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Santos G.,Agronomia na area de Protecao de Plantas | Francischini A.C.,Agronomia na area de Protecao de Plantas | Constantin J.,State University of Maringa | Oliveira Jr. R.S.,State University of Maringa | And 3 more authors.
Planta Daninha | Year: 2012

The occurrence of dicotyledonous weeds has limited the increase of the area of sunflower cultivation in Brazil, due to their impact on crop yield. This is a result of a shortage of products registered for the crop with broad-spectrum control. Thus, two experiments were installed to evaluate the efficacy and selectivity of the imidazolinone herbicides applied on post-emergence dicotyledonous weeds in Clearfield® sunflower crop. The experiments were conducted under field conditions at the district of Iguatemi, Maringá-PR, Brazil. Treatments consisted of two controls without herbicide application, one with weeds and the other weed-free, with sulfentrazone (200,00 g ha-1) applied preemergence and imazapic + imazapyr applied post emergence, at doses of [36.75 +12.25] [52.5 +17.5], [12.25 +36.75] [17.5 +52.5] g ha-1. The control of Euphorbia heterophylla, Conyza bonariensis, Raphanus raphanistrum, Bidens pilosa, Ipomoea grandifolia and Portulaca oleracea was evaluated. Evaluation of toxicity of the Clearfield sunflower® was also carried out, besides crop stand and yield in kg ha-1. Based on the results, it was concluded that the use of the Clearfield® system proved to be a very good option for areas with dicotyledonous weeds, allowing the application of ALS-inhibiting herbicides. In addition, the weed controls obtained ranged from fair to excellent, causing no injuries to the crop and maintaining the initial plant stand and yield. Source

Raw sugarcane harvest promotes an increase in crop residues of mulch on the soil. This new component changes the dynamics of weed infestation, also acting as a physical and chemical barrier against the action of herbicides. To improve the quality of herbicide deposition on the soil, this study aimed to evaluate the efficiency of spray nozzles and their transposition capacity on sugarcane straw. The experiment was conducted in Maringá-PR, in a completely randomized design, using a factorial scheme 8 x 7, with 8 nozzles (AD 110 02, ADIA 110 02, TT 110 02, TTIA 110 02, CV IA 02, MAG 2, ST 02 and TJ60 110) and 7 increasing amounts of straw (0, 1, 2, 4, 6, 8 and 10 t ha 1). It was observed that large quantities of straw reduce the amount of liquid sprayed and deposited on the collecting surface. The spray nozzles anti-drift fan model (AD 110 02) and empty cone with air induction (CV-IA 02) were the most efficient. Source

Ramires A.C.,Cooperativa Agroindustrial no Municipio de Floresta COCAMAR | Constantin J.,State University of Maringa | Oliveira Jr. R.S.,NAPD UEM | Guerra N.,NAPD UEM | And 2 more authors.
Planta Daninha | Year: 2010

Mixtures of broadleaf herbicides and glyphosate have been adopted during postemergence weed control in RR® soybeans mainly to improve the efficacy of this herbicide when applied on tolerant weeds, to provide residual weed control or to prevent the selection of resistant biotypes. This work aimed to evaluate the efficacy of glyphosate alone or in tank mixtures with other broadleaf herbicides to control Euphorbia heterophylla and Ipomoea grandifolia, at two growth stages (1-to-3 leaves and 4-to-6 leaves). Thus, four greenhouse assays were carried out: glyphosate (480 and 960 g a.e. ha-1) applied alone or combined in tank mixtures with chloransulammethyl (30.24 g ha-1), chlorimuron-ethyl (12.5 g ha-1), imazethapyr (80 g ha-1), fomesafen (62.5 g ha-1), lactofen (72.0 g ha -1), flumiclorac-pentyl (30.0 g ha-1) and bentazon (480 g ha-1). All experiments were arranged in a randomized block design, with four replicates. For both weeds, the use of 960 g ha-1 of glyphosate alone was sufficient, when application was performed at 1-3 leaf stage. For applications performed at 4-6 leaf stage for E. heterophylla, increased weed control in relation to glyphosate applied alone can be achieved by using mixtures with protox inhibitors. In relation to I. grandifolia at the 4 6 leaf stage, fomesafen and flumiclorac-penthyl decreased weed control when added to glyphosate at 480 g a.e. h-1. On the other hand, mixtures containing glyphosate at 960 g a.e. ha-1 provided increased weed control. In general, control of E. heterophylla and I. grandifolia was improved when herbicide treatments were applied at 1-3 leaf stage, either using glyphosate alone or mixed with other broadleaf herbicides. Source

Alonso D.G.,State University of Maringa | Constantin J.,Dep. de Agronomia | Oliveira Jr. R.S.,Dep. de Agronomia | Arantes J.G.Z.,State University of Maringa | And 4 more authors.
Planta Daninha | Year: 2011

An active ingredients mixture of different action mechanisms is an essential tool to prevent or manage areas with resistant weeds. However, it is important that such a mixture provides adequate selectivity to the crop. The aim of this work was to evaluate glyphosate selectivity to glyphosate-resistant (RR) soybean, and also verify if there is selectivity in mixtures with other active ingredients applied postemergence aimed at new control strategies, which might be used in RR soybean cultivation. The herbicides and respective rates (g ha-1) evaluated were: glyphosate (720, 960, 1,200, and 1,440), and the mixtures of glyphosate (960) with cloransulam-methyl (30.24), fomesafen (125), lactofen (72), chlorimuron-ethyl (12.5), flumiclorac-pentyl (30), bentazon (480), or imazethapyr (80). All treatments were applied in postemergence when the soybean crop was at V2 to V3 stage. Treatments with glyphosate or in mixtures with postemergent herbicides showed visual effects of phytotoxicity when applied to the glyphosate-resistant soybean. Effects such as reduction in plant height, crop closure, number of pods per plant, and hundred grain weight could be observed. However, the effects related to plant development were mostly transient and did not persist during the crop cycle. Among the studied treatments, only the mixture of glyphosate and lactofen was not selective to the crop, promoting negative effects on most characteristics analyzed and consequently reducing grain yield. Source

Guerra N.,NAPD UEM | Oliveira Jr. R.S.,State University of Maringa | Constantin J.,State University of Maringa | Oliveira Neto A.M.,NAPD UEM | And 2 more authors.
Planta Daninha | Year: 2011

In Brazil, most of the areas planted with cotton are located in the cerrado regions of Mato Grosso and Bahia, in naturally acidic soil. The objective of this work was to study the influence of soil acidity on the persistence of trifloxysulfuron-sodium and pyrithiobac-sodium, using a bioindicator as detection technique. Four experiments were conducted simultaneously: two with trifloxysulfuron-sodium (7.5 and 15 g ha -1), and two with pyrithiobac-sodium (70 and 140 g ha -1), using a completely randomized design with four replications in a factorial scheme (3x8+3). Treatments were composed by three types of soil (at pH levels 4.2, 4.9 and 5.5), eight sowing dates for the bio-indicator (0, 30, 60, 90, 120, 150, 180, and 210 DAA), and three control treatments, without herbicide application. The persistence of trifloxysulfuron-sodium at doses of 7.5 g ha -1 was not influenced by the pH values. However, at a dose of 15 g ha -1 the highest increase in the persistence of biological activity was observed in soil with higher pH. When pyrithiobac-sodium was applied to the soil with lower pH, at doses of 70 and 140 g ha -1, a longer time period was needed for persistence to reduce. But at 210 DAS there were no differences in the persistence of pyrithiobac-sodium (70 g ha -1) between the different pH values. However, at the dose of 140 g ha -1 of pyrithiobac-sodium, the soil with the highest pH showed the highest persistence of this herbicide. Source

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