Efficiency of a reduced herbicide rate for Brachiaria brizantha control in sugarcane

Abstract

-At different growth stages, weeds present different sensitivities to herbicides. Thus, the registered herbicide rate may be reduced under specific conditions, while maintaining satisfactory weed control. This study evaluated the efficiency of reduced rates of the formulated herbicide mixture Velpar K WG ® (hexazinone + diuron) + Volcane ® (MSMA) for Brachiaria brizantha control at different growth stages. Optimum weed control efficiency was obtained when applying 50% of the recommended rate in younger plants (plants with one to four leaves). In late applications, it is necessary to increase the herbicide rates and, under these conditions, 90% of the recommended rate for (diuron + hexazinone) + MSMA was estimated to be the most economical one.Keywords: Saccharum spp., hexazinone, diuron, MSMA RESUMO -Em estádios diferentes de crescimento, as plantas daninhas apresentam sensibilidade diferenciada aos herbicidas. Desse modo, as doses registradas dos herbicidas podem ser reduzidas em condições específicas, mantendo-se o controle satisfatório das plantas daninhas. Neste trabalho, avaliou-se a eficiência de subdoses da mistura dos herbicidas formulados Velpar K WG ® (hexazinone + diuron) + Volcane ® (MSMA) no controle de Brachiaria brizantha em diferentes estádios de crescimento. Ótima eficiência de controle da espécie daninha foi obtida com aplicação de 50% da dose recomendada, quando os herbicidas foram aplicados em plantas mais jovens (plantas com uma a quatro folhas

Weed Management in Beans Using Subdoses of Fluazifop-P-Butyl + Fomesafen

“…when working with acifluorfen + bentazon, found a higher control degree at 7 DAT, when weeds were at lower development stages (2 and 4 leaves); this corroborates the results of this study. Some studies have pointed out that lower doses of herbicides usually cause a better control effect when applied on younger weeds (Dieleman et al, 1996;Rizzardi and Fleck, 2004;Tironi et al, 2012).…”

“…The economic threshold dosage (ETD) was the one at which the productivity loss curve, as US$ ha -1 , intercepted the control cost (Rizzardi and Fleck, 2004;Tironi et al, 2012). For these authors, ETD is the herbicide dose at which the monetary loss of productivity equals the control cost provided by the use of the dose on the label of the herbicide, adding the application cost.…”

“…These results partially corroborate the ones found by other authors in soybean cultures, when studying sida and black-jack control, with a 75% reduction of the label doses of the commercially formulated mixture of acifluorfen + bentazon (Rizzardi and Fleck, 2004 ); of wheat, with a lower use than the one producers had been applying at diclofop-methyl + fenoxaprop-p-ethyl + mephenepyr-diethyl, to control Lolium rigidum (Barros et al, 2005); and sugarcane, with up to a 50% reduction in herbicide doses (diuron + hexazinone) + MSMA when used on young Brachiaria brizantha plants (Tironi et al, 2012). Considering the aforementioned, it can be concluded that the use of fluazifop-p-butyl + fomesafen at all doses and application periods caused low phytotoxicity to the bean culture in general, being lower than 5.5% and 11.8%, with three and eight trefoils, respectively.…”

“…However, when carried out through the application of herbicides, it can cause negative effects both for the crop and the agroecosystems (Tironi et al, 2012;Fontes et al, 2013).…”

Economic Threshold Levels for Signal Grass Control in Sugarcane Cultivars

“…Some weed species have greater competitive ability, such as those of Brachiaria spp., which are usually found in sugarcane fields (Barbosa et al, 2013). B. brizantha doi: 10.1590/S0100-83582016340400004 promotes yield loss of 45.67% in sugarcane when not controlled (Tironi et al, 2012).…”