisulbrom in other products, and UK late-blight resistance guidelines list such co-formulations for the OSBPI group.<sup>[9](https://projectblue.blob.core.windows.net/media/Default/Imported%20Publication%20Docs/AHDB%20Cereals%20%26%20Oilseeds/Disease/FRAG/FRAG-UK%20potato%20late%20blight%20guidelines%20%28October%202024%29.pdf)</sup>\n\n## Resistance\n\nFRAC assigns the QiI group a resistance risk assumed to be medium to high, with resistance management required.<sup>[1](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)</sup> In *Phytophthora litchii*, the causal agent of litchi downy blight, the sensitivity of 147 field isolates to amisulbrom averaged an EC50 of 0.24 ± 0.11 μg/mL. Laboratory-selected resistant mutants showed significantly lower fitness than their parental isolates in vitro, and cross-resistance was detected between amisulbrom and cyazofamid. Amisulbrom could not inhibit cytochrome bc1 activity carrying the H15Y or the G30E + F220L point mutations in cytochrome b, and molecular docking indicated that H15Y or G30E decreases the binding energy between amisulbrom and the target protein. The study concluded that *P. litchii* may have a medium resistance risk to amisulbrom.<sup>[10](https://pubmed.ncbi.nlm.nih.gov/37071710/)</sup>\n\n## Regulatory status and toxicology\n\nOn 1 July 2014, Commission Implementing Regulation (EU) No 193/2014 added amisulbrom to Annex I of Directive 91/414/EEC.<sup>[11](https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2020.6170)</sup> Its approval, originally set to expire on 30 June 2024, was extended by Commission Implementing Regulation (EU) 2024/1892 to 15 September 2026, and a renewal application submitted on 28 September 2021 is under evaluation.<sup>[4](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32024R1892)</sup><sup> • </sup><sup>[12](https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A32026R1826)</sup> EU approval conditions direct member states to pay particular attention to the risk to aquatic and soil organisms and to require risk mitigation measures where appropriate.<sup>[13](https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A02011R0540-20241101)</sup>\n\nPubChem's aggregated hazard profile describes amisulbrom as having low mammalian toxicity while being a reproduction toxicant, moderately toxic to birds and honey bees, and posing a greater risk to aquatic species and earthworms.<sup>[2](https://pubchem.ncbi.nlm.nih.gov/compound/Amisulbrom)</sup> French classification of the 200 SC product carries the hazard phrases H351 (suspected of causing cancer, carcinogenicity category 2) and H410 (very toxic to aquatic organisms with long-lasting effects).<sup>[7](https://ephy.anses.fr/ppp/hm-amisulb-200-sc)</sup> An EFSA review of maximum residue levels concluded that no risk to consumers was identified.<sup>[11](https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2020.6170)</sup>\n\n## References\n\n1. [QiI Fungicides, FRAC](https://www.frac.info/frac-teams/working-groups/qi-fungicides/qii-fungicides/)\n2. [Amisulbrom, CID 10238657, PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/Amisulbrom)\n3. [LEIMAY, registro 25362 (amisulbrom), Agrometea](https://agrometea.com/productos/leimay-25362)\n4. [Commission Implementing Regulation (EU) 2024/1892, EUR-Lex](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32024R1892)\n5. [Amisulbrom, EU regulatory data, pesticidi.org](https://new.pesticidi.org/eu-podaci/supstanca/915)\n6. [Exploring Mechanisms of Resistance to Respiratory Inhibitors in Field Strains of Botrytis cinerea, Applied and Environmental Microbiology](https://journals.asm.org/doi/10.1128/aem.00931-10)\n7. [HM AMISULB 200 SC, Ephy (ANSES)](https://ephy.anses.fr/ppp/hm-amisulb-200-sc)\n8. [Zorvec Entecta, Corteva Agriscience](https://www.corteva.com/uk/products-and-solutions/crop-protection/zorvec-entecta.html)\n9. [Fungicide Resistance Management in Potato Late Blight, FRAG-UK (October 2024)](https://projectblue.blob.core.windows.net/media/Default/Imported%20Publication%20Docs/AHDB%20Cereals%20%26%20Oilseeds/Disease/FRAG/FRAG-UK%20potato%20late%20blight%20guidelines%20%28October%202024%29.pdf)\n10. [Resistance Risk and Resistance-Related Point Mutations in Target Protein Cyt b of the Quinone Inside Inhibitor Amisulbrom in Phytophthora litchii, PubMed](https://pubmed.ncbi.nlm.nih.gov/37071710/)\n11. [Review of the existing maximum residue levels for amisulbrom, EFSA Journal 2020](https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2020.6170)\n12. [Commission Implementing Regulation (EU) 2026/1826, EUR-Lex](https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A32026R1826)\n13. [Consolidated Implementing Regulation (EU) No 540/2011, EUR-Lex](https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A02011R0540-20241101)\n\n---\n*Topic: Encyclopedia › Life and health › Applied biology and nonhuman health › Plant disease and plant protection › Pesticides › Fungicides › Phenylamide and oomycete-specific fungicides*\n\n*Initially written Oct 21, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n",
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