ABSTRACT
The addition of adjuvants can change the physicochemical properties of the spray solutions of plant protection products, improving the quality of the application. The aim therefore, was to evaluate the effects of the association of 15 plant protection products with four agricultural adjuvants, on the surface tension, pH and electrical conductivity of the spray solution. A separate analysis was carried out for the three product categories: insecticides, fungicides and herbicides. A completely randomised design (CRD) was used in a 5 x 6 factorial scheme with four replications: five adjuvants and six products. The concentration of the solutions was specified by adopting a spray volume of 200 L ha-1 and the dose recommended by the manufacturers. The characteristics to be evaluated were the surface tension, electrical conductivity and pH of the solution. Average values were compared by Scott-Knott test at 0.05 significance. Given the significant interaction between factors, results for the plant protection products on the physico-chemical characteristics proved to be dependent on the adjuvants and vice versa. Among the adjuvants, phosphatidylcoline + propionic acid resulted in the greatest reduction in the pH of the solution. Only the herbicide chlorimuron-ethyl had no effect on the surface tension of the solution, which was reduced by the remaining products. All the products affected electrical conductivity, the greatest increases being obtained with the herbicides 2,4-D dimethylamine and glyphosate.
Key words:
Surfactants; Physicochemical properties; Spray solution; Spraying