L.L. Foloni

Glyphosate sustainability in South American cropping systems

South America represents about 12% of the global land area, and Brazil roughly corresponds to 47% of that. The major sustainable agricultural system in South America is based on a no-tillage cropping system, which is a worldwide adopted agricultural conservation system. Societal benefits of conservation systems in agriculture include greater use of conservation tillage, which reduces soil erosion and associated loading of pesticides, nutrients and sediments into the environment. However, overreliance on glyphosate and simpler cropping systems has resulted in the selection of tolerant weed species through weed shifts (WSs) and evolution of herbicide-resistant weed (HRW) biotypes to glyphosate. It is a challenge in South America to design herbicide- and non-herbicide-based strategies that effectively delay and/or manage evolution of HRWs and WSs to weeds tolerant to glyphosate in cropping systems based on recurrent glyphosate application, such as those used with glyphosate-resistant soybeans. The objectives of this paper are (i) to provide an overview of some factors that influence WSs and HRWs to glyphosate in South America, especially in Brazil, Argentina and Paraguay soybean cropped areas; (ii) to discuss the viability of using crop rotation and/or cover crops that might be integrated with forage crops in an economically and environmentally sustainable system; and (iii) to summarize the results of a survey of the perceptions of Brazilian farmers to problems with WSs and HRWs to glyphosate, and the level of adoption of good agricultural practices in order to prevent or manage it.

Controle químico do aguapé (Eichhornia crassipes)

Six assays were carried out under greenhouse conditions to study the efficacy of diquat, glyphosate, sulfosate, imazapyr, 2,4-D, metsulfuron-methyl, sulfentrazone and imazapic in controlling Eichhornia crassipes (Mart.) Solms. The same CO2 pressurized sprayer was used in all assays. Diquat , glyphosate , imazapyr and sulfentrazone were studied in the first assay. Diquat and glyphosate were highly efficient in controlling E. crassipes. The symptoms developed faster in diquat-treated plants. The symptoms promoted by imazapyr and sulfentrazone were progressive all over the experimental period, suggesting that higher control intensity could be achieved obtained during a longer observation time. Waterhyacinth control was studied in the second assay, using diquat, glyphosate, imazapyr, imazapic, 2,4-D, metsulfuron-methyl, and sulphosate. Diquat, glyphosate, imazapyr and 2,4-D showed good control of waterhyacinth The control promoted by diquat and 2,4-D showed quick results. Imazapyr showed slow control action. Under the experimental conditions, imazapic, sulfosate and metsulfuron-methyl did not show good control of this aquatic weed. Waterhyacinth control promoted by imazapyr and glyphosate sprayed at 3, 6, and 9 hours before simulated rain were studied. Glyphosate was more efficient in controlling E. crassipes than imazapyr. For glyphosate, the interval between spraying and rain did not affect the final control (thirty days after spraying), but the development of the symptom was faster at higher doses. In the fourth assay, waterhyacinth control was studied using diquat sprayed during the day or at night. The herbicide was efficient in controlling waterhyacinth at 1,0 L ha-1 or higher. Night spraying showed faster symptoms than day-spraying, but the symptons were similar in the final control. In the fifth assay, diquats waterhyacinth control efficacy was studied. It was sprayed during the day or night, at intervals of 30, 60 and 120 minutes between spraying and simulated rain. Diquat was very efficient in controlling waterhyacinth, mainly at 2,00 L ha-1. Herbicide action was stronger during night spraying when broader intervals occurred between spraying and the first rain. A last assay was carried out under field conditions, to study waterhyacinth control by imazapyr sprayed on E. crassipes grown in small ponds. All the doses promoted a good waterhyacinth control. The effects were faster at higher doses.

Distribution of environmental compartments of herbicides used in the cotton, coffee and citrus cultures

The aim of this paper was to evaluate the environmental fate of herbicides (acetochlor, 2,4-D, diuron, clomazone, thidiazuron, paraquat, simazine, fluazifo-p-butil, clethodim, oxufluorfen, flumioxazin, carfentrazone-ethyl, ametrina, trifluralin and MSMA) in cotton, coffee and citrus cultivation areas, applying the level I fugacity model. The methodology basically used the chemical and physical characteristics of the pesticides, environmental compartments and the fugacity equations. The preliminary evaluation of risk of contamination due to the use of these pesticides on the cultures studied was carried out swiftly, based on the chemical and physical properties of these products as the level I fugacity model was applied. For most of the herbicides evaluated, the water compartment was the most vulnerable. The prediction evaluation study using fugacity level I was found to be a relevant tool for the environmental fate of the herbicides studied for cotton, coffee and citrus cultures.

Metodologia para avaliação de impacto ambiental de macrófitas em mesocosmos

This experiment aimed to analyze the methodology applied to evaluate the environmental impact caused by the use of herbicide to control macrophytes. The design and construction of the tanks are described in detail as well as the insertion of blades for periphyton and sediment sampling to evaluate the bentonic comunities. The flow-through method was used and several parameters of water quality were measured and residues detected in the water colunm and sediment. The flow-through methodology was chosen to create a situation closer to reality so that the results obtained could more precisely reflect the likely risks caused by chemical control of macrophytes. Some adjustments need to be made in this methodology for a better characterization of the effluents and calibration of the system.

Alteração física e morfológica em solos cultivados com citros e cana-de-açúcar, sob sistema tradicional de manejo

The continuos use of the soil interferes in its intrinsic characteristics, which changes according to the use and management applied. This present study evaluates some pedologic alterations, resulting from traditional soil management system, in citrus (Citrus sinensis) and sugar cane (Saccharum officinarum) fields subjected to extended planting cycles for a long period. Field and laboratory observations were undertaken in vertical profiles of the Red Latosol in Bariri County, State of Sao Paulo when morphological descriptions and laboratory analyses (particle size distribution, porosity, bulk density, organic matter, water infiltration rates and micromorphology) were established with some parameters evaluated by means of measure comparisons. The results obtained revealed that the intensive cultivation practices promoted significant soil structure alterations, with difficulty to root growth in both cases. In sugar cane fields, the intensive management promoted great soil structure alterations even in the deeper layers with changing in the voids geometry, which cause planar voids and fissures. In citrus cultivation, the deeper root systems and reduced soil mobility worked together for a greater aggregate stability, promoting adequate root development compared to the sugar cane.

Comportamento do herbicida tebuthiuron em solo de cultivo de cana-de-açucar utilizando lisimetro de drenagem modificado

RESUMO - O tebuthiuron e um dos herbicidas mais usados no plantio de cana-de-acucar,no Estado de Sao Paulo. Estudos tem sido realizados para determinar o indice de lixiviacaodo tebuthiuron e monitorar sua presenca nos mananciais de aguas superficiais esubterrâneas, ainda sem uma conclusao definitiva. Com o objetivo de avaliar, em condicoesde campo, a movimentacao vertical do herbicida tebuthiuron em Latossolo Vermelhodistroferrico de textura argilosa, testou-se, em ambiente controlado, a hipotese de que otebuthiuron apresenta baixa mobilidade vertical e pequeno potencial de contaminacao deaguas subterrâneas. O trabalho foi conduzido no Campo Experimental da Faculdade deEngenharia Agricola da Unicamp, utilizando-se lisimetro de drenagem modificado de 2 m dediâmetro e 3 m de profundidade, com dez pontos verticais, por meio dos quais foram coletadasamostras de agua da chuva. As amostras foram submetidas a Analise Cromatografica Liquidade Alta Eficiencia. Os dados obtidos indicaram presenca decrescente do herbicida nasamostras coletadas no periodo de marco a agosto de 2006: amostra 1 – 0,020 g i.a. (5,3%); 2– 0,016 g i.a. (4,3%); 3 – 0,015 g i.a. (4,0%); 4 – 0,014 g i.a. (3,7%); 5 – 0,014 g i.a. (3,7%); 6 –0,007 g i.a. (1,9%); 7 – 0,002 g i.a. (0,5%); e 8 – 0,001 g i.a. (0,3%) do total aplicado na areado lisimetro (0,3768 g i.a.), confirmando a hipotese de baixa mobilidade vertical dotebuthiuron em Latossolo Vermelho distroferrico de textura argilosa, indicando, para essesolo, pequeno potencial de contaminacao das aguas subterrâneas.Palavras-chave: herbicida, lixiviacao, movimentacao vertical, aguas subterrâneas.ABSTRACT - Tebuthiuron is one of herbicides most used on sugar cane in the state of Sao Paulo.Studies have been carried out to determine tebuthiuron leaching index and to monitor its presencein surface and groundwater sources, with no definitive conclusion been reached yet. The aim ofthis research was to evaluate the vertical movement of tebuthiuron under field conditions on ClayeyDystroferric Red Soil. The tested hypothesis was based on the low vertical mobility and smallpotential of groundwater contamination by tebuthiuron. The trial was carried out at the ExperimentalField College of Agricultural Engineering – UNICAMP, using a modified drainage lysimeter, 2 metersof diameter and 3 meters depth, with 10 vertical points where rain water samples were collected.The samples were submitted by High Performance Liquid Chromatography (HPLC).The data foundindicated a decreasing presence of the herbicide in the samples collected through time – March toAugust, 2006: sample 1 – 0. 020 g a.i. (5.3%); 2 – 0.016 g a.i. (4.3%); 3 – 0.015 g a.i. (4.0%); 4– 0.014 g a.i. (3.7%); 5 – 0.014 g a.i. (3.7%); 6 – 0.007 g a.i. (1.9%); 7 – 0.002 g a.i. (0.5%); 8– 0.001 g a.i. (0.3%) – total applied in the lysimeter area (0. 3768 g i.a.), confirming the hypothesisthat tebuthiuron vertical mobility is low in Clayey Dystroferric Red Soil, with clayey texture,indicating small potential of groundwater contamination on this soil.Keywords: herbicide, leaching, vertical mobility, groundwater.

Avaliação de tratamentos químicos e mecânicos no controle de plantas daninhas na cultura do algodão

The objective of this work was to evaluate the efficacy of different combinations of integrated herbicide treatments, applied at PPI, pre, post, mechanical cultivation and direct spray on cotton crop (Gossypium hirsutum). The trial was conducted in the field, being cotton crop cultivar IAC-20 the experiment area. The treatments were tested with the following products: trifluralina at the dose of 1.068 kg a.i./ha; alachlor at the dose of 1.584 kg a.i/ha; M.S.M.A. at the doses of 1.44 and 1.68 kg a.i./ha; nicosulfuron at the doses of 0.0201; 0.030 and 0.040 kg a.i./ha; diuron at the doses of 1.0 and 1.5 kg a.i./ha; lactofen at the dose of 0,18 kg a.i./ha; cyanazine at the doses of 1.0 and 1.5 kg a.i./ha and diuron at the doses of 1.0 and 1.5 kg a.i./ha. The herbicide treatments were conducted at incorpored pre-planting (IPP), preemergence (PRE), postemergence (POS); mechanical cultivation (MC) and directed spray (DS).The results lead to the conclusion that the system trifluralina (IPP), alachlor(PRE), MC, M.S.M.A. + lactofen presented the highest yielding.The herbicide systems with the application of trifluralina (IPP), alachlor (PRE), M.S.M.A. (POS), MC approximately 50 to 60 D.A.P. and the application through direct spray of diuron, lactofen + cyanazine, lactofen + diuron, M.S.M.A. + cyanazine, M.S.M.A. + lactofen and M.S.M.A. + diuron, in general, promoted the control of weeds.

Controle do arroz vermelho através do herbicida sulfosate isolado e em misturacom adjuvantes

This research aimed to evaluate the efficacy of the herbicide sulphosate applied alone and in mixture with different adjuvants, compared to the herbicide glyphosate, both sprayed at low volume, to control red-rice (Oryza saliva L.) inpre planting condit ions of the rice crop. The experiment was conducted in the field; using the irri gated rice vari ety IAC -101. The fallow land was flooded for two days and after the area was drained, the red-rice began to germinate. When the weed reached approximately 20-25cm height, the herbicides were applied. Rice crop planting was performed 16 days after application at 60-80 seeds/linear meter density, 3cm depth and of 21 .8 cm inter-row spacing. The following treatments were tested: sulphosate at 1.20; 1.44 and 1.68K g a.i./ha and glyphosate at 1.20; 1.44 and 1.68Kg a.i./ha, which were applied alone and in mixture with the following adjuvants: Poliglicol, Organosil icone and Amina Graxa, be sides an untreated check. The following observations were made to evaluate the treatments effects: visu al phyt otoxic ity; % cont rol of red-rice; red-rice height (cm); crop height (cm) and the herbicides sulphosate, commercial formulation of Zaap at 2.5; 3.0 and 3.5 l/ha; glyphosate, Rodeo and Roundup commercial formulations, respectively, at 1.85; 2.22 and 2.59 1/ha, applied alone (except Rodeo) and in mixture with the adjuvants Mojante, Silwet and Frigate, resulted in excellent level of control of red-rice, when applied at post-emergence and total area, at pre-planting condition of rice crop implanted in direct planting system.

Avaliação de herbicidas aplicados em pós-emergência sobre e sob a palha em cana crua e o destino ambiental

This study aimed to evaluate the efficiency of several herbicides, applied alone or mixed in post-emergence on ratoon sugarcane crop, mechanically harvested under a no-burn system, to assess differences in performance when applied over or under the straw. In addition, based on the concept of sustainability and environmental risk evaluation, mathematical models were used to evaluate the fate of these herbicides. The experiment was carried out in the municipality of Bariri-SP, in the Della Colletta Processing Plant section of Santo Antonio Farms sugarcane (RB 72 754 cultivar) cultivated areas. Ratoon sugarcane was planted with 1.40 m spacing on Red-Yellow Argisol soils with 5% declivity. The experiment was arranged in a randomized block design in 14 plots (trifloxulfurom-sodium+ametryn 720 and 960; mesotrione 192 and 292.6; mesotrione and ametryn 292.6+1500; mesotrione+trifloxysulfuron-sodium 182.8+720; metribuzin 2680; trifloxysulfuron-sodium+ametryn+hexazinone+diuron 720+900; amicarbazine 45; hexazinone+diuron 1320; trifloxysulfuron-sodium+sulfentrazone 720+700 (all of the above cited in grams of active ingredients)); control; weeded control, and four replicates, for each type of application (over or under the straw), side by side. The following evaluations were carried out: phytotoxicity, height, stand, efficiency of control of Digitaria horizontalis, Cenchrus echinatus, Emilia fosbergii and Sida cordifolia, number of stalks and first stalk. A fugacity-level I mathematical model was used including the following compartments: air, water, soil, sediment, biota, strain, leaves and roots. The results showed that the herbicides trifloxysulfuron+diuron, mesotrione, metribuzin, ametryn, hexazinone+diuron, amicarbazone and sulfentrazone, alone or in combination, applied in post-emergence on sugarcane were highly efficient in controlling the major weeds present. Application of these herbicides over or under no burn sugarcane straw did not show differences of control efficiency nor of any other parameter. Application of the fugacity model aimed at evaluating preferential behavior showed that all the herbicides tended to have greater distribution in the water compartment.

Programa de manejo da tiririca (Cyperus rotundus) na cultura da cana-de-açúcar com aplicação isolada ou seqüencial de MSMA

Even after years of studying and experimentation, purple nutsedge (Cyperus rotundus) is still a serious problem to sugarcane crop, demanding constant search for new management alternatives. Thus, this work aimed to determine a purple nutsedge management program for a highly infested sugarcane area, using isolated or sequential applications of MSMA, in two successive years. Thus, one trial was conducted twice in the same area from 1994 to 1996, i.e., comprising two successive agricultural years of sugarcane crop, variety SP 71-1406. Ten treatments were adopted considering isolated or sequential applications of MSMA over infestations of purple nutsedge, the dominant species in the area. After MSMA applications, height and treatment selectivity to sugarcane crop were evaluated, as well as height and percent control of purple nutsedge and number, fresh mass and viability of tubers. It was concluded that the herbicide MSMA had initial negative effects on height and selectivity to sugarcane crop, that decreased throughout the evaluations, and were not observed at the end of the experiment. Although isolated MSMA application provided efficient purple nutsedge control, reinfestation occurred. Sequential application, for the two highest rates, resulted in constant control level. The analysis of number, mass and viability of tubers is in agreement with the visual control data for area disinfestation.