Preemergence herbicides on weed control in elephant grass pasture

Abstract

Elephant grass (Pennisetum purpureum Schum.) is an important forage crop that has been proposed as a potential feedstock for bioenergy production. However, weed interference is a major factor limiting elephant grass production. Field experiments were conducted in 2014 and 2015 to evaluate preemergence herbicides for selective weed control in an elephant grass pasture. Herbicide treatments included atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, diuron + hexazinone, sulfentrazone, imazethapyr, and atrazine at label use rates. Weedy and weed-free treatments were included. Atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine did not cause phytotoxicity on elephantgrass 35 days after treatment (DAT). However, diuron + hexazinone and imazethapyr were the most phytotoxic on elephantgrass, resulting in 81 and 70% phytotoxicity in 2014, and 7 and 6% phytotoxicity in 2015 respectively 35 DAT. All treatments provided effective weed control (>81%) with the exception of ethoxysulfuron (0 and 11% in 2014 and 2015, respectively), and atrazine (59% in 2014). These results show that atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine were selectives when applied in preemergence in elephant grass pasture.Index terms: Bioenergy; biofuel; napier grass; forage; Pennisetum purpureum. RESUMOO capim-elefante (Pennisetum purpureum Schum.) é uma planta forrageira importante que tem sido proposta como matéria-prima potencial para a produção de bioenergia. No entanto, a interferência das plantas daninhas é um fator limitante na produção do capim-elefante. Experimentos de campo foram realizados em 2014 e 2015 para avaliar herbicidas aplicados em condições de pré-emergência para o controle seletivo de plantas daninhas em pastagem de capim-elefante. Os tratamentos herbicidas incluíram atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, diuron + hexazinone, sulfentrazone, imazethapyr e atrazine em doses normalmente recomendadas no rótulo. Foram incluídas as testemunhas sem capina e capinadas. Atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone e atrazine não causaram fitotoxicidade em capim-elefante aos 35 dias após os tratamentos (DAT). No entanto, diuron + hexazinone e imazethapyr foram os mais fitotóxicos ao capim-elefante, resultando em 81 e 70% de fitotoxicidade em 2014, e 7 e 6% em 2015, aos 35 DAT, respectivamente. Todos os tratamentos de controle de plantas daninhas foram eficazes (> 81%) com a exceção de ethoxysulfuron (0 e

Pasture weed biology and management in Brazil

“…Based on data from the Ministry of Agriculture, Livestock and Supply -MAPA (Ministério da Agricultura, Pecuária e Abastecimento, [MAPA] 2020), there are currently 203 products formulated in Brazil based on the 16 different active ingredients recommended for pasture weed control. Brighenti, Calsavara and Varotto (2017), in Rio de Janeiro and Minas Gerais, evaluated the selectivity of the herbicides atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, diuron + hexazinone, sulfentrazone, and imazethapyr and atrazine at doses normally recommended in the package insert during the pre-emergence of elephant grass (P. purpureum). These researchers concluded that the herbicides atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine did not cause phytotoxicity to elephant grass plants 35 d after treatment (DAT), being selective to the crop.…”

Auxinic herbicides and tembotrione sprayed on seed-propagated elephant grass

“…Although elephant grass is well adapted and widespread forage throughout Brazil, weed interference in crops is still considered one of the problems during implantation, conduction, and also after harvest (Brighenti et al, 2017b;2017c). Weeds cause damage to elephant grass production and losses can reach up to 42% of forage dry matter yield depending on weed species and its density (Brighenti et al, 2017a).…”

HPPD-Inhibiting Herbicides Alone or in Tank-Mix with Atrazine in Elephant Grass

“…However, one of the major limitations on the implantation and conduct of elephant grass fields is related to weed interference (Brighenti et al, 2017a). There is a lack of research on weed management in elephant grass, as most studies consider this species to be a weed rather than a crop (Cutts et al, 2011;Odero & Gilbert, 2012;Grey et al, 2015).…”