APPLICATION TECHNOLOGY AND EFFECTIVENESS OF AUXIN HERBICIDES IN CONTROLLING Conyza sumatrensis AND Commelina benghalensis

Abstract

The Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) and Benghal dayflower (Commelina benghalensis L.) are among the most challenging weeds to control in agricultural crops. However, synthetic auxins present a potential solution. This study aimed to assess the efficacy of auxin herbicides in controlling C. sumatrensis and C. benghalensis using two spray volumes and two types of nozzles: Turbo TeeJet® Induction (TTI) and Extended Range (XR). The research comprised four experiments conducted in a greenhouse in Curitiba, Paraná, Brazil, from November 2019 to January 2020. For C. sumatrensis, no significant differences were observed between treatments at both stages of development. Consequently, it was not possible to identify the most effective herbicide, volume, or application nozzle. However, all treatments were found to be effective by the end of the evaluations. In contrast, for C. benghalensis, 2,4-D demonstrated higher efficacy than dicamba, irrespective of the developmental stages. The reduction in spray volume from 200 to 140 L ha−1, and the use of the TTI nozzle did not impact the effectiveness of the herbicides. The stage of development did not influence the herbicide control. In this case, the target species was the predominant factor in determining the effectiveness of control.