Volunteer soybean (Glycine max) interference in bean (Phaseolus vulgaris) crops: ethoxysulfuron and halosulfuron critical level of damage and selectivity

This study aimed to determine the negative impact of volunteer soybean plants on bean crop yield and the tolerance of bean genotypes to the herbicides ethoxysulfuron and halosulfuron. To determine the impact of volunteer soybean plants on bean crops, a field experiment was developed, with sub-sub-plots, and four replications. The main plots contained two bean cultivars, while the sub-plots received two soybean sowing times (0 and 7 days after the beans had been sown), while the sub-sub plots contained five soybean plant densities (0, 5, 10, 20, and 40 plants m-2). The tolerance of the bean genotypes was evaluated with two experiments in a completely randomized design with three replications. They were arranged in a 28 x 3 factorial design (bean genotypes x herbicide doses). Each soybean plant per m2 reduced bean crop yield by 4%. The recommended doses of ethoxysulfuorn and halosulfuorn resulted in tolerance levels above 70% for all the studied bean genotypes. Highlights: The herbicides ethoxysulfuron and halosulfuron, are registered in Brazil for the control of volunteer soybean plants in bean crops. To date, the impact generated by volunteer soybean plants competing with bean plants is unknown. The tolerance of 28 bean cultivars to herbicides ethoxysulfuron and halosulfuron was determined using dose label and double the dose. The impact of volunteer soybean plants on bean crops was determined using two bean cultivars and two soybean sowing times. The bean genotypes displayed a highly variable response to the herbicides ethoxysulfuron and halosulfuron; however, when the label recommended dose of the herbicides was used, the tolerance levels observed were over 70%. Each soybean plant is capable of causing a 4% reduction in bean plant grain yield, regardless of the establishment time of the soybean plants or the bean genotype.This study aimed to determine the negative impact of volunteer soybean plants on bean crop yield and the tolerance of bean genotypes to the herbicides ethoxysulfuron and halosulfuron. To determine the impact of volunteer soybean plants on bean crops, a field experiment was developed, with sub-sub-plots, and four replications. The main plots contained two bean cultivars, while the sub-plots received two soybean sowing times (0 and 7 days after the beans had been sown), while the sub-sub plots contained five soybean plant densities (0, 5, 10, 20, and 40 plants m-2). The tolerance of the bean genotypes was evaluated with two experiments in a completely randomized design with three replications. They were arranged in a 28 x 3 factorial design (bean genotypes x herbicide doses). Each soybean plant per m2 reduced bean crop yield by 4%. The recommended doses of ethoxysulfuorn and halosulfuorn resulted in tolerance levels above 70% for all the studied bean genotypes. Highlights: The herbicides ethoxysulfuron and halosulfuron, are registered in Brazil for the control of volunteer soybean plants in bean crops. To date, the impact generated by volunteer soybean plants competing with bean plants is unknown. The tolerance of 28 bean cultivars to herbicides ethoxysulfuron and halosulfuron was determined using dose label and double the dose. The impact of volunteer soybean plants on bean crops was determined using two bean cultivars and two soybean sowing times. The bean genotypes displayed a highly variable response to the herbicides ethoxysulfuron and halosulfuron; however, when the label recommended dose of the herbicides was used, the tolerance levels observed were over 70%. Each soybean plant is capable of causing a 4% reduction in bean plant grain yield, regardless of the establishment time of the soybean plants or the bean genotype

SELEÇÃO DE ESPÉCIES DA FAMÍLIA CUCURBITACEAE E CHENOPODIACEAE PARA INDICAÇÃO DA PRESENÇA DE SAFLUFENACIL NO SOLO

O objetivo deste estudo foi selecionar espécies cucurbitáceas e quenopodiácea para serem usadas como plantas bioindicadoras da presença de saflufenacil no solo. O experimento foi realizado em delineamento inteiramente casualizado com três repetições, em bifatorial 8 x 5. O primeiro fator foi constituído pelas concentrações de saflufenacil (0; 2,45; 4,9; 9,8; 14,7; 19,6; 24,5 e 29,4 g i.a. ha-1) e o segundo pelas espécies bioindicadoras: pepino, melancia, cabotiá, abobrinha híbrida Clarita (família Cucurbitaceae) e beterraba (família Chenopodiaceae). Aplicou-se o herbicida saflufenacil em pré-emergência em Latossolo Vermelho distroférrico. Realizaram-se quatro avaliações de estande e estatura de planta, determinando-se no final do experimento as massas das partes aéreas verde e seca das espécies. Os resultados deste estudo permitiram classificar as espécies estudadas conforme o nível de tolerância ao herbicida saflufenacil: abobrinha = cabotiá > melancia > beterraba = pepino

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

Ethoxysulfuron no controle de plantas daninhas na cultura do feijoeiro comum

It is necessary to identify new herbicides with a wide spectrum of weed control for bean crops, and have an adequate security margin for this crop. The main objectives of this work were to evaluate the potential use of ethoxysulfuron herbicide on controlling weeds and three soybean cultivars between bean crop, as the tolerance of IAC Imperador bean cultivar to this herbicide. An experiment was conducted on field with a split-plot design. At the whole plot were allocated the doses of ethoxysulfuron (0; 10.4; 20.8; 41.6; 62.5; and 83.3 g ha-1) and, at the subplots, the three soybean cultivars (AMS Tibagi, Dow 5D634 e Nidera 5909) were allocated with weeds (Bidens spp., Ipomoea spp.). Additionally, it was included an extra treatment without weeds and herbicide application. The Ethoxysulfuron controlled Ipomoea spp. and soybean plants, but didn’t control Bidens spp. It was found a differential tolerance between the soybean cultivars, and the AMS Tibagi cultivar showed to be slightly tolerant. Doses up to 20.8 g ha-1 are sufficient to satisfactorily control Ipomoea spp. and soybean plants, but not for Bidens spp. The herbicide provided an increment of bean yield, however, it wasn’t enough to achieve the extra treatment yield. The IAC Imperador bean cultivar showed moderate tolerance to ethoxysulfuron, and its plants can recover quickly after any injurie.É necessário identificar novos herbicidas com amplo espectro de controle de plantas infestantes para a cultura do feijão e, que possuam margem de segurança adequada para a cultura. Os objetivos deste trabalho foram, avaliar o potencial uso do herbicida ethoxysulfuron para o controle de plantas infestantes em meio a cultura do feijão, assim como a tolerância da cultivar de feijão IAC Imperador a este herbicida. Um experimento foi conduzido a campo em delineamento de blocos ao acaso com parcelas subdivididas. Nas parcelas principais foram alocadas as doses de ethoxysulfuron (0; 10,4; 20,8; 41,6; 62,5 e 83,3 g ha-1) e nas sub parcelas três cultivares de soja (AMS Tibagi, Dow 5D634 e Nidera 5909) + as plantas infestantes (Bidens spp., Ipomoea spp.). Adicionalmente foi incluído um tratamento extra sem infestantes e sem aplicação do herbicida. Ethoxysulfuron controlou as plantas de Ipomoea spp. e soja, mas não as de Bidens spp. Constatou-se tolerância diferencial entre as cultivares de soja avaliadas, em que a cultivar AMS Tibagi indica ser ligeiramente mais tolerante que as demais cultivares. Doses de até 20,8 g ha-1 são suficientes para controlar satisfatoriamente plantas de Ipomoea spp. e soja, no entanto, não as de Bidens spp. O herbicida proporcionou incremento no rendimento de grãos de feijão, todavia, não foi suficiente para alcançar o rendimento da testemunha extra. A cultivar de feijão IAC Imperador demostrou tolerância moderada ao ethoxysulfuron, além disso, as plantas tendem a se recuperar rapidamente da injúria do herbicida

FATORES AMBIENTAIS QUE AFETAM A EFICÁCIA DE GLIFOSATO: SÍNTESE DO CONHECIMENTO

A presente revisão objetivou organizar e sintetizar o conhecimento disponível na literatura com respeito aos fatores ambientais que afetam a eficácia do glifosato. Foram abordados os seguintes aspectos: temperatura, umidade relativa do ar, solo, irradiância, disponibilidade de nutrientes e o estado nutricional das plantas, ocorrência de chuva após a aplicação do produto, assim como a interação entre o ambiente e as características morfológicas e fenológicas das plantas. Verificou-se que, em geral, temperatura e estado nutricional das plantas ótimos para o crescimento vegetal favorecem a eficácia do glifosato no controle de infestantes. Umidade relativa do ar superior a 65 % tende a facilitar a absorção do herbicida. Irradiância elevada auxilia a ação de glifosato, mas há espécies vegetais em que o sombreamento parcial favorece o controle com o herbicida. A maioria dos trabalhos da literatura consultados trata da avaliação do efeito de fatores isoladamente. No entanto, como em condições reais ocorre a associação dos fatores de estresse mencionados há a necessidade de trabalhos de campo que avaliem a interação entre eles

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)

Tolerance of dry bean cultivars to saflufenacil

The herbicide saflufenacil is a Protox inhibitor, with differential translocation mode in comparison to other herbicides with the same mechanism of action. Selectivity, efficacy and safety to the environment are important characteristics for practical application of a herbicide in agriculture. The aim of this study was to determine the tolerance of ten dry bean cultivars to saflufenacil, applied on preemergence. The experiment was conducted in split plot randomized blocks design with ten dry bean cultivars (IAPAR 81; IPR Tiziu, IPR Corujinha; BRS Estilo; BRS Talismã; BRS Esplendor; BRS Campeiro; BRS Radiante, BRS Vereda and Jalo Precoce) allocated in plots and saflufenacil concentrations (0, 14.7 and 29.4 g ha- 1) in subplots. Evaluations were performed at 21 and 28 days after application (DAA) and plant height at 28 and 35 DAA. At physiological maturity were evaluated plant height, first pod height , number of pods per plant, 400 grains weight and dry beans grain yield. The cultivar Talismã showed low sensitivity to the herbicide and the cultivar Jalo Precoce high sensitivity to the herbicide, considering all variables analyzed

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