Controle químico de plantas daninhas em povoamentos de restauração florestal

Abstract

Objetivou-se avaliar o emprego do tratamento químico, com herbicida a base de glifosato, na formação de povoamentos de restauração florestal em áreas com predominância de braquiária, em comparação ao controle mecânico. O tratamento químico foi realizado através de capina em faixas de 1,2 m, antes do plantio, e quando a braquiária apresentava altura média de 30 cm, aplicando-se glifosato na dose de 1,44 kg ha-1, nas entrelinhas. O tratamento com controle mecânico consistiu de capinas em faixas de 1,2 m nas linhas de plantio e roçadas nas entrelinhas. Utilizaram-se 10 espécies arbóreas, plantadas no espaçamento 3,2 x 1,7 m. Avaliou-se sobrevivência e crescimento em altura das espécies aos 6, 18 e 30 meses após o plantio e o diâmetro ao nível do solo aos 30 meses. Os custos envolvidos na aplicação e na manutenção de cada tratamento, até 30 meses após o plantio, também foram avaliados. A taxa de sobrevivência sofreu pouca influência dos tratamentos utilizados. Em todas as épocas de avaliação do tratamento químico, as 10 espécies florestais obtiveram maior crescimento em altura, comportamento semelhante ao diâmetro ao nível do solo aos 30 meses. O tratamento mecânico apresentou custo de manutenção, aproximadamente, três vezes superior ao tratamento com glifosato.

Grasses Control Strategies in Setting Restoration Stand of the Atlantic Forest

“…Herbicide applications occurred in less number than mowing operations (Table 1), as also reported by Santos et al (2018). The greatest number of applications occurred in the chemical treatment, with mean of one intervention at every 4.0 months in the total experiment period.…”

“…Results are suggesting that herbicide application in total area is more effective than the remaining strategies adopted in this study. Santos et al (2018) evaluated the employment of using predominant glyphosate herbicide treatment and mechanical treatment only in the forest setting stands in forestry restoration areas highly infested by brachiaria grasses and reported similar results to this current study. The authors reported that for glyphosate herbicide applications, it were necessary up to 13 months and that at 30 months the plants growth in height and diameter were significantly higher in the chemical treatment, in parallel to the costing of the mechanical treatment to be nearly three times more expensive.…”

“…Weed control in forest restoration is usually performed by employing mechanical techniques, as mowing and hoeing. However, as underlined by Vasic et al (2009) in areas infested by fast-growing weeds, as the brachiaria grasses, the mechanical method is not so effective, in addition to having high cost attached to labour force (Gonçalves et al, 2018;Santos et al, 2018). Thereby, it is important to pursue controlling alternatives to weed species in forest setting stands aiming forestry restoration.…”

“…Chemical control via herbicides is one of the alternatives. On the other hand, regarding mechanical method, the application of glyphosate herbicide effectively eradicates weeds and promotes a greatest growth of tree species (Santos et al, 2018). The physicochemical characteristics of glyphosate indicate high water solubility (Sw; 10,500 mg L −1 ), acid dissociation constant (pKa; 2.3), as well as low octanol-water partition coefficient (Kow) (Log Kow; −3.2), indicating strong hydrophilicity and a low Dissipation Time (DT50) (15 d), being a non-persistent product in the soil (PPDB, 2019).…”

EFFECTS OF ROOT DEFORMATION AND LIGHT AVAILABILITY ON GROWTH AND BIOMASS ALLOCATION OF Senna multijuga SEEDLINGS (Rich) H. S. Irwin & Barneby

“…and Urochloa decumbens, which can reach up to 1.5 m in height and are diffi cult to control (Weidlich, 2011;Ferreira et al, 2016). Therefore, in the fi rst months after planting, intensive mechanical and chemical weeding around seedlings are necessary to avoid and control the competition for light, water, and nutrients with native and exotic spontaneous plants (César et al, 2014;Santos et al, 2018). Weeding represents a signifi cant part of maintenance costs in forest restoration projects, and the procedures used to control the competition of tree seedlings with fastgrowing plants are sometimes ineffi cient and costly (Brancalion et al, 2009).…”