diflufenican

Diflufenican was discovered with a common intermediate method (CIM), and trialled in England and France between 1981 and 1983.{{cite journal |last1=Cramp |first1=Michael C. |last2=Gilmour |first2=James |last3=Hatton |first3=Leslie R. |last4=Hewett |first4=Richard H. |last5=Duck |first5=Donald |last6=Nolan |first6=Christopher J. |last7=Parnell |first7=Edgar W. |title=Design and Synthesis of N-(2,4-difluoropheny1)-2-(3-trifluoromethylphenoxy)-3-pyridinecarboxamide (diflufenican), a Novel Pre- and Early Post-emergence Herbicide for Use in Winter Cereals |journal=Pesticide Science |date=30 Oct 1985 |volume=18 |pages=15–28 |doi=10.1002/ps.2780180103}} A simple intermediate is reacted and recombined. Diflufenican derives from 2-chloronicotinic acid, one product replaced the chlorine with a phenoxy group, one receives an aniline group, and then both are recombined into DFF.{{cite journal |last1=Changling |first1=Liu |last2=Guan |first2=Aiying |last3=Yang |first3=Jindong |title=Efficient Approach To Discover Novel Agrochemical Candidates: Intermediate Derivatization Method |journal=Journal of Agricultural and Food Chemistry |date=17 December 2014 |volume=64 |issue=1 |doi=10.1021/jf5054707}}

The Australian Acceptable Daily Intake for diflufenican is set at 0.2 mg/kg/day, based on the NOEL of 16.3 mg/kg/day. With an oral rat {{LD50}} of >5000 mg/kg, diflufenican is not toxic to mammals,{{cite web |title=Diflufenican Standard SDS |url=https://labchem-wako.fujifilm.com/sds/W01W0104-2812JGHEEN.pdf |publisher=FujiFilm |access-date=7 August 2024}} nor to honeybees.{{cite journal |last1=Soltani |first1=Nader |last2=Willemse |first2=Christian |last3=Sikkema |first3=Peter H. |title=Biologically effective dose of diflufenican applied preemergence for the control of multiple herbicide-resistant waterhemp in corn |journal=Weed Technology |date=3 June 2024 |url=https://www.cambridge.org/core/journals/weed-technology/article/biologically-effective-dose-of-diflufenican-applied-preemergence-for-the-control-of-multiple-herbicideresistant-waterhemp-in-corn/725B407A461593F51D0E20811FB8CE32 |doi= 10.1017/wet.2024.42 |format= pre-proof |doi-access=free }}

By inhalation, the air LC₅₀ is 2.34 mg/L, for rats. It is not irritating to the skin and eyes, tested on rabbits. In dogs over 90 days, a NOEL of 1000 mg/kg daily was found. By the Ames Test, it is non-mutagenic.

To birds, diflufenican is not toxic. LD₅₀ of >2150 mg/kg (quail), >4000 mg/kg (mallard ducks). For fish, the LC₅₀ is 56–100 mg/L (rainbow trout), 105 mg/L (carp). DFF does not inhibit the growth of algae. Non-toxic to earthworms.

Diflufenican has high persistence in soil but has low mobility, and low bioaccumulative potential. It is toxic to aquatic life. (See toxicology section for details).

Diflufenican rapidly metabolises in cereals to carbon dioxide via nicotinamide and nicotinic acid, and leaves no detectable residue after 200–250 days. In soil, similar degradation to CO₂ is seen, with a half life of 15 to 30 weeks.

Targeted weeds display bleaching and chlorotic spotting, followed by pink and purple foliage and necrosis. Symptoms typically begin 3–4 days after application. DFF's residual activity may last 8 weeks.{{cite web |title=4Farmers Diflufenican 500 Label |url=https://4farmers.com.au/wp-content/uploads/2018/06/65174-Diflufenican-500-leaflet-A3-VISUAL-1.pdf |publisher=4Farmers Australia |access-date=7 August 2024}}

Diflufenican inhibits carotenoid synthesis, without which photosynthesis begins to fail and the plant is vulnerable to damage from sunlight, causing growth cessation and necrosis. It is absorbed by germinating seedlings. Usually applied at 125–250 g/ha pre-emergence or shortly after, often with other cereal herbicides.{{cite book |last1=Tomlin |first1=Clive |title=The Pesticide Manual Incorporating the Agrochemicals Handbook |date=1994 |publisher=The Royal Society of Chemistry |location=State Library of Western Australia |isbn=0-948404-79-5 |page=335 |edition=Tenth}}

Diflufenican is a Group F, (Australia), F1 (global) or Group 12 (numeric) resistance class herbicide.{{cite web |title=Australia Herbicide Classification Lookup |url=https://hracglobal.com/tools/australia-classification-lookup/ |website=Herbicide Resistance Action Committee |language=en}}

Diflufenican is an indicator of soil trace element deficiencies; it induces deficiency symptoms in crops.{{cite web |title=Bromoxynil Diflufenican Infosheet |url=https://4farmers.com.au/wp-content/uploads/2018/06/4F-Bromoxynil-Diflufenican.pdf |website=4farmers.com.au |publisher=4Farmers Australia}}

Diflufenican is registered in the United Kingdom and the European Union, for professional and amateur use.{{cite web |title=Agency Opinion on the classification and labelling of diflufenican (ISO) |url=https://www.hse.gov.uk/chemical-classification/classification/harmonised-classification-self-classification/cwbsd-aacc-0308.pdf |website=www.hse.gov.uk |publisher=United Kingdom Health and Safety Executive |access-date=13 September 2024 |date=June 2022}} It is also approved in New Zealand.{{cite web |title=APPROVAL: DIFLUFENICAN |url=https://www.epa.govt.nz/assets/RecordsAPI/Diflufenican_HSR003251.pdf |publisher=Environmental Protection Authority of New Zealand |date=30 April 2021}}

Diflufenican is often applied at 50–100 g/ha, or lower if part of a herbicide mixture, e.g. as little as 9 g/ha with bromoxynil.{{cite web |title=4Farmers Bromoxynil DFF Label |url=https://4farmers.com.au/wp-content/uploads/2018/06/68042-Bromoxynil-diflufenican-leaflet-297x420-VISUAL.pdf |website=4farmers.com.au |publisher=4Farmers Australia |access-date=28 August 2024}}

Diflufenican has shown control over: wild radish, wild turnip, turnip weed, multiply herbicide resistant waterhemp (applied pre-emergence), hedge mustard, Indian hedge mustard, charlock, deadnettle, prickly lettuce, pheasant's eye, Galium aparine, ivy-leaved speedwell and Veronica persica; and suppression of capeweed, crassula, night-scented stock, marshmallow, corn gromwell, chickweed, hyssop loosestrife, Skeleton weed, speedwell, amsinckia, Paterson's curse, rough poppy, sorrel, toad rush, stinging nettle and shepherd's purse.

Diflufenican has been sold in formulations containing (not limited to): isoproturon, ioxynil, mecoprop, bromoxynil, diclofop-methyl, and pendimethalin.{{cite news |last1=Impey |first1=Louise |title=How agchem firms are breathing new life into old pesticide actives|date=2015 |work=Farmers Weekly}} Furthermore, compatibility is reported with: simazine, alpha cypermethrin, metribuzin and quizalofop, in addition to compatibility with most grass herbicides.

Diflufenican has been applied to crops, including: wheat, barley, field peas, lentils, lupins and oilseed poppy.

• Diflufenican
• DFF
• Brodal

{{reflist}}

== External links ==

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Category:Group 12 herbicides