One or more of the vital processes must be disrupted in order for a herbicide to kill a weed. Since movement to sites is essential for continued plant growth, these herbicides have the potential to kill simple perennial and creeping perennial weeds with only one or two foliar applications. Symptoms are evident on new growth first. Most injury appears only after several days or weeks.
Plants die slowly.
The effects associated with auxins help set them apart from other downwardly mobile herbicides. Bending and twisting of leaves and stems is evident almost immediately after application. Soil activity varies from almost none to long residual depending on herbicide and dose. All are organic acids which take on a negative charge after ionization of acids and salts. Esters are hydrolyzed to acids or salts in both plants and soils.