DOSES DA MISTURA DE IMAZAPIQUE + IMAZETAPIR NA SUPRESSÃO DE UROCHLOA RUZIZIENSIS

Abstract

Intercropping grain crops with forage grasses requires management strategies that ensure initial pasture suppression without compromising its survival. The objective of this study was to evaluate the efficacy of subdoses of the ready-mix imazapic + imazethapyr in suppressing Urochloa ruziziensis (cultivars Comum and BRS Integra), aiming for intercropping with imidazolinone-tolerant sorghum. The experiment was conducted in the field in Rio Verde GO, using a randomized block design with four replications. Treatments consisted of the application of seven herbicide doses (0; 0.07; 0.14; 0.35; 0.7; 1.4, and 2.1 L c.p. ha⁻¹) at the three-tiller stage of the forages. Phytotoxicity was evaluated at 7, 14, 21, and 28 days after application (DAA), along with morphological characteristics, dry mass production, and weed community at 81 days after sowing. Results showed that phytotoxicity followed a quadratic behavior, peaking at 21 DAA. Although high doses (2.1 L ha⁻¹) caused phytotoxicity above 70%, it was observed that at the recommended commercial dose (1.4 L ha⁻¹), injury levels remained close to 60% for cv. Comum and 58% for BRS Integra, falling within acceptable limits for temporary suppression. There was efficient control of the general weed community, except for Eleusine indica in the cv. Comum area. There was no statistically significant reduction in final dry mass production or tillering of the forages. It is concluded that the mixture of imazapic + imazethapyr, especially at the commercial dose, promotes satisfactory initial suppression with subsequent plant recovery, demonstrating the recovery potential of U. ruziziensis cultivars for use in intercropping systems.