On its own, glyphosate acid is not water soluble enough to be readily sprayed and taken up by the plant. Therefore, glyphosate is commonly applied as a solution of its salt form in water. In addition, herbicides products contain additional chemical substances, such as surfactants, to improve their solubility and enhance penetration of the active substance into plants.
Surfactants, which are also commonly used in washing powders, washing-up liquids and shampoos, make the waxy surfaces of plants more penetrable and the herbicide stickier, so it is not washed off by rain immediately after spraying.
The fast uptake of glyphosate is crucial to prevent the herbicide being washed off by rain after spraying. Many glyphosate-based products also contain surfactants of various types and concentrations that improve leaf absorption, retention and coverage.
- Wauchope R D, Butler TM, Hornsby AG, Augustijn-Beckers PWM, Burt JP. (1992) The SCS/ARS/CES pesticide properties database: Select values for environmental decision making. Reviews of Environmental Contamination & Toxicology 123: 1-155. As cited by Seeling 1994.