Alternatives for chemical management of sourgrass

Intensive use of Glyphosate has been selected multiple resistant sourgrass biotypes in the areas of intensive agriculture in Brazil. Thus, it is important that viable management alternatives are evaluated for this invasion, which currently is regarded as the main problem of Brazilian agriculture. The study aimed to evaluate strategies for chemical management of sourgrass. Three trials divided according to the weed development stages were performed: Post-Initial (up to tillering), Post-Delayed (one to four tillers) and Adult-Plant (adult stage characterized by the beginning of the reproductive phase). The sourgrass seeds were collected from biotypes with evidence of Glyphosate tolerance in the municipality of Rio Brilhante - MS. In each trial were evaluated thirteen treatments and one witness, where the treatments were herbicide mixtures applications with subsequent sequential applications at different dates (7, 10 and 14 days after the first application) and the herbicides application without mixtures. Sourgrass plants are tolerant to Glyphosate and Clethodim herbicides. Formulated mixtures of Paraquat + Diuron and Haloxifop are the most suitable for controlling sourgrass plants derived from seeds, regardless of the control period. Treatments that have the Haloxyfop herbicide in the first application provided better control when compared to the other treatments with mixtures and sequential applications at all stages of applications