WEED MANAGEMENT IN CORN INTERCROPPED WITH Urochloa ruziziensis

Weed populations in monocrop or succession planting systems increase under inadequate management conditions. However, intercropping Urochloa ruziziensis with corn and precise adjustments in herbicide doses can facilitate management. This study sought options for chemical weed control in corn intercropped with U. ruziziensis. Two experiments were conducted in the 2022 winter harvest, in the municipalities of Cafezal do Sul and Brasilândia do Sul, State of Paraná. The experimental design was randomized blocks with 10 treatments and 4 replications. The treatments were: Control, atrazine (2.0 L c.p. ha-1), atrazine+nicosulfuron (2.0 L + 0.4 L c.p. ha-1), atrazine+mesotrione in three dose combinations (1.0 L + 0.5 L; 1.5 L+ 0.75L and 2.0 L + 0.5 L, b.w. ha-1, respectively), terbuthylazine in three doses (1.5 L, 2.0 L and 2.5 L c.p. ha-1), and terbuthulazine+mesotrione (1.5 L+ 0.2 L c.p. ha-1). The application occurred at the six-leaf stage of corn (V6). The variables evaluated were the percentage of control at 7, 14, 21, 28, 35, and 42 days after application, based on a visual scale of injury and dry biomass of weeds and U. ruziziensis. The treatments with terbuthylazine+mesotrione (750+96 c.p. ha-1) and atrazine+mesotrione (1,000+50 g c.p. ha-1) were the most efficient in controlling weeds in all evaluation periods, with a control above 80%. Treatments atrazine+mesotrione, terbuthylazine (3 doses), and terbuthylazine+mesotrione resulted in lower weed dry mass. Values of dry mass of U. ruziziensis subjected to atrazine (1,000 c.p. ha-1) and terbuthylazine+mesotrione (750+96 c.p. ha-1) applications were higher even compared to the non-application of herbicides.