Herbicide adjuvants, surfactants and oils

Page last updated: Thursday, 3 August 2017 - 9:47am

Please note: This content may be out of date and is currently under review.

Surfactants, wetting agents, anti-drift thickeners and petroleum oils can where required be used to improve the effectiveness of using herbicides.


The word ‘surfactant’ is a contraction of the words ‘surface active agent’, and includes both emulsifiers and wetting agents.


Emulsifiers are usually added to the product by the manufacturer to allow the herbicide to mix with water.

Wetting agents

Wetting agents are added to many spray mixtures, particularly when the plant to be sprayed has leaves with a waxy or hairy surface, or is otherwise difficult to wet. In some circumstances, the use of a wetting agent will cause too much of the spray material to run off the foliage, resulting in reduced uptake of the chemical. Therefore wetting agents should be used only when recommended, and then at no higher than the recommended rate.

Please note: surfactants (wetting agents) should never be used for selective weed control unless specified in the label recommendations.

Crop oils

Crop oils can act as carriers for herbicides, anti-evaporants and aid entry of the herbicide into the plant.

Drift control agents

Drift control agents (or thickeners) increase droplet size, and therefore minimise the formation of small droplets which may cause a drift problem.