Aplicación de mezclas de herbicidas pre-emergentes como tecnología clave para un manejo eficiente de malezas en mandioca (Manihot esculenta Crantz)

Abstract

Cassava (Manihot esculenta Crantz) is a crop of great importance for food security and representas a fundamental source of raw material for starch industries, contributing Paragauay´s economic income. It possesses broad adaptation to different soil and climatic conditions, making it strategic for agroindustrial development. This work was carried out with the objective of evaluating the efficacy of different active ingredients and their combinations applied pre-emergence for weed control in cassava. A randomized complete block design was implemented with eight treatments and three replications, in two locations in the Eastern Region of Paraguay. The treatments were: Clomazone 50% (2.5 l ha⁻¹) + Sulfentrazone 50% (0.5 l ha⁻¹); Flumioxazin 48% (150 g ha⁻¹) + Pyroxasulfone 85% (200 g ha⁻¹); Metolachlor 96% (2 l ha⁻¹) + Flumioxazin 48% (150 g ha⁻¹); Flumioxazin 48% (150 g ha⁻¹) + Clomazone 50% (2.5 l ha⁻¹); Flumioxazin 48% (150 g ha⁻¹); Metolachlor (2 l ha⁻¹); Pyroxasulfone 85% (200 g ha⁻¹) and a Control (no application). Control assessment was performed using the ALAM (1974) visual scale at 21 days after application (DAA), and the percentage of control was considered the main variable for this study. Data were subjected to ANOVA and Tukey's test (p ≤ 0.05). The treatments with Clomazone + Sulfentrazone (99.53%), Flumioxazin + Pyroxasulfone (99.1%), and Metolachlor + Flumioxazin (98.43%) showed optimal control (≥91%), with no significant differences among them. Flumioxazin alone and Metolachlor alone presented "Very good" control (89.33% and 88.67%, respectively), while Pyroxasulfone alone achieved "Good" control (78.33%). Herbicide combinations with different mechanisms of action were more effective than individual applications, with mixtures containing Flumioxazin and Clomazone standing out.