Conditions of use of boom sprayers in the micro-region of Pato Branco, PR, Brazil

The technical inspection of agricultural sprayers is responsible for generating important subsidies to inform and guide their users. In this sense, the aim of this study was to evaluate the working conditions of boom sprayers regarding their conservation status in order to identify the problems that interfere with quality sprayings. Sixty-three agricultural sprayers from rural properties were evaluated in the micro-region of Pato Branco, PR. Less than half of applicators (42.9%) performed some type of training and 58.7% of the operators had knowledge about the working pressure indicated by the spray tip manufacturer, but 24.3% of them were working with the pressure out of the recommended or with a damaged manometer. The manometer was present and operative in only 71.4% of the sprayers. Only 54% of the collected flows were in accordance with that informed by the operator. Most of the interviewed producers still do not have adequate criteria for choosing spray tips nor frequency of their replacement

Glyphosate resistance in ryegrasspopulations: study of molecular aspects and population dynamics supporting predictive models for control

Tesis Doctoral.[PT] Azevém (Lolium spp.) é uma espécie infestante amplamente disseminada em áreas de lavoura em todo o mundo. Devido à rusticidade e alta taxa de crescimento, essa espécie é amplamente cultivada, tanto para a cobertura de solo quanto para produção de forragem. O uso intensivo de herbicidas com o mesmo mecanismo de ação resultou na seleção de populações de azevém resistentes, principalmente ao glyphosate. Os objetivos da tese foram: 1) Caracterizar a resposta ao glyphosate e determinar o fator resistência em populações de azevém coletados nas Regiões Sul e Sudoeste Paranaense. 2) Estudar o envolvimento do mecanismo relacionado ao local de ação na resistência ao glyphosate em populações de azevém. 3) Obter informações sobre a demografia de azevém, em populações suscetível e resistente ao glyphosate. 4) Desenvolver e validar um modelo empírico para descrever a emergência de azevém com base no acúmulo térmico do solo. 5) Desenvolver um modelo cohort-estocástico de dinâmica populacional de azevém em populações suscetível e resistente ao glyphosate e simular estratégias de manejo para a espécie sob o efeito de dois cenários climáticos. Diversos experimentos foram desenvolvidos em casa de vegetação, laboratório e a campo pertencentes a UTFPR, Campus Pato Branco, Brasil e IAS/CSIC, Espanha. Em áreas de lavoura das regiões Sul e Sudoeste do Paraná, foram coletadas amostras de sementes de 44 populações de azevém e submetidas a ensaios de resposta a doses do herbicida glyphosate. Em populações resistentes (MR20AR, VT05AR e RN02AR) e suscetíveis (MR05AS, VT07AS e RN01AS) ao glyphosate foi estudado o mecanismo de resistência relacionado ao local de ação. Para o estudo de demografia, nas populações resistentes e suscetíveis, foram avaliados os parâmetros emergência, sobrevivência de diferentes cohorts de plantas e potencial de produção de sementes. Modelo baseado no acúmulo térmico para descrever a emergência de azevém foi desenvolvido e validado. Foi desenvolvido um modelo de dinâmica de populações para as populações suscetível e resistente ao glyphosate. Há elevada variabilidade de resposta das populações de azevém ao glyphosate, com fator resistência variando entre 1,37 e 5,5. Em duas (MR20AR e RN02AR) das três populações resistentes estudadas, foi detectado o aumento do número de cópias do gene da EPSPs (11 a 57x). Em relação à demografia, as plântulas apresentaram rápida taxa de emergência (≈30 dias) sob condições favoráveis, com sobrevivência de acordo com os cohorts de plantas (média de 2 a 10%), e produção de sementes fortemente regulada pela densidade de plantas (90% com 50 pl m-2). As populações resistentes (13830 s pl-1) diferiram das suscetíveis (20300 s pl-1) apenas quanto ao potencial de produção de sementes em baixa densidade. O modelo baseado no acúmulo térmico no solo se mostrou eficiente em descrever a emergência de plântulas da espécie, sendo necessário 390 TT para o início da emergência e 590 TT para atingir 90% de emergência. O modelo de dinâmica de populações demonstrou que o banco de sementes das populações suscetível e resistente tende a se estabilizar em patamares semelhantes (≈20000 s m-2) e que o incremento médio de temperatura de 2,5°C resultou em aumento do número de sementes presentes no banco (≈25000 s m-2). As estratégias de interferência química das plantas ou a rotação de cultura com trigo/soja ou aveia/milho demonstraram alta eficiência e foram capazes de suprimir o banco de sementes em mais de 75%. Conclui-se que a amplificação gênica é um mecanismo relacionado com a resistência de plantas de azevém ao glyphosate na Região Sul do Brasil. Os modelos preditivos desenvolvidos na presente tese fornecem uma melhor compreensão do desenvolvimento populacional de azevém assim como modelo termal poderá ser utilizado como ferramenta para auxiliar no manejo da espécie.[EN] Ryegrass (Lolium spp.) is a weed widely spread in farming areas around the world. Due to its rusticity and high growth rate, this species is widely cultivated, both for soil cover and forage production. The intensive use of herbicides with the same mechanism has led to the selection of herbicide-resistant Italian ryegrass populations, especially to glyphosate. The objectives of this thesis were: 1) Characterize the response to glyphosate and assess the resistance index in Italian ryegrass populations collected in the South and Southwest Regions of Paraná State. 2) Study the involvement of a target site mechanism resistance to glyphosate in Italian ryegrass populations. 3) Get information on the demography of Italian ryegrass populations, susceptible and resistant to glyphosate. 4) Develop and validate an empirical model to describe Italian ryegrass emergence based on soil thermal accumulation. 5) Develop a cohort-stochastic model of Italian ryegrass population dynamics in susceptible and glyphosate resistant populations and simulate management strategies for this species under the effect of two climate scenarios. Several experiments have been developed in the greenhouse, laboratory and field of UTFPR, Campus Pato Branco, Brazil and IAS/CSIC, Córdoba, Spain. In farming areas in the South and Southwest Regions of Paraná State, seeds samples from 44 Italian ryegrass populations were collected and tested for glyphosate response. In resistant (MR20AR, VT05AR and RN02AR) and susceptible (MR05AS, VT07AS and RN01AS) populations to glyphosate, the target site mechanism herbicide resistance was investigated. For the demography study, in resistant and susceptible populations, the parameters, emergence, survival and potential for seed production were evaluated. The model based on thermal accumulation to describe the Italian ryegrass emergence was developed and validated. The demographic parameters were combined with literature data to develop a population dynamics model for susceptible and resistant populations, including different management strategies and the effect of the average temperature increase of 2.5°C. High variability in response of Italian ryegrass populations to glyphosate was observed, with resistance index ranging from 1.37 to 5.5. In two populations (MR20AR and RN02AR), an increase in the number of copies of the EPSPs gene (11 to 57x) was detected. Regarding demography, under favourable conditions, seedlings have a rapid emergence (≈30 days), survival depends on plant cohorts (average 2 to 10%), seed production is strongly adjusted by plant density (90% with 50 pl m-2) in both populations. Resistant populations (13830 s pl-1) differed from the susceptible (20300 s pl-1) only in the seed production potential in low-density. The model based on the soil thermal accumulation proved efficient in describing the seedlings emergence, requiring 390 TT for the beginning of the emergence and 590 TT to reach 90% emergence. The population dynamics model showed that the seed bank of susceptible and resistant populations tends to stabilize at similar levels (≈20000 s m-2) and that the average temperature increase of 2.5°C resulted in an increase in the number of seeds present in the bank (≈25000 s m-2). Chemical management strategies and crop rotation with soybean/oat or corn/wheat demonstrated high efficiency and were able to suppress the Italian ryegrass seed bank by more than 75%. It is concluded that gene amplification is a mechanism involved in resistance of Italian ryegrass plants to glyphosate in South Region of Brazil. The predictive models developed in this thesis provide a better understanding of Italian ryegrass population development and the thermal model for emergence, could be used as a tool to assist in this species management.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Prediction of Italian ryegrass (Lolium multiflorum L.) emergence using soil thermal time

Italian ryegrass (Lolium multiflorum L.) is a highly competitive weed widely disseminated worldwide that affects both summer and winter crops. The development of predictive emergence models can contribute to optimizing weed management. The aim of this study was to develop and validate an empirical emergence model of Italian ryegrass based on soil thermal time. For model development, cumulative emergence in two locations was obtained, and the model was validated with data collected in an experiment conducted independently. Three commonly used emergence models were compared (Gompertz, Logistic, and Weibull). The relationship between emergence and soil thermal time was described best by the Gompertz model. The Gompertz model predicted Italian ryegrass emergence start at 300 thermal time (TT), reaching 50% emergence at 444 TT, and 90% at 590 TT. Model validation performed well in predicting Italian ryegrass emergence and proved to be efficient at describing its emergence. This is a potential predictive tool for assisting farmers with Italian ryegrass management.The authors are grateful to the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Universidade Tecnologica Federal do Paraná (UTFPR), Instituto de Agricultura Sostenible Consejo Superior de Investigaciones Científicas (IAS-CSIC) and HRAC-BR (Associação Brasileira de Ação a Resistência de Plantas Daninhas aos Herbicida) for the infrastructure and financial support

Temporal selectivity of saflufenacil herbicide for the common bean crop of a brazilian oxisol

The temporal selectivity of an herbicide refers to the time interval required between its soil application and crop sowing to prevent damage to crop development and reproduction. Using field bioassays, this study aimed to determine the temporal sensitivity of the herbicide saflufenacil when used with a crop. The study was conducted in two time periods during 2011/2012 and 2012/2013 and employed a split-plot, randomized block experimental design. The main plots were assigned to seven time intervals between herbicide application and bean sowing (0, 5, 10, 15, 25, 35, and 50 days), and the subplots were assigned to groups in which saflufenacil was absent or present (0 and 29.4 g ai ha-1). We determined the stand and the plant height at 7, 14, and 21 days after sowing (DAS), and the first pod height, the number of pods per plant, the number of seeds per pod and the grain yield at maturity. Saflufenacil negatively affected the development of the IPR-Tiziu bean; at 21 DAS, the stand and the plant height at maturity were the variables most sensitive to the herbicide. A minimum interval of 15 days between herbicide spraying and bean sowing was necessary to prevent a reduction in grain yield.

Seed germination and emergence of Eragrostis tenuifolia (A. Rich.) Hochst. ex Steud. in response to environmental factors

Eragrostis tenuifolia is a weed species that is gaining ground in Brazil. This weed occurs in pastures, grasslands, crop fields, and roadsides. The objective of this study was to examine the effects of different environmental factors on E. tenuifolia seed germination and seedling emergence. The optimum constant temperature for germination was around 35-30°C. It was also found that 85% of seeds germinated under a 30/20°C alternate temperature regime. Light appears to have a positive effect on seed germination. No seedlings emerged when seeds were buried 3 cm or deeper. The results suggested that E. tenuifolia has the potential to spread into pastures and in no-tillage crop systems in Brazil. Measures such as the use of cover crops and/or soil cultivation can be used to limit germination and seedling emergence, respectively

Atividade da enzima acetolactato sintase em Euphorbia heterophylla com resistência múltipla aos herbicidas inibidores da ALS e da protox

The objective of this study was to determine the activity of the enzyme acetolactate synthase in biotypes of wild poinsettia (Euphorbia heterophylla) with multiple resistance to ALS- and Protox- inhibitors in the presence and absence of imazapyr, imazethapyr and nicosulfuron. We conducted in vitro assay of ALS enzyme extracted from plants of Vitorino, Bom Sucesso do Sul and Medianeira biotypes (with multiple resistance) and a susceptible population in the absence and presence of imazapyr, imazethapyr and nicosulfuron. In the absence of herbicides, biotypes with multiple resistance showed higher affinity for the substrate of the enzyme compared with the susceptible population. The herbicides imazapyr, imazethapyr and nicosulfuron had little effect on the enzyme activity of ALS-resistant biotypes and, conversely, high inhibitory effect on ALS of the susceptible population. Resistance factors were very high, greater than 438, 963 and 474 for Vitorino, Bom Sucesso do Sul and Medianeira biotypes, respectively. The resistance to ALS inhibitors is due to the insensitivity of ALS to herbicides of both imidazolinone and sulfonylurea groups, characterizing a crossresistance.O objetivo deste trabalho foi determinar a atividade da enzima ALS em biótipos de leiteiro (Euphorbia heterophylla) com resistência múltipla aos inibidores da ALS e da Protox na presença e ausência dos herbicidas imazapyr, imazethapyr e nicosulfuron. Efetuou-se ensaio in vitro da enzima acetolactato sintase (ALS) extraída de plantas dos biótipos Vitorino, Bom Sucesso do Sul e Medianeira (com resistência múltipla aos inibidores da ALS e da Protox) e de um biótipo suscetível, na ausência e presença dos herbicidas imazapyr, imazethapyr e nicosulfuron. Na ausência dos herbicidas, os biótipos com resistência múltipla demonstraram maior afinidade da enzima pelo substrato piruvato em comparação ao biótipo suscetível. Os herbicidas imazapyr, imazethapyr e nicosulfuron produziram reduzido efeito sobre a atividade da enzima ALS dos biótipos resistentes e, ao contrário, elevado efeito inibitório sobre a ALS do biótipo suscetível. Os fatores de resistência foram elevados, superiores a 438, 963 e 474 para os biótipos Vitorino, Bom Sucesso do Sul e Medianeira, respectivamente. A resistência observada deve-se à insensibilidade da enzima ALS aos herbicida

Tolerância do feijoeiro ao herbicida ethoxysulfuron e o mecanismo envolvido no processo

The objectives of this study were to determine the effect of herbicide ethoxysulfuron on the development of commom bean (Phaseolus vulgaris), to evaluate the impact of the herbicide on the crop grain yield and to determine the mechanism of tolerance of common bean to ethoxysulfuron. Field experiments were carried out with several doses of ethoxysulfuron to determine its effect on the grain yield of two varieties of common bean (“IPR Andorinha”, “IPR Tangará”). The mechanism of plant tolerance was evaluated through several methods, including the analysis of the ALS enzyme sensitivity to herbicide and the use of P450 inhibitors (the insecticides malathion + chlorpyrifos) and the use of antidote (mefenpyr-diethyl). When the rate of ethoxysulfuron was 83.2 g ha-1, the grain yield loss reached 25% (IPR Tangará) and 35% (IPR Andorinha). The ALS enzyme activity was severely reduced even at low concentrations ethoxysulfuron (1 μM), indicating that the mechanism of tolerance is not the insensitivity of the herbicide target enzyme. The inhibitors of herbicide detoxification increased the sensitivity of the bean plants to ethoxysulfuron, and the antidote (stimulator of herbicide degradation) mitigated the herbicidal effect. These results strongly support the hypothesis that the mechanism of tolerance of common bean plants to ethoxysulfuron is enhanced herbicide detoxification.Os objetivos deste trabalho foram determinar o efeito do herbicida ethoxysulfuron sobre o desenvolvimento do feijoeiro (Phaseolus vulgaris), avaliar o impacto do herbicida sobre o rendimento de grãos e determinar o mecanismo de tolerância do feijoeiro ao ethoxysulfuron. Em campo, foram realizados dois experimentos com doses crescentes de ethoxysulfuron, a fim de determinar o seu efeito sobre o desenvolvimento e o rendimento de grãos de dois cultivares (cvs.) de feijão (IPR Andorinha e IPR Tangará). O mecanismo de tolerância das plantas foi determinado através da análise de sensibilidade da enzima ALS ao herbicida, do uso de inseticidas inibidores da P450 (malathion + chlorpyrifos) e do uso de antídoto (mefenpyr-diethyl). Quando a dose de ethoxysulfuron foi de 83,2 g ha-1, as perdas de rendimento de grãos atingiram 25% (IPR Tangará) e 35% (IPR Andorinha). A atividade da enzima ALS foi severamente reduzida mesmo em baixas concentrações (1μM) de ethoxysulfuron, sugerindo que o mecanismo de tolerância não é a insensibilidade da enzima alvo do herbicida. Os inibidores da degradação aumentaram a sensibilidade das plantas de feijão ao ethoxysulfuron, e o antídoto (estimulador da detoxificação) mitigou o efeito herbicida. Esses resultados suportam a hipótese de que o mecanismo de tolerância das plantas de feijoeiro ao herbicida ethoxysulfuron é a metabolização das moléculas

Atividade da enzima acetolactato sintase em Euphorbia heterophylla com resistência múltipla aos herbicidas inibidores da ALS e da protox

The objective of this study was to determine the activity of the enzyme acetolactate synthase in biotypes of wild poinsettia (Euphorbia heterophylla) with multiple resistance to ALS- and Protox- inhibitors in the presence and absence of imazapyr, imazethapyr and nicosulfuron. We conducted in vitro assay of ALS enzyme extracted from plants of Vitorino, Bom Sucesso do Sul and Medianeira biotypes (with multiple resistance) and a susceptible population in the absence and presence of imazapyr, imazethapyr and nicosulfuron. In the absence of herbicides, biotypes with multiple resistance showed higher affinity for the substrate of the enzyme compared with the susceptible population. The herbicides imazapyr, imazethapyr and nicosulfuron had little effect on the enzyme activity of ALS-resistant biotypes and, conversely, high inhibitory effect on ALS of the susceptible population. Resistance factors were very high, greater than 438, 963 and 474 for Vitorino, Bom Sucesso do Sul and Medianeira biotypes, respectively. The resistance to ALS inhibitors is due to the insensitivity of ALS to herbicides of both imidazolinone and sulfonylurea groups, characterizing a crossresistance.O objetivo deste trabalho foi determinar a atividade da enzima ALS em biótipos de leiteiro (Euphorbia heterophylla) com resistência múltipla aos inibidores da ALS e da Protox na presença e ausência dos herbicidas imazapyr, imazethapyr e nicosulfuron. Efetuou-se ensaio in vitro da enzima acetolactato sintase (ALS) extraída de plantas dos biótipos Vitorino, Bom Sucesso do Sul e Medianeira (com resistência múltipla aos inibidores da ALS e da Protox) e de um biótipo suscetível, na ausência e presença dos herbicidas imazapyr, imazethapyr e nicosulfuron. Na ausência dos herbicidas, os biótipos com resistência múltipla demonstraram maior afinidade da enzima pelo substrato piruvato em comparação ao biótipo suscetível. Os herbicidas imazapyr, imazethapyr e nicosulfuron produziram reduzido efeito sobre a atividade da enzima ALS dos biótipos resistentes e, ao contrário, elevado efeito inibitório sobre a ALS do biótipo suscetível. Os fatores de resistência foram elevados, superiores a 438, 963 e 474 para os biótipos Vitorino, Bom Sucesso do Sul e Medianeira, respectivamente. A resistência observada deve-se à insensibilidade da enzima ALS aos herbicida

Integração de coberturas mortas com atrazina para manejo de plantas daninhas na cultura do milho

The use of cover crops can contribute to the reduction of the dose required for weed control. The aim of this work was to assess the growth of weeds and productivity of corn from different degrees of black oat cover and velvet bean and atrazine doses. Two experiments were conducted in the experimental area, both was conducted in randomized blocks in a split plot design with four replications. In the main plots were randomized, four straw levels (0, 0.75, 1.5 and 3 times the amount originally produced) oat (Exp 1) or velvet bean (Exp 2). In the subplots were randomized to four doses of atrazine (0, 2100, 4200 and 8400 g ha-1). It was evaluated the weed density and crop yield. The utilization of straw species coverage on the ground, even at high levels, was not enough to exercise total control of weeds. Atrazine was not effective in weed control only in the treatment with 2100 g ha-1 of the herbicide and no velvet bean straw on the ground, but the straw of this species realized suppressive effect, supplementing the effect of the herbicidal dose. Levels in 2775 and 5550 kg ha-1 of velvet bean straw reduce the productivity of corn. Integrating the use of oat or velvet bean straw with low dose of atrazine (2100 g ai ha-1), results in effective weed control systems and more suitable cropping systems in the environmental aspect, both by reducing the use of herbicides as taking advantage of the benefits of no-till system.O uso de plantas de cobertura do solo pode contribuir para a redução da dose necessária para o controle de plantas daninhas. O objetivo deste trabalho foi avaliar o desenvolvimento de plantas daninhas e a produtividade da cultura do milho a partir de diferentes níveis de cobertura de aveia preta e mucuna preta e doses de atrazina. Dois experimentos foram realizados a campo, em delineamento de blocos ao acaso, em parcelas subdivididas, com quatro repetições. Em ambos experimentos, nas parcelas principais foram alocados quatro níveis de palha (0, 0,75, 1,5 e 3 vezes a quantidade originalmente produzida). O primeiro experimento foi constituído de palha de aveia preta e o segundo de palha de mucuna preta. Nas subparcelas de ambos experimentos foram alocadas quatro doses de atrazina (0, 2100, 4200 e 8400 g ha-1). Foram avaliadas a densidade de plantas daninhas e a produtividade da cultura. A utilização da palha das espécies de cobertura sobre o solo, mesmo em níveis elevados, não foi suficiente para exercer o controle pleno das plantas daninhas. A atrazina não foi eficiente no controle das plantas daninhas apenas no tratamento com 2100 g ha-1 do herbicida e ausência de palha de mucuna preta sobre o solo, mas a palha desta espécie de cobertura exerceu efeito supressor, complementando o efeito desta dose de herbicida. Os níveis de 2775 e 5550 kg ha-1 de palha de mucuna preta reduzem a produtividade do milho. A integração do uso de palha de aveia preta ou de mucuna preta com a utilização de dose baixa de atrazina (2100g ia ha-1), resulta em sistemas de cultivo eficazes no controle de plantas daninhas e mais adequados quanto ao aspecto ambiental, tanto pela redução do uso de herbicidas quanto pelo aproveitando dos benefícios do sistema de plantio direto