A review of the factors influencing the absorption and efficacy of lipophilic and highly water-soluble post-emergence herbicides

It is well known that post-emergence herbicide uptake into plant foliage and efficacy varies with plant and chemicals, and can be greatlyinfluenced by adjuvants and environmental conditions. The penetration of herbicides into plant leaves is related to the physicochemicalproperties of the active ingredients, especially molecular size and lipophilicity. For a specific herbicide, uptake varies greatly with plantspecies and there is no simple method at the moment to quickly evaluate the leaf surface permeability of a plant. Furthermore, currentevidence suggests that highly-water soluble, ionic herbicides may be more sensitive to some environmental conditions (low humidity andrapid drop drying) than lipophilic herbicides. Various adjuvants are being used to increase the penetration of herbicides into target plantfoliage, but their effect varies with chemicals and plant species. The mechanisms of action of adjuvants in enhancing herbicide uptake remainunclear despite the effort made during the last three decades. A better understanding of the transcuticular transport of herbicides andthe mode of action of adjuvants should lead to a more rational use of herbicides and minimize their negative impact on the environment.[...