Physicochemical Properties of Adjuvants: Values and Applications¹

Abstract

The physicochemical properties of adjuvants determine their function and impact upon biological activity. Various physicochemical parameters are key to modifying both the preretention events and postretention consequences of adjuvant usage, irrespective of whether the adjuvants are tank-mix additives or built into a formulation. This paper discusses several key adjuvant parameters for a range of adjuvant chemistries alone and in mixtures. In addition, the misleading use of terms such as nonionic surfactant and hydrophile–lipophile balance is addressed. From a more coherent understanding of the parameters involved, it can be shown that there are ways of predicting the required properties of an adjuvant to solve specific delivery problems. The recognition that different problems often require quite different approaches illustrates that good adjuvants do not exist per se, only materials that should be rationally selected for specific reasons. The chemistry of the herbicide and the nature of its targets will dictate adjuvant selection criteria.

Potential of adjuvants to reduce drift in agricultural spraying

“…However, when applied at low concentration (0.165%), it increased the drift of the applied product, which represents an increase of 22% in regard of the water and 57% in regard of itself, when applied at high concentrations of 0.60% (Figure 1). These variations were expected, since the physical and chemical properties of the adjuvant determine their functions and depend on the relative proportion of each component in the mixture, including water (STOCK & BRIGGS, 2000. FIGURE 1.…”

Physicochemical Compatibility of Agrochemical Mixtures in Spray Tanks for Paddy Field Rice Crops

“…In general, mixing different products to the spray mix did not exert too much influence on the pH values considered ideal for each agrochemical. Herbicides efficiency can be increased when the pH is in values close to 5.0 (Stock and Briggs, 2000). However, the association of herbicide Kifix® with different agrochemicals significantly interfered in the spray mix pH, making it more acidic, with values ranging between 2.19 and 2.22.…”

Glyphosate Efficacy of Different Salt Formulations and Adjuvant Additives on Various Weeds

“…In relation to herbicide targeting efficiency, adjuvants may be used to modify spray droplet formation, droplet impaction and spray retention of the leaf surface, spreading, coverage and deposit formation [27]. Surfactants play an important role in the retention and absorption of glyphosate by the plant surface.…”