Seletividade e eficÃcia agronÃmica do herbicida mesotrione na cultura do milho / Mesotrione selectivity and efficacy for weed control in corn (Zea mays)

AUTOR(ES)

Danilo Augusto Silva Furtado

DATA DE PUBLICAÇÃO

2004

RESUMO

Development of herbicide molecules may be a tool for searching of new active ingredients with less environment impact and reduced resistant biotypes dissemination, keeping or even increasing efficacy of already existing compounds. This study had the objective of evaluating the effects of mesotrione application on weed control and corn (Zea mays) development comparatively to other herbicides. Eight herbicide treatments were used under field conditions and one handweeded plot. The herbicides used were: mesotrione (120 g ha-1), mesotrione (144 g ha-1), atrazine + vegetable oil (1200 + 900 g ha-1), atrazine + s-metolachlor (1295 + 1015 g ha-1), atrazine + nicosulfuron (1000 + 24 g ha-1), atrazine + foramsulfuron + iodosulfuron-methyl-sodium (1000 + 22,5 + 1,5 g ha-1), nicosulfuron (50 g ha-1) and foramsulfuron + iodosulfuron-methyl-sodium (45 + 3 g ha-1). Herbicides were applied at earlier stages of weed development when corn plants were at V4 development stage. The efficacy of these herbicides was evaluated on three weed species grown on the experimental area: Digitaria horizontalis, Ipomoea grandifolia and Richardia brasiliensis. Mesotrione at 120 and 144 g ha-1 showed the lowest control among the herbicides, ranging from 42 to 76% control. Atrazine + nicosulfuron showed the highest control (80 to 94%). No visual symptoms of phytotoxicity was observed on corn plants. A greenhouse bioassay was conducted using two corn hybrids (BRS 1031 and BRS 3123) and five mesotrione rates: 0, 36, 72, 144 (recommended) and 288 g ha-1. As in field conditions, no visual symptoms of phytotoxicity was detected, although mesotrione decreased hybrids above ground dry matter. As mesotrione rates increased to 144 g ha-1, a decrease on dry matter (20%) was noticed. At rates higher than 144 g ha-1, dry matter was stabilized up to 288 g ha-1.

ASSUNTO(S)

fitotecnia corn weed planta daninha herbicida herbicide milho

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