Lixiviação de saflufenacil e residual após períodos de seca

Abstract

RESUMO -O objetivo deste trabalho foi avaliar a lixiviação de saflufenacil em Latossolo Vermelho-Amarelo (textura média, pH 5,6) e Latossolo Vermelho distrófico (textura argilosa, pH 5,2 e pH 6,0), assim como os efeitos de períodos de seca no residual desse herbicida. A lixiviação de saflufenacil (0,10 g i.a ha -1 ) e, adicionalmente, a lixiviação de diuron + hexazinone (1.170 + 330 g i.a. ha -1 ) foram avaliadas sob simulação de chuva (40 mm). O herbicida saflufenacil aplicado em solo argiloso com pH 6,0 apresentou lixiviação até a profundidade de 25 cm, porém ela foi mais pronunciada na faixa de 15 a 20 cm. Quando o herbicida foi aplicado no mesmo solo, mas com pH 5,2, houve lixiviação até a profundidade de 15 cm. Em solo de textura média, a lixiviação foi elevada até a profundidade de 25 cm. Para diuron+hexazinone, no solo argiloso, independentemente do pH, houve lixiviação até 25 cm de profundidade. Todavia, em solo de textura média a lixiviação ocorreu até 40 cm de profundidade. Em relação ao efeito residual do saflufenacil após períodos de seca (0, 15, 30, 45, 60 e 90 dias) em um Latossolo Vermelho distrófico (textura argilosa), foi verificado efeito fitotóxico no bioindicador maior ou igual a 80% até os 28 dias de seca.Palavras-chave: calagem, comportamento, herbicida, solo.ABSTRACT -This work aimed to evaluate saflufenacil leaching in Red Yellow Latosol (medium texture, pH 5.6) and Dystrophic Red Latosol (clay texture, pH 5.2 and 6.0) and to evaluate the effect of drought on the residual herbicide. The leaching of saflufenacil (0.10 g a.i. ha -1 ) and hexazinone + diuron (1,170 + 330 g a.i. ha -1 ) was evaluated under simulated rainfall of 40 mm. Saflufenacil in clay soil with a pH of 6.0, showed leaching at a depth of 25 cm, but was more pronounced in the range between 15 and 20 cm. When the herbicide was applied in the same soil with pH 5.2, leaching occurred at depths of 10 to 15 cm. In medium texture, soil leaching occurs up to a depth of 25 cm. In the case of diuron + hexazinone, leaching can be seen in clay soil, regardless of pH, up to a depth of 25 cm, up to a depth of 40 cm in medium soil. Regarding the residual effect of saflufenacil after periods of drought (0, 15, 30, 45, 60 and 90 days) in (clay) Latosol, a phytotoxic effect on the bio-indicator, greater than or equal to 80%, was observed at 28 days of drought.

<b>Temporal selectivity of saflufenacil herbicide for the common bean crop of a brazilian oxisol

“…The soil persistence of approximately 90 days noted by Monquero et al (2012) was much higher than that observed in our study, which can be explained by the lack of soil moisture after the application of saflufenacil, as reported by the authors, which acted to inhibit herbicide dissipation. Moreover, a study carried out in the United States on a soil classified as a Sequatchie loam found that saflufenacil had a halflife of 21.4 days (Mueller et al, 2014).…”

“…Long periods of drought reduce the persistence of this herbicide as 28 days of drought maintained herbicidal activity at 80% effectiveness, and 90 days of drought reduced herbicidal activity to 8% effectiveness (Monquero et al, 2012).…”

Selectivity of Saflufenacil Applied Singly and in Combination With Glyphosate on Coffee and Citrus Crops

“…Monquero et al (2012) showed that the saflufenacil presented high leaching in two Latosols (Oxisols) with different textures, which was more pronounced in the sandy texture. Saflufenacil is a moderated acid, which has pKa of 4.3.…”

“…However, the strong dependence on glyphosate in croplands has resulted in loss of its effectiveness in weeds, that became tolerant to this herbicide due to selection pressure (MOREIRA et al, 2007;OWEN, 2008;POWLES, 2008;YAMAUTI et al, 2010). Thus, the combination of herbicides with different mechanisms of action may be a viable alternative to ensure the success in weed managements.…”

“…Glyphosate has a high adsorption capacity in the soil (CHEAH et al, 1997), on the other hand, studies suggest that the saflufenacil in the root zone is readily available in the soil solution for leaching, degradation or plant uptake (MONQUERO et al, 2012;PAPIERNIK et al, 2012;MATALLO et al, 2014).…”