Atrazine efficacy on populations of Smut grass and Razor grass

Abstract

Talquezal (Paspalum virgatum L.) and smut grass (Sporobolus indicus (L.) R. Br.) are important weeds in pasture areas in the northern region of the state of Mato Grosso, causing significant damage to ranchers. being considered difficult species due to their morphological and physiological similarity with forages in pasture areas. Therefore, the objective of this work was to evaluate the level of injury of atrazine applied in pre-emergence of the weeds Paspalum virgatum L. (P. virgatum) and Sporobolus indicus (L.) R. Br. (S. indicus) by means of dose-response curve in two textural classes. Two independent experiments were carried out, one for each species, in two soil types (Cambisol - sandy loam texture and Dystrophic Red Argisol - clayey texture), using the percentage grade scale to verify the level of injury for P. virgatum and S. indicus and dry matter at the end of the experiments. For the control of S. indicus, for both studied soils, the required doses were lower than the recommended dose of atrazine for corn (2.000 g ha^-1) at 15, 30 and 60 DAA (Days After Application) and at 60 DAA for dry matter. Atrazine controlled P. virgatum, since 15 DAA, at doses below the manufacturer's recommendation for corn (250 ha^-1). Atrazine provided efficient control of P. virgatum and S. indicus (dose less than 2.000 g. ha^-1) when applied in pre-emergence of the studied species. Promising in pre-emergence management for corn-forage intercropping.