Fluazifop

In the 1970s, a number of agrochemical companies were working to develop new herbicides to be complementary to the auxin phenoxyacetic acid types such as 2,4-D, which had activity on broad-leaved weeds but were safe to grass crops such as the cereals.

Then the Japanese company Ishihara Sangyo Kaisha (ISK) found improved biological activity in an analogue, chlorazifop, which replaced the aryloxy portion of diclofop with a pyridine ring containing the same two chlorine substituents.

[14][15][6] Their selectivity for grasses arises because they target the plastid isoform of the enzyme present only in these species, making them ineffective on broad-leaved weeds and other organisms including mammals.

[5] The estimated annual use of fluazifop in US agriculture is mapped by the US Geological Service and shows that in 2018, approximately 200,000 pounds (91,000 kg) were applied — almost exclusively in soyabean.

[20] The environmental fate and ecotoxicology of fluazifop-P are summarised in the Pesticide Properties database[1] and a very extensive risk assessment of the compound was made by the USDA Forest Service.

Diclofop : X = CH, R 1 = R 2 = Cl Chlorazifop : X = N, R 1 = R 2 = Cl Fluazifop: X = N, R 1 = CF 3 , R 2 = H Haloxyfop : X = N, R 1 = CF 3 , R 2 = Cl
US Geological Survey estimate of fluazifop use in the USA to 2018