Control of amaranthus palmeri resistant to als and epsp inhibitors with pre and postemergence herbicides in intercropping of corn and marandu grass.

The Palmer´s amaranth is in eradication process at Mato Grosso, due to its potential risk to national agriculture. The objective of this work was to study management alternatives of this species, with a randomized block design and factorial scheme (2 x 5) with four blocks, two systems ([single and intercropping maize with marandu grass (Urochloa brizantha cv. Marandu)]. and three herbicidal treatments (ae g ha-1 ): atrazine (2,500) PRE, atrazine (2,500) PRE / atrazine + tembotrione (1,500 + 50) POST and atrazine + tembotrione (1,500 + 50) POST. The herbicides were applied with CO2 pressurized sprayer and application volume of 200 L ha-1 . The control of Palmer?s amaranth and marandu grass intoxication were evaluated at 7 and 21 days after application (DAA) with grades from 0 to 100. At 7 and 21 DAA, the applications in POST and PRE + POST showed similar control of the Palmer´s amaranth, without influence of the cultivation systems. At 7 and 21 DAA, there was effect of the system in the application only in PRE and non-weeded control, without differing among them, being the greater control in the intercropping (> 80% in the two evaluations). There was no significant difference (p