César Tiago Forte

Manejo de plantas daninhas em milho RR® com herbicidas aplicados isoladamente ou associados ao glyphosate

Objetivou-se com este trabalho avaliar a eficacia e a seletividade de herbicidas aplicados isoladamente ou em mistura de tanque na cultura do milho RR®. O delineamento experimental utilizado foi de blocos casualizados com quatro repeticoes. Os tratamentos avaliados foram: testemunha infestada, testemunha capinada, glyphosate, glyphosate + [atrazine + simazine], glyphosate + [atrazine + simazine], glyphosate + tembotrione, glyphosate + mesotrione, glyphosate + nicosulfuron, glyphosate + 2,4-D, glyphosate + [atrazine + S-metolachlor], glyphosate + [atrazine + S-metolachlor], glyphosate + S-metolachlor, glufosinate ammonium, [nicosulfuron + mesotrione], glyphosate + [nicosulfuron + mesotrione] e glyphosate + [nicosulfuron + mesotrione] + [atrazine + simazine]. A fitotoxicidade ocasionada pelos herbicidas ao hibrido de milho SYN Supremo VIP3 e o controle de Urochloa plantaginea e de Digitaria ciliaris foram avaliados aos 7, 14, 21 e 28 dias apos a aplicacao dos tratamentos. Na pre-colheita da cultura, determinou-se o controle das plantas daninhas e, em dez plantas por unidade experimental, foram analisadas as variaveis relacionadas aos componentes de rendimento de graos, como altura de insercao da espiga, comprimento da espiga, o numero de fileiras e de graos por fileiras e por espigas de milho. Na colheita do milho, avaliou-se a massa de mil graos e a produtividade de graos. Observou-se que todos os tratamentos herbicidas ocasionaram baixa fitotoxicidade ao milho, exceto a mistura em tanque aplicada em pos-emergencia composta por glyphosate + 2,4-D e glyphosate + mesotrione, que demonstraram as maiores injurias nas quatro epocas avaliadas. A maioria dos herbicidas mostrou bom controle de D. ciliaris e U. plantaginea, com excecao da mistura de glyphosate + 2,4-D na pre-colheita. A mistura em tanque de glyphosate + [atrazine + simazine] aplicada em pos-emergencia demonstrou a maior produtividade de graos. Conclui-se que, dependendo da associacao de herbicidas, ocorre efeito sinergico tanto para o controle das plantas daninhas como para a fitotoxicidade da cultura, sendo a produtividade de graos a principal variavel influenciada.

Simulated drift of herbicides applied alone and in tank mix in grapevine

1 Professor from the Federal University of Fronteira Sul, Chapecó, SC, Brazil. 2 Professor from the Federal University of Fronteira Sul, Erechim, RS, Brazil. 3 Undergraduate student in Agronomy from the Federal University of Pampa, Itaqui, RS, Brazil. 4 PhD student in Agronomy from the Federal University of Santa Maria, Santa Maria, RS, Brazil. *Author for correspondence: leandro.galon@uffs.edu.br.

Effect of herbicides in the oxidative stress in crop winter species

Most herbicides applied in crop field, stay in the soil for a period, affecting next crop or even the plants using as green manure. Nowadays, the use of herbicides grow to increase productivity, mainly in the grain producing region north of Rio Grande do Sul state. The objective of this study was to evaluate the effects of herbicides fomesafen and sulfentrazone on antioxidant system in Avena sativa1, Vicia sativa2, Raphanus sativus and Lupinus albus. The plants were exposed to varying concentrations of fomesafen3 (0, 0.125, 0.25 and 0.5 kg ha -1) and sulfentrazone (0, 0.3, 0.6 and 1.2 kg ha-1). For this, the activities of, ascorbat peroxidase, catalase and guaiacol enzymes were analyzed, and the levels of MDA were quantificated. Fomesafen and sulfentrazone promoted alterations in balance of plants generating oxidative stress and elicited the response of the antioxidant system of plants, mainly in the high doses of fomesafen, for the species V. sativa and R. sativus. At the same time, the 1,2 kg ha -1 dose of sulfentrazone generated lipid peroxidation for V. sativa, R. sativus and L. albus. Additionally, A. sativa was the species that demonstrated low alterations on antioxidant system with the exposure to herbicide fomesafen and sulfentrazone. Thus, we can we can suggest that the species present a better response in defense of the oxidative stress generated by the herbicides.

Weed Interference in the Morphophysiological and Nutritional Characteristics of Erva-Mate ( Ilex paraguariensis )

The erva-mate (Ilex paraguariensis) represents an alternative crop for agricultural exploitation in South Brazilian farms with potential to export the harvested product. However, there is scarce information about the interference caused by weeds on this crop. The objective of this work was to evaluate the interference of weed species on the morphophysiological and nutritional characteristics of erva-mate. The experiment was installed in greenhouse at the Federal University of Fronteira Sul (UFFS), Campus Erechim/RS, Brazil, in randomized blocks design, arranged in a 4 × 6 factorial scheme, with four replications. In factor A, weed species (Urochloa plantaginea—Alexandergrass, Bidens pilosa—Hairy beggarticks, Ipomoea indivisa—Morning glory and Conyza bonariensis—Hairy fleabane) were allocated, and in B the populations of these species competing with the erva-mate (0, 1, 2, 3, 4 and 5 plants per pot) were considered. The variables evaluated in erva-mate were sub-stomatal CO2 concentration, photosynthetic rate, CO2 consumed, stomatal conductance, transpiration rate, water use efficiency, height, stem diameter, leaf area and shoot dry mass. Concentrations of nitrogen (N), phosphorus (P), calcium (Ca) and magnesium (Mg) were also evaluated. Overall, all weed species and densities among the tested ones harmed the development of erva-mate plants, which was considered as low competitive with weeds.

Effectiveness of different fungicide formulations and number of applications in controlling wheat leaf rust

Mestrando no programa de Pós Graduação em Fitopatologia da Universidade Federal de Viçosa. Viçosa, MG, Brasil; Doutorando no programa de Pós Graduação em Agronomia da Universidade Federal de Santa Maria. Santa Maria, RS, Brasil; Bacharel em Agronomia, Erechim, RS, Brasil; Doutorando no programa de Pós Graduação em Fitotecnia da Universidade Federal do Rio Grande do Sul. Porto Alegre, RS, Brasil; Professora Adjunta de Fitopatologia da Universidade Federal da Fronteira Sul, Erechim, RS, Brasil. Autor para correspondência: Jhonatan Paulo Barro ( jhonatanbarro@gmail.com) Data de chegada: 14/01/2017. Aceito para publicação em: 18/04/2017. 10.1590/0100-5405/174240

HABILIDADE COMPETITIVA DE CULTIVARES DE FEIJÃO COM PICÃO-PRETO

Weed interference is a factor that limits the productivity of beans and, among these, hairy beggarticks is one of the main species competing with the crop for environmental resources. Thus, the aim of this study is to evaluate the competitive ability of black bean cultivars (BRS Campeiro, IPR Uirapuru, SCS204 Predileto and BRS Supremo) in the presence of a biotype of hairy beggarticks. The experimental design is a completely randomized block with four replications. Treatments were arranged in a replacement series, consisting of a proportion of the crop and the hairy beggarticks: 100:0; 75:25; 50:50: 24:75, and 0:100, which corresponds to 40:0, 30:10, 20:20, 10:30, and 0:40 plant pots. We accomplished competitive analysis through diagrams applied to the replacement series, as well as using relative competitive indices. The leaf area and shoot dry mass were evaluated at 40 days after emergence of the species. There was competition between bean cultivars and hairy beggarticks for the same environmental resources, causing negative interference in the growth of the species, independent of the proportion of plants. Bean cultivars had a lower relative loss by reducing the morphological variables of the hairy beggarticks, thereby demonstrating superiority in its competitive ability in relation to the weed. Interspecific competition is less damaging than intraspecific competition for both species.

Fitorremediação de solo contaminado com herbicidas inibidores de FSII e de ALS

Alternative to decontaminate the soil is the phytoremediation practice. In this way, this study aimed to evaluate the phytoremediation potential of the following species: vetch, radish, cereal rye, black soybean and coloniao grass, grown in a soil contaminated with atrazine and chlorimuron ethyl + sulfometuron-methyl. The herbicides were applied in pre-emergence of the species. Two experiments were installed, the first one tested the phytoremediation potential of the species and the second one used the cucumber as bioindicator culture to prove if the soil had been depolluted. The variables evaluated at 40 days after emergence (DAE) were: phytotoxicity (%), height (cm) and dry mass of the aerial part of the plants (g). There is a great variation in the selectivity of the cultures to the two herbicides, and the chlorimuron-ethyl + sulfometuron-methyl mixture presented the highest phytotoxicity symptoms, both for the phytoremediation species and for the bioindicator culture. The results allowed to conclude that the management the black soybean presented a greater potential of phytoremediation of soil contaminated with chlorimuron-ethyl + sulfometuron-methyl and that the colonium grass was the species that demonstrated satisfactory potential as phytoremediation plant of contaminated soil with atrazine.

Habilidade competitiva de cultivares de soja transgênica convivendo com plantas daninhas

The aim of this work was to determine the competitive ability of soybean cultivars in the presence of cobbler’s pegs and wild poinsettia in association in di...

Fitotoxicidade de clomazone associado com dietholate à cultura do trigo

Nowadays it has become important to test new alternatives herbicide molecules, even if they are not registered for the control of weeds that infest wheat, to evaluate the phytotoxicity to culture and the ability to manage resistant weeds to the products used for this purpose. Thus, an experiment was conducted to evaluate the Phytotoxicity of clomazone associated or not to the dietholate safener applied on wheat. The experiment was conducted in a completely randomized design, arranged in a factorial scheme (5 x 4) + 2 + 2, with four replications. In the factor allocated to dietholate doses (0, 120, 240, 360 and 480 g per 100 kg of seed) and the B clomazone doses (0, 198, 396 and 594 g ha -1 ). Additional Treatments were the control treatments infested and without the application of herbicide, and the application in post-emergence of iodosulfuron-methyl (5 g ha -1 ) and pyroxsulam (18 g ha -1 ). The increase in clomazone doses caused increased phytotoxicity to wheat, with or without the safener . The dietholate showed no ability to protect the wheat from the phytotoxic effects of the herbicide clomazone. The use of clomazone associated with dietholate for weed control on wheat is not recommended. The pyroxsulam was the herbicide that caused minor injuries to wheat.