Efeito de adjuvantes na calda e do estádio de desenvolvimento das plantas, no controle do capim-colonião (Panicum maximum) com glyphosate
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Data
1992-01-01
Autores
Durigan, Julio Cezar [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira da Ciência das Plantas Daninhas
Resumo
O objetivo do presente trabalho foi estudar a possibilidade da redução de dosagens de glyphosate (N-(fosfonometil)-glicina) em função de aumentos na quantidade de óleo vegetal e uréia adicionados como adjuvantes à calda. Além disso, avaliou-se o efeito desse herbicida aplicado isolado ou combinado com os adjuvantes, em três estádios de crescimento do capim-colonião. Os experimentos foram instalados nas entrelinhas de pomares de citros, variedade Pera Rio, do município de Barretos/SP, com altas infestações de capim-colonião, no ano de 1990. Testou-se o glyphosate isolado, na dosagem de 1,8 kg/ha de equivalente ácido (e.a.) e nas dosagens de 1,44, 1,08 e 0,72 kg/ha, adicionadas de 1,0, 2,0 e 3,0 l/ha de óleo vegetal e utilizou-se uma testemunha, tratada apenas com água. As plantas de capim-colonião mediam 1,5 m de altura. em outro experimento, o herbicida foi testado isoladamente na dosagem de 1,08 kg e.a./ha, e combinado com 2 l/ha de óleo vegetal ou 0,3% de uréia, sob os três estádios de crescimento do capim-colonião: a) 0,6m de altura e início do florescimento e frutificação; b) 1,5m de altura, florescimento e frutificação plenos; c) 0,5m de altura, na forma de rebrota da touceira após roçada da planta adulta, início de florescimento e frutificação. A adição de 2 l/ha de óleo vegetal na calda de pulverização, permitiu redução de 0,72 kg/ha do e.a. do glyphosate, sem prejuízos para o controle em relação a aplicação isolada na dosagem de 1,80 kg/ha. Nas mesmas condições, a adição de 0,2% de uréia proporcionou redução de 0,36 kg/ha do e.a. do herbicida. O controle sempre foi menor quando as plantas estavam mais velhas, o que pode ser resolvido com a aplicação dos produtos sobre a rebrota de tais plantas, após a roçada. A aplicação do herbicida, isolado ou com aditivos, no início do florescimento e frutificação das plantas, quer seja no seu desenvolvimento inicial ou após a brotação da soqueira, promoveu a inviabilização das sementes produzidas, diminuindo sensivelmente o número de dissemínulos viáveis no banco de sementes dessa espécie, presentes no solo.
Two trials were carried out to study the possibility of the reduction of glyphosate rates through the addition of different quantities of vegetal oil and urea as adjuvants. These treatments were studied on Panicum maximum plants at three differents qrowth stages. The experiments were conducted in 1990, in citrus orchards containing high densities of P. maximum. In the first trial, the glyposate was sprayed alone (1.80 kg a.e./ha) and at the rate of 1.44, 1.08 and 0.72 kg a.e./ha, plus vegetal oil at the rate of 1.0, 2.0 and 3.0 l/ha and urea at the concentration of 0.2%, 0.3% and 0.4% in the herbicide solution. A control plot was sprayed with pure water. In this essay, the P. maximum plants were 1.5m high. In the second essay glyphosate (1.08 kg a.e./ha) was sprayed alone and in mixture with vegetal oil (2.0 l/ha) and urea (0.3% on P. maximum plants at three differents growth stages. The stages were: a) 0.6m high at the start of the flowering and frutification, b) 1.5m high, full flowering and frutification stage, and c) 0,5m high from regrowth after cutting of old plants. The addition of vegetal oil (2.0 l/ha) was enough to make possible the glyphosate rate reduction to 0.72 kg a.e./ha, showing the same efficacy of the glyphosate rate of 1.80 kg/ha, sprayed alone. The addition of urea (0.2%) made possible to reduce in 0.36 kg a.e./ha the rate of herbicide. The herbicide s efficacy was reduced in older plants, but it was very effective when applied over regrowth plants. The glyphosate when applied at the flowering stage, avoided development of the P. maximum seeds, reducing the seeds bank enrichment.
Two trials were carried out to study the possibility of the reduction of glyphosate rates through the addition of different quantities of vegetal oil and urea as adjuvants. These treatments were studied on Panicum maximum plants at three differents qrowth stages. The experiments were conducted in 1990, in citrus orchards containing high densities of P. maximum. In the first trial, the glyposate was sprayed alone (1.80 kg a.e./ha) and at the rate of 1.44, 1.08 and 0.72 kg a.e./ha, plus vegetal oil at the rate of 1.0, 2.0 and 3.0 l/ha and urea at the concentration of 0.2%, 0.3% and 0.4% in the herbicide solution. A control plot was sprayed with pure water. In this essay, the P. maximum plants were 1.5m high. In the second essay glyphosate (1.08 kg a.e./ha) was sprayed alone and in mixture with vegetal oil (2.0 l/ha) and urea (0.3% on P. maximum plants at three differents growth stages. The stages were: a) 0.6m high at the start of the flowering and frutification, b) 1.5m high, full flowering and frutification stage, and c) 0,5m high from regrowth after cutting of old plants. The addition of vegetal oil (2.0 l/ha) was enough to make possible the glyphosate rate reduction to 0.72 kg a.e./ha, showing the same efficacy of the glyphosate rate of 1.80 kg/ha, sprayed alone. The addition of urea (0.2%) made possible to reduce in 0.36 kg a.e./ha the rate of herbicide. The herbicide s efficacy was reduced in older plants, but it was very effective when applied over regrowth plants. The glyphosate when applied at the flowering stage, avoided development of the P. maximum seeds, reducing the seeds bank enrichment.
Descrição
Palavras-chave
vegetal oil, Urea, óleo vegetal, Uréia
Como citar
Planta Daninha. Sociedade Brasileira da Ciência das Plantas Daninhas , v. 10, n. 1-2, p. 39-44, 1992.