Search

Understanding the effects of temperature on Fusarium graminearum infection can provide theoretical guidance for chemical control of Fusarium head blight (FHB). Here, we evaluated the effects of various temperatures on biological fitness development of wild-type sensitive strain 2021 and carbendazim-resistance mutants conferring β2-tubulin substitutions F167Y, E198K, and E198L. The results showed that mycelial growth and conidiation of four strains increased with the increase in temperature between 10 and 25°C. Conidia of F167Y displayed strong adaptability to low temperature. The virulence of the four strains was largely similar at the same temperature, showing an upward trend between 10 and 25°C. At 10°C, the hyphal growth of all strains was significantly inhibited, metabolism was slowed down, and the accumulation of secondary metabolites decreased. Subsequently, the production of deoxynivalenol (DON) and its intermediates pyruvate and aurofusarin decreased at low temperature, and the expression of DON biosynthesis-related genes Tri5, FgPK, and AUR decreased accordingly. At the same temperature, the aurofusarin production of the strains F167Y and E198K was higher than that of strains 2021 and E198L. The contents of DON and pyruvic acid in carbendazim-resistance mutants were higher than those in the wild-type strain 2021. The sensitivity of four strains to different fungicides changed at various temperatures. The sensitivity to most fungicides increased with decreasing temperature. The carbendazim-resistance mutants showed positive cross-resistance with other benzimidazoles. However, there was no cross-resistance to pyraclostrobin and azoles. These results would direct us to use fungicides preventing the infection of F. graminearum with changeable atmospheric temperature at the wheat flower stage.

Made available in DSpace on 2022-04-28T19:44:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The aim of this study was to assess the efficacy of imazamox for control of S. molesta and to assess the effects of plant decomposition on environmental indicators after application of this herbicide in microcosm conditions. The following rates were used: 600, 700, 800 and 900 g ai ha−1 and spray volume 50 L ha−1. Control efficacy was determined as the percentage (from 0 to 100%) of visible injury symptoms in the plants, biochemical and chemical oxygen demand (BOD5 and COD), water quality variables, chlorophyll a and pheophytin a at 0, 7, 15, 30, 45 and 60 days after application (DAA) and fresh and dry biomass at 60 DAA. Imazamox was effective in controlling 94% of S. molesta with 900 g ai ha−1; it reduced 95% of fresh weight and 92% of dry weight of plant at 60 DAA, and reduced chlorophyll a of the plants for all rates. For BOD5, there was an increase for all rates at 15, 30 and 45 DAA with restoration of the parameters at 60 DAA, and for COD, there was an increase at 60 DAA with 700 and 900 g ai ha−1. For temperature, pH, dissolved oxygen and electrical conductivity, there was no significant effect after spraying. Imazamox was effective in controlling S. molesta with 900 g ai ha−1 without causing significant effects on the physical-chemical parameters of water quality. College of Agricultural and Veterinary Science São Paulo State University University Center of the Barretos Educational Foundation Ecosafe - Agriculture and Environment Department of Plant Health College of Agricultural and Veterinary Science São Paulo State University College of Agricultural and Veterinary Science São Paulo State University Department of Plant Health College of Agricultural and Veterinary Science São Paulo State University

Walnut blight (WB), caused by the bacterium Xanthomonas arboricola pv. juglandis,continues to be a serious disease of walnut in northern China, where weather conditions favor disease development. From 2013 to 2017, WB incidences in walnut cv. ‘Liaoning 1’ were investigated in three areas (Dalian,Suizhong and Jianchang areas) in the Liaoning province, northeastern China. WB incidence was high in Dalian (23.72%) and Suizhong (24.31%) but was low in Jianchang (12.98%). Relative humidity is a key meteorological factor that affected the differences between areas. Ten walnut cultivars were surveyed in 2013, 2015, and 2017 for their susceptibility to blight. Lateral-bearing walnut cultivars showed a higher incidence and were found more susceptible to WB compared with terminal-bearing cultivars. In order to test the most effective chemical spray methods, bactericide screening trials were conducted comprising 12 different types of bactericides and mixtures in 2015. The combination of kasugamycin+mancozeb was most effective in controlling WB incidence resulting in lowest fruit disease incidence (2.63%). Subsequently, minimal spray trials were studied to determine the most effective chemical control as well as timing and frequency of application in 2017. The study confirmed these results of studies done in California: the best timing for the first spray application was at 30%–40% pistillate flower emergence and subsequently spray times were at 6 days and 16 days interval. Results of this study provide essential information to better understand the complexity of this walnut disease toward developing effective control management strategies globally.

The prevention of fungal spoilage is an essential consideration in wheat storage. Recent studies have revealed that volatile organic compounds (VOCs), possibly with natural fungicidal properties, could be produced from stored wheat grains. In this study, the antifungal effect of hexanal, a main component of VOCs from stored wheat, against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method. And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content, fatty acid values, germination percentages and vigor of 16% and 18% moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor. The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal (fatal) concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid, respectively. The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor. During 5-week storage of high-moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor, the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples, and fatty acid values were slightly higher in 18% moisture wheat than in 16% moisture wheat. The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content. These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.

Glyphosate application avoids some problems associated with manually controlling Carpobrotus. However, before it can be extended, we must understand whether residual glyphosate affects the restorat...

Fusarium head blight (FHB) is a serious disease of wheat and barley that not only lowers yield but also contaminates the grain with associated mycotoxins such as deoxynivalenol (DON). Chemical control options for FHB and DON include application of triazole fungicides at the anthesis or flowering stage. This presents practical challenges for growers in managing FHB, as the appropriate timing window typically lasts only 3 to 4 days. If this small window is missed, due to weather conditions or technical problems, fungicide application is less effective in controlling FHB and DON. The present work was conducted over 2 years (2019 and 2020) to test the efficacy of a new fungicide (pydiflumetofen + propiconazole) from Syngenta labeled as Miravis Ace in controlling FHB and DON content at 50% head emergence (Feekes 10.3), anthesis (Feekes 10.5.1), and end of flowering (Feekes 10.5.3) stages. Prosaro 421 SC, a standard FHB control triazole fungicide, was used at all three stages for comparison with the test fungicide. Miravis Ace application at 50% head emergence provided significant control over the nontreated check for FHB incidence (2020), FHB severity (2019), and DON content (2019) with control efficacies as high as 51, 69, and 52%, respectively. However, mean control percentages relative to the check were highest with Miravis Ace at anthesis in both 2019 and 2020 for all the FHB parameters. In conclusion, 50% head emergence provides statistically significant control on FHB and DON, but anthesis was the most effective application stage for Miravis Ace.

The control of rodent pests with novel rodenticides is an important strategy subsequently they are cost-effective in reduction of agriculture damage in the urban environment. The current field stud...

Cotton bollworm, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae), is one of the most important and key pests of cotton in Iran. This study was carried out with the aim of investigating the efficacy of several different insecticides on cotton bollworm in three regions of Golestan province, Iran, in a completely randomized design with 4 replications and 7 treatments. Experimental treatments include: Proclame-Fit® 150 g/ha, Profenofos® 2.5 lit/ha, Cypermethrin® 150 ml/ha, Indoxacarb® 250 ml/ha, Karvin® 1.5 lit/ha, Fenpropathrin® 1 lit/ha and control (water without insecticide). Samplings unite of cotton bollworm larvae was 10 cotton plants per plot which were recorded the number of immature pests per plant at the before spraying, 3, 7, and 14 days after spraying. The larval mortality of treatments was modified by the Henderson-Tilton formula to determine the efficiency percentage. According to the results obtained in Bandar-e Gaz, Proclame-Fit® and Karvin® had the highest long-term effect 50.85% and 59.86%, respectively, and Profenofos® had a suitable short-term effect with 74.82% mortality percentage. In Gonbad-e Kavous, Proclame-Fit®, Profenofos® and Karvin® with 96%, 94.33 % and 80% have shown a suitable lethal-short-term effect on cotton bollworm larvae. In Ramian, Proclame-Fit®, Profenofos ® and Karvin ® showed the highest short-term effect on cotton bollworm larvae, 83.18 %, 88.97 % and 88.37%, respectively. Based on the results, to control cotton bollworm, Proclame-Fit ® and Profenofos® are recommended as appropriate insecticides with the recommended doses.

Respiration involves the inward and outward movement of air into the lungs. This process facilitates gaseous exchange. The rate of respiration therefore regulates the partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the blood. Spontaneous respiration occurs as a result of rhythmic discharge of motor neurons innervating respiratory muscles. Nerve impulses from the brain are responsible for this rhythmic discharge. The rhythmic contraction and relaxation of respiratory muscles alternatively fill the lungs during inspiration and empty them in expiration. This rhythmic discharges from the brain are regulated by changes in arterial PaO2, PaCO2 and hydrogen ion (H+) concentration, which is called the chemical control of respiration.

This study aimed to evaluate the selectivity of post-emergent herbicides in cassava in two application times. The experiments were carried out in a greenhouse at the Federal University of Tocantins - UFT, Campus Gurupi. The experimental designed was completely randomized arranged in a 5x2 factorial scheme, composed by the combination of 5 herbicide molecules with different mechanisms of action (mesotrione, carfentrazone-ethyl, chlorimuron-ethyl, nicosulfuron and imazethapyr) applied in two seasons, 30 and 45 days after emergence (DAE), with four repetitions. The cultivar used was “Cacau melhorada”. The visual intoxication of the culture was evaluated. The results obtained were subjected to analysis of variance, by the F test, with the averages analyzed statistically by the LSD mean test, at 5% probability. The treatments based on mesotrione, and chlorimuron-ethyl were not toxic to the culture, promoting results similar to those observed for control. There were differences in the level of tolerance to the studied herbicides, between the times of application of the herbicides.

Little is known about best herbicidal weed option for weed eradication in soybean in agro-climatic circumstances of Sargodha, Punjab, Pakistan. A two year field study was accomplished at College of Agriculture experimental site Sargodha in spring seasons of 2018 and 2019 to evaluate the efficacy of different herbicides adjacent to major weeds present in soybean. The study consisted of 8 herbicide treatments including two pre-emergence herbicides (pendimethalin at 489.1 g a.i. ha-1, pendimethalin + S-metolachlor at 731.1 g a.i. ha-1) which are applied immediately after sowing and six post-emergence herbicides (oxyfluorfen at 237.1 g a.i. ha-1, metribuzin at 518.7 g a.i. ha-1, quizalofop-p-ethyl at 148.2 g a.i. ha-1, acetochlor at 741 g a.i. ha-1, halosulfuron at 37 g a.i. ha-1and topramezone at 21.5 g a.iha-1) which were used 25 days subsequent to sowing. In contrast to control, all herbicides have shown significant decline in weed density (up to 94%) and dry weight (up to 88%); and caused significant increases in plant height (up to 85%), pod bearing branches (up to 77%), number of pods per plant (up to 83%), 100-seed weight (up to 37%) and seed yield (up to 160%) of soybean. Among herbicides, topramezone at 21.5 g a.i ha-1 gave significantly the highest (1234 and 1272 kg ha-1 in the year 2018 and 2019) seed yield of soybean and HEIs (1.28 and 1.03 in year 2018 and 2019, respectively). However, oxyfluorfen at 237.1 g a.i. ha-1, pendimethalin + S-metolachlor at 731.1 g a.i. ha-1, pendimethalin at 489.1 g a.i. ha-1, quizalofop-p-ethyl at 148.2 g a.i.ha-1 followed it. The regression analysis depicted a significant negative moderate relationship of soybean seed yield with weed dry weight (R2 = 0.7074), and pods per plant (R2 = 0.7012) was proved to be the main yield component responsible for higher yield of soybean.

The objective of this study was to evaluate the genetic control integrated to the chemical control of Asian soybean rust (ASR) and the effects of these measures on crop yield. The experiment was conducted in Erechim, Rio Grande do Sul State, Brazil, in 2016/17 and 2017/18 crop years, under a randomized block design, in a subdivided plot scheme (cultivars in the plots and fungicides in the subplots), with four replicates. The following cultivars were used: BMX Vanguarda (without ASR tolerance); TMG 7062; TMG 7262, and TMG 7161, tolerant to ASR (Inox™ Technology cultivars). The fungicides used were: T1) control (without application of fungicides); T2) azoxystrobin + benzovindiflupyr; T3) difenoconazole + cyproconazole; T4) trifloxystrobin + prothioconazole, and T5) epoxiconazole + fluxapyroxad + pyraclostrobin. Four fungicide applications were carried out at the V6, R1, R5.1 and R6 stages. During the experiment, for the calculation of the area under disease progress curve (AUDPC), disease severity was assessed at 7-day intervals in a random sample of 10 trifolia per plot. After harvest, yield components were determined: number of grains per plant, thousand grain weight (g), and yield (kg ha-1). In 2017/18 crop year, the fungicide difenoconazole + cyproconazole was not efficient for ASR control. The soybean cultivars TMG 7062, TMG 7161 and TMG 7261 delayed the disease progression; however, only TMG 7161 presented tolerance in the presence of the inoculum in 2016/17 and 2017/18 crop years. The association between chemical and genetic control is shown to be efficient for ASR control. RESUMO Objetivou-se avaliar o controle genético integrado ao controle químico da ferrugem asiática da soja (FAS) e os efeitos dessas medidas sobre a produtividade da cultura. O experimento foi conduzido em Erechim/RS, nas safras 2016/17 e 2017/18, sob delineamento de blocos casualizados, em esquema de parcela subdividida (cultivares, nas parcelas; e fungicidas, nas subparcelas), com quatro repetições. Foram utilizadas as seguintes cultivares: BMX Vanguarda (sem tolerância à FAS); TMG 7062; TMG 7262; e TMG 7161, tolerantes à FAS (cultivares com tecnologia Inox™). Os fungicidas utilizados foram: T1) testemunha (sem aplicação de fungicidas); T2) azoxistrobina + benzovindiflupyr; T3) difenoconazol + ciproconazol; T4) trifloxistrobina + protioconazol; e T5) epoxiconazol + fluxapiroxade + piraclostrobina. Foram realizadas quatro aplicações de fungicidas nos estádios V6; R1; R5.1; e R6. Durante a condução do experimento, para o cálculo da área abaixo da curva de progresso da doença (AACPD), avaliou-se a severidade da doença, com intervalos de 7 dias, em uma amostra aleatória de 10 trifólios por parcela. Após a colheita, determinou-se os componentes de rendimento: número de grãos por planta, peso de mil grãos (g), e a produtividade (kg ha-1). Na safra 2017/18 o fungicida difenoconazol + ciproconazol não foi eficiente para o controle da FAS. As cultivares de soja TMG 7062, TMG 7161 e TMG 7261 retardaram o progresso da doença, entretanto somente a cultivar TMG 7161 apresentou tolerância sob a presença do inóculo nas safras 2016/17 e 2017/18. A associação entre controle químico e genético mostra-se eficiente no controle da FAS.

Hazelnut naturally grows as a multi-stemmed tree. The basal sprouts, known as suckers, grow throughout the season. Suckers are removed to promote a single trunk that facilitates production mechanization and increased yield. In western Oregon, herbicides are the most common method of sucker control, and at least four applications per season are performed in the spring and summer seasons. This study evaluated the efficacy of foliar-applied herbicides currently registered for sucker control in hazelnuts. Season-long and short-term field studies were conducted to assess the efficacy of herbicides to control hazelnut suckers. In the season-long studies, four consecutive applications of treatments that contained 2,4-D, glufosinate, or paraquat provided 50% to 80% control, maintained sucker height at 50 cm or less as compared to 155 cm for the nontreated control, and reduced sucker biomass by 87% as compared to the nontreated control. The short-term study results confirmed the efficacy of 2,4-D, glufosinate, and paraquat for sucker control, and in this study, carfentrazone and saflufenacil reduced sucker biomass to a level comparable to 2,4-D or glufosinate treatment. These results confirm that 2,4-D, glufosinate, paraquat, carfentrazone, and saflufenacil can be used for sucker control in hazelnut and emphasize the necessity of multiple applications during the growing season to control suckers in hazelnut. Proper herbicide selection is important to control suckers with success.

Vanadium bearing stone coal is an important vanadium resource in China, and roasting is the foundation for extracting vanadium from stone coa1. In this paper, the blank roasting kinetics of illite type vanadium bearing stone coal is studied using the derived kinetics equations of disc-shaped particles. Stone coal samples were roasted at the set temperature and time, the roasted clinker was leached with sulfuric acid. The roasting effect was judged by the leaching rate of vanadium, and the kinetics and mechanism of the roasting reaction were discussed. The results show that the blank roasting process of stone coal is divided into two stages. The first stage activation energy is 159.50 kJ/mol, which follows the control of chemical reaction kinetics; the second stage activation energy is 256.45 kJ/mol, which belongs to diffusion control. In addition, As the roasting reaction proceeds, it can be noted that chemical reaction control can be quickly transformed into diffusion control. The apparent activation energy of the diffusion control is greater than that of the chemical reaction control, which indicates that diffusion is the controlling factor that affects the conversion efficiency of vanadium during the blank roasting process of stone coal. The results of blank roasting kinetics model of disc-shaped particles established in this study are in good agreement with the experimental analysis results, which also verifies the accuracy of this model.

Made available in DSpace on 2020-12-12T02:48:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Digitaria insularis (sourgrass) is a monocotyledon weed of difficult control and high invasive behavior. Atrazine is widely applied in the Americas to control weeds in maize culture, but its efficiency against D. insularis is limited. The incorporation of atrazine into poly(epsilon-caprolactone) nanocapsules increased the herbicidal activity against susceptible weeds; however, the potential of this nanoformulation to control atrazine-tolerant weeds including D. insularis has not yet been tested. Here, we evaluated the post-emergent herbicidal activity of nanoatrazine against D. insularis plants during initial developmental stages. The study was carried out in a greenhouse, using pots filled with clay soil. Plants with two or four expanded leaves were treated with conventional or nanoencapsulated atrazine at 50 or 100% of the recommended dosage (1,000 or 2,000 g ∙ ha−1), followed by the evaluation of physiological, growth, and control parameters of the plants. Compared with conventional herbicide, both dosages of nanoatrazine induced greater and faster inhibition of D. insularis photosystem II activity at both developmental stages. Atrazine nanoencapsulation also improved the control of D. insularis plants, especially in the stage with two expanded leaves. In addition, nanoatrazine led to higher decreases of dry weight of four-leaved plants than atrazine. The use of the half-dosage of nanoatrazine was equally or more efficient in affecting most of the evaluated parameters than the conventional formulation at full dosage. Overall, these results suggest that the nanoencapsulation of atrazine potentiated its post-emergent herbicidal activity against D. insularis plants at initial developmental stages, favoring the control of this atrazine-tolerant weed. Agronomy Department Londrina State University Department of Environmental Engineering São Paulo State University (UNESP) Department of Animal and Plant Biology Londrina State University Department of Environmental Engineering São Paulo State University (UNESP) CNPq: 306583/2017-8

Weed management consists of a fundamental practice in cassava, with mechanical and chemical control widely used. The objective of this work was to evaluate the efficacy of pre-emergence herbicides, as well as to determine the interaction of these with weeding complementation in the weed management in cassava. Two experiments were conducted in Junqueiro (Alagoas). In 2015/16, the experimental design was based on randomized blocks, with treatments distributed in a split-split-plot scheme, with four replications. In the main plot, four pre-emergence associations of clomazone + flumioxazin in different doses were evaluated, in addition to a control without herbicide. In the subplots, the Caravela and Pretinha cassava cultivars were evaluated, while in the sub-subplots the control complementation was evaluated using or not the manual weeding. In the 2016/17, the plot design and layout remained the same as for 2015/16, except for the composition of the herbicide treatments, since the standardization of clomazone dose has been chosen, varying only the doses of flumioxazin. The association of clomazone and flumioxazin has shown efficacy in weed control, with a greater residual as higher doses are used. This association provided higher shoot and root yield. Weeding complementation along the cassava cycle can increase its yield. Made available in DSpace on 2021-01-12T09:07:35Z (GMT). No. of bitstreams: 1 The-use-of-pre-emergence.pdf: 170867 bytes, checksum: 80de9e49815b7f83b26d681e0ae096a7 (MD5) Previous issue date: 2020

As a control measure against weeds, the use of herbicides is an effective and inexpensive alternative. However, there are no products recommended for the cultivation of cowpea in Brazil, making it necessary to search for alternative solutions. The objective of this study was to evaluate the effect of herbicides applied in the pre- and post-emergence on cowpea nodulation and production under conditions of the Amazonian savannah. Two experiments were carried out in a randomized block design with four replicates, using the cowpea cultivar BRS Aracê subjected to the pre-emergence herbicides: Metribuzin, Sulfentrazone, S-metolachlor, Pendimethalin, Oxadiazon, Alachlor, Metribuzin + Pendimethalin, Metribuzin + Alachlor and Quizalofop-p-ethyl, Bentazon, Fomesafen, Imazethapyr, Imazamox + Bentazon, Quizalofop-p-ethyl + Imazethapyr, Quizalofop-p-ethyl + Ima-zamox and Quizalofop-p-ethyl + Bentazon, and post-emergence herbicides: Quizalofop-p-ethyl, Bentazon, Fomesafen, Imazetha-pyr, Imazamox + Bentazon, Quizalofop-p-ethyl + Imazethapyr, Quizalofop-p-ethyl + Imazamox, and Quizalofop-p-ethyl + Bentazon. The number of nodules in each plant, the dry matter of nodules, dry matter of roots and the grain yield were evaluated. According to the results obtained, the management of weeds in pre- or post-emergence according to the herbicide used affects the nodulation and productivity of cowpea under the conditions of the Amazonian savannah. The herbicides Metribuzin in pre-emergence, and Fomesafen and the mixture of Quizalofop-p-ethyl + Imazethapyr in post-emergence are not recommended for weed control in cowpea. The application of Oxadiazon, Alachlor, and Pendimethalin in pre-emergence can be considered interesting because they do not inhibit the development of the root system or the nodulation of cowpea which provides a greater grain yield. Regarding weed control strategies at post-emergence, the application of the herbicide Imazethapyr and the combination of the herbicides quizalofop-p-ethyl + imazamox, Quizalofop-p-ethyl + Bentazon and Imazamox + Bentazon allow satisfactory levels of grain yield, root system development and nodulation of cowpea. RESUMEN Como medida de control contra las malezas, el uso de herbicidas es una alternativa efectiva y asequible. Sin embargo, no hay productos recomendados para el cultivo de frijol caupí en Brasil, por lo que es necesario buscar soluciones alternativas. El objetivo de este estudio fue evaluar el efecto de herbicidas aplicados en pre- y post-emergencia sobre la nodulación y productividad del frijol caupí bajo las condiciones de la sabana amazónica. Se realizaron dos experimentos en bloques al azar con cuatro repeticiones, utilizando el cultivar de frijol caupí BRS Aracê sometido a los herbicidas pre-emergentes: Metribuzina, Sulfentrazona, S-metolaclor, Pendimetalina, Oxadiazón, Alaclor, Metribuzina + Pendimetalina, Metribuzina + Alaclor y Quizalofop-p-etil, Bentazona, Fomesafen, Imazetapir, Imazamox + Bentazona, Quizalofop-p-etil + Imazetapir, Quizalofop-p-etil + Imazamox y Quizalofop-p-etil + Bentazona, y herbicidas post-emergentes: Quizalofop-p-etil, Bentazona, Fomesafen, Imazetapir, Imazamox + Bentazona, Quizalofop-p-etil + Imazetapir, Quizalofop-p-etil + Imazamox, Quizalofop-p-etil + Bentazona. Se evaluaron el número de nódulos por planta, la masa seca de nódulos, la masa seca de raíces y el rendimiento de grano. Según los resultados obtenidos en este estudio, el manejo de malezas en pre o post-emer-gencia de acuerdo con el herbicida utilizado afecta la nodulación y el rendimiento de grano de frijol caupí bajo condiciones de la sabana amazónica. Los herbicidas Metribuzina en pre-emergen-cia, y Fomesafen y la mezcla de Quizalofop-p-etil + Imazetapir en post-emergencia no se recomiendan para el control de malezas en frijol caupí. La aplicación de Oxadiazón, Alaclor y Pendimetalina en la pre-emergencia puede considerarse interesante porque no inhiben el desarrollo del sistema radicular o la nodulación de frijol caupí lo que proporciona un mayor rendimiento de grano. En lo relacionado con las estrategias de control de malezas posteriores a la emergencia, la aplicación del herbicida Imazetapir y la combinación de los herbicidas Quizalofop-p-etil + Imazamox, Quizalofop-p-etil + Bentazona e Imazamox + Bentazona permiten niveles satisfactorios de rendimiento de grano, desarrollo del sistema de raíces y nodulación de frijol caupí.

The new species Phytophthora oleae is a pathogen recently reported causing fruit rot on olive orchards in Italy and root rot in a natural wild-olive forest in Spain. Potassium phosphite, fosetyl-Aluminium and metalaxyl were evaluated in pot experiments for root disease control. All the three systemic products led to a significant decrease of root necrosis caused by olive Phytophthora pathogens (P. cryptogea, P. megasperma and P. oleae) when applied at recommended doses to inoculated seedlings, even though fosetyl-Aluminium did not significantly inhibit mycelial growth in vitro. The tested products have potential to protect commercially planted olive orchards from these Phytophthora pathogens, including the new species P. oleae in natural woodlands that, in turn, put at risk cultivated olive orchards.

Stalk rot in maize plants is commonly associated with many species of the genus Fusarium. This disease affects the seedbed and the establishment of maize crops because of seeds contaminated with different pathogens of this genus. Maize crops in the Ubate Valley, in the province of Cundinamarca, are currently infected by this disease, which reduces the yield and final quality of the maize seeds. This research evaluated the effects of thermal and fungicide treatments on pathogens of the genus Fusarium associated with maize seeds. Seeds were treated at 50°C, 55°C and 60°C with dry heat and hot water. Mycelial colonization of seeds, germination percentage, seedling length, and fresh weight were evaluated as variables. In in vitro tests, the fungicides fludioxonil + metalaxyl-M, tebuconazole + trifloxystrobin, prochloraz + difenoconazole and carboxin + captan were evaluated at 0.5, 1.0 and 1.5 the commercial dose on the radial growth and conidial germination of Fusarium subglutinans and Fusarium graminearum isolates. The most effective heat treatments on Fusarium colonization of maize seeds were obtained with the two heat sources at 55°C without a significant reduction in the percentage of germination and seedling length and fresh weight. Commercial doses of the evaluated fungicides completely inhibited the radial growth of F. graminearum and only commercial doses of carboxin + captan and prochloraz + difenoconazole completely inhibited F. subglutinans growth. Germination inhibition of F. subglutinans and F. graminearum conidia was found with fludioxonil + metalaxyl-M at the three evaluated doses. RESUMEN El volcamiento en plantas de maíz es causado por la pudrición del tallo comúnmente asociado a varias especies del género Fusarium. Esta enfermedad afecta el semillero y el establecimiento de cultivos de maíz por el uso de semilla contaminada con diferentes patógenos de este género. Actualmente los cultivos de maíz en el Valle de Ubaté, Cundinamarca están siendo afectados por esta enfermedad, reduciendo el rendimiento y la calidad final de las semillas. Por esto, este estudio evaluó el efecto de tratamientos térmicos y con fungicidas sobre patógenos del género Fusarium asociados a semillas de maíz. Las semillas fueron tratadas a 50°C, 55°C y 60°C con calor en seco y agua caliente. Como variables se evaluaron la colonización micelial de la semilla, el porcentaje de germinación y la longitud y el peso fresco de las plántulas. En pruebas in vitro, se evaluaron los fungicidas fludioxonil + metalaxyl-M, tebuconazole + trifloxystrobin, prochloraz + difenoconazol y carboxin + captan en 0.5, 1.0 y 1.5 la dosis comercial sobre la inhibición del crecimiento radial y germinación de conidias de aislamientos de Fusarium subglutinans y Fusarium graminearum. Los tratamientos térmicos más efectivos sobre la colonización de Fusarium en semillas de maíz se presentaron con las dos fuentes de calor a 55°C sin una reducción significativa en el porcentaje de germinación, la longitud y el peso fresco de plántulas. Las dosis comerciales de los fungicidas evaluados inhibieron completamente el crecimiento radial de F. graminearum y solo las dosis comerciales de carboxin + captan y prochloraz + difenoconazol inhibieron completamente el crecimiento de F. subglutinans. Inhibición de germinación de conidias de F. subglutinans y F. graminearum se encontró con fludioxonil + metalaxyl-M a las tres dosis evaluadas.

Botrytis cinerea is a necrotrophic fungus that affects various plant species. Chemical control is a necessity and as much as possible, eco-friendly conditions and bioresources to obtain these chemicals should be used. In this context, a series of products was obtained from salicylaldehyde using zinc as a powerful reagent and tested for antifungal activity against Botrytis cinerea

Background The noxious annual herb, Parthenium hysterophorus L. (Asteraceae), is an invasive weed of global significance, threatening food security, biodiversity and human health. In South Africa, chemical control is frequently used to manage P. hysterophorus, however, concern surrounds increasing atmospheric CO2 levels, which may reduce the efficacy of glyphosate against the weed. Therefore, this study aimed to determine the susceptibility of P. hysterophorus to glyphosate (1L/ha: recommended) after being grown for five generations in Convirons under ambient (400 ppm) and elevated (600 and 800 ppm) CO2 . Results Glyphosate efficacy decreased with increasing CO2 , with mortalities of 100, 83 and 75% recorded at 400, 600 and 800 ppm, respectively. Parthenium hysterophorus experienced enhanced growth and reproduction under elevated CO2, however, glyphosate application was highly damaging, reducing the growth and flowering of plants across all CO2 treatments. Physiologically, glyphosate-treated plants, in all CO2 treatments, suffered severe declines of >90% in chlorophyll content, maximum quantum efficiency (F v /Fm ), photon absorption (ABS/RC), electron transport (ET 0 /RC) and performance index (PI ABS ), albeit at slower rates for plants grown under elevated CO2 . Low levels of recovery from glyphosate were documented only for plants grown under elevated CO2 and was attributed to their increased biomass. Conclusion These results suggest that increasing CO2 levels may hinder chemical control efforts used against P. hysterophorus in the future, advocating for further investigation using multigenerational CO2 studies and the maintenance of effective spraying programs at present. © 2020 Society of Chemical Industry.

Asian soybean rust is an aggressive disease and chemical control must be handled assertively to minimize productivity damage. The objective was to evaluate systemic fungicides and multisite mancozeb, combined or not, and the effects on disease control and soybean yield, cv. 'BMX Lança'. The work was conducted in the field in the 2016/17 and 2017/18 crops, in a randomized complete block design, with four replications. The following treatments were evaluated: T+P) trifloxystrobin + prothioconazole; A+B) azoxystrobin + benzovindiflupyr; T+P+MB) trifloxystrobin + prothioconazole + mancozeb; A+B+MB) azoxystrobin + benzovindiflupyr + mancozeb; MB) mancozeb; and Control (without fungicide application). After the occurrence of the first symptoms of the disease, the severity (%) was evaluated in five trifolia per plot, every seven days, making it possible to calculate the area under the disease progress curve (AUDPC). The yield components and productivity (kg ha-1) were also evaluated. In both crops, the combination of systemic fungicides and mancozeb reduced the severity (%) and progress of Asian rust, reaching a control above 81%. Treatment with trifloxystrobin + prothioconazole + mancozeb (T+P+MB) obtained the highest percentages of control (94.5% - 2016/17, and 93.7% - 2017/18) of Asian rust, and provided, in the 2016/17 crop, productivity at 15 sc ha-1, in relation to the fungicide applied alone (T+P). The combination of systemic fungicides and mancozeb, as proposed in this work, reduces the severity and progress of Asian rust and ensures the maintenance of the productive potential of the soybean.

Background The plant hormone ethylene exerts a huge influence in the whole life cycle of plants, especially stress-resistance responses. With the development of functional genomics, that the action mechanism of ethylene takes part in mediated plant architecture has been clarified gradually, such as plant roots, stems, leaves, fiber elongation and so on. Accordingly, the application of ethylene on crops chemical control and genetic improvement is greatly expanded. From the view of ethylene mediated plant architecture in crops, here reviewed advances in ethylene biosynthesis and signal transduction pathway, stress-resistance responses and the yield potential enhance of crops in recently 20 years. On these grounds, the objectives of this paper were to provide scientific reference and a useful clue for the crop creation of ideal plant type.

Field trials were conducted across nine different environments in Kentucky in 2017 and 2018 that evaluated a fungicide containing benzovindiflupyr + azoxystrobin + propiconazole applied to hybrid corn (Zea mays) at the six-leaf collar stage (V6) or at silking (R1) and a sequential application timing (V6 + R1). Results indicated that treatments that included an R1 application provided the best foliar disease control and were the only treatments that preserved yields compared with the nontreated control. A single application at R1 did not differ from the sequential V6 + R1 application for disease control or yield response, suggesting that Kentucky corn growers likely can rely on a more cost-effective single fungicide application at R1 for foliar disease management and improve return on fungicide investment rather than making multiple applications at different timings.

Improving chemical control over the nucleation and growth of colloidal nanocrystals advances optoelectronic applications. Here, we find that added glycol ethers promote the nucleation of PbS nanocrystals over the formation of metastable clusters, offering orthogonal control of nanocrystal size at reaction completion. This effect correlates with multidentate co-ordination to Pb(oleate)2.

Fil: Parra Morales, Laura Beatriz. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Patagonia Norte. Centro de Investigaciones en Toxicologia Ambiental y Agrobiotecnologia del Comahue. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias. Centro de Investigaciones en Toxicologia Ambiental y Agrobiotecnologia del Comahue; Argentina

Population explosions of the stable fly (Stomoxys calcitrans) have become a serious concern for livestock producers near sugarcane mills in some regions of Brazil due to the insect’s massive reproduction on sugarcane byproducts and waste. Despite the limited efficiency of insecticides for controlling stable fly outbreaks, producers still rely on chemical control to mitigate the alarming infestations in affected areas. This study evaluated the susceptibility of S. calcitrans populations to cypermethrin in the state of Mato Grosso do Sul, Brazil. Stable flies were tested from three field populations and two colonies, established from flies previously collected at sugarcane mills. Wild flies were collected with Nzi traps in areas of sugarcane plantations. Both wild and colonized flies were exposed to eleven concentrations of cypermethrin in impregnated filter paper bioassays. All the populations proved to be resistant to cypermethrin, with resistance factors among field populations ranging from 6.8 to 38.6. The intensive use of insecticides has led to the development of pyrethroid resistance in stable fly populations in the proximities of sugarcane mills in the state of Mato Grosso do Sul.

Herein, we report a modular synthetic route to access tetra-arylated thiophene compounds with four different substituents with programmed chemical control provided by an ester activating/directing group. This method enables the functionalization of individual positions of thiophene sequentially via regioselective halogenations and cross-coupling reactions. The reaction sequence described provides tetra-arylated thiophenes in higher yields than previous routes and employs practical reaction protocols, simple catalytic systems, and short reaction times.

Seeds are a fundamental and essential part of the persistent growth in agriculture production, as 90% of crops are produced from seeds that require constant treatment to prevent seed-borne and seasonal diseases and damage from insects. Seed treatment is a method of applying some definite agents to the seed before sowing to make seeds resistant to pathogens, insects, and other pests. Seed priming is an advanced seed treatment technique that is used to avoid the consequences of traditional treatment procedures. In priming, seeds are subjected to effective solutions depending on the characteristics of the seeds, which improves performance under controlled environments and in field conditions. Seed biopriming is a single, attractive, and cost-effective approach to induce disease resistance and increase germination. In a broader sense, it is a biological strategy and an effective alternative to chemical control that is unique in that it uses live beneficial microbes.

Rattail fescue (Vulpia myuros (L.) C.C. Gmel.) is a self-pollinating winter annual grassy weed of winter annual crops. The problems with V. myuros are mostly associated with no-till cropping systems where glyphosate application before sowing or emergence of the crop is the most important control measure. Ineffective V. myuros control has been reported following glyphosate applications. Experiments were performed to study the effectiveness of glyphosate on V. myuros, and determine the causes of the lower performance of glyphosate on V. myuros compared to other grass weeds. Estimated GR50 values demonstrated that V. myuros was less susceptible to glyphosate than Apera spica-venti regardless of the growth stage. Within each species, glyphosate efficacy at different growth stages was closely related to spray retention. However, the low susceptibility to glyphosate in V. myuros was not caused by lower retention as previously suggested. A significantly lower shikimic acid accumulation in V. myuros compared to A. spica-venti was associated with a higher activity of the EPSPS enzyme in V. myuros. Nevertheless, the relative responses in EPSPS activity to different glyphosate concentrations were similar in the two grass species, which indicate that EPSPS from V. myuros is as susceptible to glyphosate as EPSPS from A. spica-venti suggesting no alternation in the binding site of EPSPS. The results from the current study indicate that V. myuros is less susceptible to glyphosate compared to A. spica-venti, and the low susceptibility of V. myuros is caused by an increased EPSPS enzyme activity.

Root-knot nematodes can cause tremendous losses in vegetable crops. Farmers usually rely on synthetic nematicides to protect their crops. Recently, newly released nematicides are giving farmers an alternative in chemical control for nematodes. In the present study, the efficacy of vintage nematicide was compared to that of a relatively new nematicide, fluopyram. The latter was always more effective in substantially lower concentrations than oxamyl. Fluopyram paralyzed more than 80% J2s after 24 h immersion at the concentration of 0.25 μL L−1, while the percentage was increased close to 100% after immersion for 48 and 96 h. Similar levels of dead J2s were observed after immersion of J2s in oxamyl at concentrations higher than 8 μL L−1 (24 and 48 h) or 4 μL L−1 (96 h). An evident decrease of egg differentiation was observed when fluopyram concentration was increased to 8 μL L−1, while no significant decrease in egg differentiation was recorded at any concentration of oxamyl. Egg hatching was decreased at concentrations of fluopyram higher than 4 μL L−1, while no reduction was observed even when the concentration of oxamyl was increased to 64 μL L−1. The efficacy of fluopyram in soil was superior compared to that of oxamyl. For the first time, the systemic action of fluopyram is recorded in trials with tomato plants. On the other hand, compared to oxamyl, fluopyram seems to be more toxic to non-target organisms such as the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis bacteriophora.

Made available in DSpace on 2022-05-01T09:31:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-07-01 Droplet size is one of the most important factors that affect spray deposition and weed control through the use of herbicides. The aim of this study was to evaluate the influence of the droplet size on the spray deposition and control of Euphorbia heterophylla and Urochloa ruziziensis by using glyphosate. The treatments included spraying glyphosate with fine, medium, coarse, very coarse, and ultra-coarse droplet sizes to determine the deposition, uniformity of distribution, visual control, and dry weight reduction (DWR). The treatments were compared with the values of the dose required to achieve 50% DWR or 50% visual control (C50) at 7, 14, 21, and 28 days after herbicide application. Fine and medium droplet sizes afforded high deposition values and low distribution uniformities in E. heterophylla. Fine and medium droplet sizes yielded the lowest C50 on visual control and DWR in E. heterophylla, respectively. The droplet size did not affect the spray deposition on U. ruziziensis plants; however, the larger droplets had less uniformity of distribution. In U. ruziziensis plants, spraying glyphosate with coarse and medium droplet sizes yielded the lowest values of C50 to visual control and DWR, respectively. Universidade Estadual Paulista “Júlio de Mesquita Filho” Faculdade de Engenharia Universidade Estadual Paulista “Júlio de Mesquita Filho” Faculdade de Ciências Agrárias e Tecnológicas Universidade Estadual Paulista “Júlio de Mesquita Filho” Faculdade de Ciências Agronômicas Universidade Estadual Paulista “Júlio de Mesquita Filho” Faculdade de Engenharia Universidade Estadual Paulista “Júlio de Mesquita Filho” Faculdade de Ciências Agrárias e Tecnológicas Universidade Estadual Paulista “Júlio de Mesquita Filho” Faculdade de Ciências Agronômicas

Experiment was conducted to assess the efficacy of different fungicides against Phomopsis blight of brinjal caused by Phomopsis vexans in-vivo conditions. Among all the tested fungicides the minimum disease intensity and maximum per cent disease control was recorded after third spraying with 0.1 per cent carbendenzim (10.35% & 69.25%)and followed by 0.05 per cent propiconazole (11.41% & 66.10%) this treatment remains at par with each other and significantly superior over rest of the treatments. The higher yield of brinjal fruits was obtained with 0.1 per cent carbendenzim i.e. 185.52 q ha-1 and followed by 0.05 per cent propiconazole i.e. 183.78 q ha-1. But the highest incremental cost:benefit ratio 1:14:8 was recorded by 0.05 per cent propiconazole due to lowest market prize on Phomopsis blight of brinjal.

Summary: Therapeutic mouthwash (MW) is an adjunctive tool along with a regular oral hygiene routine of daily tooth brushing and daily flossing. Previous systematic reviews have demonstrated that it is effective against dental biofilm and gingival inflammation, for prevention of dental caries, and for managing one’s bad breath condition according to the active ingredients. MWs prevent the microorganisms from bacterial adhesion that corresponds to the initial step in biofilm formation.This review summarized the current state of evidence such as anti-biofilm, anti-gingivitis and cariostatic properties of MWs by evaluating systematic reviews from the past six years. The anti-biofilm property has been proven to be effective, with strong evidence of three main clinical efficacies.The most commonly studied active agent was chlorhexidine gluconate (CHX), followed by essential oil (EO) and cetylpyridinium chloride. All the systematic reviews are in complete agreement that CHX and EO provide statistically significant improvements in terms of plaque and gingival indices. These effects have held up over the years as the number of studies has increased. While the use of fluoride MW is proven to be effective in improving the oral health of both children and adults, the quality of evidence is still regarded as low. Keywords: Dental biofilm, Mouthwash, Chemical control, Gingivitis, Dental caries

The purpose of the research: to characterize the modern methods of determining the effectiveness of insecticides, acaricides, regulators of development and repellents against ectoparasites of carnivores. Materials and methods. The analysis of the literature date and the results of our research to evaluate the effectiveness of insecticides, acaricides, regulators of development and repellents against ectoparasites of carnivores. Results and discussion. Details describes modern methods for determining the effectiveness of insecticides, acaricides, repellents and regulators of development against ectoparasites of carnivores as well as in conditions in vitro. The methods of determining the insecticidal and acaricidal properties of the active compounds (substances) by forced contact of insects and mites with surface treated topically applying acaricides, rate determination occurrence state knockdown and lift height of mites on treated material, accounting sucking ticks velocity contacted with test substances. The repellent activity of substances with respect to ixodid mites is studied by the method of cut off concentration, the concentration gradient method, etc.