Varieties of Diphenyl ether herbicides

Currently, there are 11 species of diphenyl ether herbicides developed globally, mainly including fomesafen, lactofen, oxyfluorfen, acifluorfen, bifenox, ethoxyfen-ethyl, fluoroglycofen ethoxyfen-ethyl, chlomethoxyfen, and aclonifen (Figure 1). Another two diphenyl ether herbicides, nitrofen and chlornitrofen, have been banned in many countries due to their high mammalian toxicity.

Mechanisms of Action

Diphenyl ether herbicides enter the plant mainly through the shoot apex and midrib, targeting protoporphyrinogen oxidase, inhibiting chlorophyll synthesis, and damaging cell membranes in sensitive plants.

Targets

Diphenyl ether herbicides are to be targeted at the young shoots of annual weeds in soybean and peanut fields and are more effective against broadleaf weeds. These herbicides are applied to the soil surface primarily as soil treatments. However, under unfavourable conditions (e.g. irregular temperatures and rainfall), the use of diphenyl ether herbicides to control broadleaf weeds in soybean fields can lead to phytotoxicity and inhibit soybean growth, especially with some highly active and selective herbicides, such as oxfluorfen, fumonisin and flumioxazin. In addition, these herbicides are susceptible to phytotoxicity in succeeding crops even at low concentrations in the soil. Symptoms of phytotoxicity mainly include leaf curling, scorch-type lesions and, in severe cases, scorching of the entire leaf surface.