Avaliação dos herbicidas Auxo e Bullet no controlo de infestantes na cultura do milho (Zea mays L.)

Abstract

Corn productivity in Mozambique is affected by several factors, including the dependence on human labor for weeding, leading to reduced yields and a reduction in cultivated areas. Therefore, to minimize this dependence, this study aimed to evaluate the effect of the herbicides Bullet and Auxo on weed control in corn crops. The experiment was conducted from December 2022 to March 2023, in the experimental field of the Faculty of Agronomy in Maputo. The experimental design adopted was a randomized complete block design (RCBD), with four treatments and four replicates. The treatments evaluated were: control (no weed management), manual weeding, Bullet 70% SC (2.5 l/ha), and Auxo 33.7% (120 ml/ha). The variables analyzed for the weeds were: abundance, coverage, aerial biomass, control efficiency, and application time. For corn, these were: plant height, number of grains per row, ear weight, and average yield. ANOVA was performed with the Fisher-Hayter test at a 5% significance level, and means were compared with the Tukey-Kramer test at a 5% significance level. Thirteen weed species were identified, with Cenchrus brownii Roem & Schult being the most abundant and having the greatest coverage, and the lowest weed biomass was found in the treatment with the pre-emergent Bullet (73.56 g). Hand weeding required 34.2 man-days/ha, while Bullet and Auxo required 6.47 and 9.75 man-days/ha, respectively. In terms of control efficacy, Weeding (86.67%) and Bullet (87.98%) were considered very good, while Auxo achieved 64.98%, classified as sufficient. All weed management treatments showed higher average yields than the control (0.765 tons/ha). Sacha (1,247 tons/ha) and Auxo (1,234 tons/ha) were the most productive. The use of herbicides resulted in lower production costs, with Bullet being the most economical (production cost of 4,114 MT) and Auxo the most profitable (gross margin of 32,330 MT).