Graminicide Application Timing Influences Red Rice (Oryza sativa) Control and Seedhead Reduction in Soybean (Glycine max)¹

Abstract

Several graminicides were evaluated at various application timings for control and seedhead suppression of red rice (Oryza sativa) in soybean (Glycine max). One application of clethodim, fluazifop-P, quizalofop-P, or sethoxydim at any timing did not control red rice more than 86% 2 wk after treatment. Emergence of red rice seedlings subsequent to applications reduced control later in the season. At a naturally infested location, seedhead reduction was greatest, regardless of graminicide, when application was delayed until the four-leaf stage. At a second location, seedhead reductions were highest following graminicide applications at the two-leaf stage of growth. No single graminicide application completely eliminated red rice seedhead production. Soybean yields were reduced when graminicide application was delayed until the boot stage at both locations, and following two-leaf stage applications at the naturally infested location.

Interação competitiva de Brachiaria brizantha e B. plantaginea sob doses reduzidas de fluazifop-p-butil, aplicadas em diferentes épocas

“…Diversos trabalhos demonstram que o estádio de desenvolvimento das espécies daninhas interfere na eficácia dos herbicidas (Askew et al, 2000;Johnson & Hoverstad, 2002). Com relação às gramíneas, Smeda & Putnam (1990) O delineamento experimental adotado foi o de blocos casualizados, com quatro repetições e arranjo fatorial 6x3, sendo seis doses de fluazifop-p-butil (7,5; 12,5; 18,75; 31,25; 43,75 e 62,5 g ha -1 ), aplicadas em três épocas (14, 24 e 34 dias após a emergência das plantas -DAE), e uma testemunha sem herbicida.…”

Natural Grassland Response to Herbicides and Application Timing for Selective Control of Tall Fescue, an Invasive Cool-Season Grass

“…Additionally, clethodim treatments enhanced grassland forb abundance and richness. The timing of herbicide application is an important factor to consider when managing weeds in agroecosystems (Askew et al 2000), especially invasive, nonnative plants in natural areas where conservation of species diversity is a top priority. Clethodim application timing is an important factor to consider for invasive grass control in natural grasslands due to the nontarget herbicide impact on desirable native grass species.…”

Estágios Fenológicos Associados Ao Controle Químico No Manejo De Spermacocea Densiflora Originada De Sementes E Rebrota

“…Entretanto, na mistura do glifosato com outros herbicidas, é importante avaliar o estádio fenológico das plantas daninhas no momento da aplicação, para evitar controle ineficaz e consequente aumento nos custos de produção (GALON, 2013). O controle eficiente de plantas daninhas com o uso de herbicidas em pós-emergência depende, sobretudo, do estádio de desenvolvimento das plantas-alvo (ASKEW; SHAW, 2000;JOHNSON;HOVERSTAD, 2002;FLECK et al, 2008). Assim, o objetivo deste trabalho foi avaliar o efeito de diferentes herbicidas isolados ou associados ao glifosato, aplicados em pós-emergência, no controle de S. densiflora em plantas oriundas de sementes ou rebrota em diferentes estádios fenológicos.…”