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de Assis H.L.B.,São Paulo State University | Cesarin A.E.,São Paulo State University | Nepomuceno M.P.,São Paulo State University | Salgado T.P.,Herbae Consultoria e Projetos Agricolas Ltda | Alves P.L.C.A.,São Paulo State University
Cerne | Year: 2015

Eucalyptus plantations in Brazil expanded to the Midwest region of the country in areas previously occupied by pastures, especially of Brachiaria decumbens (signal grass), making it the main weed in eucalyptus plantation. This work aimed to evaluate the efficiency of haloxyfop-P-methyl to control B. decumbens infesting eucalyptus seedlings. This experiment was set up in three situations: monoculture eucalyptus, eucalyptus in coexistence with B. decumbens and the weed cultivated alone. Haloxyfop-p-methyl was applied 67 days after plating the seedlings at doses of 0; 48 and 96 g.i.a.ha-1. Only the highest dose (96 g.i.a.ha-1) of haloxyfop-p-methyl provided good weed control. The herbicide, at the tested doses, was selective for eucalyptus and the relationship between eucalyptus and B. decumbens resulted in negative interference for both species. © 2015, Federal University of Lavras. All rights reserved.

De Souza M.C.,São Paulo State University | Da Costa Aguiar Alves P.L.,São Paulo State University | Salgado T.P.,Herbae Consultoria e Projetos Agricolas Ltda.
Scientia Forestalis/Forest Sciences | Year: 2010

Currently Brazil is one of the leading paper and pulp producers in the world market, where Sao Paulo State boasts the greatest production. Because of the pulp prices falling in the world market and the low costs of a second coppice rotation, two experiments (started May and December, 2000) were conducted to evaluate the effects of weeds and of weed-free periods (0, 3, 6, 9, 12, 15 and 18 months) on the growth of Eucalyptus grandis second coppice plants. The field trials were set up in a randomized block design with four replicates and the experimental plots consisted of three rows of fve plants. The December weed community was composed mainly of Brachiaria decumbens (Surinam grass) and Panicum maximum (Guinea grass) and the May weed community was composed mainly by B. decumbens and Digitaria insularis (Sour-grass). Weeds had a low negative influence on growth, diameter development and macronutrients content of E. grandis second coppice plants. In both experiments, slight reductions in growth were observed only between the fully weeded and weed-free periods, after 18 months.

Salgado T.P.,Herbae Consultoria e Projetos Agricolas Ltda | Alves P.L.C.A.,São Paulo State University | Kuva M.A.,Herbae Consultoria e Projetos Agricolas Ltda | Takahashi E.N.,Fibria Celulose e Papel | And 2 more authors.
Planta Daninha | Year: 2011

This work was carried out to evaluate intoxication symptoms caused by glyphosate application. It was constituted by four assays with glyphosate applications (360 g a.e. L-1) on eucalyptus. In all assays, seedlings were transplanted into 5.OL plastic pots. In assays 1 and 2, increasing herbicide volumes were applied on the stem. In the first one, a glyphosate solution of 3% (v/v) was applied at the volumes 0, 1, 5, 10, 20, 40, 80 and 160 μL solution per plant, and in the second, glyphosate solution of 2% (v/v) was applied at volumes 0, 1, 5, 15, 30, 60, 90, 120 and 150 μL solution per plant. In assays 3 and 4, glyphosate was sprayed on the plants. The rates in the third assay were: 0, 7.2 10-7, 7.2 10-6, 7.2 10-5, 7.2 10-4, 7.2 10-3, 7.2 10-2, 7.2 10-1, 7.2, 72, 360 and 720 g a.e. of glyphosate ha 1, and in the fourth assay, the rates were: 0, 9, 18, 36, 72, 144, 288, 432, 576, 720, 1.080, 1.440 and 2.160 g a.e. of glyphosate ha-1. All assays were arranged in a randomized design, with three replications. Height, leaf area, and dry mass of the leaves and stem were evaluated in the plants and the results were submitted to regression analysis. When applied on the stem, doses of 40.78 and 51.41 μL per plant of glyphosate solution, 3 and 2% (v/v), respectively, were sufficient to reduce eucalyptus development in 50%. When applied on the plants, more developed plants showed greater sensitivity.Rates of 277.4 and 143.3 g a.e. ha-1 reduced eucalyptus growth in 50%, in assays 3 and 4, respectively.

Ferreira R.V.,São Paulo State University | Contato E.D.,Herbae Consultoria e Projetos Agricolas Ltda | Kuva M.A.,Herbae Consultoria e Projetos Agricolas Ltda | Ferraudo A.S.,São Paulo State University | And 3 more authors.
Planta Daninha | Year: 2011

The aim of this study was to evaluate the possibility of grouping stands of sugarcane harvested mechanically, and without previous straw burning in the region of Ribeirão Preto-SP, according to the potential of weed infestation. Clustering analysis and other multivariate analysis techniques were applied, using as variable the relative rate of infestation assigned by visual assessments, in two phases: in the first, twenty sugarcane plots with an 18-month cycle were selected. These areas were used to compare two methods to estimate the specific composition of the weeds, namely, a phytosociological analysis, described by Mueller-Dombois & Ellenberg (1974) and an analysis of the visual percentage of general coverage (GC) and specific coverage (SC). In the second phase, the specific composition of the weed community was evaluated in 189 plots in areas of ratoon sugarcane harvested in 2008, attributing to these plots only GC and SC. Based on the information obtained on the weed community, a database was built, and subjected to exploratory analysis of multivariate statistical techniques. For the main species within the stands (DIGNU, ARACH, IPOHF, MRRCI and IPOQU, followed by CYPRO, ELEIN and EPHHS), 75% of coinciding results were verified between the two methods. It was found that the visual assessments of species coverage percentage may substitute, for purposes of convenience, flexibility and applicability, the phytosociological evaluations, as these assessments provided good detection capability of the main weeds in each stand. The techniques of multivariate statistics showed that the plots can be grouped according to similarities in infestation intensity and species composition.

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