Marcelo Rodrigues dos Reis

Quantification of the fate of mesotrione applied alone or in a herbicide mixture in two Brazilian arable soils

The effects of mesotrione, S-metolachlor, and terbuthylazine, applied in mixture, on soil biodegradation remain insufficiently researched. However, herbicide mixtures have been a common practice in agricultural systems in the last years. Understanding the fate of soil-applied herbicides may help on planning weed management tactics towards more sustainable and efficient weed control. Therefore, this study evaluated the fate of mesotrione alone and in mixture with S-metolachlor and terbuthylazine when applied to two contrasting arable Brazilian soils. Mineralization and degradation experiments were conducted using 14C-mesotrione alone or in mixture. From the 49-day laboratory incubation data, increased mineralization half-life of mesotrione was observed for the mixture of herbicides, ranging from a 4-day increase for the sandy loam soil to a 1-day increase in the sandy clay texture soils. Mesotrione degradation rate had a twofold increase in the sandy loam compared to the sandy clay soil. Two metabolites can be identified from mesotrione degradation, 4-methyl-sulfonyl-2-nitrobenzoic acid (MNBA) and 2-amino-4-methylsulfonyl benzoic acid (AMBA). Indices for the score of ubiquity in groundwater indicated mesotrione possesses leaching potential for both soils. Applying mesotrione alone or in mixture did not influence the amount of bound residues from mesotrione. However, mesotrione degradation rate was influenced by soil texture regardless if applied alone or in mixture. Mesotrione biotransformation was relatively quick, indicating that this herbicide has low persistence and, consequently, low residual effect on crops and weeds when present in similar soils to this present study.

Residual tembotrione and atrazine in carrot

ABSTRACT Carrot (Daucus carota L.) is a vegetable crop that is grown throughout the year across various regions of Brazil in rotation or in succession to other cultures. Herbicide residual effect has emerged as a concern, because of the possibility of carryover. Thus, the objective of this study was to evaluate the effect of tembotrione and atrazine residues – in mixture and isolated – on carrot planted in succession to corn. The experiment was designed in randomized blocks with five replications. Treatments consisted of tembotrione (50.4 g ha−1), tembotrione (100.8 g ha−1), tembotrione + atrazine (50.4 g ha−1+ 2 L ha−1), tembotrione + atrazine (100.8 g ha−1+ 2 L ha−1), and atrazine (2.00 L ha−1) applied eight months before carrot seeding, plus a control treatment with no herbicide application. Investigated variables were shoot dry mass, productivity, and classification of carrot roots. The presence of atrazine and tembotrione decreased dry mass in the area, and only tembotrione reduced total root productivity. Thus, there is a carryover effect to tembotrione application that reduces the dry matter accumulation of shoot and total productivity, and an atrazine + tembotrione (100.8 g ha−1) mixture reduces the total productivity after application of these herbicides to soil.

Pollutants Transformation and Metabolite Accumulation in Soils

Abstract After use by a wide range of activities and applications, and/or after made available by accidental sources, chemicals of various types remain as major pollutants in the main environmental compartments including soils. Organisms, including plants, and animals/humans, can be exposed to and impacted by soil-associated pollutants. Once in soils, the transformation of pollutants can be possible via chemical, photochemical, and surface-induced reactions. Eventually, the severity of toxicity of various metabolites mainly associated with the pollutant transformation products to parent material and/or organisms can differ. Considering recent literature this chapter: (1) introduces major pollutants encountered by the organisms or with their easy access to the soil medium, (2) overviews major mechanisms underlying transformation of pollutants in soils and the respective formation of metabolites, (3) highlights major techniques available for the determination of pollutants-transformation products and metabolites, and (4) lists the so far least explored aspects in the current context.

Efeito do herbicida tembotrione sobre o desenvolvimento da batata

Os residuos do herbicida tembotrione no solo, proveniente de cultivos de milho, podem afetar o crescimento de culturas sensiveis, como a batata, em sucessao. Neste sentido, objetivou-se avaliar o efeito do herbicida tembotrione sobre o crescimento e o desenvolvimento da batateira. Realizou-se um experimento de campo em delineamento em blocos casualizados, com quatro repeticoes. Os tratamentos foram incorporados ao solo um dia antes do plantio da batata cultivar Atlantic e constituidos de quatro doses de tembotrione: 8,4; 16,8; 33,6 e 50,4 g ha -1 , representando 8,4; 16,8; 33,6 e 50% da dose recomendada para a cultura do milho, e um tratamento controle (sem herbicida e capinada). Aos 60 e 90 dias apos o plantio foram avaliadas a massa de materia fresca de tuberculo (MMFT), o numero de hastes (NH), o numero de tuberculos (NT) por planta e a massa de materia seca total (parte aerea + haste) (MMST). A MMFT, NT e MMST decresceram com o aumento das doses do tembotrione, sendo que as maiores reducoes encontradas, nas duas epocas avaliadas, foram na dose de 50,4 g ha -1 i.a. O numero de hastes nao foi influenciado pelas doses do herbicida tembotrione independente da epoca avaliada. Os resultados obtidos indicaram que a presenca de tembotrione no solo reduziu o crescimento e a quantidade de tuberculos produzidos pela batateira.

GROWTH ANALYSIS OF HYBRID Eucalyptus urograndis (E. grandis x E. urophylla) IN RESPONSE TO SIMULATED DRIFT OF AUXINIC HERBICIDES

1 Received on 01.08.2015 accepted for publication on 25.08.2017. 2 Universidade Federal de Lavras, Programa de Pòs-Graduação em Enegenharia Florestal, Lavras, MG Brasil. E-mail: <gisleancarvalho@hotmail.com>. 3 Universidade Federal do Tocantins,Programa de Pòs-Graduação em Produção Vegetal, Gurupi, TO Brasil. E-mail: <erasmolemus@uft.edu.br>. 4 Universidade Federal de Viçosa, Departamento de Agronomia, Rio Paranaíba, MG Brasil. E-mail: <marceloreis@ufv.br>. 5 Universidade Estadual Paulista Júlio de Mesquita Filho, Programa de Pós-Graduação em Ciência Florestal,Botucatu, SP Brasil. E-mail: <girlanio_holanda@hotmail.com>. 6 Universidade Federal do Tocantins,Departamento de Agronomia, Gurupi, TO Brasil. E-mail: <andre.amaral.uft@hotmail.com>. 7 Universidade Federal de Lavras, Programa de Pòs-Graduação em Biotecnologia Vegetal, Lavras, MG Brasil. E-mail: <p.c.magnani@hotmail.com>. *Corresponding author.

Seletividade inicial de herbicidas aplicados em pós-emergência da crotalária

Among the practices that aim to confer sustainability of the agricultural soil, the use of green manure and/or cover crops such as crotalaria are advocated. The management of weeds is one of the practices for the success of crotalaria. However, the information about the selectivity of herbicide are scarce and these are of paramount importance. The objective of this study was to evaluate the selectivity of different herbicides applied in post-emergence of showy crotalaria ( Crotalaria spectabilis ). Two experiments were conducted in a greenhouse in a randomized completely randomized design with four replications. In the first one the following herbicides were tested. The first experiment involved the following herbicides (g. i.a.ha -1 ): atrazine (500 and 1000), bentazon (720), carfentrazone-ethyl (3.75), clomazone (400), diclosulam (20), diuron (800), ethoxysulfuron (18), flumioxazin (10), mesotrione (60), oxadiazon (500), tembotrione (40), atrazine + flumioxazin + carfentrazone-ethyl (300 + 5 + 2), and a control without application. In the second were used, bentazon (400), clomazone (400), diclosulam (10 and 15), diuron (400), ethoxysulfuron (15), bentazon + diclosulam (200 + 7.5), diclosulam + diuron (7.5 + 200), bentazon + diuron (200 + 200) and a control without application. Phytotoxicity was evaluated at 7, 14, 21 and 28 days after application (DAA) and aerial dry matter (ADM) at 28 DAA. In both experiments the herbicides bentazon, clomazone, diclosulam and ethoxysulfuron caused low injuries to the crop and low reduction in ADM. The herbicides atrazine, mesotrione, oxadiazon and atrazine + flumioxazin + carfentrazone-ethyl provided high levels of injuries and high reduction in ADM. The herbicides bentazon, clomazone, diclosulam and ethoxysulfuron were selectivity for post-emergence application of the crop.

Glyphosate Formulations on Nutritional Condition and Productivity of Roundup Ready Soybean

ABSTRACT We evaluate the effect of different commercial formulations of glyphosate on the nutritional status of Roundup Ready soybeans (TMG 125). The experiment was conducted under field conditions for two agricultural years. The experimental design used was randomized blocks with four repetitions. The treatments were the implementation of Roundup Original, Trop, Roundup Ultra, Roundup WG, Roundup Transorb R and Zapp QI formulations, all at a dose of 720 g e.a. ha−1 of glyphosate and two controls (weeding and no weeding). There was no difference in the accumulation of macronutrients. In the second year of evaluation (2011/2012), manganese (Mn) accumulation was affected by the Trop formulations, Roundup Transorb, Zapp QI, Roundup Ultra, Roundup WG. To the accumulation of zinc (Zn), there was a reduction in the application of Trop formulations and Zapp QI. However, this reduction observed did not influence the response of plants in relation to the productive yield.

Dinâmica de plantas daninhas após aplicação de oxadiazon com simulação de lâminas d’água e incorporação de material orgânico - DOI:10.5039/agraria.v9i1a3679

Objetivou-se, neste trabalho, determinar o efeito do oxadiazon no comportamento da comunidade de plantas daninhas em diferentes momentos de aplicacao de lâminas d’agua e incorporacao de material orgânico. Utilizou-se o delineamento em blocos casualizados com tratamentos dispostos em esquema fatorial 5 x 2, com 4 repeticoes. Os tratamentos foram constituidos pela combinacao da incorporacao (8 t ha-1) ou nao de material orgânico no solo e do momento de aplicacao de lâminas d’agua (0; 10 mm antes; 10 mm depois e sequencial de 10 mm antes e depois da aplicacao do oxadiazon); alem da testemunha (0 mm e 0 g ha-1 de oxadiazon). Foram obtidas a densidade relativa, a frequencia relativa, a abundância relativa, o indice de valor de importância (IVI) e o indice de similaridade (IS) da flora de plantas daninhas. Nao houve interacao significativa entre o material orgânico e as lâminas d’agua. A especie Cyperus rotundus apresentou maior IVI, independente do tratamento avaliado, seguidas da Urochloa decumbens , Galinsoga parviflora , Bidens pilosa e Melampodium perfoliatum . A maior similaridade (IS = 0,75) foi observada entre o tratamento que recebeu a aplicacao de 10 mm de lâmina d’agua antes associado com o de 10 mm depois de aplicacao do oxadiazon.

Períodos de interferência de plantas daninhas na cultura do girassol

A interferencia de plantas daninhas na cultura do girassol pode reduzir significativamente a produtividade de aquenios. O objetivo deste trabalho foi determinar o Periodo Anterior a Interferencia e o Periodo Total de Prevencao a Interferencia da comunidade infestante sobre a produtividade de aquenios e de oleo da cultura do girassol. O experimento foi conduzido em campo, na area da Faculdade de Ciencias Agronomicas FCA/UNESP, na Fazenda Experimental Lageado, municipio de Botucatu (SP), no ano agricola de 2007/2008. O delineamento experimental foi o de blocos casualizados, com quatro repeticoes. Os tratamentos foram compostos por parcelas constituidas por periodos de controle e de presenca de plantas daninhas. Para os periodos de controle, a cultura foi mantida livre das plantas daninhas pelos periodos crescentes de 7, 14, 21, 28, 35, 42, 49 e 110 dias apos a emergencia do girassol. Para os periodos de convivencia, a cultura foi mantida na presenca da comunidade infestante pelos mesmos periodos. Foram avaliadas as seguintes variaveis: Diâmetro de capitulos, produtividade de aquenios, rendimento de oleo de girassol, densidade e materia seca das plantas daninhas e indices fitossociologicos. O periodo anterior a interferencia foi de 35 DAE da cultura para a produtividade de aquenios, sendo que o periodo total de prevencao a interferencia estendeu-se ate 24 DAE. Para o rendimento de oleo, o periodo anterior a interferencia foi de 25 DAE, enquanto que o periodo total de prevencao a interferencia prolongou-se por 14 DAE.