Mixtures of 2,4-D and dicamba with other pesticides and their influence on application parameters

Abstract

Due to the evolution of resistant weeds to glyphosate, the new technologies Xtend® and Enlist® cropping systems are expected to boost the use of auxin herbicides dicamba and 2,4-D. This study examined the effects of two formulations of 2,4-D and dicamba in tank-mixtures with other pesticides on selected physico-chemical properties of the spray solution, such as stability and pH, as well as other characteristics, such as size in dropcard and surface tension. The research included two factors, factor A comprised the herbicides dicamba and 2,4-D amine and choline salts and a auxin herbicide-free treatment, while factor B comprised 12 pesticides commonly sprayed in Brazil (i.e., five formulations of glyphosate, clethodim, haloxyfop-p-methyl, trifloxystrobin + prothioconazole, azoxystrobin + benzovindiflupyr, mancozeb, chlorantraniliprole, and thiamethoxam + lambda-cyhalothrin). Stability and pH, surface tension, and droplet parameters of the tank-mixtures were analyzed. No incompatibility was observed in the tank mixtures tested. Mixing dicamba with clethodim and haloxyfop-p-methyl resulted in pH values below 4.5. Auxin herbicides did not show pH buffering capacity and did not prevent pH changes when the others pesticides were added to the tank-mixtures. All mixtures affected surface tension of herbicides relative to the single solutions. The results support the use of auxin herbicides with other pesticides, given that the use of auxin herbicides will probably increase, following the adoption of new dicamba and 2,4-D technologies.