Influence of Adjuvants on the Surface Tension, Deposition and Effectiveness of Herbicides on Fleabane Plants

Abstract

The use of herbicides is widespread in weed management, and adjuvants are added to the spray solution to improve the effectiveness of applications. The goal was to evaluate the influence of adjuvants added to the herbicides saflufenacil and glyphosate, isolated or in combination, and the effects on the surface tension, deposition and effectiveness in post-emergence applications to control Conyza sumatrensis. Experiments were conducted completely randomized experimental design to evaluate surface tension (TS), deposition and herbicide effectiveness. The treatments were glyphosate, glyphosate + saflufenacil and saflufenacil with or without the adjuvants Natur’al óleo®, Assist®, Aterbane®, Sillwet L-77 and Dash HC® (surface tension). For the experiments about mixture deposition and herbicide effectiveness, the factorial scheme 3 x 5 was adopted in the experiment performed in April, where factor A corresponded to the combination of the herbicieds glyphosate, saflufenacil and glyphosate + saflufenacil, and factor B was the addition of the adjuvants Natur’al óleo®, Assist®, Aterbane®, Sillwet L-77. For experiments conducted in November, the adjuvant Dash HC® was added, and the 3x6 factorial design was adopted. The adjuvants reduced the ST of the herbicide mixture, and Silwet L-77® was the most effective one. However, the ST reduction did not influence the mixture deposition on C. sumatrensis plants. The use of adjuvants did not result in an effective control for the applications with sole glyphosate.

Physicochemical properties, droplet size and volatility of dicamba with herbicides and adjuvants on tank-mixture

“…This characteristic directly influences pesticides efficacy as droplet coverage and droplet size will affect droplet evaporation and absorption rate in plants 28 , 29 . As also observed in the present study, adjuvants may reduce surface tension and contact angle values when compared to herbicide mixtures without adjuvants 30 .…”

Can Control of Glyphosate Susceptible and Resistant Conyza sumatrensis Populations Be Dependent on the Herbicide Formulation or Adjuvants?

“…The proper use of adjuvants is imperative in cases of glyphosate applications, since they reduce the surface tension of the spray liquid and may improve the efficacy of the treatments [32]. Sumatran fleabane has been reported to be more sensitive to glyphosate in earlier rather than more advanced growth stages, due to altered morphological characteristics of the leaf tissues and subsequently lower deposition of the herbicide [13,31,32].…”

“…The proper use of adjuvants is imperative in cases of glyphosate applications, since they reduce the surface tension of the spray liquid and may improve the efficacy of the treatments [32]. Sumatran fleabane has been reported to be more sensitive to glyphosate in earlier rather than more advanced growth stages, due to altered morphological characteristics of the leaf tissues and subsequently lower deposition of the herbicide [13,31,32]. The dose-response assays in the present study revealed that the susceptibility of C. sumatrensis to herbicidal treatments at the rosette stage (BBCH [16][17][18] varied among populations and depended on the glyphosate formulation and the addition of adjuvants.…”

Study of the Effects of Adjuvants Associated With Insecticides on the Physicochemical Properties of the Spray Solution and Characterization of Deposits on Wheat and Maize Leaves Under Simulated Rain

“…The addition of adjuvants to the spray solution interferes with the application of phytosanitary products, modifying certain properties of the spray solution and/or increasing its biological efficiency. The adjuvants can alter the physicochemical properties of the spray solution, thus altering factors such as wettability, adhesion, and spreading of spray droplets and contributing to better retention and penetration of the active ingredient (Azevedo & Castelani, 2013). However, this improvement has not been observed for all adjuvants; it depends on the product used and the biological target (Melo et al, 2014).…”