Quantificação do controle químico de plantas daninhas através de diferentes formas de absorção

Abstract

Resumo-O trabalho objetivou quantificar a intensidade de ação de herbicidas no controle de Brachiaria decumbens (BRADC) e Digitaria horizontalis (DIGHO), através de diferentes formas de absorção. Para tanto, três experimentos foram conduzidos em estufas plásticas representados pelos herbicidas atrazine (3,00 kg i.a. ha-1 + óleo mineral Assist ® 0,5% v/v), oxyfluorfen (0,72 kg i.a. ha-1) e isoxaflutole (0,06 kg i.a. ha-1), aplicados em pós-emergência inicial. Três possibilidades de absorção (radicular, foliar e radicular + foliar) e uma testemunha foram estudadas em solos de textura arenosa e argilosa, constituindo fatorial 4 x 2, com cinco repetições. Para o isolamento da absorção dos herbicidas foi utilizado canudos plásticos e papel alumínio para garantir a presença ou ausência de proteção das plântulas ou solo. Observou-se que a absorção foliar e radicular de isoxaflutole controlou eficientemente a BRADC nos solos de textura arenosa e argilosa aos 15 DAA (dias após aplicação). Para DIGHO, o isoxaflutole proporcionou controle eficiente através da via radicular, na ordem de 1,9 e 5,6 vezes, superior a via foliar para os solos arenoso e argiloso aos 15 DAA. A absorção foliar de oxyfluorfen controlou a BRADC (> 93,0%) na ordem de 16,8 e 15,1 vezes superiores a via radicular para os solos de textura arenosa e argilosa. A espécie DIGHO não foi satisfatoriamente controlada pelos herbicidas atrazine e oxyfluorfen por nenhuma das diferentes vias de absorção e tipos de solo.

Potencialização da eficiência do mesotrione em mistura com inibidores de Fotossistema II em diferentes vias de absorção de capim-colchão

“…For foliar absorption pathway, it was observed that only mesotrione + atrazine association presented satisfactory control at 14 DAA, being this effect significantly lower to root absorption pathway and foliar + root absorption pathway, but characterized as synergistic action. Maciel et al (2007) also observed that isolated atrazine application did not promote satisfactory control of D. horizontalis in any of pathways absorption studied. Table 4.…”

“…For treatments with soil isolation, it was used aluminum foil secured with duct tape to protect the entire soil surface of experimental units, exposing only plants aerial part to spray nozzles, according to methodology described by Maciel et al (2002;2007). Thirty minutes after herbicides applications in post-emergence, plastic straws and aluminum foil were carefully removed, avoiding plants contamination.…”

“…Weeds importance in production systems, justifies the necessity of efficient methodologies, simple and economically viable for more rigorous evaluations of herbicides effectiveness with wide absorption possibility (Maciel et al, 2002;2007). In this context, there are several possibilities of studying foliar and root absorption of herbicides, and the choice of the most appropriate method depends on the experimental objectives, procedure facility and specialized instrumentation availability (Devine et al, 1993).…”

Interference of the Association Oxyfluorfen + Flumioxazin and the Addition of Mineral Oil on a Phytosociological Survey

“…The mixture of oxyfluorfen and flumioxazin with the addition of mineral oil provided low efficiency in controlling Digitaria horizontalis (Jamaican crabgrass); this is confirmed by the high importance value index (IVI) of this species, reaching 100% or more at all the mixture doses (Figure 1). The low efficiency in controlling D. horizontalis by the herbicide oxyfluorfen was confirmed by Maciel et al (2007), where control reached a maximum of 23% in different soil types and modes of absorption. Carvalho et al (2014) also did not reach an effective control for the genus Digitaria with the application of oxyfluorfen on the irrigated onion culture.…”