Alternatives to paraquat for the chemical control of Italian ryegrass, wild oat and Sumatran fleabane

Abstract

With the banning of paraquat, it is necessary to plan for the use of alternative herbicides in the desiccation of weeds. In this sense, herbicides such as glufosinate, saflufenacil, diquat, glyphosate, clethodim are highlighted in different mixtures. Glufosinate, especially in mixtures, is believed to be effective in controlling Lolium perenne ssp. multiflorum (Italian ryegrass), Avena fatua (wild oat) and/or Conyza sumatrensis (Sumatran fleabane). The aim was to evaluate the efficacy of glufosinate alone, or in mixtures, in the control of Italian ryegrass, wild oat and Sumatran fleabane, as an alternative to paraquat. The experiment was carried out in an experimental area located in the city of Cruz Alta, state of Rio Grande do Sul (RS), Brazil, in November 2020. A completely randomized design was used, with four replications. The treatments consisted of the application of glufosinate, saflufenacil, diquat, glyphosate and clethodim, alone or in combinations. The control of Italian ryegrass, wild oat and Sumatran fleabane was evaluated at 7, 14, and 28 days after application. Glufosinate at mixtures was effective in controlling weeds, being almost always superior to that observed for diquat alone or in mixtures. To achieve the same efficacy of the mixtures, the rate of glufosinate must be at least 700 g a.i. ha^-1. The application of glufosinate (400 g a.i. ha^-1) in mixtures with saflufenacil, glyphosate and clethodim was effective in controlling Italian ryegrass, wild oat and Sumatran fleabane. The alone application of glufosinate proved to be effective in controlling all weeds at the maximum applied dose (700 g a.i. ha^-1). Glufosinate, alone or in mixtures, is thus characterized as an alternative to paraquat in the control of weeds.