Dep. de Fitotecnia

Paraguaçu Paulista, Brazil

Dep. de Fitotecnia

Paraguaçu Paulista, Brazil
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Franca A.C.,Federal University of Vales do Jequitinhonha and Mucuri | Freitas M.A.M.,Federal University of Viçosa | Fialho C.M.T.,Federal University of Viçosa | Silva A.A.,Dep. de Fitotecnia | And 3 more authors.
Planta Daninha | Year: 2010

This study evaluated the effects of glyphosate on the growth of three arabica coffee cultivars. A factorial (3 × 5) was arranged in a randomized block design with four replications, with treatments consisting of three coffee varieties: Catucaí Amarelo (2 SL), Oeiras (MG-6851) and Topázio (MG-1190) and five glyphosate doses (0, 57.6, 115.2, 230.4 and 460.8 g ha-1). The herbicide was applied when the coffee plants reached 21 pairs of leaves, before reaching their upper third ones. At 45 and 120 days after glyphosate application (DAA), increase in leaf area, stem diameter, number of leaves and plagiotropic branches was evaluated, being initially measured on the day the herbicide was applied, and plant intoxication rate at 10, 45 and 120 DAA. Dry matter of leaves, roots and stem, and root length and density were measured at 120 DAA. Symptoms of coffee plant intoxication caused by glyphosate were similar in different cultivars, being characterized by chlorosis and leaf narrowing. Increase in the number of leaves, plagiotropic branches and stem diameter, regardless of the cultivar, was not affected by glyphosate. Cultivar Topázio was the most sensitive to glyphosate, in terms of accumulation of leaf area, root dry matter and root density.


Melo C.A.D.,DFT UFV | Medeiros W.N.,DFT UFV | Tuffi Santos L.D.,Federal University of Minas Gerais | Ferreira F.A.,Dep. de Fitotecnia | And 2 more authors.
Planta Daninha | Year: 2010

The aim of this study was to evaluate herbicide leaching in three soil profiles. Doses of 0.50 and 0.75 kg ha-1 sulfentrazone, 0.113 and 0.169 kg ha-1 isoxaflutole, and 0.72 and 1.08 kg ha-1 oxyfluorfen were applied on the surface of 30 cm high PVC columns filled with the three soil following types: one with a sandy loam texture and two clayey ones with low and high organic matter contents. After applying these herbicides, the columns were submitted to two rounds of 40 mm-simulated rain with a 24h interval between them. Herbicide leaching was detected by bioassay method using sorghum (Sorghum bicolor) plants. Both the activity and movement of the herbicide sulfentrazone in the soil profile increased after application of the highest dose. After application of 0.75 kg ha-1 of sulfentrazone, the highest downward movement was observed in the sandy loam soil, down to 27.5 cm, followed by the clayey soils with low and high organic matter contents, down to 25.0 and 17.5 cm, respectively. A high leaching potential was observed of isoxaflutole, which exceeded 22.5 cm in depth for the three soils and both doses studied. However, oxyfluorfen remained adsorbed in surface layers of soil only. When comparing the types of soil, the highest herbicide activity and movement occurred in the sandy loam soil. soxaflutole presented greater mobility than sulfentrazone, while oxyfluorfen showed low leaching potential.


Silva A.A.,Federal University of Viçosa | Lima C.F.,Dep. de Quimica | Queiroz M.E.L.R.,Dep. de Quimica | Franca A.C.,Federal University of Vales do Jequitinhonha and Mucuri | D'antonino L.,Dep. de Fitotecnia
Planta Daninha | Year: 2010

The objective of this study was to determine the half-life (t1/2) for the herbicide ametryn in Red-Yellow Latosol (LVA) and Red-Yellow Ultisol (PVA) with different pH values. Thus, plastic pots coated inside with plastic film were filled with 330 g of samples from the soils under study (LVA with pH values adjusted to 4.4, 4.9 and 5.8, and PVA pH 5.9), collected in degraded pastures without herbicide application. Ametryn was applied on these soil samples at a dose of 5.0 ha L-1. Twelve hours after application, the first soil samples were extracted from the pots to determine the concentration at zero time, and every five days new samples were removed from the other pots (two per time) to determine ametryn concentration over time. Ametryn extraction from the soil matrix was performed by Solid Liquid Extraction with Partition at Low Temperature (SLE-PLT) and quantified by liquid chromatography. A biological test for indirect determination of herbicide persistence was also carried out. Results indicated that ametryn half-life (t1/2) on the soils evaluated was 26, 19, 12 and 11 days in LVA soil pH 4.4; pH 4.9; pH 5.8 and PVA pH 5.9, respectively. Both methods (chromatography or bioassay) used to evaluate ametryn persistence in soils showed that degradation of this herbicide is strongly influenced by soil pH and organic matter content.


Viana R.G.,Federal University of Viçosa | Ferreira L.R.,Dep. de Fitotecnia | Ferreira M.C.,São Paulo State University | Teixeira M.M.,Federal University of Viçosa | And 3 more authors.
Planta Daninha | Year: 2010

This study aimed to evaluate the distribution profile and droplet spectra of low drift spray nozzles TTI110015, AI110015 and AI11001 under different operational conditions. The volumetric distribution was determined on a test table (patternator), by analyzing the coefficient of variation (CV) of a computer simulated spraying boom at pressures 200, 300 and 400 kPa, height of 30, 40 and 50 cm in relation to the patternator and nozzle spacing from 40 to 100 cm. Volumetric Median Diameter (VMD), span (A.R.) and percentage of droplets below 100 μm (% 100 μm) diameter, at pressures 200, 300 and 400 kPa were evaluated. Nozzles were adequate at pressure 200 kPa only for band application and at pressures 300 and 400 kPa only for total area application. Satisfactory CV (under 7%) was obtained, when highest pressure and lowest space between nozzles were applied. Droplet size (VMD) was reduced as pressure was increased. Nozzles TTI110015 and AI11015 at all pressures and nozzle AVI11001, at 200 kPa, presented extra coarse droplets and coarse droplets with AVI11001 at pressures 300 and 400 kPa. Nozzles AI and TTI presented more uniform droplet size at the highest pressure than nozzle AVI, considering the span value. Nozzles presented a low percentage of droplets below % 100 μm, especially nozzles TTI110015 and AI110015, with reduced drift risk.


Tavares S.S.,Federal University of Alagoas | Tavares S.S.,Federal University of Viçosa | Ramos-Sobrinho R.,Federal University of Viçosa | Gonzalez-Aguilera J.,Dep. de Fitotecnia | And 3 more authors.
Planta Daninha | Year: 2012

Begomoviruses are whitefly-transmitted, single-stranded DNA viruses that are often associated with weed plants. The aim of this study was to further characterize the diversity of begomoviruses infecting weeds (mostly Sida spp.) in Brazil. Total DNA was extracted from weed samples collected in Viçosa (Minas Gerais state) and in some municipalities of Alagoas state in 2009 and 2010. Viral genomes were amplified by RCA, cloned and sequenced. A total of 26 DNA-A clones were obtained. Sequence analysis indicated the presence of 10 begomoviruses. All viral isolates from Blainvillea rhomboidea belonged to the same species, Blainvillea yellow spot virus (BlYSV), thereby suggesting that BlYSV may be the only begomovirus present in this weed species. Four isolates represent new species, for which the following names are proposed: Sida yellow blotch virus (SiYBV), Sida yellow net virus (SiYNV), Sida mottle Alagoas virus (SiMoAV) and Sida yellow mosaic Alagoas virus (SiYMAV). Recombination events were detected among the SiYBV isolates and in the SiYNV isolate. These results constitute further evidence of the high species diversity of begomoviruses in Sida spp. However, the role of this weed species as a source of begomoviruses infecting crop plants remains to be determined.


Albuquerque J.A.A.,Dep. de Fitotecnia | Melo V.F.,Dep. de Solos e Engineering Agricola | Siqueira R.H.S.,UFRR | Martins S.A.,UFRR | And 3 more authors.
Planta Daninha | Year: 2012

The aim of this work was to identify the occurrence of weeds after five years of notillage corn cultivation in the Amazonian savannah. A phytosociological survey was conducted involving collection, identification, and quantification of the weeds, after corn harvest during June and July, 2010. The investigated properties included botanical classes, families, species, number of individuals, frequency, density, abundance, relative frequency, relative density, relative abundance, importance value index, propagation method, and life cycle. The emergent vegetation in the study area had 419 species, nine of which were identified as Dicotyledons, while six were identified as Monocotyledons. Species in the Ciperaceae family were the most abundant, while the families Poaceae, Ciperaceae, Asteraceae, Malvaceae, and Fabaceae exhibited the highest number of individuals and species frequency per plot. Only the Cordia curassavica shrubby growth habit was identified. Cyperus rotundus species showed the highest values in all the phytosociological parameters evaluated, with an importance index value 1.5 times higher than that of Brachiaria humidicola which had the second highest value (40.49).


Machado A.F.L.,Federal University of Tocantins | Ferreira L.R.,Dep. de Fitotecnia | Santos L.D.T.,Federal University of Minas Gerais | Ferreira F.A.,Dep. de Fitotecnia | And 3 more authors.
Planta Daninha | Year: 2010

The objective of this study was to assess the photosynthetic efficiency and water use by eucalyptus clones submitted to the herbicide glyphosate. The experiment was performed in a 4 x 5 factorial, with four eucalyptus clones (57, 386, 1203 and 1213), four doses of glyphosate (43.2, 86.2, 129.6 and 172.8 g ha -1) and a control without herbicide, considered zero dose, with four replications. At 7, 14, 21 and 28 days after herbicide application (DAA), plant intoxication was evaluated and at 7 and 21 DAA, stomatal gas flow (U- μmol s -1), photosynthetic activity (A-μmol m -2 s -1), stomatal conductance (Gs- mol m -1 s -1), transpiration (E- mol H2O m-2 s -1) and water use efficiency (WUE- mol CO 2 mol H 2O -1). At 50 DAA, the eucalyptus plants were collected and placed in a forced-ventilation oven at 70 °C until constant weight to determine dry mass. At 21 DAA, clone 1203 was found to be the most sensitive to the herbicide. There was no difference among the clones for the assessed physiological variables. At 21DAA, it was verified that increasing doses of glyphosate led to a reduction in stomatal conductance, stomatal gas flow rate, photosynthetic rate and water use efficiency. Plants of clones 1213 and 1203 showed a higher accumulation of dry mass. Increasing doses of glyphosate promoted less accumulation of dry mass in the eucalyptus plants. Glyphosate negatively affected growth, photosynthetic efficiency and water use of the evaluated clones.


Maciel C.D.G.,Dep. de Fitotecnia | Guerra N.,Academicos de Agronomia | Oliveira Neto A.M.,Academicos de Agronomia | Poletine J.P.,Dep. de Fitotecnia | And 2 more authors.
Planta Daninha | Year: 2010

This work aimed to evaluate static superficial tension, pH and foam production in glyphosate + chlorimuron-ethyl tank mixtures with or without adjuvants. The experiment consisted of two stages, with the first stage being arranged in a complete randomized design, with six treatments and 20 replications, represented by glyphosate (540.0 g a.e. ha -1) and chlorimuron-ethyl (7.5 g ha -1) solutions, isolated and in tank mixtures in the following formulations: Polaris™, Roundup Ready™, Classic™, Polaris™ + Classic™, Roundup Ready™ + Classic™ and check (water). The second stage was also arranged in a complete randomized design, with 70 treatments and 20 replications, in a 2 x 5 x 7 factorial scheme constituted by two mixtures of glyphosate with chlorimuron-ethyl (Polaris™ + Classic™ and Roundup Ready™ + Classic™), 5 adjuvants (Joint Oil™, Nimbus™, Assist™, Natur' Oil™ and Agr' Óleo™) and 7 adjuvant doses (0.000; 0.031; 0.062; 0.125; 0.250; 0.500 and 1.000% of v/v). Polaris™ and Roundup Ready™ solutions, isolated or in tank mixtures with Classic™, characterized by static superficial tensions of 43.2 and 35.9 mN m -1 and medium pHs, around 4.5 to 4.6, respectively. Polaris™ + Classic™, Roundup Ready™ + Classic™ and Classic™ solutions showed the highest foam quantity and persistence during the time, compared to Polaris™ and Roundup Ready™ mixtures. Adjuvants promoted reduction of static superficial tension when associated with Polaris™ + Classic™ and Roundup Ready™ + Classic™ mixtures, being characterized in efficiency by this decreasing order: Nimbus™ (36.5% and 25.8%) < Joint Oil™ (32.2% and 25.2%) < Agr' Oil™ (21.2% and 13.4%) < Natur' Oil™ (17.4% and 10.6%) < Assist™ (8.5% and 10.6%). Adjuvants promoted reduction of foam quantity and persistence in the Polaris™ + Classic™ and Roundup Ready™ + Classic™ mixtures, with small variations in the medium levels of pH of the solutions lower than 0.5.


Ferreira E.A.,Federal University of Vales do Jequitinhonha and Mucuri | Galon L.,Faculdade da Amazonia FAMA | Franca A.C.,Federal University of Vales do Jequitinhonha and Mucuri | Silva A.A.,DFT UFV | And 4 more authors.
Planta Daninha | Year: 2010

In the last years, the sugarcane harvesting process has undergone changes imposed by law, environmental awareness or social pressure, leading to the exclusion of the traditional slash and burn before harvesting and inclusion of crude sugarcane harvest. This process is denominated crude harvesting. The adoption of this new harvesting system promoted alterations in the entire sugarcane tillage system, including wider row spacing and the formation of a mulching layer due to the deposition of sugarcane residues on the soil surface. This new crop management system affects directly the weed dynamics in these areas and soil fertility as well. Weed shifting has been observed, producing weed species with higher germination and emergence capacity under a thicker straw layer, compared to those unable to germinate due to the physical or allellopathic action of the straw. In addition, pre-emergence herbicides are usually less efficient under this system due to their retention in the straw, not reaching the soil in sufficient concentrations to promote weed control. In this literature review, the major results involving weed management in crude sugarcane areas are described to provide information to researchers, extension workers, and farmers on how to improve sugarcane integrated weed management, mainly under this new harvesting process. The results show that reduction of herbicide dependence is feasible, leading to improved soil quality in these fields.


Maciel C.D.G.,Dep. de Fitotecnia | Poletine J.P.,Dep. de Fitotecnia | Oliveira Neto A.M.,ESAPP FUNGE | Guerra N.,ESAPP FUNGE | Justiniano W.,ESAPP FUNGE
Planta Daninha | Year: 2010

A phytosociological assessment was carried out to identify weed communities occurring on the sidewalks of Paraguacu Paulista-SP, considering three possible types of weed infestation on sidewalks. Weeds were identified and quantified in all the main neighborhoods of this municipal district, being subdivided into 180 sampling points in strips positioned on the curb line of the sidewalk, the center of the sidewalk and the edge of the wall. Eleven families and 21 species were identified with the Poaceae, Asteraceae, Euphorbiaceae and Amaranthaceae families registering the highest numbers and frequencies of species in the three side walk positions. The highest importance value indices (IVI) for the species identified in the curb lineand center of the sidewalk were: Eragrotis pilosa (50.3 and 56.6), Chamaesyce prostrata (48.2 and 57.6) and Chamaesyce hirta (30.3 and 36.4); for the edge of the wall, the highest IVI were: C. prostrata (60.6), Phyllanthus tenellus (44.3) and C. hirta (36.2).

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