Trifluralin is a commonly used pre-emergence selective herbicide. With about 14 million pounds (6,400 t) used in the United States in 2001,[3] and 3–7 million pounds (1,400–3,200 t) in 2012,[4] it is one of the most widely used herbicides. Trifluralin is also used in Australia.[5] Introduced in 1964, Trifluralin was the first organofluorine compound used as an agrochemical.[6]
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| Names | |
|---|---|
| Preferred IUPAC name
2,6-Dinitro-N,N-dipropyl-4-(trifluoromethyl)aniline | |
| Other names
Treflan
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.014.936 |
| KEGG | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C13H16F3N3O4 | |
| Molar mass | 335.283 g·mol−1 |
| Appearance | Yellow crystals |
| Density | 1360 kg/m3 [2] |
| Melting point | 46 to 47 °C (115 to 117 °F; 319 to 320 K) |
| Boiling point | 139 to 140 °C (282 to 284 °F; 412 to 413 K) (at 4.2 mmHg) |
| 0.0024 g/100 mL | |
| Solubility in acetone | >1000 g/L[2] |
| Hazards | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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>5000 mg/kg (rat, oral) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Trifluralin is generally applied to the soil to control annual grass and broadleaf weed species. It inhibits root development by interrupting mitosis and thus can control weeds as they germinate.[7]
Discovery
editSelective herbicides were unavailable in the 1950s to protect soybean and cotton (2,4-DNP could have been used but had to be exactingly applied lest it destroy the crops), so Lilly Research Laboratories screened ~2000 compounds from 1958 to 1980 blindly looking for a result. Trifluralin was initially thought a failure, yet the plots stayed free of weeds weeks later.[6] Application by incorporation into the top soil instead was eight times more potent.[8] Pre-plant soil incorporation was a new technique at the time. It is unclear why trifluralin's exotic 4-trifluoromethyl was tested so early (1960), before more common candidates such as fluoro, bromo, or iodo.[6]
Environmental regulation
editTrifluralin has been banned in the European Union since 20 March 2008, primarily due to high toxicity to aquatic life.[9]
Trifluralin is on the United States Environmental Protection Agency list of Hazardous Air Pollutants as a regulated substance under the Clean Air Act.[10]
Applications
editTrifluralin is typically sold as emulsifiable concentrate[11] or granules.[2] Application rates vary, such as 0.8-3.0 L of 480 g/L formulation per hectare, typically diluted with water,[5] and other compatible herbicides, e.g. isoproturon,[2] to be sprayed in one go.
Commercial formulations have included trifluralin mixtures with: linuron, napropamide, metribuzin, clomazone,tebutam, bromoxynil and ioxynil, isoproturon, terbutryn, trietazine, neburon and isoxaben.[2]
Crops trifluralin is used in include: Wheat, barley, cotton, triticale, rye, sunflowers, sugar cane, peas, canola, safflower, peanuts, tobacco, pigeon peas, lupins, lucerne, linseed, legume seed, strawberry, lentils, faba beans, chickpeas, cowpeas, lablab, mung beans, borlotti beans, red beans, adzuki beans,[5] citrus fruit, lettuce, capsicums, tomatoes, artichokes, onions, garlic, brassicas, sugar beet, parsnips, carrots or soya.[2]
Environmental behavior
editTrifluralin breaks down into many products as it degrades, ultimately being incorporated into soil-bound residues or converted to carbon dioxide (mineralized). Among the more unusual behaviors of trifluralin is inactivation in wet soils. This has been linked to transformation of the herbicide by reduced soil minerals, which in turn had been previously reduced by soil microorganisms using them as electron acceptors in the absence of oxygen. This environmental degradation process has been reported for many structurally related herbicides (dinitroanilines) as well as a variety of explosives such as TNT and picric acid.[12]
Trifluralin has a long half-life in soil of ~180 days, but it is accepted at high application rates because of its low soil mobility and high volatility.[6] It is extremely resistant to leaching, and shows little lateral soil movement.[2]
Ultraviolet light can cause degradation. Trifluralin is stable to hydrolysis.[2]
Trifluralin is safe for mammals and chickens, even in large amounts.[13] Mammals eliminate 85% after oral consumption within 72 hours. It is toxic to fish though: LC50 for rainbow trout is 10-40 μg/L.[2]
Trade names
edit- Trifluralin
- Treflan
- Trilin
- Trust
- Tri-4
- Edge
- Snapshot (formulation of isoxaben and trifluralin)
References
edit- ^ Merck Index, 11th Edition, 9598.
- ^ a b c d e f g h i Tomlin, Clive (1994). The Pesticide Manual Incorporating the Agrochemicals Handbook (Tenth ed.). State Library of Western Australia: The Royal Society of Chemistry. p. 1025. ISBN 0-948404-79-5.
- ^ 2000-2001 Pesticide Market Estimates, United States Environmental Protection Agency
- ^ "Pesticides Industry Sales and Usage 2008 – 2012 Market Estimates" (PDF).
- ^ a b c "4Farmers Trifluralin 480 Leaflet" (PDF). 4farmers.com.au. 4Farmers Australia. Retrieved 28 May 2024.
- ^ a b c d Epp, Jeffery B.; Schmitzer, Paul B.; Crouse, Gary D. (4 July 2017). "Fifty years of herbicide research: comparing the discovery of trifluralin and halauxifen-methyl". Pest Management Science. 74 (1): 9–16. doi:10.1002/ps.4657. PMID 28675627. Retrieved 6 August 2024.
- ^ Grover, Raj; Wolt, Jeffrey D.; Cessna, Allan J.; Schiefer, H. Bruno (1997). "Environmental Fate of Trifluralin". Reviews of Environmental Contamination and Toxicology. Vol. 153. pp. 1–64. doi:10.1007/978-1-4612-2302-3_1. ISBN 978-1-4612-7492-6. PMID 9380893.
- ^ Anderson, W. Powell; Richards, Anna Beth; Whitworth, J. Wayne (Jul 1967). "Trifluralin Effects On Cotton Seedlings". Weeds. 15 (3): 224–227. doi:10.2307/4041209. JSTOR 4041209. Retrieved 6 August 2024.
- ^ "European Union - Final Regulatory Action".
- ^ "Initial List of Hazardous Air Pollutants with Modifications". United States Environmental Protection Agency. 16 December 2015. Retrieved 16 December 2021.
- ^ "4Farmers Trifluralin 480 Infosheet" (PDF). 4farmers.com.au. 4Farmers Australia.
- ^ Tor, Jason M.; Xu, Caifen; Stucki, Joseph M.; Wander, Michelle M.; Sims, Gerald K. (2000). "Trifluralin Degradation under Microbiologically Induced Nitrate and Fe(III) Reducing Conditions". Environmental Science & Technology. 34 (15): 3148–3152. Bibcode:2000EnST...34.3148T. doi:10.1021/es9912473.
- ^ Worth, H. M.; Anderson, R. C. (1965). "The toxicity of trifluralin, Treflan, an herbicide, to mammals and chickens". SWC. 18: 711–712.
External links
edit- Trifluralin in the Pesticide Properties DataBase (PPDB)