Its mode of action has been uncertain, with evidence suggesting it might interfere with carotenoid biosynthesis or inhibit the enzyme protoporphyrinogen oxidase (PPO).

[5][6] The nitrophenyl ethers are a well-known class of herbicides, the oldest member of which was nitrofen, invented by Rohm & Haas and first registered for sale in 1964.

The first patent for this material was published in December 1975,[10] Celamerck scientists were also working on analogs retaining the 4-nitrodiphenyl ether framework and in 1978 filed a patent of relatively narrow scope which claimed compounds having an amine group adjacent to the nitro substituent and also having an additional chlorine atom between the amine and the oxygen of the diphenyl ether.

[11] The detailed mechanism of action for nitro diphenyl ether herbicides such as acifluorfen was unknown at the time they were invented.

[13] By 1992, it was becoming clear that most compounds of this class inhibit the enzyme protoporphyrinogen oxidase (PPO), which leads to an accumulation of protoporphyrin IX in the plant cells.

[14][15][16] Aclonifen was shown to be an inhibitor of PPO but in addition had effects on carotenoid synthesis, by inhibition of phytoene desaturase at similar concentrations in vitro.

It is normally applied pre-emergence (before weeds are visible in the crop) and controls or suppresses species including Alopecurus myosuroides, Anthemis cotula, Chenopodium album, Fallopia convolvulus, Galium aparine and Viola arvensis when used at application rates of 600 g a.i.