Glyphosate-resistant hairy fleabane (Conyza bonariensis) exhibits a larger number of trichomes and altered stomatal density relative to the susceptible counterpart

Following the adoption of Roundup Ready crops, glyphosate spraying frequency increased, while the use of other herbicide modes of action was neglected. Herbicide-resistant biotypes were reported in three major Conyza species in Brazil, including Conyza bonariensis, increasing growers' bottom line. Considering that leaf surface structures affect proper herbicide deposition, uptake, and performance, this study aimed to characterize epicuticular surface components in glyphosate-resistant (R) and -susceptible (S) C. bonariensis. Conyza spp. seeds were collected in 36 locations in Brazil, and plants were subjected to resistance screening tests by spraying glyphosate at 720 and 1440 g ae ha-1 (0.5X and 1X the label recommended rate, respectively). For resistance level characterization, C. bonariensis biotypes with contrasting responses were selected for glyphosate dose-response assays. Leaf tissues for epicuticular surface analysis were harvested from newly-obtained R and S biotypes at two growth stages. Histological cuts were made on a leaf area of 25 mm² with a blade. Samples were fixed in Karnowsky solution, gradually changed to 100% ethanol, critical-point dried with CO2, and coated with gold, followed by stomatal and trichome density quantification using scanning electron microscopy. Results indicated a poor control with glyphosate in 33 of 36 Conyza spp. biotypes, and a high (31.5) resistance factor was calculated after dose-response trials. Leaf surface analysis indicated that C. bonariensis leaves are amphistomatic and exhibit tectorial trichomes. A higher number of trichomes and altered stomatal density (number.mm²) were quantified in R compared to the S counterpart, potentially reducing glyphosate uptake and effectiveness.

Herbicide efficacy in the fall management of Richardia brasiliensis, Commelina benghalensis, Conyza sumatrensis AND Digitaria insularis

Other herbicides, alone or in combination with glyphosate, may be effective in controlling Richardia brasiliensis, Commelina benghalensis, Conyza sumatrensis e Digitaria insularis. Therefore, the aim of this study was to evaluate the efficacy of herbicides, alone or in combination, in the control of these weeds in the off-season. Three composite experiments were conducted by applying herbicides, alone or in combinations. Experiments 1 and 2 were conducted in Palotina, State of Paraná (PR), Brazil. Experiment 3 in Iporã, PR, Brazil. The three during fall 2017 in fallow areas after soybean harvest. The experiment was a randomized complete block design with 4 replications and weed control at 7, 14, 21, 28, 35, and 42 days after application (DAA). The control of R. brasiliensis and C. benghalensis was evaluated in the three experiments, the control of C. sumatrensis, in experiments 1 and 2, while the control of D. insularis was evaluated only in experiment 3. Data were subjected to analysis of variance and F-test (p < 0.05). The treatment means values of experiments 1 and 2 were compared by Tukey's test (p < 0.05), and the treatment mean values of experiment 3 were grouped by the Scott and Knott test (p < 0.05). Some herbicide combinations were effective in controlling R. brasiliensis, C. benghalensis, in a single or sequential application. Herbicide combinations were effective in controlling C. sumatrensis with sequential application. Herbicide combinations in a single application did not provide satisfactory final control (≥ 80%) for D. insularis.

Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) control in soybean with combinations of burndown and preemergence herbicides applied in the off-season

Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) can be found in many different agricultural environments and impact different crops, such as soybeans and corn. It is believed that the application of burndown and preemergence herbicides in the off-season are effective in controlling Sumatran fleabane in soybean crops. The objective was to evaluate the effectiveness of burndown and preemergence herbicides in the off-season, with one or two applications, in the control of Sumatran fleabane in soybean cultivation. Five field experiments were conducted in Maripá, state of Paraná (PR), Brazil. The treatments consisted of the application of burndown herbicides in combinations with preemergence ones, with one or two applications. Control of Sumatran fleabane and soybean yield were evaluated. With the set of experiments, it is highlighted that the strategy combining more applications, with different herbicides, burndown and preemergence, is more promising in the control of Sumatran fleabane. When comparing synthetic auxins, dicamba and triclopyr stand out. For sequential application, worse performance was observed for diquat. Combinations between burndown and preemergence herbicides were effective in controlling Sumatran fleabane, for pre sowing application in soybean. With emphasis on managements with sequential applications of saflufenacil with glufosinate or glyphosate. The strategy combining more applications, with different herbicides, burndown and preemergence herbicides, is more promising in the control of Sumatran fleabane.

Herbicide performance in the control of Conyza spp. where three plant heights

Intensive use of the herbicide glyphosate has led to herbicide resistant Conyza spp. populations. Thus, there is a need to indicate alternative herbicides and the appropriate developmental stage for controlling these populations. This study identifies alternatives for controlling glyphosate-resistant horseweed, with treatment applications at different plant heights. For this purpose, field experiments were conducted in the 2016/17 and 2017/18 crop years. The evaluated treatments were: glyphosate (540 g ae ha-1), glyphosate (1080 g ae ha-1), glyphosate (2160 g ae ha-1), glyphosate (3240 g ae ha-1), glyphosate + 2.4-D (1080 + 1005 g ae ha-1), glyphosate + saflufenacil (1080 + 49 g ae/ai ha-1), paraquat (400 g ai ha-1), diquat (400 g ai ha-1), ammonium glufosinate (600 g ai ha-1), and control (without application). These treatments were applied to plants with a maximum of 5 cm; plants between 6 and 15 cm; and plants between 16 and 25 cm. The results showed that glyphosate did not control weeds, regardless of rate. With the exception of 2,4-D, which needs complementation with sequential application of another contact herbicide, all alternatives were viable for the control of Conyza spp. plants with a maximum height of 5 cm.

Control of conyza bonariensis with glyphosate associated to adjuvants applied with different spray nozzles / Controle de conyza bonariensis com glyphosate associado a adjuvantes aplicados com diferentes pontas de pulverização

The study aimed to evaluate the control of Conyza bonariensis in delayed post-emergence stage using different spray nozzles and solutions with and without adjuvants; and to verify the occurrence of resistance to glyphosate, determining the dose-response curve. The experimental design was randomized in factorial (6 spray nozzles x 5 spray solution) in twenty repetitions. The treatments were represented by spray nozzles: XR 110015 XR 11002, TT 11002 AIXR 11002, AIC 11002 and AI 11002. Tested spray solution were: glyphosate; glyphosate + Nimbus®; glyphosate + Agral®; Glyphosate + LI-700® and without herbicide application. The use or not of adjuvants in the spray solution did not differ statistically from the solution containing the herbicide only. The spray nozzles AIXR 11002, TT 11002 and XR 11002 presented best results of control the horseweed from the evaluation of 07 days after application (DAP) and 28 DAP and such spray nozzles maintained the best average of control percentage. The higher dry matter reductions of horseweed were obtained by spray nozzles 110015 XR, TT 11002 and 11002 XR compared with the control. The population evaluated presents biotypes that resist to doses of 2.880 g.ha-1 a.e. of glyphosate. It is concluded that the evaluated biotypes presents tolerance to glyphosate, independent of your association or not with adjuvants.

O estudo teve como objetivo avaliar o controle de Conyza bonariensis no estádio pós-emergência tardia, empregando diferentes pontas e caldas com e sem adjuvantes; e verificar a ocorrência de resistência ao glyphosate, determinando a curva dose resposta. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial (6 pontas de pulverização x 5 caldas de pulverização) em vinte repetições. Os tratamentos foram representados pelas pontas de pulverização: XR 110015, XR 11002, TT 11002, AIXR 11002, AIC 11002 e AI 11002. As caldas testadas foram: glyphosate; glyphosate + Nimbus®; glyphosate + Agral®; glyphosate + LI-700® e sem aplicação do herbicida. O uso ou não de adjuvantes na calda não diferiram estatisticamente da calda contendo somente o herbicida. As pontas AIXR 11002, TT 11002 e XR 11002 apresentaram melhores resultados de controle da buva a partir de 07 dias após a aplicação (DAP) e aos 28 DAP e tais pontas mantiveram as melhores médias de porcentagem de controle nas demais avaliações. As maiores reduções de massa seca de buva foram obtidas pelas pontas XR 110015, TT 11002 e XR 11002 quando comparada com a testemunha. A população avaliada apresenta biótipos que resistem a doses de 2.880 g.ha-1 de e.a. do glyphosate. Conclui-se que os biótipos avaliados apresentam tolerância ao glyphosate, independente de sua associação ou não com os adjuvantes.

Development stages horseweed in soybeans competition / Estádios de desenvolvimento da buva em competição com soja

The objective of this study was to evaluate the relative competitive ability of soybean with different development stages of hairy fleabane. Two experiments were conducted in greenhouse, in a completely randomized design. In the experiment it was tested soybean and hairy fleabane competition at different stage of development (rosette and 15 cm height) at the proportions 100:0, 75:25, 50:50, 25:75 and 0:100, and total plant population was 315 plant m-2. The variables evaluated were plant height, leaf area, and shoot dry matter (leaves and stems). Competitive analysis was performed by diagrams and interpreting the competitiveness index. The soybean has greater competitive ability that horseweed for both development stages. The intraspecific competition is more intense for soybean when in hairy fleabane rosette stage, and the competitive relations are equivalent between soybean and hairy fleabane of 15 cm tall. The both hairy fleabane stages were injured in the soybeans competition.(AU)

O objetivo deste trabalho foi avaliar a habilidade competitiva relativa da cultura da soja com buva de diferentes estádios de desenvolvimento. Foram realizados dois experimentos em casa de vegetação, em delineamento inteiramente casualizado. Os experimentos testaram a competição de soja e buva (estádio roseta e plantas com 15 cm de estatura) nas proporções de 100:0, 75:25, 50:50, 25:75 e 0:100, com população equivalente a 315 plantas m-2. As variáveis avaliadas foram estatura, área foliar e matéria seca da parte aérea (folhas e caule). A análise da competitividade foi realizada por aplicação de diagramas e interpretações dos índices de competitividade. Os resultados da competição da soja com buva de diferentes estádios de desenvolvimento evidenciam que o cultivar de soja BRS Estância RR, em geral, possui mais habilidade competitiva que a buva, independentemente do estádio de desenvolvimento. A competição intraespecífica é mais intensa para a cultura quando em competição com buva em estádio de roseta, enquanto para a soja com buva de 15 cm as relações de competição se equivalem. O desenvolvimento da buva é prejudicado na competição com a soja.(AU)

Soybean yield loss and economic thresholds due to glyphosate resistant hairy fleabane interference / Perda de rendimento da soja e nível de dano econômico pela interferência de buva resistente ao glifosato

The interference of glyphosate resistant hairy fleabane (Conyza bonariensis) has caused yield losses in soybean crop. Knowledge of the economic threshold is an important aspect for the economic management of resistant weeds. Because of it, the interference of the glyphosate resistant hairy fleabane density on the soybean yield loss was evaluated, as well as to estimate the economic threshold. Two experiments were conducted to verify the effect of different weed densities on the yield of two soybean cultivars (BRS Estância and BMX Turbo). Weed density ranged from 0 to 124 plants m-2. The yield of the BRS Estância decreased by 1.4% to the increase of one single plant, while for the BMX Turbo the loss was 25.9%. Soybean yield and economic threshold were lower for the BMX Turbo cultivar compared to the cultivar BRS Estância, which can be attributed to the genotype, competitive ability, weed development stage and/or environment. Increases in crop yield expectation, soybean price and herbicide efficiency reduce the economic threshold, indicating that the adoption of control measures should be taken when the weed density is low. Due to the high cost of hairy fleabane control, it is only feasible at high densities.(AU)

A interferência de plantas de buva (Conyza bonariensis) resistente ao herbicida glyphosate tem causado perdas de produtividade na cultura da soja. O conhecimento do nível de dano econômico é um importante fator para o manejo econômico de plantas daninhas resistentes na cultura da soja. Para isso, foi avaliada a interferência da densidade de buva resistente ao glyphosate sobre a perda de rendimento da soja, bem como estimado o nível de dano econômico. Dois experimentos foram conduzidos para verificar o efeito de diferentes densidades da planta daninha sobre a produtividade de dois cultivares de soja (BRS Estância e BMX Turbo). As densidades de buva variaram de 0 a 124 plantas m-2. A produtividade do cultivar BRS Estância reduziu 1,4% ao aumento de uma planta, enquanto para o cultivar BMX Turbo a perda foi de 25,9%. A produtividade da soja e o nível de dano econômico foram menores para o cultivar BMX Turbo, em comparação com o cultivar BRS Estância, o que pode ser atribuído ao genótipo, à habilidade competitiva, ao estádio de desenvolvimento da buva e/ou a ambiente. Aumentos na expectativa de produtividade da cultura, no preço da soja e na eficiência dos herbicidas reduzem o nível de dano econômico, indicando que a adoção de medidas de controle deve ser tomada quando a população de buva é baixa. Em função do elevado custo de controle da buva, este somente é viável em altas densidades.(AU)

Diterpenos de ageratina vacciniaefolia, conyza trihecatactis, gnaphalium graveolens y evaluación del efecto antiinflamatorio y citotóxico / Diterpenos of ageratina vacciniaefolia, conyza trihecatactis, gnaphalium graveolens and evaluation of the anti-inflammatory and cytotoxic effect

Se estudiaron plantas autóctonas de páramos colombianos, preconizados por la medicina tradicional como antiinflamatorios y citotóxicas, con el fin de identificar los compuestos responsables de las acciones terapéuticas mencionadas y hacer uso de sus extractos en el control de problemas como el cáncer y la inflamación. Se investigaron mezclas de hojas y tallos de especímenes de Ageratina vacciniaefolia, Conyza trihecatactis y Gnaphalium graveolens, pertenecientes a la familia Asteraceae, recolectadas en los páramos de Sumapaz y Cruz verde situados al sureste y nororiente de la ciudad de Bogotá (Colombia), en la cordillera oriental de los Andes. La obtención de los extractos y fracciones de las diferentes especies se realizó utilizando solventes de baja, mediana y alta polaridad. Los compuestos fueron monitoreados mediante Cromatografía en Capa Fina (CCF) y separados por Cromatografía en Columna (CC). Para su identificación se utilizaron técnicas espectroscópicas como RMN (experimentos 1H y 13C, HSQC, HMBC). La actividad antiinflamatoria se realizó mediante el modelo experimental del edema en la pata de ratas Wistar, inducido por la inyección plantar de carragenina (Muniappan & Sundarara, 2003) y un estudio histopatológico. Finalmente los ensayos de citotoxicidad frente a la línea celular OCI-AML3 fueron realizados mediante citometría de flujo. De las fracciones de Conyza trihecatactis se aislaron las siguientes sustancias: Ent-(13R)-labdan-14-en-8,13-diol, Ent-(13R)-8-hidroxilabdan-14-en-13-O-ß-D-xilopiranosa y el Ent-(13R)-labdan-8(17),14-dien-13-O-ß-D-xilopiranosa. De las fracciones de Ageratina vacciniaefolia se aislaron: Ácido kaur-16-en-19-oico, Ácido (-)9, 15-dihidroxikaur-16-en-19-oico, Ácido (+) kaur-16-en-19-oico y el ß-D-glucopyranosil éster del Ácido(-)-17-(ß-xilopiranosa)-kauran-19-oico. De las fracciones de Gnaphalium graveolens se aisló el ácido ent-kaur-9(11), 16-dien-19-oico. La fracción de acetato de etilo, obtenida del extracto en éter de petróleo de Conyza trihecatactis mostró un buen resultado en la actividad antiinflamatoria a la quinta y séptima hora del tratamiento a una concentración de 300mg/kg; de igual manera esta fue la fracción más activa en los ensayos de citotoxicidad a una concentración de 10µg/mL.

Flavonoids of Erigeron canadensis / 中国中药杂志

<p><b>OBJECTIVE</b>To study the flavonoids of Erigeron canadensis.</p><p><b>METHOD</b>The constituents of EtOH extraction from the whole plant of E. canadensis were isolated and purified by repeated column chromatography. These compounds were identified by their physical and spectral data.</p><p><b>RESULT</b>Twelve flavonoids were isolated and identified as quercetin-7-O-beta-D-galactopyranoside(1),quercetin(2), luteolin(3), apigenin(4),5,7,4'-trihydroxy-3'-methoxy flavone(5), quercetin-3-alpha-rhamnopyranoside(6), quercetin-3-O-beta-D-glucopyranoside(7), apigenin-7-O-beta-D-glucopyranoside(8), luteolin-7-O-beta-D-glucuronide methyl ester(9),4'-hydroxy baicalein-7-O-beta-D-glucopyranoside(10),baicalein(11),rutin(12).</p><p><b>CONCLUSION</b>Compound 1 was isolated from the Compositae family for the first time. Compound 5 and 9 were firstly isolated from the genus Erigeron. Compound 3,4,7,8 and 11 were isolated from E. canadensis for the first time.</p>

Efecto antiinflamatorio y antimicótico del extracto alcohólico y composición química del aceite de hojas de Conyza bonariensis (L) Cronquist (canilla de venado) / Anti-inflammatory and antimitotic effect of the alcoholic extract and chemical composition of the oil from Conyza bonariensis (L) Cronquist (deer shinbone) leaves

Introducción: la especie Conyza bonariensis (L.) Cronquist, comúnmente llamada canilla de venado, es de origen americano. Objetivos: contribuir al estudio farmacológico y toxicológico de los extractos alcohólicos y a la evaluación química del aceite de hojas de C bonariensis de Ecuador. Métodos: se emplearon 2 tinturas a 50 por ciento con etanol a 70 y 90 por ciento de hojas secas. Se realizó un estudio fitoquímico a través del sistema acoplado de cromatografía gaseosa-espectrometría de masas, se determinó el efecto antimicótico mediante inhibición de dilución en placa con siembra en superficie por diseminación, y antiinflamatorio en el modelo de edema de la oreja inducido por aceite de Croton en ratones albinos de la línea OF1. Resultados: el tamizaje fitoquímico mostró presencia de aceites esenciales, triterpenos-esteroides, compuestos fenólicos, flavonoides, quinonas, antocianidinas, saponinas y compuestos reductores. Se determinó estructuras a 32 componentes del aceite esencial extraído de las hojas y el sesquiterpeno: trans-b-farneseno resultó el componente mayoritario con 70,82 por ciento, este compuesto se informa por primera vez en esta especie. El extracto hidroalcohólico (25 µL a cada lado de las orejas tratadas) inhibió significativamente la inflamación comparado con bencidamina. Conclusiones: los extractos hidroalcohólicos mostraron efecto antiinflamatorio en las condiciones experimentales del estudio y se determinó la composición química del aceite de hojas de C. bonariensis

Introduction: the Conyza bonariensis (L) Cronquist species, usually called deer shinbone is of American origin. Objectives: to contribute to the pharmacological and toxicological study of alcoholic extracts and to the chemical assessment of C. bonariensis leaf oil from Ecuador. Methods: two 50 percent tinctures of 70 percent and 90 percent ethanol content in dry leaves were used. A phytochemical study was conducted by an combined system of mass spectrometry and gas chromatography; the amniotic effect was determined using plate dilution inhibition with surface culturing by dissemination, and the anti-inflammatory effect in the Croton oil induced ear edema model in OF1 line albino mice. Results: the phytochemical screening showed the presence of essential oils, triterpene-steroids, phenolic compounds, flavonoids, quinones, anthocyanidines, saponins and reducing compounds. The structures of 32 essential oil components extracted from the leaves were identified along with and the sesquiterpene trans-b-farnesene that was the major component (70.82 percent), this compound is reported for the first time in this species. The hydroalcoholic extract (25 µL on each side of the treated ears) significantly inhibited inflammation compared to benzidamine. Conclusions: hydroalcoholic extracts showed anti-inflammatory effect in the experimental conditions of the study and the chemical composition of C. bonariensis leaf oil was identified